GB2059135A - Tape format having both video and audio information on same tracks and apparatus for recording and/or replaying same - Google Patents

Abstract

Audio and video information is recorded and/or replayed using a multiplexing technique with which the capacity to independently edit that information is preserved. Compatible portions of audio and video information are disposed at separate locations along the same tape tracks with the space along each track being apportioned by time-compressing each type of information before it is recorded and time-expanding each type of information before it is replayed. <IMAGE>

Description

SPECIFICATION Tape format having both video and audio information on same tracks and apparatus for recording andior replaying same Record and/or replay systems are known wherein analog video information is recorded on continuous longitudinal tape tracks, or on intermittent tape tracks at a prescribed angle to the direction of tape motion such as in quadruplex and helical scan systems. In these tape systems, each channel of audio information is typically recorded at baseband on a separate longitudinal tape track. These audio tracks are completely independent of the video tape tracks and therefore the audio and video information can be independently edited. However, the separate audio and video tracks require that separate audio and video transducers be utilized to record and replay the information.

Digital record and/or replay systems with the audio and video information recorded on independent tracks are also possible. Generally, the video information would be digitized and recorded at the limiting wavelength in the required number of tracks with a rotary transducer such as in present day analog, quadruplex or helical machines. Each audio channel would be digitized and recorded longitudinally in the required number of parallel tracks.

Because it is desirable to minimize tape usage however, such machines are generally run at relatively low linear tape speeds. The wavelength recorded on the tape is equal to the relative speed between the recording transducers and the tape, divided by the recording frequency. The minimum recorded wavelength is determined by the size of the gap in the transducers and the limiting frequency at which the polarization of the magnetic particles of the tape can be changed. Consequently, as the tape-to-head speed decreases for a given channel bandwidth the minimum wavelength criterion may be exceeded and more parallel tracks operating at a lower frequency are required.

Separate audio and video heads, and all of the record and replay electronics associated therewith, can be avoided by multiplexing the digitized audio in with the digitized video during the recording process. However, the individual audio channels and the video channel would then no longer be separate and therefore, the capability of independently editing these channels would be lost.

Both the audio and video could also be simultaneously recorded onto the same tape tracks, with the video recorded as FM modulation of a carrier and with the audio directly recorded at baseband. In such an arrangement however, the FM carrier cannot be operated in saturation to provide maximum video signal-to-noise ratio because such saturation would distort the audio signal. Of course, this system does not provide for independently editable channels either.

In accordance with a preferred embodiment of the present invention, compatible audio and video information is formated to be at separate locations along the same tape tracks. An essentially conventional head and record/replay electronics may be utilized to accomplish multiplexing while providing the capability of independently editing that information.

Space is obtained on the tracks by time-compressing both the audio and video information prior to their being recorded on the tape and by time-expanding both the audio and video information when they are replayed from the tape tracks.

In the drawings: Figure I illustrates the tape track format in one preferred embodiment of the invention; Figure 2 is a block diagram of a tape record and replay system (not shown in its entirety) for utilizing the track format of Figure 1; Figure 3 is a block diagram for a more specific embodiment of the compression means in the tape record and replay system of Figure 2; Figure 4 is a block diagram for a more specific embodiment of the expansion means in the tape record and replay system of Figure 2; and Figure 5 is a block diagram of a TV recording and replay system wherein the number of tracks in a sequence relating to individual field is not equal to the number of audio channels.

As discussed previously, compatible segments of discrete video and audio information are recorded on separate tracks in most conventional tape formats being utilized for today's record and/or replay systems. in the tape format of this invention, compatible audio and video information are recorded at separate locations along the same tape tracks.

