Analog-to-digital converters (ADC): purpose, device, application. How to quickly and efficiently digitize old videotapes using a computer, video camera or other equipment with your own hands at home
Accuracy, speed and stability are prerequisites for technology that processes digital and analog signals. Television offers users high quality picture and sound by ensuring stable signal transmission over modern telecommunications.
What is the difference between an analog signal and a digital signal?
The difference between an analog and digital signal is the encoding that is used to transmit it. The signal is digitized by an analog-to-digital converter, after which high-quality image and sound reaches the receiving device.
Unlike digital, an analog signal can be partially distorted, while a digital signal is either completely absent or provides excellent quality. While analog signals are only accepted by devices that operate on the same principle as the transmitter, a digital signal can be transmitted to many different digital devices. In addition, digital encoding is protected from unauthorized access: to decrypt the binary code, you must have the address of the receiving device.
Digital signal processing
The process of signal digitization is the conversion of a continuous analog signal into a discrete digital one. To filter out interference during this process, digital signal processors are used - real-time computing devices that process signals arriving at a constant speed. Not only continuously incoming signals, but also data recorded on media can be digitally processed. In this case, the processor speed indicator is not so important: the data is still stored for processing.
There is time and frequency signal processing; the first type requires the use of oscilloscopes. Signal and image processing using wavelets can improve non-stationary, intermittent and special types of signals.
How to boost your digital TV signal
The image quality on a digital TV depends on many factors: operating conditions, choice of the correct installation method, design features of the device, physical distance of the repeater. As a result, the image quality is not always stable; there is interference, which can be dealt with using autonomous amplification devices.
Such devices are capable of:
- receive the weakest television signal;
- reduce the interference coefficient to a minimum value;
- improve signal quality in several bands.
Amplifiers are used as an affordable alternative to replacing an antenna, but the devices can be overloaded by powerful signals and are susceptible to lightning strikes.
Digital signal filtering
Digital filters restore distorted signals and suppress frequencies outside the broadcast range. The basic design of the filter is a linear system that responds to signal jumps and perceives a certain signal frequency.
Depending on their functions, filters are divided into several types:
- low-pass filters delay signal components above a specified value;
- High-pass filters pass signals above a specified frequency. This value is also called the stopping frequency;
- Bandpass filters pass signals that are within a certain frequency range.
A quality filter is determined by:
- signal rise time;
- absence of overshoot;
- stop lane width;
- uniformity of bandwidth.
If all of the indicated indicators are high, after processing by the filter the signal is clear and transmitted at a stable speed.
Digital Signal Decoding
The signal decoding procedure is aimed at improving the quality of the reproduced image or sound that comes from a central device, not peripheral projectors and presentation systems.
Visually, the work of the decoder is characterized by high accuracy of image reproduction. Decoders come with the ability to receive encoded signals in compressed form and then transmit these signals to a decoder.
The equipment is used when creating copies of audiovisual materials and when transmitting signals to devices located at a considerable distance. For example, a digital decoder is used as a device for connecting satellite digital television services.
How to convert an analog signal to digital for TV
Owners of old TV models do not always have the opportunity to upgrade to modern digital equipment. In this case, an analog-to-digital converter must be connected to the antenna receiving the signals. Such a device is capable of receiving a digital signal, converting it to analog, and broadcasting it in this form on a TV. As a result, converter owners enjoy stable broadcasting and high quality digital television without changing their equipment to a more expensive and modern one.
Most of these devices automatically search for digital channels to feed to the owner's TV.
A device that converts analog signals into digital ones
An analog-to-digital converter (ADC) creates a discrete code from a standard analog signal; its task is to transform a certain voltage value into a binary code accessible to digital technology. An indicator of the efficiency of a signal is its bit depth, which shows the number of discrete values available for output in one operating cycle. Depending on the coding of the individual device, this value is given in bits or trits.
Depending on the type of conversion, ADCs of direct, serial and parallel types are distinguished. Conveyor modifications that combine several stages are common. A measure of device performance is the sample rate, which is the rate at which digital values are produced from the incoming analog signal.
A device that converts a digital signal into an analogue signal
Digital-to-analog converter (DAC) is a device for converting binary code into continuous current. At the input, the device receives pulse-code modulation, which is decrypted using appropriate codecs. Equipment performance is determined by the bit depth, sampling frequency, monotonicity and dynamic range in which the converter can operate.
Modern converters belong to the class of microcontrollers, the simplest of which is a pulse-width modulator. This type of device allows you to control the speed of electrical machines and is used in high-end audio equipment. DACs are located at the beginning of the analog system, so their performance determines the speed of the entire chain and its resistance to external influences.
Digital to analog converters for TV
Video signal converters are equipment for converting discrete code into a continuous voltage stream. Typically, such equipment is used for televisions or projectors. The design is based on a small board on which a program for converting digital code into a composite signal is installed. Structurally, the element is a flash memory with a simple serial interface. Often, such devices are equipped with video enhancement technology, which allows owners to receive a stable, high-quality signal.
Decoding Device Manufacturers and Suppliers
Decoding devices are often included in other equipment for transmitting and receiving signals with different purposes and technical characteristics. Therefore, manufacturers and suppliers offer the entire range of necessary equipment.
The list of Merlion, a supplier of devices for organizing wide-range video surveillance, includes modern decoders that convert various types of analog and digital signals.
"MS Max" is a company specializing in the sale of equipment for film production, studio equipment and radio stations. Customers are offered a wide selection of specialized equipment, including digital-analog decoders for older model TVs.
Telecom SB is a supplier of specialized equipment for ensuring security and installing security systems at facilities for various purposes. The range includes ready-made solutions for video surveillance and individual units of equipment.
