JP2003196933A - Device for reproducing compressedly encoded sound data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reproducing device for compressedly encoded sound data capable of reproducing a recording medium on which compressedly encoded sound data divided in a frame unit are made a packet for recording so as to be able to quickly reproduce sound to eliminate sound cut off in a normal reproduction mode, in switching sound streams, in a special reproduction mode, or the like. <P>SOLUTION: In decoding compressedly encoded sound data read from a recording medium 18 in a frame unit, the compressedly encoded sound data are supplied to the same decoding circuit 22 in a frame unit in making a change between a normal reproduction mode and a special reproduction mode for the compressedly encoded sound data, or between the normal reproduction mode for the compressedly encoded sound data and a plurality of streams. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing apparatus for reproducing compression-encoded audio data from a recording medium such as an optical disc on which packetized compression-encoded audio data is recorded.

[0002]

As is well known, in recent years, not only audio data but also moving image data can be compressed and recorded on an optical disk having a diameter of 12 cm, which is the same as an audio CD (compact disk). ing. An example of this type of optical disc is a CD-ROM (Read Only Memory).
y) etc. are widespread in a wide range of fields from educational to karaoke.

FIG. 6 shows an optical disc of this type,
Of the compression-encoded audio data A and the moving image data V,
The physical recording format is shown. That is, the audio data A and the moving image data V are separated in units called sectors S, which are physical reference data amounts. Then, each sector S is recorded on the optical disc as a data stream DS in which each sector is arranged in a time division manner.

Here, each sector S is composed of a header area HA and a data area DA. Among them, in the header area HA, various management information for indicating the type of data recorded in the data area DA and the like is recorded. Also, in the data area DA, compression-coded audio data, moving image data, and the like are recorded.

On the other hand, at present, only about 2 hours of moving image data corresponding to a movie and voice data of eight different languages are compression-encoded and recorded at high density on an optical disc having the same diameter as a CD. In addition, an optical disc known as a DVD (Digital Video Disk), which can record sub-picture data representing subtitles in 32 different languages, has also been developed.

In the case of this DVD, compression-coded audio data and moving image data are divided into units called packets corresponding to the above-mentioned sectors. And
Each packet is recorded on the optical disc as a data stream in which each packet is arranged in a time division manner. Also,
Like each sector, each packet is composed of a header area and a data area.

FIG. 7 shows a plurality (two in the illustrated case) of voice packets AP in which compression-encoded voice data is recorded.
1 and AP2 are shown. These voice packets AP1,
AP2 is composed of a header area PHA and a voice data area ADA. Of these, the packet header area P
Various management information for indicating the type of data recorded in the audio data area ADA is recorded in the HA.

Further, in the audio data area ADA, compression-encoded audio data is divided and recorded in units called frames. And each frame is
Each includes a synchronization signal and compression-coded audio data sampled within a unit time.

Here, the compression-encoded voice data is restored to the original voice data by detecting a synchronization signal during reproduction and performing a decoding process in frame units. The length of one frame is 24 msec in the MPEG standard and 32 in the AC-3 standard when the sampling frequency of the compression-encoded audio data is 48 kHz.
It becomes msec.

FIG. 8 shows a means for detecting a synchronization signal for each frame from this compression-coded audio data. That is, the bit stream of the compression-encoded audio data supplied to the input terminal 1 is directly extracted from the output terminal 2 and used for decoding, and is also supplied to the synchronization pattern detection circuit 3 and the frame length information extraction circuit 4, respectively. Supplied.

Of these, the synchronization pattern detection circuit 3 detects the pattern of the synchronization signal from the input bit stream, and outputs the detected synchronization signal to the frame synchronization detection circuit 5. This frame synchronization detection circuit 5
When the window signal output from the synchronization window generation circuit 6 is in the open state, the synchronization signal output from the synchronization pattern detection circuit 3 is determined to be a normal frame synchronization signal and is output to the output terminal 7, and It is output to the frame length information extraction circuit 4.

The frame length information extraction circuit 4 extracts the frame length information contained in the frame from the bit stream based on the frame synchronization signal output from the frame synchronization detection circuit 5, and the extracted frame length. The information is output to the frame length determination circuit 8. The frame length discriminating circuit 8 discriminates the frame length based on the input frame length information and outputs the discriminating signal to the synchronization window generating circuit 6. Then, this synchronization window generation circuit 6
On the basis of the input discrimination signal, it generates a window signal that is in an open state at the expected position of generation of the synchronization signal of each frame, and outputs it to the frame synchronization detection circuit 5.

FIG. 9 shows the relationship between the bit stream of the compression coded audio data, the sync signal detected by the sync pattern detection circuit 3 and the window signal output from the sync window generation circuit 6. As shown in FIG. 9, a sync signal is detected by the sync pattern detection circuit 3 at the beginning of each frame in the bit stream, and when the sync signal is detected, the sync window generation circuit 6 outputs the sync signal. The state in which the open window signal is in the open state (high level) indicates that synchronization is achieved.

