JPH10340542A - Multi-stream data recording medium, its data transmitting/reproducing device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize transmission, reception or recording and reproduction of a high definition signal while satisfying constraint of a transmission rate. SOLUTION: Six channels which can be arranged into one stream of an analog signal source 10, are divided to form plural streams, the signal of a first stream is made to a 96 kHz sampling frequency, the signal of a second stream is made to a 48 kHz, and the scale is made different among the streams. This scale is such that the total bit transmission rate summing up bit transmission rates of the signals of the plural streams satisfies the bit transmission rate of a predetermined regulation. The signals of each stream are applied with a process for correcting a phase deviation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-stream data recording medium and a data transmission / reproducing apparatus and method therefor. For example, a high-quality audio signal is recorded on a disk, and a recorded signal is reproduced. This is an effective technique to do. The present invention can also be used as a method and apparatus for transmitting and receiving multi-stream data.

[0002]

2. Description of the Related Art Conventionally, various methods have been known as methods for transmitting and receiving data, and for recording and reproducing data. However, recently, with the progress of multi-channel and high-quality signals, improvements in data transmission and reception, data recording and reproduction methods are required. In order to improve the quality, it is necessary to increase the sampling frequency and the number of quantization bits, and the number of such channels (the sampling frequency is high and the number of quantization bits is large) is increased. If the number increases, the transmission rate cannot be satisfied, and it becomes difficult to increase the number of channels.

[0003]

As described above, in a data recording / reproducing or data transmission / reception system, when the data sampling frequency and the number of quantization bits increase, the transmission rate on a transmission line or a recording medium is satisfied. become unable.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a multi-stream data recording medium, a recording / reproducing method and a recording / reproducing apparatus capable of realizing transmission / reception or recording / reproduction of a high-quality signal while satisfying restrictions on a transmission rate. It is in.

[0005]

According to a recording medium and a recording apparatus of the present invention, one stream is divided into a plurality of streams, and a scale is varied between signals of the plurality of streams. Scale processing is performed so that the total bit transmission rate obtained by summing the bit transmission rates of the stream signals satisfies a predetermined bit transmission rate that is determined in advance, and the scale processing is performed between the signals of each stream. , A recording medium that records a plurality of streams subjected to this processing, and a recording apparatus for recording the streams. In the present invention, the signals having different scales have different sampling frequencies, and the different frequencies have an integral multiple.

According to the recording medium and method described above, a high-quality signal can be handled within a standard of a bit transmission rate by allocating a signal having a high importance to a stream having a high transmission rate. There is no phase shift between the signals.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. First, an example of a recording medium according to the present invention is an optical disk capable of high-density recording.
An example will be described.

The maximum transfer (transmission) rate of one stream signal is 6.144 Mbps or less, and the maximum transfer rate which is the total transfer rate of all stream signals is 9.8 Mbps.
s or less. One stream is a digital signal including, for example, stereo R and L channels (two main channels).

Next, a case where an audio signal of, for example, 6 channels is recorded as the signal to be recorded on the recording medium will be specifically described. The six channels mentioned here are, for example, R, L, C, SR,
SL and SW, and signals corresponding to each channel are generated. It is also possible to distinguish R and L as main channels and the others as sub-channels. Then, if the signal of each channel is reproduced and supplied to the speaker, a three-dimensional sound effect is obtained. Here, according to the method of the present invention, the above-mentioned six channels are generated as a first stream and a second stream, instead of being constructed into one stream. in this case,
R and L with high importance are selected as channels constituting the first stream, and C, SR, SL and SW are selected as channels constituting the second stream. Here, the signal of the first stream has a sampling frequency f
s is high, and the signal of the second stream has a sampling frequency of fs / 2 (1 / integer).

FIG. 1 specifically shows a first stream signal processing system and a second stream signal processing system. In the analog signal source 10, signals of R, L, C, SR, SL, and SW channels in the surround system are prepared and supplied to the sampling unit 11. The sampling unit 11 converts the signal of each channel to 96 kHz.
, And the sampling signal is supplied to the quantization unit 12.
, Quantized to 24 bits, and converted to a PCM (pulse code modulation) signal.