Reasons for digital signal loss
Most often, the quality of digital TV broadcasting suffers due to improper placement of the coaxial cable. For this reason, the signal is extinguished, reaching the TV in a weak, reduced form.
The picture may deteriorate if the TV is located near a tower or a powerful indoor antenna. In this case, the TV tuner automatically suppresses the too intense signal, causing interference.
There is no digital television signal, what to do?
A common reason for the lack of a digital television signal is incorrectly connected equipment. There are frequent cases of antenna breakdowns and loose connections of individual elements. A possible reason for the lack of signal is the distance from the central antenna.
Solution to the problem:
- checking equipment for functionality;
- installation of signal amplifiers;
- calling a technician to re-install the cable.
More about digital signals at the exhibition
The exhibition “Communication” presents a large number of professional equipment for working with digital signals. At the exhibition you can get acquainted with the latest technological achievements in the field of signal conversion and high-quality image and sound transmission.
During the exhibition, you can learn about the features of the digital broadcasting standard, which is necessary for continuous signal transmission and ensuring high quality image and sound.
In electronics, signals are divided into: analog, discrete and digital. Let's start with the fact that everything we feel, see, hear is mostly an analog signal, and what the computer processor sees is a digital signal. It doesn't sound entirely clear, so let's understand these definitions and how one type of signal is converted to another.
In electrical representation, an analog signal, as its name suggests, is an analogue of a real quantity. For example, you feel the ambient temperature constantly throughout your life. There are no breaks. At the same time, you feel not only two levels of “hot” and “cold”, but an infinite number of sensations that describe this value.
For a person, “cold” can be different, it can be autumn coolness and winter frost, and light frosts, but “cold” is not always a negative temperature, just like “warm” is not always a positive temperature.
It follows that an analog signal has two features:
1. Continuity in time.
2. The number of signal values tends to infinity, i.e. An analog signal cannot be accurately divided into parts or calibrated by dividing the scale into specific sections. Methods of measurement are based on a unit of measurement, and their accuracy depends only on the value of the scale division; the smaller it is, the more accurate the measurement.
Discrete signals- these are signals that represent a sequence of reports or measurements of some quantity. Measurements of such signals are not continuous, but periodic.
I'll try to explain. If you install a thermometer somewhere, it measures an analog value - this follows from the above. But by actually monitoring its readings, you receive discrete information. Discrete means separate.
For example, you woke up and found out how many degrees there were on the thermometer, the next time you looked at the thermometer at noon, and the third time in the evening. You do not know at what speed the temperature changed, uniformly or abruptly, you only know the data at that moment in time that you observed.
This is a set of levels, like 1 and 0, high and low, present or not. The depth of information reflection in digital form is limited by the bit capacity of a digital device (logic set, microcontroller, processor, etc.). It turns out that it is ideal for storing Boolean data. An example can be given as follows: for storing data of the “Day” and “Night” types, 1 bit of information is enough.
Bit- this is the minimum value for representing information in digital form; it can store only two types of values 1 (logical one, high level), or 0 (logical zero, low level).
In electronics, a bit of information is represented as a low voltage level (close to 0) and a high voltage level (depending on the specific device, often coincides with the supply voltage of a given digital node, typical values are 1.7, 3.3. 5V, 15V).
All intermediate values between the accepted low and high levels are a transition region and may not have a specific value, depending on the circuit design, both the device as a whole and the internal circuitry of the microcontroller (or any other digital device) may have a different transition level, for example for 5 -tivolt logic voltage values from 0 to 0.8V can be taken as zero, and voltage values from 2V to 5V as one, while the gap between 0.8 and 2V is an indefinite zone; in fact, with its help, zero is separated from one.
The more accurate and capacious values need to be stored, the more bits are needed; here is an example table with a digital display of four time of day values:
Night - Morning - Day - Evening
For this we need 2 bits:
In general, analog-to-digital conversion is the process of converting a physical quantity into a digital value. A digital value is a set of ones and zeros perceived by the processing device.
Such a transformation is necessary for the interaction of digital technology with the environment.
Since an analog electrical signal repeats its shape as an input signal, it cannot be written digitally “as it is” since it has an infinite number of values. An example is the process of recording sound. It looks like this in its original form:
It represents the sum of waves with different frequencies. Which, when expanded into frequencies (for more details on this, see Fourier transforms), one way or another, can be brought closer to a similar picture:
Now try to imagine this as a set like “111100101010100”, it’s quite difficult, isn’t it?
Another example of the need to convert an analog value into a digital one is its measurement: electronic thermometers, voltmeters, ammeters and other measuring instruments interact with analog values.
How does the transformation happen?
First, look at the diagram of a typical conversion of an analog signal to digital and vice versa. We will return to it later.
In fact, this is a complex process that consists of two main stages:
1. Signal sampling.
2. Quantization by level.
Signal sampling is the determination of the time intervals over which the signal is measured. The shorter these intervals, the more accurate the measurement. The sampling period (T) is the period of time from the beginning of data reading to its end. Sampling frequency (f) is the reciprocal of:
After reading the signal, it is processed and stored in memory.
It turns out that during the time that the signal readings are read and processed, it can change, thus distorting the measured value. There is a theorem by Kotelnikov and the following rule follows from it:
The sampling frequency must be at least 2 times greater than the frequency of the sampled signal.
This is a screenshot from Wikipedia, with an excerpt from the theorem.
To determine the numerical value, quantization by level is necessary. A quantum is a certain interval of measured values, averaged to a certain number.
Those. signals of magnitude from X1 to X2 are conditionally equated to a certain value of Xy. This is reminiscent of the division value of a dial gauge. When you take readings, you often compare them to the nearest mark on the meter's scale.
So it is with quantization by level, the more quanta, the more accurate the measurements and the more decimal places (hundredths, thousandths, and so on values) they can contain.