Although this format could be utilized in longitudinal scan or quadruplex tape record and/or replay systems, one preferred embodiment thereof for use in helical scan record andior replay systems is shown in Figure 1.The track format shown in Figure 1 differs from the conventional format (such as, in the United States Society of Motion Pictures and Television Engineers, type C), in that information from a plurality of separate audio channels is included with compatible video information on the same tape tracks which are normally reserved for video information only. Therefore, the space along the edge of the tape normally reserved for the audio information, is available for other purposes and is designated as "CUE/TIME CODE," "SYNC TRACK," "CO N- TROLTRACK," and "SPACE FOR TWO LONGlTU- DINALTRACKS" in Figure 1.Those skilled in the art will of course realize without further explanation that the track format of this invention is not limited to the track format of Figure 1.

To utilize the tape format of this invention, a digital means for recording audio and video information at separate locations along the same tracks is included in the record system, while a digital means for replaying the video and audio information from separate locations along the same tracks is included in the replay system. Preferred embodiments of such digital record means and digital replay means are shown in Figure 2 as separate portions of a record and replay system which is not shown in its entirety.

The digital record means includes a compression means 10 for condensing both the audio and video information relative to their real time values in accordance with the length of the tape tracks so that compatible audio and video information can be recorded on separate portions along each track. The digital replay means includes an expansion means 12 for extending the audio and video information replayed from the separate portions along each track to restore their real time values. The actual number of audio information channels recorded with the video information on each track is limited by the magnetic wavelength of the tape. However, the magnetic characteristics of tape are continually being improved and tape-to-head speeds are being decreased, so that more than the four audio information channels shown in Figure 1 may be recorded.

In Figure 2, the video and audio information are recorded on the tape and/or replayed therefrom by a scanner 14 which conventionally includes a headwheel (not shown) having transducers disposed around its periphery. The scanner 14 operates in cooperation with a tape transport system (not shown) to scan tracks on the tape in record, replay or erase modes.

Separate memories are utilized in the compression means 10 to condense the audio and video information before they are recorded on the tape.

The video information is quantized in digital form such as an 8 bit parallel format and applied to a video record memory 16. Each channel of audio information is also quantized in digital form such as a 14 bit parallel format and applied to an audio record memory 18. Avideo record sampling clock - - 20 and a video compression clock 22 respectively, determine the rates at which real time information is written onto and time condensed information is read out from the video record memory 16. An audio record sampling clock 24 and an audio compression clock 26 respectively, determine the rates at which real time information is written into and time condensed information is read out from each audio record memory 18. The video and audio inputs are also applied to the sampling clocks 20 and 24 respectively, for synchronization purposes.

The rates of the sampling clocks 20 and 24 are less than the rates of the compression clocks 22 and 26 respectively, so that the durations of the video and audio information that passes from the memories 16 and 18 are condensed relative to their real time values. These clock rates will depend on the frequency of the video and audio information, as well as on the number of audio channels to be utilized. For the sake of convenience, only one audio memory 18 is shown in Figure 2, however, three other such memories would also be required for the tape format of Figure 1 where four audio channels are included.

All of the audio channels will normally use the same sampling and compression clocks 24 and 26. However, individual clocks for each channel may be utilized where particular information compression ratios are desired to accommodate discontinuous or burst type data.

Time condensed video and audio information from the memories 16 and 18 is applied to a record switch means 28 for sequentially gating that information to each tape track through at least one transducer on the scanner 14. A means 30 for synchronizing the video and audio record memories 16 and 18 with the position of the scanner 14 is also included in the compression means 10. This synchronizing means 30 applies a control signal to the record switch means 28 and causes the video information to be recorded on one portion and the audio information on another portion of each tape track.

Separate memories are also utilized in the expansion means 12 to extend the time-condensed audio and video information to their real time values. The time-condensed video information is applied to a replay memory 32 and each channel of timecondensed audio information is applied to an individual replay memory 34 by a replay switch means 36 for sequentially gating that information from each tape track through at least one transducer on the scanner 14. A means 38 for synchronizing the video and audio replay memories 32 and 34 with the position of the scanner 14 is also included in the expansion means 12 and applies a control signal to the replay switch means 36 which separates each tape track into the portions of time-condensed information that relate to the video and each audio channel.