By the way, as described above, the compression-encoded voice data is divided into frame units, and the voice packet AP
When recording in the audio data area ADA of 1 and AP2, it is rare that exactly one or an integral multiple of the number of frames is exactly recorded in the audio data area ADA without waste. That is.

Therefore, the capacity of the audio data area ADA,
As a result, in order to use the capacity of the optical disk without waste, one frame K + 1 is used as indicated by the diagonal lines in FIG.
Needs to be divided into two voice packets AP1 and AP2 and recorded. However, if one frame is divided into two audio packets AP1 and AP2 and recorded in this way, it takes a few frames of reproduction time to detect a synchronization signal during reproduction of audio data. There are problems such as breaks.

Further, since a maximum of eight audio streams can be recorded on the above-mentioned DVD, sound breaks will occur even when streams are switched, that is, when languages are switched. Furthermore, even during special reproduction such as high-speed reproduction, audio packets are not continuously read out, resulting in sound interruption.

[0017]

As described above, in the conventional means for packetizing compression-encoded voice data divided into frame units, one frame is divided into two in order not to waste the voice packet capacity. Since the audio packets are divided and recorded into one audio packet, there is a problem that sound interruption occurs during normal reproduction, switching of audio streams, special reproduction, and the like.

Therefore, the present invention has been made in consideration of the above circumstances, and it is possible to quickly reproduce sound and eliminate sound interruption during normal reproduction, switching of audio streams, special reproduction, and the like. Another object of the present invention is to provide a very good reproduction apparatus for compressed coded audio data, which can reproduce a recording medium in which compressed coded audio data divided into frame units is packetized and recorded.

[0019]

In the reproducing apparatus for compression-coded audio data according to the present invention, one sector having a fixed length, which is a physical reference data amount, is set as one packet, and is decompressible in a frame unit. The compression-encoded voice data is packetized, and the compression-encoded voice data is recorded from a recording medium in which a packet sequence in which each packet is completed by one or an integral multiple of the number of frames is recorded. A reproducing apparatus for reproducing, which includes demodulation means for demodulating data read from a recording medium, signal processing means for performing error correction processing on data from the demodulation means, and one or a number of frames from the packet. A separation unit for extracting and separating and extracting in frame units; and a decoding unit for decoding the compression-coded audio data obtained from the separation unit in frame units, The issue unit, the normal reproduction of the compressed encoded audio data and at the time of trick play, the compression-encoded audio data in frames is that configured to be supplied.

Further, the compression-encoded audio data reproducing apparatus according to the present invention compresses a plurality of streams which are decompressible in frame units, with one fixed-length sector, which is a physical reference data amount, as one packet. Packetized encoded audio data, and compressed encoded audio data is reproduced from a recording medium on which a packet sequence in which each packet is completed by one or an integral multiple of frames is recorded. Which is a reproducing apparatus for demodulating data read from a recording medium, signal processing means for error-correcting data from the demodulating means, and one or an integral multiple of frames from a packet. A separating means for separating and extracting in frame units, and a decoding means for decoding the compression-encoded audio data obtained from the separating means in frame units. For example, the decoding means, when switching between the normal reproduction and multiple streams of compressed encoded audio data,
This is configured so that compression-encoded audio data is supplied in units of frames.

According to the above configuration, when the compression-coded audio data read from the recording medium is decoded on a frame-by-frame basis, the compression-coded audio data is switched between normal reproduction and special reproduction, or The compressed coded audio data is supplied to the same decoding means frame by frame at the time of normal reproduction of the compressed coded audio data and switching between a plurality of streams.

Thus, when switching between normal playback and special playback, or switching between normal playback and audio stream, it is possible to quickly play back audio and eliminate sound interruption. It is possible to reproduce the recording medium on which the compression-coded audio data divided into units is packetized and recorded.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings. That is, FIG.
Shows the structure of the voice packet AP11. The voice packet AP11 is composed of a packet header area PHA and a voice data area ADA. this house,
The packet header area PHA includes a voice data area ADA.
Various management information for indicating the type of data recorded in is recorded.

Further, in the audio data area ADA, compression-encoded audio data is divided and recorded in units called frames. In this case, one audio data area ADA is set so that one or an integral multiple of the number of frames is recorded exactly exactly and without waste. That is, one audio data area ADA is 1
One or an integer multiple of the number of frames is set to be completed.

By setting the voice data area ADA of the voice packet AP11 in this way, one frame is divided into two voice packets and is not recorded as in the conventional case, so that it takes time to detect the synchronization signal. As a result, it becomes possible to quickly reproduce audio during normal reproduction, switching of audio streams, special reproduction, and the like, and it is possible to prevent sound interruption.

When the packet length of the voice packet AP11 is fixed, additional data is attached to the voice packet AP11. FIG. 2 shows an example in which a padding packet PP is provided as additional data. In addition, FIG.
An example in which a stuffing ST is provided as additional data is shown.

That is, in FIG. 2, voice packet A
P11 is a packet header area PHA and an audio data area A completed by one or an integral multiple of frames.
It is composed of DA and is adjusted by the padding packet PP so that the amount of data obtained by adding the voice packet AP11 and the padding packet PP is fixed.