More precisely, the number of decimal places is rather determined by the bit capacity of the ADC.
The picture shows the process of quantizing a signal using one bit of information, as I described above, when a high level value is taken when a certain limit is exceeded.
On the right is the signal being quantized and recorded as two bits of data. As you can see, this signal fragment is already divided into four values. It turns out that as a result, the smooth analog signal turned into a digital “stepped” signal.
The number of quantization levels is determined by the formula:
Where n is the number of bits, N is the quantization level.
Here is an example of a signal divided into a larger number of quanta:
From here it is very clear that the more often the signal values are taken (the higher the sampling frequency), the more accurately it is measured.
This picture shows the conversion of an analog signal to digital form, and to the left of the ordinate (vertical axis) is the recording in digital 8-bit form.
Analog-to-digital converters
The ADC or Analog-to-Digital Converter can be a separate device or built into the .
Previously, microcontrollers, for example the MCS-51 family, did not contain an ADC; an external microcircuit was used for this, and it became necessary to write a subroutine for processing the values of the external IC.
Now they are found in most modern microcontrollers, for example the AVR AtMEGA328, which is the basis of most popular ones; it is built into the MK itself. In the Arduino language, reading analog data is done simply with the AnalogRead() command. Although the microprocessor installed in the equally popular Raspberry PI does not have it, so not everything is so simple.
In fact, there are a large number of options for analog-to-digital converters, each of which has its own disadvantages and advantages. It doesn’t make much sense to describe which within this article, since this is a large amount of material. Let us consider only the general structure of some of them.
The oldest patented version of the ADC is the Paul M. Rainey patent, "Facsimile Telegraph System," U.S. Patent 1,608,527, Filed July 20, 1921, Issued November 30, 1926. This is a 5-bit direct conversion ADC. From the name of the patent comes the idea that the use of this device was associated with data transmission via telegraph.
If we talk about modern direct conversion ADCs, they have the following circuit:
From this we can see that the input is a chain that produces a signal at its output when it crosses some threshold signal. This is bit depth and quantization. Anyone who is even a little strong in circuit design has seen this obvious fact.
For those who are not strong, the input circuit works like this:
The analog signal goes to the “+” input, to everything at once. The outputs marked “-” receive a reference voltage, which is decomposed using a chain of resistors (resistive divider) into a number of reference voltages. For example, the series for this chain looks like this:
Urefi=(1/16, 3/16, 5/16, 7/16, 9/16, 11/16, 13/16)*Uref
In parentheses, separated by commas, it is indicated what part of the total reference voltage Uref is supplied to the input of each input voltage.
Those. each of the elements has two inputs, when the voltage at the input is signed «+» exceeds the voltage at the input with the “-” sign, then a logical one appears at its output. When the voltage at the positive (non-inverting) input is less than at the negative (inverting) input, then the output is zero.
The voltage is divided in such a way that the input voltage is divided into the required number of digits. When the input voltage is reached, a signal appears at the output of the corresponding element, and the processing circuit outputs the “correct” signal in digital form.
Such a comparator is good for data processing speed, all elements of the input circuit operate in parallel, the main delay of this type of ADC is formed from the delay of 1 comparator (they still operate simultaneously in parallel) and the delay of the encoder.
However, there is a huge disadvantage of parallel circuits - the need for a large number of comparators to obtain a high-bit ADC. To get, for example, 8 bits, you need 2^8 comparators, which is as many as 256 pieces. For a ten-bit one (Arduino has a 10-bit ADC, by the way, but of a different type) you need 1024 comparators. Judge for yourself the feasibility of this processing option and where it may be needed.
There are other types of ADCs:
successive approximation;
delta-sigma ADC.
Conclusion
Converting an analog signal to a digital one is necessary to read parameters from analog sensors. There is a separate type of digital sensors, they are either integrated circuits, for example DS18b20 - its output is already a digital signal and it can be processed by any microcontrollers or microprocessors without the need to use an ADC, or an analog sensor on a board that already has its own converter. Each type of sensor has its own pros and cons, such as noise immunity and measurement error.
Knowledge of conversion principles is mandatory for everyone who works with microcontrollers, because not every modern system has such converters built in; you have to use external microcircuits. As an example, we can cite this board, designed specifically for the Raspberry PI GPIO connector, with a precision ADS1256 ADC.
Hi all.
In today's review we will talk about an audio converter that converts a digital signal into an analogue one.
With the development of technology, our habits and needs, unfortunately, do not go away. So I, having replaced the old TV with a more progressive model, sadly discovered that it did not have a 3.5 mm jack for connecting headphones or other acoustics. And since before that I had a 2.1 audio system connected to the TV, devoid of digital connectors, and I didn’t plan to stop using it in the future, since I was completely satisfied with its sound, the question naturally arose about how to connect it. Also, sometimes I plug in headphones to the TV so that loud noises don't wake up other members of my family.
Having studied the possible options, it became clear that the simplest and most logical way to solve my problem would be to buy a converter that can turn digital sound into analog. Fortunately, there are no problems with such converters and anyone can choose a converter equipped with the necessary connectors.
Before placing an order, in order to secure the transaction as much as possible, it was decided to check the seller using a local service. The results of the verification showed that the seller is reliable and can be trusted. Detailed data obtained as a result of the check can be viewed.
The parcel was sent quite quickly and spent about a month on the way. Anyone can view parcel tracking information.
The converter is supplied without any original packaging; my copy came in a regular plastic bag. Despite the fact that, apart from a thin layer of bubble wrap, nothing protected the contents of the parcel, its contents were not damaged during the journey. So, in addition to the converter itself, the package included: instructions, a 1A network adapter, a power connection cable about 1 meter long, and an optical cable 1.5 meters long.