A video replay sampling clock 40 and a video expansion clock 42 respectively, determine the rates at which time-condensed information is written into and real time information is read out from the video replay memory 32. An audio replay sampling clock 44 and an audio expansion clock 46 respectively, determine the rates at which time-condensed information is written into and real time information is read out from each audio replay memory 34. The rates of the sampling clocks 40 and 44 are greater than the rates of the expansion clocks 42 and 46 respectively, so that the durations of the video and audio information that passes from the memories 32 and 34 are extended to restore their real time values.

These clock rates will also depend on the frequency of the video and audio information, as well as on the number of audio channels to be utilized. For the sake of convenience, only one audio replay memory 34 is shown in Figure 2; however, three other such memories would also be required for the tape format of Figure 1 where four audio channels are replayed.

All of the audio channels may utilize the same sampling and expansion clocks 24 and 26 or individual clocks for each channel may be utilized where particular information expansion ratios are desired.

In helical scan TV recording and/or replay systems, each successive field or predetermined segment of video information is recorded on a plurality of sequential tape tracks. Such record and/or replay systems may also be adapted to the tape format of this invention. Digital means for recording video and audio information at separate locations along each track in each track sequence would be incorporated into the record unit, while digital means for replay ing video and audio information from separate locations along each track in each track sequence would be incorporated into the replay unit.One preferred embodiment of the digital record means is shown in Figure 3 and includes a compression means 50 for condensing both the audio and video information relative to their real time values in accordance with the length of the tape tracks so that compatible audio and video information can be recorded on separate portions along each track in each track sequence. One preferred embodiment of the digital replay means is shown in Figure 4 and includes expansion means 52 for extending the time-condensed audio and video information on the separate portions along each track in each track sequence to their real time values.

For each tape track in each track sequence, the compression means 50 of Figure 3 condenses the video information and each channel of audio information with a separate memory. Real time video information for each tape track in each track sequence is applied to a video record memory 54 by a video multiplexing means 56 for distributing information from a digital video input to each track in each track sequence through separate video record memories 54. The nature of the recording memories 54 depends on the processing format selected, such as only one input and output terminal would be necessary thereon for information in serial form or a plurality of input and output terminals would be necessary thereon for information in parallel format.

A A clock 58 and a clock divider 60 driven therefrom are applied to the multiplexing means 56 and cooperate therewith to distribute the digital video information to the number of tracks in each track sequence. The rate of the clock 58 is the same as the rate at which the digital video information is sampled and the clock divider 60 divides the rate of the clock 58 by the number of tracks in each track sequence. The clock divider 60 is also applied to write real time information into the record memory 54, while a time transition clock 62 is applied to read time-condensed information out from the record memory 54. The rate of the time transition clock 62 is greater than the rate of the clock divider 60 and therefore, the information that passes through the video record memories 54 is condensed relative to its real time value.The time-condensed information passes from each video record memory 54 to a coding and digital formating means 64 for providing error correction or concealment. The time transistion clock 62 is further applied to a formating clock 66 and cooperates therewith to pass the information through the coding and digital formating means 64 to a record switch means 68 for gating the video and audio information into a tape scanner 70.

It should be noted that a sync signal is applied to the clock 58 and the time transition clock 62 to reference the recorded video information to its source. Furthermore, for the sake of convenience, only one combination of video record memory 54 and record switch means 68 is shown in Figure 3 for a single track in the track sequence and similar combinations for each of the other tracks in the track sequence would be required.

