Er zijn dacht ik inderdaad video recorders die digitaal audio kunnen opnemen, zelfde als het DAT principe.
Interessante link over video recorders en audio
http://repairfaq.cis.upenn.edu/sam/icets/vcr.htm
Sound Recording
Mono
In case of a mono video recorder, the audio signal which corresponds with the image is transferred to a separate, fixed audio head. As in an audio cassette deck, this head writes an audio track in longitudinal direction of the tape. This is called linear or longitudinal track recording.
The video recorder has two erase heads. One is a wide erase head covering the whole tape width which automatically erases all existing image, synchronization and sound information when a new recording is made. The other erase head is smaller and positioned at the position of the audio track. With this erase head, the soundtrack can be erased separately, without affecting the video information. In this way, separate audio can be added to a video recording. This is called audio dubbing, and can be particularly useful when making your own camera recordings.
The linear audio track does have some restrictions. Due to its low tape speed, it is not suitable for hi-fi recordings. Moreover, the audio track is so narrow (0.7 mm for VHS and 1.04 mm for Betamax) that not even stereo sound can be recorded properly. The frequency range is limited as is the dynamic range (which relates to the amount of decibels), and the signal-to-noise ratio is not very high.(The signal-to-noise ratio relates to amount of noise compared to the total signal. The higher this ratio, the less noise and the better the signal will be). The sound quality of the mono track can be improved by a noise reduction system. There is a way to get superior hi-fi stereo sound quality on a videotape (used in hi-fi video recorders,) which will be discussed later.
Hi-fi Stereo Sound
Hi-fi video recorders were developed for improved sound quality. The most common quality of video images is HQ. (The recorder is labeled 'VHS High Quality Hi-fi Stereo'). Conventional mono video recorders use linear audio registration, which does not allow hi-fi recordings. A special method was therefore devised to record stereo sound with hi-fi quality.
In the case of hi-fi, the audio signal is also put on tape via revolving heads similar to the video signal, not on the linear track. As there is no space between the video tracks, as the video tracks lie right next to each other with no space in between, the audio tracks need to be recorded in the same place as the video tracks. The way this is realized is by recording the audio signal under (deeper than) the video signal.
Hi-fi video recording, where the audio signal is recorded at a deeper level, after which the video signal is recorded on top.
In hi-fi video recorders, the audio signal is modulated to a high carrier frequency. This is realized via FM modulation, with the right channel stereo signal at a slightly higher frequency than the left channel. The corresponding video and audio signals are written to tape immediately after each other. First the FM audio signal is registered at a deep level in the tape's magnetic coating. Straight after the audio signal, the video signal is recorded. As the frequency of the video signal is higher than the audio signal, it will not register as deep in the tape coating as the audio signal. The video signal erases the audio signal in the top layer and records the video signal instead. Thus, the audio and video signal tracks are written in the same magnetic layer, separately, one on top of the other. The entire magnetic coating is only 0.004 mm thick. To ensure that the two do not interfere, the audio and video tracks are written on tape from a different angle, by means of a different head with a different azimuth setting.
To guarantee compatibility with cassettes not recorded in stereo hi-fi, the fixed audio recording/playback heads remain in place. So, a hi-fi video recorder always has two audio registration systems installed. This offers possibilities for amateur video makers to do audio dubbing using an audio mixer to combine the sound of the hi-fi track with other sounds and to write the mix to the linear audio track. In this way synchronized recordings will be left intact.
Quality Audio Recorders
A hi-fi video recorder is also suitable as a high-quality audio recorder, not only because of the professional recording quality, but also because of the long play possibilities and the low recording costs.
The specifications of hi-fi video sound registration systems equal those of professional tape decks and compact discs. The entire sound spectrum can be covered without any problems, and the dynamic range is 80 dB, close to the 90 dB that compact discs can cover. (As the video recorder is a recording medium, a couple of good microphones can actually cover the whole 80 dB range.) Recordings made on a hi-fi video recorder result in almost unmeasurable wow and flutter and very little harmonic distortion. The low tone quality of a hi-fi video recorder is remarkably good compared to tape recordings of cassette decks. A disadvantage is that sound editing is not possible via a VCR. Instead, the required tape segments can be copied unto another tape without hardly any loss of sound quality.
A hi-fi-video recorder needs to be tuned very accurately. As the two rotating audio heads function alternately, the recorded sound consists of successive particles and need to fit together perfectly. If they do not, the result is rumble, which is a humming sound. In high quality, well-tuned hi-fi video recorders you will not hear this sound.