This kit is enough for the converter to be used immediately. You won't have to buy anything.
The instructions are printed in English, the size is A5 paper. 
In principle, there is nothing particularly interesting here. If only the technical characteristics of the converter.
The converter itself is a small box with several connectors on each side. On its upper part there is information about what it is and on which side there are connectors working for “input”, and on which side for “output”. The dimensions of the converter are quite compact - 50 * 40 * 26 mm, so you can throw it behind the TV, where it will not be visible and will not attract attention. 
On the reverse side there is the well-known “Made in China” inscription, as well as a couple of icons and a statement that this equipment complies with the requirements of the RoHS directive, which limits the content of harmful substances. 
The converter itself is made with high quality. Nothing moves or rattles inside. The case does not crack when compressed. No cracks, gaps or anything like that were found. The plastic also has no foreign odor.
So, on the “input” side there are 3 connectors: fiber optic Toslink, coaxial, and also a connector for connecting power. Looking ahead, I will say that I immediately put the included network adapter aside. The converter works perfectly from the 1A USB connector available on the TV. In addition, there is no such thing as energy saving, believe the converter only works when the TV is on. 
On the “output” side there are also several connectors: a pair of RCA “tulips”, a 3.5 mm miniJACK, as well as an indicator LED that informs us about the status of the converter: it glows red during its operation. 
There is nothing else interesting in the appearance of the converter, which means we can move on to its practical tests. First, let's use the supplied Toslink cable and connect the converter to the network. 
It can be seen that the red diode located on the converter lights up. In the same way, the cable itself began to glow red, which indicates that everything is working normally. By connecting the fiber optic cable to the converter on the other side, and plugging 3.5 mm into it on the other. audio system connector, at first I didn’t hear anything :(But then it dawned on me that I needed to select the desired sound source in the TV settings. After which everything worked as it should.
Now about the most important thing - about performance. The converter works great. No noises, wheezing, squeaks or other unpleasant sounds were heard. Moreover, this applies equally to the sound in headphones and to the 2.1 audio system. The sound itself is loud and clear. No worse than what I had before on my old TV when connected via standard 3.5 mm. connector What I also liked is that it is possible to simultaneously connect several gadgets. That is, one can be connected via tulips, and the second via 3.5 mm. connector So you don't have to constantly switch wires. 
To sum up everything that was written here, I can say that I liked the converter and I consider the purchase a successful one. Everything works exactly as it should. There were no problems with connection or setup. So if your TV also has exclusively “digital” audio connectors, then you can turn your attention to a similar product - it will again help you hear the sound in your headphones :) Although, to be honest, I don’t really understand the desire of manufacturers to get rid of “analog” "exits...
That's probably all. Thank you for your attention and your time.
Today we will talk about how to quickly and efficiently digitize old videotapes using a computer, video camera or other equipment with your own hands at home. We will also consider simple techniques for digitizing audio and video recordings yourself or how to convert an analog signal to digital
Over the past period, video system owners have accumulated a huge number of archives. Of course, if we are talking about films or TV shows, then they can be found on current media, but not everything can be found. For this reason, many people continue to keep an old video player, which is used to watch “tape rarities”.
Magnetic film, unfortunately, is short-lived: it ages, the magnetic layer deteriorates over time, the recording first loses quality, and then is not suitable for viewing at all. If you do not give this due importance, one day it will turn out that the unique wedding ceremony, filmed on tape and carefully stored in a designated place so that it can be viewed with trepidation on the next anniversary of your own wedding, is hopelessly spoiled
Since VCRs are gradually falling out of use, giving way to DVD and Blu-ray players, I want to be able to watch home videos using the player.
In addition, there is an opinion that film cassettes cannot store video without loss for a long time; over time, the quality of the recording inevitably begins to deteriorate. Any re-recording also degrades the quality of analog video. But a film transferred to digital format can be rewritten many times without losing quality.
If home analog video is digitized, it can be edited, bad moments cut out, music, titles, etc. added, and the resulting film after processing can be converted into any convenient format and stored on any digital storage medium (hard drive, CD, DVD, Blu -ray disk, flash drive).
Detailed video instructions:
YouTube Video
What you need to digitize VHS tapes:
Video recorder.
A device for converting analog information into digital information.
Computer or laptop.
Capture program.
Well, with a VCR and a computer everything is clear. All video editing programs, starting with MovieMaker, have capture functions, so there are no problems with the capture program.
Let's consider options for possible devices for converting an analog signal to a digital one.
Firstly, this is a video capture board or card - ADC (analog-to-digital converter). On one side, the card is connected to a VCR via composite and S-Video inputs, and on the other, to a computer via USB.
Secondly, a TV tuner, which, in addition to displaying television programs on a computer, can digitize video.
Thirdly, some video cameras (usually miniDV) that have, in addition to a DV output, also a DV input, can digitize analog video. In this case, the camera is connected between the VCR and the computer, and it directly carries out digitization (without recording to its tape).
Fourthly, there are special VHS converters that replace the VCR and capture card at once:
The basic requirements are a computer, a video camera or a VCR that can play old video cassettes. A DVD burner drive to record the finished video film to DVD.
Digitizing a video cassette is actually very simple and if you have at least a little knowledge (at the level of how to connect equipment), then you can easily do it yourself.
However, digitization will require special equipment that you will need to purchase.
First you need to find a VCR. A video player would be fine too. Before inserting a cassette and pressing "PLAY", clean the tape drive. Do not use cleaning tapes; they will not help, since the VCR most likely has not been used for a long time. To clean the insides of the VCR GOOD, unscrew the screws that hold the cover and remove it (the cover). It is better to use special products to clean the video head. It is advised not to use alcohol, but if there is nothing else at hand, then it will do. Moisten an ear stick with video head cleaner and use light pressure to wipe the video head several times. Then, without waiting for the product to evaporate, wipe the video head with a special chamois for cleaning glasses. Don't forget to wipe the pressure roller too.