Next, the signals of the C, SR, SL, and SW channels have a sampling frequency of 96 kHz to 1 /
2 is converted to a frequency of 48 kHz. 96 kHz R,
The signal of the L channel is input to the phase matching unit 14,
The phases are adjusted so that the phase correspondence between the samples can be obtained. Actually, the same delay amount as that of the frequency conversion unit 13 is set in the phase matching unit 14. Next, the delayed 96 kHz R and L channel signals are input to the framing unit 15 and are framed every predetermined number of samples. The framing will be described later. Each of the C, SR, SL, and SW channels of 48 kHz after frequency conversion is input to the framing unit 16 and is framed every predetermined number of samples. Each of the framed signals is input to the packetizing unit 17 and is converted into a packet of a predetermined format. And a stream of 96 kHz system (referred to as a first stream),
Thus, a stream of a kHz system (hereinafter referred to as a second stream) is obtained. However, these two streams are identified by attaching an identifier (ID) to the packet header. The packets of these two streams are further packed, multiplexed and output, and recorded on the disk 18 via a recording processing unit (not shown).

When the signal recorded on the disk 18 is reproduced, the following processing is performed. The signal optically read from the disk 18 is input to the packet processing unit 21 via a demodulation unit (not shown) that performs error correction, demodulation, and the like. In the packet processing unit 21, the stream is identified with reference to the identifier of the packet header. With this identification, the packets of the first stream,
The packets of the second stream can be identified, and the signals of each stream are sorted. So-called demultiplexing. The signal of the first stream is input to the frame processing unit 22, where the frame is released.
It is output as an L channel signal. The signal of the second stream is input to the frame processing unit 23, the frame is released, and the signal is output as signals of the C, SR, SL, and SW channels.

Here, the signals of the R and L channels are input to a phase matching unit 24, and the signals of the C, SR, SL and SW channels are converted into frequency conversion units 25 for converting a sample frequency from 48 kHz to 96 kHz. Is input to

The signals of the R and L channels which are phase-matched and have the same sample frequency, and C, SR, SL,
Each signal of the SW channel is input to the 96 kHz digital-to-analog converter 26, PCM-decoded, converted to an analog signal, and output.

With the above processing, high-quality R and L channel signals and C, SR, SL and SW channel signals can be reproduced. FIG. 2 shows a data configuration example of the audio stream.

The audio stream is composed of a plurality of audio packs. The audio pack includes a pack header, a packet header, and an audio data section. Further, other data such as stuffing bytes and / or padding packets are inserted into the audio pack as necessary.

When the audio data portions of each pack are taken out, aggregated and connected, this aggregate is composed of a plurality of groups of frames (GOF). Further, one GOF is composed of a plurality of (20) frames (F0 to F19). Looking at one frame, it is composed of a number of samples corresponding to a reproduction time of 1/600 second.

According to the present invention, as described above, when the sample data in one frame is reproduced,
The number of samples is set to be seconds. For this purpose, a 96 kHz stream (first stream)
The number of samples in one frame differs from the 48 kHz stream (second stream).

FIG. 3A shows samples present in a frame in comparison between the first stream and the second stream. FIG. 3B shows the sample clock frequency in comparison. In the present invention, the phase adjustment unit 14 adjusts the phase of the first stream and the second stream to create a frame. Then, in the framing units 15 and 16, the same presentation time stamp is added to the head of the corresponding frame of the first and second streams (the frame that should be the same in time). As a result, when the frames are released by the frame processing units 22 and 23 during reproduction and supplied to the digital-to-analog conversion unit, the release timing of each frame may be such that frames having the same presentation time stamp are released simultaneously.

The present invention is not limited to the above embodiment. In the above embodiment, R, L, C, S
All signals of each channel of R, SL, SW are 96 kHz
Sampled by z. But from the beginning, R,
The signal of the L channel and the signal of the C, SR, SL, and SW channels may be handled separately.