Each channel of real time digital audio information for each track in the track sequence is applied to an audio record memory 72 through a coding means 74 for providing error correction or concealment. The nature of each record memory 72 also depends on the processing format selected, such as only one input and output terminal would be necessary thereon for information in serial format or a plurality of input and output terminals would be necessary thereon for information in parallel format. Real time information is passed through the coding means 74 and written into the record memory 72 at a rate determined by a clock 76 having the same rate as the rate at which the digital audio information is sampled. A time transition clock 82 is applied to readout time-condensed information from the record memory 72.The rate of the time transition clock 82 is greater than the rate of the clock 76 and therefore, the information that leaves the audio record memories 72 is condensed relative to its real time value in proportion to the ratio of these clocks. This timecondensed information is applied to the record switch means 68 through a digital formating means 84 for distributing the audio information of the channel in serial format to the number of tracks in the track sequence and for providing a serialized format when a parallel processing format is utilized.

Outputs from both a scanner tachometer 78 and the clock 76 are applied to an audio gate generator 80 which has its output applied to both the record switch means 68 and the time transition clock 82.

Information is passed through the digital formating means 84 at a rate determined by the transition clock 82 and an audio formating clock 86 which is driven therefrom.

It should be noted that the sync signal is also applied to the time transition clock 82 to reference the recorded audio information to its source. Furthermore, for the sake of convenience, only one audio record memory 72 for a single audio channel is shown in Figure 3 and additional audio channels would require additional record memory 72, while each track in the tape sequence would have a separate input to record switch means 68 as explained previously.

For each tape track in the track sequence, the expansion means 52 of Figure 4 extends the video information and each channel of audio information with a separate memory. Time-condensed video information for each tape track in the track sequence is applied to a video replay memory 90 through a coding and digital formating means 92 for providing error correction or concealment. The nature of the replay memories 90 depends on the processing format selected in the same manner as discussed previously for the video memories 54. The timecondensed video information is applied to the coding and digital formating means 92 from a replay switch means 94 for gating the video and audio information from the tape scanner 70. Outputs from the time transition clock 62 and the formating clock 66 are applied to determine the rate at which the time-condensed information passes through the coding and digital means 92 and is written into the replay memory 90. Output from the clock divider 60 is applied to determine the rate at which real time information is read out from the replay memory 90 to a video multiplexing means 100 for accumulating the video information of each track in the track sequence at a digital video output. Since the rate of the time transition clock 62 is greater than the rate of the clock divider 60, the time-condensed information that enters the video replay memories 90 is extended in proportion to the ratio of these clocks, so that the real time value of the audio information is restored.

Output from the clock 58 and the clock divider 60 are applied to the multiplexing means 100 to pass the real time video information in serial format from the number of tracks in the track sequence to the digital video output.

Because the expansion means 52 must extend the video information in inverse proportion to the amount it is condensed by the compressor means 50, the clocks 58, 60, 62 and 66 are common to both the expansion and compression means 52 and 50.

Furthermore, for the sake of convenience, only one combination of video replay memory 90 and replay switch means 94 is shown in Figure 4for a single track in the track sequence and similar combinations for each of the other tracks in the track sequence would be required.

Each channel oftime-condensed audio information from each track in the track sequence is applied to an audio replay memory 104 through a digital formating means 106 for accumulating serialized audio information of that channel from the number of tracks in the track sequence. The nature of the replay memories 104 depends on the processing format selected in the same manner as previously discussed for the audio record memories 72. The time-condensed audio information is applied to the digital format means 106 from the replay switch means 94. Outputs from the formating clock 86 and the time transition clock 82 are applied to determine the rate at which time-condensed information passes through the digital formating means 106 and is written into the replay memory 104.Output from the clock 76 is applied to determine the rate at which real time information is read out from the replay memory 104 to a digital outputforthe channel through a decoding means 108 for providing error correction or concealment. Since the rate of the time transition clock 82 is greaterthan the rate of the clock 76, the time-condensed information that enters the audio replay memories 104 is extended in proportion to the ratio of these clocks, so that the real time value of the audio information is restored. Output from the clock 76 is also applied to the decoding means 108 to pass the real time audio information in serial format to the digital output for the audio channel.

Because the expansion means 52 must extend the audio information in inverse proportion to the amount it is condensed by the compression means 50, the clocks 76,82, and 86 are common to both the expansion and compression means 52 and 50.