To connect a VCR to a video capture card or an external USB video capture device, you will need this wire, it is called “RCA video” or in common parlance “tulip”. When connecting the cable, ensure that the signal matches the signal. That is, we connect the yellow plug to the yellow video output, and connect the other end to the yellow video input on the card (USB device). Do the same with the white and red plugs. If you mix it up, nothing will burn, it just won’t work.
We connect the cable to the video outputs on the back panel of the tape recorder (sometimes the tape recorder has video and audio outputs on the front panel). They are usually designated "video out" and "audio out". We connect the yellow “tulip” to “video out”, red to the right channel of the audio signal (labeled “R” on the tape recorder) and white to the left channel of the audio signal (labeled “L” on the tape recorder). And not because it’s necessary, it’s accepted. Don't be alarmed if your tape recorder is missing one of the audio channels on the back panel. It's just that your tape recorder is "mono". This means you only need to connect the left (white) audio channel. Leave the right one hanging in the air. The photo just shows a “mono” VCR.
Look at the back of the system unit. The place where the cable from the monitor comes is your video card. If you see three multi-colored (red, white and yellow) connectors on it, then you have a video card with RCA. This is a regular cable for connecting a VCR or camcorder directly to the equipment, and you probably have it. Some video cards do not have a yellow RCA connector (video) and instead have an S-Video connector. To connect to such a video card, you will need an S-Video adapter from RCA to S-Video or a ready-made S-Video and RCA audio cable.
There are video cards that only have S-Video. We connect the video signal to such a video card via S-Video, and connect the sound from a tape recorder or camera through the computer’s sound card. Some video cards only have S-Video video output (not to be confused with video input). That is, such a video card can only transmit a signal, for example, to a TV. You need to study the instructions for the video card. The method described above is quite complicated, if you do not have sufficient experience, then it is better not to try it. You will get nothing but a headache. Therefore, the best option is to digitize the videotape via a video capture card or USB video capture device. The last method will be the most preferable for beginners.
One simple way is to purchase a video capture card and connect a camcorder or VCR to your computer through it. The complexity of this method lies in the fact that it is necessary to open the system unit and insert a video capture card into a free computer slot on the motherboard. And then install the drivers for the video capture card. If you do not have knowledge in this area, take the system unit to the service center and they will do everything for you for an additional fee. Prices for video capture cards range from several thousand rubles (for professional video cards the prices are much higher and they require certain skills in working with relevant programs). This method still has limitations (you need to install a card, additionally download capture programs, etc.).
The easiest way to digitize videotapes is to buy a USB video capture device. There are a sufficient number of them on the market.
You buy such a device, insert it into a free USB connector on your computer and follow the instructions to convert the video archive into digital form. Prices for USB video capture devices start from a thousand rubles. You can find such a device on the Internet by typing the phrase “usb video capture” in the search bar “Yandex” or “Google”. Everything is so simple that there is no point in describing the process in this article. I bought it, connected it, installed the drivers from the disk, connected the VCR and recorded.
Pay attention to the products of Pinnacle and MAGIX companies. Most likely, the box with such a device will contain a disc with software for video capture, simple editing and recording of digitized video on DVD. Therefore, you will not need to search the Internet for programs to capture, compress, edit and burn video to DVD.
Well, one of the preferred and relatively expensive solutions for digitizing videotapes at home. Products of the Japanese company Grass Valley (formerly Canopus). ADVC 55 and ADVC 110. Both devices connect to the computer via a FireWare (IEEE 1394) port. The port connector can be four or six pin. Four-pin circuits are usually installed on laptops, and six-pin on regular computers. They can be located both on the front part of the system unit and on the back side, in the same place as all other connectors (USB, sound, etc., depending from the motherboard). A six-pin cable connector is connected to ADVC 55; any cable connector can be connected to ADVC 110. The pictures clearly show the connection connectors.
The ADVC 55 can only digitize an analog signal from a VCR to your computer.The ADVC 110 is a bidirectional converter, meaning it can both digitize a video signal to a computer and convert a digital signal to analog and transfer it to your tape recorder for recording. When using ADVC 110, there is no desynchronization of video and audio.
Both devices work without drivers. When connecting via a six-pin FireWare cable, you do not need to use a power supply. To digitize old cassettes, it is still preferable to use ADVC 110.
Software required for digitizing videotapes
Combined with additional hardware, you will also need special software to capture, compress and edit video on your computer.
There are a lot of such programs, from free and freely distributed to paid ones. There is no need to list them. Search the Internet, you will find a description of how to use them and the programs themselves;). For example, to capture video you can use WinDV (a wonderful microscopic program with a size of just under forty kilobytes!), for compression the good old Canopus Pro Coder or the constantly evolving Adobe Media Encoder. If you need to burn video to DVD, use DVD Lab Pro (note that for DVD video you need to compress it into mpeg2 format)
If you're into digitization, you'll need a lot of hard drive space. Uncompressed video takes up approximately 10-14 gigabytes per hour of material on your hard drive. Take this into account when digitizing.
Working with such large files means you need a powerful computer. For comfortable editing of your videos, the frequency of the processor and its modification is crucial. Thus, the latest Intel ivy bridge processors include technology that allows you to reduce the time for calculating the final material several times.
What is bitrate? Video bitrate is the amount of information transmitted within a second. It follows from this that the higher the bitrate of the video, the higher its quality, the clearer the picture, the fewer artifacts, etc. And the more space on your hard drive is needed to store this video and, accordingly, the more time it takes to transmit it over the network.