FIG. 4 shows another embodiment of the present invention. That is, the analog signals of the R and L channels are sampled by the sampling unit 41 at 96 kHz, and the C and S channels are sampled.
The analog signals of the R, SL, and SW channels are sampled at 48 kHz by the sampling section 42. Then, each sample is quantized by a 24-bit quantization unit 43. Next, samples of the R and L channels, and C and
The phase matching with the samples of the SR, SL, and SW channels is performed by the phase matching unit 44. The phase matching is performed in the same manner as in the previous embodiment by using a 96 kHz system and 48 frames in frame units.
The signals of the kHz system are phase-matched. Then, the phase-matched samples are framed by the framer 45,
Next, the packetizer 46 converts the packet into a packet of a predetermined format. Then, a first stream of the 96 kHz system and a second stream of the 48 kHz system are obtained. These two streams have an identifier (I
D) is attached. The packets of these two streams are further packed, multiplexed and output, and recorded on the disk 18 via a recording processing unit (not shown).

When the signal recorded on the disk 18 is reproduced, the following processing is performed. The signal optically read from the disk 18 is input to the packet processing unit 51 via a demodulation unit (not shown) that performs error correction, demodulation, and the like. In the packet processing unit 51, the stream is identified with reference to the identifier of the packet header. With this identification, the packets of the first stream,
The packets of the second stream can be identified, and the signals of each stream are sorted. So-called demultiplexing. The signals of these streams are input to the frame processing unit 52, and the frames are released.
The signals are output as R and L channel signals and C, SR, SL and SW channel signals.

Here, the signals of the R and L channels are 96
kHz input to the digital-to-analog conversion unit 53
Decoding and conversion to analog signals are performed, and C, SR, S
The signals of the L and SW channels are input to a 48 kHz digital-to-analog converter 54, where they are subjected to PCM decoding and conversion to analog signals.

Through the above processing, high-quality R and L channel signals and C, SR, SL and SW channel signals can be reproduced. Various embodiments are possible as a method of obtaining synchronization between the signals of the first and second streams.

FIG. 5 shows an example of a method for obtaining synchronization between the signals of the first and second streams. That is, for example, FIG.
As shown in (A), for frames to be reproduced at the same time between the streams, the same time information t (n-1), t (n), t (n;
+1),... The addition of the time information is performed by, for example, as shown in FIG.
At 16, it is provided from the system control unit 60.

Further, at a packet level, the presentation stamp included in the packet can synchronize the first and second streams.
That is, FIG. 6 shows an audio pack, which has a pack header and a packet header. Audio data is arranged following the packet header.

FIG. 7 schematically shows a pack header of the audio pack. First, there is a pack start code (4 bytes), and then a system clock reference (SCR) is described. The system clock reference (SCR) indicates the loading time of this pack. If the value of this SCR is smaller than the value of the reference time inside the apparatus, the pack to which this SCR is added is loaded into the audio buffer. It is. In the pack header, the program multiplexing rate is described in 3 bytes. Further, the stuffing length is also described in one byte. The control circuit can determine the read address of the control information by referring to the stuffing length by the control circuit.

FIG. 8 shows the contents of the packet header of the audio packet. The packet header includes a packet start code prefix for notifying the start of the packet, a stream ID indicating what kind of data (audio, video, sub-picture, etc.) the packet has, and data indicating the length of the packet stream. . The packet elementary stream (PE
S) describes various information such as a flag indicating prohibition or permission of copying, a flag indicating whether the information is original information or copied information, and a length of a packet header.
Furthermore, a presentation time stamp (PTS) for synchronizing the output of the packet with another video or sub-picture is described. This presentation time stamp allows the first and second streams to be synchronized.

Further, in the first packet of the first field in each video object, information such as a flag indicating whether or not a buffer is described and a buffer size are described. It also has 0-7 byte stuffing bytes. In addition, a sub-stream I for indicating an audio stream, a linear PCM or another compression method, and an audio stream number.
D. The lower bits of the sub-stream ID can be used to distinguish between channels or the first and second streams.

Further, the number of audio frames in which the first byte is arranged in this packet is described in 8 bits. Furthermore, a 16-bit pointer is used to indicate the first audio frame in the packet to be reproduced at the time pointed by the PTS, that is, the first byte of the unit to be accessed first. This pointer is described by the byte number from the last byte of this information. The pointer indicates the first byte address of the audio frame. In addition, an audio enhancement flag indicating whether or not high-frequency enhancement has been performed, a mute flag for obtaining mute when audio frame data is all 0, and a frame number to be accessed first in an audio frame group (GOF) are also described. Have been. Also, the length of the quantization word, that is, the number of quantization bits, sampling frequency,
The number of channels, dynamic range control information, and the like are described.