Furthermore, for the sake of convenience, only one audio replay memory 104form single audio channel is shown in Figure 4 and additional audio channels would require additional replay memories 104, while each track in the tape sequence would have a separate replay switch means 94 as explained previously.

In Figure 3 and 4, the number of tape tracks included in each sequence that relates to an individual field is not determined by the number of audio channels. To illustrate this, a block diagram of a TV recording and replay system using a 2 track sequence per field but with 3 audio channels, is shown in Figure 5. Each audio channel is distributed over all of the available tracks in the sequence whether that sequence includes only a single track or ten tracks.

Claims (12)

1. A tape format for a record and/or replay system, wherein; audio and video information are disposed at separate locations along the same tracks.

2. In a tape record system of the type wherein compatible video and audio information are recorded on the tape: digital means for recording the video and audio information at separate locations along the same tape tracks.

3. A tape record system as in claim 2 wherein said digital means includes means for compressing both the audio and video information relative to their real time values in accordance with the length of the tape tracks so that compatible audio and video information can be disposed on separate portions along each track.

4. A tape replay system for tape which has been recorded with compatible video and audio information at separate locations along the same tape tracks, comprising: digital means for replaying the audio and video information from separate locations along the same tape tracks.

5. A tape replay system as in claim 4 for tape with the video and audio information on the tape tracks both compressed relative to their real time values said digital replay means includes means for expanding the audio and video information to restore their real time values.

6. In a tape record and replay system of the type wherein compatible video and audio information are recorded on the tape or replayed therefrom: digital means for recording the video and audio information at separate locations along the same tape tracks and for replaying the audio and video information therefrom.

7. A tape record and replay system as in claim 6 wherein said digital means includes: compression means for condensing both the audio and video information relative to their real time values in accordance with the length of the tape tracks so that compatible audio and video information can be disposed on separate portions along each track; and expansion means for extending the audio and video information received from the separate portions along each track to restore their real time values.

8. A tape record and replay system as in claim 7 wherein said compression means includes record switch means for gating the video and audio information from separate digital inputs to at least one record transducer with time-condensed video information being applied to said record switch means by a video record memory, while time-condensed audio information is applied to said record switch means by an audio record memory, and means is included for synchronizing said record transducers with said record switch means; and wherein said expansion means includes replay switch means for gating video and audio information from at least one replay transducer to separate digital outputs with timecondensed video information being applied by said replay switch means to a video replay memory, while time-condensed audio information is applied by said replay switch means to an audio replay memory, said video and audio replay memories restoring said real time values upon readout, and means is included for synchronizing said replay transducers with said replay switch means.

9. A tape record and replay system as in claim 8 wherein predetermined segments of compatible video and audio information are recorded with each segment being recorded on a plurality of sequential tape tracks, said compression means including input means for distributing digital video information to each track in said track sequence through a separate combination of video record memory and record switch means and also including formating means for distributing digital information from said audio record memory to each track in said track sequence individually through said separate record switch means; and wherein predetermined segments of compatible video and audio information are replayed with each segment being replayed from said plurality of sequential tape tracks, said expansion means including means for gating information to said digital video output from each track in said track sequence through a separate combination of video replay memory and replay switch means and also including formating means for accumulating digital audio information from each track in said track sequence individually through said separate replay switch means to said audio replay memory.

10. A tape recording and replay system as in claim 9 wherein the audio information for a plurality of channels is recorded on each track in said track sequence said compression means including a combination of said audio record memory and said formating means for each audio channel; and wherein the audio information for a plurality of channels is replayed from said plurality of sequential tape tracks, said expansion means including a separate combination of said output formating means and said audio replay memory for each audio channel.

11. A tape with video and audio information recorded thereon in a format substantially as hereinbefore described with reference to Figure 1 or Figure 5 of the accompanying drawings.

12. A tape record and/or replay system substantially as hereinbefore described with reference to Figure 2 or to Figure 3 and for Figure 4 of the accompanying drawings.