DVD capacity
When digitizing or "compressing" higher quality video for DVD, you need to consider the capacity of DVD discs. As you already know, there are DVD discs with a capacity of 4700 megabytes (or 4.7 gigabytes) and 8500 megabytes (8.5 gigabytes). The 9400 megabyte (9.4 gigabyte) drives should be mentioned, but they are double-sided, not double-layer. When using such a disc, you will need to remove the DVD and turn it over to the other side, and this is not very convenient. And the price of such discs is high. It's easier to use two 4.7 GB disks. These are the parameters you should start from when digitizing video for DVD. Plus, you need to decide whether you need a menu on a DVD disc. If yes, then we subtract about 300 megabytes from the picture quality.
Video length
So, we chose the DVD capacity. Now we look at the time of the video material that needs to be digitized. It is worth noting that a video lasting more than two hours is still not worth recording on a DVD with a capacity of 4.7 gigabytes. If you wish, of course you can, but the quality of the picture will suffer greatly. Especially "home videos".
In general, a DVD has 4.7 gigabytes, and it’s better to record an hour of video on home video. This is due to the fact that in “home video” there is a lot of dynamics, not dynamics in the frame, but sudden and constant movement (shaking) of the video camera, which has a very bad effect on the “compressibility” of the video material.
Constant or variable bitrate
Constant bitrate is when the encoder program encodes video material at the same bitrate throughout the entire video. On a 4.7 gigabyte DVD, the constant bitrate for a two-hour video will be 4500-4700 kb/s (kilobits per second).
Variable bitrate is when the encoder program compresses video material with different bitrates. For example, you shot from a tripod or the source material contains static objects (walls, mountains, roads, a picture hanging on the wall, a flower on the windowsill, a spoon on the table). If these objects do not move in the frame, then these objects are digitized with a low bitrate, and with a higher bitrate the program digitizes moving objects, that is, where quality is needed. From experience, if you set the bitrate from 4700 to 8000, then the program is “afraid” to set a high bitrate when digitizing, slightly reducing the image quality. Digitization with variable bitrate allows you to find a compromise between the quality and size of the final material. The most ideal digitization option is digitization with a variable bitrate in two passes.
One or two passes
Some encoder programs allow you to select the number of passes when digitizing with a variable bitrate. It takes twice as long, but the result is worth it. What is it for. During the first pass, the encoder program analyzes the video material, “marking” areas where the bitrate should be increased or, conversely, decreased. With this digitization method, the program will digitize video material with the highest possible quality.
Bitrate selection
Here you need to choose between quality and size. The dry numbers are:
DVD 4.7 gigabytes - 2 hours of material, bitrate 4500-4700, average quality.
DVD 4.7 gigabytes - 1 hour of material, bitrate 8900, high quality.
You should not choose the highest possible bitrate for a DVD disc (9200); some DVD players begin to “stutter” when playing discs with this bitrate. The optimal option is 8900-9000.
Encoder programs
Perhaps the standard in this area is the paid Canopus ProCoder. Ease of use coupled with enormous capabilities and the highest quality is our choice. We can also recommend Adobe Media Encoder. Among the free ones, I can recommend iWisoft Free Video Converter, XMedia Recode.
In fact, the list of programs is very extensive and by rummaging through the search engines, find the option that suits you.
The requirement for the system as a whole is that it must be equipped with a UPS (uninterruptible power supply). Its power should be enough to shut down the system correctly. Note that digitizing videotapes at home will be of higher quality if the UPS can provide power to the PC until the procedure is completed (about half an hour). However, this solution can be called unreasonably expensive in many cases. All other parameters of a personal computer directly depend on the selected digitization methods. There are several of them, they are based on hardware and software components.
The next mandatory point is to use a high-quality video player or VCR with working mechanics and clean heads. If your device for digitizing video tapes does not meet the necessary requirements, choose another option. Half the success here depends on the reliability of the signal source. Digitizing videotapes at home does not impose any other requirements; a low-frequency output, a cleaning videotape and a good cable are sufficient.
Using a TV tuner to digitize videotapes is perhaps the most affordable solution. Such a device must have a PCIe or PCI interface. We also emphasize that you can purchase any tuner for digitizing video cassettes, without paying much attention to the cost. The main thing is the presence of a low-frequency input for connecting your VCR. However, you also need to take care of the software part. A special program for digitizing videotapes iuVCR can provide a resolution of 768 by 576 pixels. This approach will subsequently allow lossless conversion of video material into DVD format with a resolution of 720 by 576 pixels.
If you do not have a VCR adapter and TV tuner and are currently considering purchasing them, please note that iuVCR works best with dedicated cards based on the Conexant BT848 or BT878 chip. About the advantages and disadvantages of a video editing card Next, we will consider a less budget solution, which, however, allows you to obtain higher video quality. We will talk about the use of a specialized video editing (video capture) card. Similar modules are available in USB and PCI versions. Solutions from Pinnacle Systems have proven themselves well, among which the Dazzle and Studio MovieBoard series deserve special attention.
A special feature of these devices is that they come with special software that provides video capture and does not require additional user actions. However, the price of such a kit is considerable, so in the future you will have to think about what you are going to do with the equipment after completing the process of digitizing your own video archive. Portable approach If you plan to digitize videotapes on a laptop or cannot install a PCI card in a desktop computer, AVerMedia DVD EZMaker 7 may be a good solution. Well, what can I say? A very interesting device, considering its miniature size, USB interface, and a huge set of connectors for connecting a video player.
Incredibly convenient if you have to do digitization outside the home, for example, while visiting friends or relatives. A digital video recorder is the most unpretentious option. This solution is suitable for those who do not have the desire or ability to understand complex computer technologies. In this case, you can use a digital video recorder. Using such a device, you can copy data from a video cassette without much difficulty: connect the output of a traditional cassette video recorder to the input of a digital one, insert it into the last DVD disc and start copying. Subsequently, the obtained result can be easily transferred to a computer for subsequent processing.