The above header information is added by the control unit of the packetizing unit at the time of recording, and is analyzed by the decoder control unit (not shown) in the audio decoder at the time of reproduction. The decoder control unit controls the packet processing unit according to the analysis result. That is, the distribution of the first and second streams and the transmission timing are controlled.

In the above description, the case of transmitting / recording a high-quality surround-sound audio signal has been described. However, the present invention is not limited to such a signal. It can be applied to Also, the presentation time information is described as being added to the beginning of a frame in frame units, but this is not a necessary condition. Since the processing time of the packet is known in advance, the time is measured by the counter from the beginning of the data area of the packet. If processing is performed on a frame basis based on this time measurement, the synchronization time between the two streams can be adjusted.

Although the above description has been made on the assumption that hardware as a disk reproducing apparatus exists, the recording medium of the present invention is not limited to the above-described embodiment, and an electronic apparatus such as a personal computer can generate a signal. means,
Alternatively, it can be used as a medium functioning as a signal reproducing means, that is, a recording medium such as a floppy disk, an optical disk, a magnetic disk, or a memory on which software is mounted.

[0034]

As described above, according to the present invention,
Transmission / reception or recording / reproduction of a high-quality signal can be realized while satisfying the restrictions on the transmission rate.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a hierarchical structure of an audio stream.

FIG. 3 is a diagram showing an audio frame and a sampling clock.

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5 is a diagram for explaining an example of synchronization of a plurality of streams.

FIG. 6 is a diagram showing a configuration example of an audio pack.

FIG. 7 is a view showing data contents of a pack header.

FIG. 8 is a view showing data contents of a packet header.

[Explanation of symbols]

 Reference Signs List 10: analog signal source 11, 41, 42: sampling unit 12, 43: quantization unit, 13: frequency conversion unit, 14, 44: phase matching unit, 15, 16, 45 ... framing unit, 17, 46 ... Packetizing part, 18 ... Disk, 21, 51 ... Packet processing part, 22, 23, 52 ... Frame processing part, 24 ... Phase matching part, 25 ... Frequency conversion part, 26 ... Digital-to-analog conversion part.

Claims (22)

[Claims] 1. A single stream is divided into a plurality of streams, and the scales of the signals of the plurality of streams are different. The scale is such that the total transmission rate of the transmission rates of the signals of the plurality of streams is: Scale processing is performed so as to satisfy a predetermined transmission rate, and between the signals of each stream, processing for correcting the phase shift between the signals of each stream caused by the scale processing is performed. And a multi-stream data recording medium on which a multi-stream subjected to this processing is recorded. 2. The multi-stream data recording medium according to claim 1, wherein the signals having different scales have different sampling frequencies, and the different frequencies have an integral multiple relationship. 3. Each of the signals has a high sampling frequency of 96 kHz and a low sampling frequency of 4 kHz.
3. The multi-stream data recording medium according to claim 2, wherein the frequency is 8 kHz. 4. The signal of the plurality of streams having different sampling frequencies is divided into frames, and the same presentation time information is added to frames that should be temporally identical between the streams. 3. The multi-stream data recording medium according to claim 2, wherein 5. The data recording medium according to claim 1, wherein said signal is a pulse code modulation signal. 6. A means for sampling a signal of a plurality of channels at a first frequency and quantizing the signal with a first quantization bit number, and a signal of a part of the quantized signals of each channel. Frequency conversion means for converting the frequency of the signal to a second frequency lower than the first frequency, and a signal of the remaining other channel different from the signal of the partial channel is delayed and output from the frequency conversion means. Phase matching means for performing phase matching with the signal of the set channel, and output means for outputting the signal output from the phase matching means as a first stream and the signal output from the frequency conversion means as a second stream. A transmission or recording device comprising: 7. A signal of a plurality of channels is sampled at a first frequency and quantized by a first quantization bit number. Frequency conversion to a second frequency lower than the first frequency, delaying a signal of the remaining other channel different from the signal of the some channels, and performing phase matching with the signal of the frequency-converted channel. An input unit into which a signal having the phase-matched signal as a first stream and a signal having the frequency-converted signal as a second stream is input; and a second frequency of a signal of the second stream. Frequency conversion means for returning to the first frequency, phase-matching means for delaying the first stream signal and performing phase matching with an output signal from the frequency conversion means, Data reproducing apparatus for multi-stream, characterized by comprising a means for outputting an output of the phasing means and digital-to-analog conversion. 8. The signal according to claim 7, wherein the signals of the first and second streams supplied to the input unit are either a reproduced signal from a recording medium or a signal from a transmission path. Data playback device. 9. A means for sampling a signal of some of the plurality of channels as a first stream, sampling at a first frequency, and quantizing with a first quantization bit number; The signal of the other channel is a second stream, and the second stream is lower than the first frequency.
Means for sampling at a frequency of 1 and quantizing with the first quantization bit number, and a phase for performing phase matching so that the quantized digital signals of the first and second streams match on a time axis. A transmission or recording apparatus comprising: a matching unit; and an output unit that outputs a digital signal output from the phase matching unit. 10. A signal of a part of the plurality of channels is used as a first stream, sampled at a first frequency, quantized by a first quantization bit number, and used for another of the plurality of channels. A channel signal as a second stream, sampled at a second frequency lower than the first frequency, quantized with the first quantization bit number, and the quantized first and second streams And an input unit to which the phase-matched digital signal is input, and a first digital-to-analog converter that converts the digital signal of the first stream from digital to analog. Conversion means, and second digital-to-analog conversion means for converting the digital signal of the second stream from digital to analog. Multi-stream data playback device. 11. The first and second signals supplied to the input unit.
13. The data reproducing apparatus according to claim 12, wherein the digital signal of the stream is either a reproduced signal from a recording medium or a signal from a transmission path. 12. A first stream for transmitting a multi-channel audio signal of a plurality of channels consisting of a main channel and a sub-channel to be recorded or transmitted to a recording medium or to a transmission path, and a second stream. , The signals of the two streams are sampled at a first sampling frequency and converted from analog to digital. The digital signal of the first stream is passed through a delay element, and the digital signal of the second stream is converted to the first signal. A multi-stream data which is converted from the sampling frequency of the first stream to a second sampling frequency lower than this frequency, the phases of the digital signals of the first and second streams are adjusted, and output as a recording signal or a transmission signal. Recording or transmission method. 13. A first stream and a second stream for recording a multi-channel audio signal of a plurality of channels consisting of a main channel and a sub-channel to be recorded or transmitted on a recording medium or transmitting it to a transmission path. , The signal of the first stream is sampled at the first sampling frequency, and is subjected to analog-to-digital conversion, and the signal of the second stream is sampled at the second sampling frequency lower than the first sampling frequency. ,