The main disadvantage of the described method is that it is suitable only for those who do not particularly care about image quality. What to do next with the rewritten videos?
In some cases, you will have to do serious editing: adjust colors, apply transitions and other effects. Individual processes include video editing (if necessary), work on sound (cleaning, volume leveling) and subtitles. Upon completion of such a painstaking task, you need to re-encode the video into the format you need and save it on DVD media. To do this, you will need a large number of different software, and in a wide range.
The set of necessary programs depends on your preferences, financial resources and hardware. For each type of processing of source video material, special programs are required. If you want video processing to become part of your profession, actively study this topic using only specialized literature. Instead of an afterword Before making a decision regarding digitizing your own video library, carefully weigh your options. This is a necessary and important matter, however, in essence, it is one-time.
If you do not intend to turn it into additional income, when purchasing equipment, consider its future fate. When your archives are not too large, are of good quality, and there is no need to carry out serious restoration, it is more profitable to turn to specialists for help, who can be found in any company that is ready to do all the necessary work. It is cheaper and easier than learning a new profession, as well as finding unique equipment. Although... working with video is always incredibly exciting.
Digitize videotapes at home with good quality! Previously it was very difficult. To “distill” a video cassette into a DVD, you had to have a fairly powerful computer, a special video capture card (which took a while to set up the first time), then everything had to be connected correctly, and only after that it was possible to enter the video from the cassette into the computer with the possibility of further recording to disk. Now everything has become much simpler, cheaper and more accessible, because the EasyCap USB device has appeared.
Having this little miracle of technology at your disposal, you can easily connect the VCR to your computer and digitize video tapes at home in a relaxed environment, without resorting to the services of third-party specialists.
Specifications:
· Includes professional and easy-to-learn and use software: Ulead video studio 8.0 SE DVD.
USB 2.0 interface
· Video and audio capture
· Control brightness, contrast, saturation and color
· Small sizes
· Allows you to capture audio without a sound card
Plug&Play
· Supports all formats: recording DVD+/-R/RW, DVD+/-VR, and DVD-Video.
Can be used for video conferencing
· Complies with USB 2.0 specification.
· Supports NTSC, PAL, Video format.
· Video input: one composite RCA, one S-Video.
Audio input: 2 RCA stereo audio
· Dimensions: 88mm*28mm*18mm.
· Supported resolution: NTSC: 720*480@30fps PAL: 720*576@25fps.
System requirements:
Free USB 2.0 port
Windows 2000/XP/Vista32bit
CPU Pentium Ⅲ 800
· 600MB of free disk space for software installation
· 4GB or more free disk space for video capture and editing.
· Memory: 256MB RAM.
· Display: minimum 1024*768.
· Sound card
Contents of delivery:
· 1 x EasyCAP USB 2.0 video-audio video capture adapter
· 1 x USB cable
· 1 x CD-ROM (Software)
Another interesting use for the EasyCap device is recording images from a Web camera. This turns the computer into a video surveillance device. This very inexpensive solution can be used for personal home or professional purposes.
In conclusion, I would like to say that purchasing an EasyCap device is advisable if you are going to digitize more than 5 VHS videotapes. If your video archive is smaller, it will be cheaper to order video dubbing to DVD at a photo center.
This type of equipment is quite difficult to attribute to any specific category of equipment. By the way, this is why the converters discussed here are very difficult to find in well-known online markets: it is not clear in which product category to search - among capture devices, among tuners or among converters? At the same time, these devices come closest to the category of converters, since their only task is to convert one type of signal to another. And how the devices can be used is a purely personal matter, and depends on the tasks and skills of the user.
Design and technical characteristics
The converters in question are supplied in identical blister packs, and at first glance they are no different from each other. Only an inconspicuous model designation will help you figure out which converter you have in front of you.
Another thing is the reverse side of the packaging. There is no need to read anything here, just look at the connectors visible under the transparent packaging.
The first device, with the model designation ET110, is designed to convert a standard computer RGB signal coming through the VGA interface (15-pin connector, otherwise called D-sub) into today's standard digital signal sent through the HDMI connector. D-sub video outputs are available in video cards of personal computers, laptops, and other video signal generation devices.
The second converter, the ET111, is busy converting the ancient composite signal to digital, which is also output via the HDMI port. Absolutely every VCR, game console or video camera of previous generations was equipped with such “tulips”.
Finally, the third converter, with the index ET113 (interesting, why not 112?), as can be seen from its connectors, digitizes the component YPbPr signal traveling through ordinary coaxial cables with “tulip” connectors. Such video outputs are available on game consoles, some VCRs and media players, even modern ones.
| ET110 | ET111 | ET113 |
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The housings of the devices are made of plastic and consist of two halves, tightly interlocked with latches. In order to find out the location of these latches, we had to significantly distort the body of one of the converters. And yet we managed to disassemble the devices. Their design turned out to be extremely similar, which is not surprising given the fact that the main electronic component that digitizes video is the same production chip.
| ET110 | ET111 | ET113 |
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Our devices are not banal adapters with soldered through outputs; they are completely independent devices, the electronics of which operate according to an active circuit, that is, they require power. To do this, each of the converters under consideration has one more “tail” - a standard USB, which should be connected to the USB port of a TV or other device. In extreme cases, an ordinary five-volt battery, the so-called power bank, which has now proliferated in abundance, will do.