A multi-stream that performs analog-to-digital conversion, passes through a phase matching unit that performs phase matching between the digital signal of the first stream and the digital signal of the second stream, and then outputs the signal as a recording signal or a transmission signal. Data recording or transmission method. 14. A multi-channel audio signal of a plurality of channels consisting of a main channel and a sub-channel to be recorded or transmitted is sampled at a first sampling frequency so as to be recorded on a recording medium or transmitted to a transmission path. Channel of the first section as a first stream, and samples of a first sampling frequency of other channels are frequency-converted to a lower second sampling frequency to form a second stream, and a digital signal of the first stream is provided. And a signal as a recording signal or a transmission signal after passing through a phase matching unit that performs phase matching between the digital signal of the second stream and the digital signal of the second stream. The digital signal of the second stream, which is the second sampling frequency, is Convert back to the first sampling frequency, and digitize the first stream. Phase-matching the signal by delaying the time required for the frequency conversion, and performing digital-to-analog conversion on the phase-matched first stream digital signal and the frequency-converted second stream digital signal. Multi-stream data playback method. 15. A first stream and a second stream for recording a multi-channel audio signal of a plurality of channels including a main channel and a sub-channel to be recorded or transmitted on a recording medium or transmitting it to a transmission path. , The signal of the first stream is sampled at the first sampling frequency, and is subjected to analog-to-digital conversion, and the signal of the second stream is sampled at the second sampling frequency lower than the first sampling frequency. ,
The digital signal of the first stream and the digital signal of the second stream are passed through a phase matching unit that performs phase matching between the digital signal of the first stream and the digital signal of the second stream. A multi-stream data reproducing method, wherein a digital signal of a first stream of a sampling frequency and a digital signal of a second stream of the second sampling frequency are each converted into a digital signal and output. . 16. The method according to claim 15, wherein the first sampling frequency is an integral multiple of the second sampling frequency. 17. A single stream is divided into a plurality of streams, and the scale of the signals of the plurality of streams is made different. The scale is such that a total transmission rate obtained by summing the transmission rates of the signals of the plurality of streams is: Scale processing is performed so as to satisfy a predetermined transmission rate, and between the signals of each stream, processing for correcting the phase shift between the signals of each stream caused by the scale processing is performed. And an electronic medium having a multi-stream data structure subjected to this processing. 18. A multi-channel audio signal of a plurality of channels including a main channel and a sub-channel to be recorded or transmitted is sampled at a first sampling frequency in order to record on a recording medium or to transmit to a transmission path. Channel of the first section as a first stream, and samples of a first sampling frequency of other channels are frequency-converted to a lower second sampling frequency to form a second stream, and a digital signal of the first stream is provided. In order for the electronic device to execute a reproduction process of a signal as a recording signal or a transmission signal after passing through a phase matching unit that performs phase matching with the digital signal of the second stream, 2 to convert the digital signal of stream 2 back to the first sampling frequency, The digital signal of one stream is delayed by the time required for the frequency conversion to perform phase matching, and the digital signal of the first stream subjected to the phase conversion and the digital signal of the second stream subjected to the frequency conversion are subjected to digital / analog conversion. A recording medium on which a software program obtained as an application signal is recorded. 19. A first stream and a second stream for recording a multi-channel audio signal of a plurality of channels including a main channel and a sub-channel to be recorded or transmitted on a recording medium or transmitting the signal to a transmission path. , The signal of the first stream is sampled at the first sampling frequency, and is subjected to analog-to-digital conversion, and the signal of the second stream is sampled at the second sampling frequency lower than the first sampling frequency. ,
The digital signal of the first stream and the digital signal of the second stream are subjected to analog-to-digital conversion, and the digital signal of the second stream is passed through a phase matching unit. In order to execute the software, software for obtaining a digital signal of a first stream of the first sampling frequency and a digital signal of a second stream of the second sampling frequency as digital-to-analog conversion signals is recorded. A recording medium characterized by the above-mentioned. 20. A multi-channel audio signal comprising a plurality of main channels and sub-channels to be recorded or transmitted, which is sampled at a first sampling frequency in order to be recorded on a recording medium or transmitted to a transmission path. Channel of the first section as a first stream, and samples of a first sampling frequency of other channels are frequency-converted to a lower second sampling frequency to form a second stream, and a digital signal of the first stream is provided. Recording medium for recording a software program for performing phase matching between the digital signal of the second stream and the digital signal of the second stream. 21. A first stream and a second stream for recording a multi-channel audio signal of a plurality of channels consisting of a main channel and a sub-channel to be recorded or transmitted on a recording medium or transmitting it to a transmission path. And the signal of the first stream is sampled at a first sampling frequency and is used as an analog-to-digital conversion signal, and the signal of the second stream is sampled at a second sampling frequency lower than the first sampling frequency. Sampled and used as an analog-to-digital conversion signal,
Recording medium for recording a software program for performing phase matching between the digital signal of the second stream and the digital signal of the second stream. 22. One stream is divided into a plurality of streams, and the scale of the signals of the plurality of streams is made different depending on a difference in sampling frequency. This scale is a sum of the transmission rates of the signals of the plurality of streams. The scale processing is performed so that the total transmission rate thus obtained satisfies a predetermined transmission rate, and the phase shift between the signals of each stream caused by the scale processing occurs between the signals of each stream. Further, the signals of the plurality of streams having different sampling frequencies are divided into frame units, and the same presentation time information is added to the frames that should be temporally identical between the streams. In this way, synchronization between frames during playback can be obtained, and this processing is performed. A multi-stream data recording medium on which a recorded multi-stream is recorded.