The main technical characteristics of the converters are given in the following table:
| Interface | ET110 | ET111 | ET113 |
| Entrance | |||
| Nutrition | USB 2.0 | ||
| Video input | D-sub 15 pin VGA cable | composite (“tulip”) | component (“tulips”) |
| Audio input | analog jack 3.5 mm | analog stereo (L/R, “tulips”) | |
| Input Resolution |
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| Exit | |||
| Maximum resolution | HDMI Type A, up to 1080p60 or UXGA (1200x1600) |
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| Other characteristics | |||
| Operating temperature | from 0 to +40 °C | ||
| Availability of indicators | power indicator | ||
| Dimensions | 102×33×16 mm | ||
| Weight (with connectors) | 91 g | 65 g | 76 g |
This and other information can be seen at.
Connection and operation
From the external and, especially, technical description of the devices, it becomes completely clear how the converters should be connected. Nevertheless, we present here diagrams of typical applications of the devices.
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As you can see, in each of the schemes the end point is a digital TV or projector. But the question arises: any modern projector or TV - with rare exceptions - is necessarily equipped with all video inputs, both digital and various analogue, including even “computer” D-sub. Of the information display devices that do not have analog inputs, the author can only remember some highly specialized monitors, like those that are installed on the “shoe” of video cameras or cameras. What prevents an ordinary user from connecting an old VCR or laptop to a modern TV directly, through the cables and adapters included with the TV? For what reason will he choose to connect through a separate, separate device, which, moreover, also supplies power?
We can’t say anything for an ordinary user, but with an “unusual” user everything is not so simple. The specifics of the “Digital Video” section, in which this article is published, requires remembering about capture devices. This is where the real difficulties begin: video capture devices are divided not only into hardware or software, stationary or portable. One of the main distinguishing features of any capture device is the type of signal that the device is able to receive and convert. Finding a universal device that has all the necessary inputs and supports all possible video standards is extremely difficult. Especially now that capture devices are equipped with a single input. And this, of course, is HDMI. Thus, having one HDMI signal capture device and several different standard converters that convert any video to a digital standard, the user will have the opportunity to digitize absolutely any source - a VHS tape recorder or camera, a game console of previous generations, a Blu-ray player or media player, a laptop , an old personal computer and so on, right up to an ultrasound diagnostic device.
But enough theory, I would like to consider those few aspects that are generally possible to study here. And the first of them, the most important, concerns the delay in signal processing and transmission. After all, the converters in question can be used as adapters between a game console and some kind of video signal display device (TV, projector). What factor is important in a game, for example in a shooter or racing and other simulators? Of course, the player's reaction.
We will not play, let the satisfied consumer play, but we will calculate the delay that may be present during signal transmission. The converters under consideration operate according to an active circuit; here, any incoming signal undergoes complete processing, converting to another standard on the fly. And this, even theoretically, takes time.
First, let's assemble a sort of spontaneous test stand. Let's connect a laptop to the TV using its VGA (D-sub) video output, and use the ET110 device as a signal converter. Exactly according to the same scheme as shown above in the first example. As a result, the laptop received a second screen, which displays the same information that is displayed on the main display. Now let’s start playing a special video on the laptop with a frequency of 60 frames per second. Here, in the video, there is a rotating arrow that makes one revolution per second, as well as a rectangle moving along the upper scale, which also runs its path in one second. All that remains is to film the resulting test bench, and the video will be recorded at the same frequency of 60 frames per second. Here is the result:
In this video you can clearly see that the signal delay is 7 sectors out of 60, that is, about 1/10 of a second. Whether this is a lot or a little, we don’t know - we’ve never been into game consoles. However, in races that were launched on a large screen from the same laptop through this converter, such a delay was not felt at all. Perhaps the masters of online shooters will be able to notice some kind of lag that annoys them, but, to be honest, I don’t really believe it.
The next question, which is also the final question in the study of such simple (but at the same time complex) devices, is the preservation of detail when transcoding the signal. The ET111 device, which digitizes composite video, is useless to study in this regard. There can’t even be any talk about any kind of detailing - this ancient standard is too merciless with the video signal, in which the pixel is not square, the aspect ratio of the frame is “wrong”, overscan areas are not visible on “tube” TVs, and even interlace ever-memorable, which reduces the vertical detail by half. Taking advantage of the opportunity, we captured several vintage VHS tapes by connecting an ET111 converter to the composite video output of the tape recorder and sending the signal to a capture device with a single HDMI input. The quality (more precisely, what VHS can provide) turned out to be quite high, no worse than during direct viewing from a tape recorder on a TV.
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But the other two devices are quite interesting to study from the point of view of detail - do these converters really not cheat with the signal, do not compress it, for example, twice, processing it, and subsequently stretching it to Full HD?
The easiest way to check this assumption is by playing a special test video file and then capturing the video stream. In the case of the ET110, the laptop will play the file, and the signal will be output through its VGA output, passed through the converter, and fed to the capture device. In the second case, the source will be a media player equipped with component video outputs. The test video file contains many lines one pixel thick, which are located at the same distance from each other. The capture results can be seen below.
The different brightness of the frames is explained by the different range of video outputs (the laptop has a “computer” brightness range), and the different clarity is also easy to explain: we remember that the video signal entering the converter goes through full processing - here they are, the results of this processing, in still frames.
conclusions
For what purposes are these inexpensive devices supposed to be used, which are full-fledged converters of analog signals of various formats into one digital one, supported by all modern display devices without exception? As already mentioned, they may be required if the TV does not have the required input. Or even in such trivial situations as the lack of necessary adapters (one of the author’s TVs was received in a limited configuration, as a result of which all of its analog inputs were unavailable due to the lack of special branded adapters).
But still, the option of capturing a video signal that has a variety of standards seems more convincing. And even preferable, considering the considerable cost of various types of capture devices. Of course, the ideal output that would suit everyone would be a signal converter similar to one of those under consideration, but with three types of input connectors at once - VGA, composite, and component. But such a solution, apparently, is not at all included in the plans of marketers.