Further, in FIG. 3, voice packet AP1
1 comprises a voice data area ADA completed by one or an integral multiple of the number of frames and a packet header area PHA to which a stuffing ST is added, and the stuffing S is set so that the voice packet AP11 has a fixed length.
I try to adjust it with T.

In the above-mentioned MPEG standard, a voice packet requires 8 bytes or more. Therefore, if the additional data is 8 bytes or more, the padding packet PP is used, and if the additional data is 7 bytes or less, the padding packet PP is used. It would be good to use the stuffing ST.

Next, FIG. 4 shows a recording means for packetizing the compression-encoded audio data in frame units as described above and recording it on a recording medium such as an optical disk. That is, the analog audio signal supplied to the input terminal 11 is supplied to the A / D (analog / digital) conversion circuit 12 and converted into digital audio data, and then output to the compression circuit 13.

The compression circuit 13 performs high-efficiency compression encoding processing on the input digital audio data in accordance with the regulations such as AC-3, and packs the obtained compression encoded audio data in frame units. Is output to. The packing circuit 14 packetizes the compression-coded voice data input in frame units together with the header data output from the header addition circuit 15 to generate a voice packet AP11 as shown in FIG.

When packetizing a fixed length, the packing circuit 14 adds the additional data such as the padding packet PP and the stuffing ST to generate the voice packet AP11 shown in FIG. 2 and FIG. ing.

The voice packet AP11 generated by the packing circuit 14 is supplied to the signal processing circuit 16 and is subjected to error correction parity addition processing.
It is output to the modulation circuit 17. The modulation circuit 17 performs a modulation process suitable for recording on the recording medium 18 with respect to the input data, and supplies the data to the recording medium 18. As the recording medium 18, various media such as an optical disc, a magnetic disc, a magnetic tape, and a semiconductor memory can be used.

Next, FIG. 5 shows a reproducing means for reading out the compression-encoded audio data packetized and recorded in the recording medium 18 as described above from the recording medium 18 and reproducing it. That is, the data read from the recording medium 18 is demodulated by the demodulation circuit 19, supplied to the signal processing circuit 20, subjected to error correction processing, and then output to the separation circuit 21.

The separating circuit 21 separates the header data and the compression-coded audio data from the packetized data. When the packetized data has additional data such as padding packet PP or stuffing ST, the separation circuit 21 also removes the additional data. The compression-coded audio data separated by the separation circuit 21 is supplied to the decoding circuit 22 in frame units.

Since compression-encoded audio data is supplied to the decoding circuit 22 in units of frames at any time, including during special reproduction, it is not necessary to carry out frame synchronization capture processing, and it is input as it is. Decompression processing is applied to compression-encoded voice data. Then, the digital audio data decoded by the decoding circuit 22 is D / A
After being converted into the original analog audio signal by the (digital / analog) conversion circuit 23, it is amplified by the amplification circuit 24 and taken out from the output terminal 25.

The present invention is not limited to the above-described embodiments, but can be variously modified and implemented without departing from the scope of the invention.

[0038]

As described above in detail, according to the present invention,
During normal playback, switching of audio streams, special playback, etc., compression-coded audio data divided into frame units was recorded in packets so that audio can be played back quickly and sound interruptions can be eliminated. It is possible to provide a very good compression-encoded audio data reproducing device capable of reproducing a recording medium.

[Brief description of drawings]

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

FIG. 2 is a view showing a modified example of the same embodiment.

FIG. 3 is a diagram showing another modification of the same embodiment.

FIG. 4 is a block configuration diagram showing a recording unit of compression-encoded audio data according to the first embodiment.

FIG. 5 is a block configuration diagram showing a reproducing means of the compression-encoded audio data in the embodiment.

FIG. 6 is a diagram showing a physical recording format of compression-coded audio data and moving image data on an optical disc.

FIG. 7 is a diagram showing a relationship between voice packets and frames in the same recording format.

FIG. 8 is a block configuration diagram showing means for detecting a synchronization signal from the same frame.

FIG. 9 is a timing chart shown for explaining the operation of the synchronization detecting means.

[Explanation of symbols]

11 ... Input terminal, 12 ... A / D conversion circuit, 13 ... compression circuit, 14 ... packing circuit, 15 ... Header addition circuit, 16 ... Signal processing circuit, 17 ... Modulation circuit, 18 ... recording medium, 19 ... Demodulation circuit, 20 ... Signal processing circuit, 21 ... Separation circuit, 22 ... Decoding circuit, 23 ... D / A conversion circuit, 24 ... Amplifying circuit, 25 ... Output terminal.

Claims (12)

[Claims] 1. A fixed length 1 which is a physical reference data amount.
Sectors are defined as one packet, and compression-encoded audio data that is decompressible in frame units is packetized, and each packet is completed by one or an integral multiple of the number of frames. A reproducing apparatus for reproducing the compression-encoded audio data from a recording medium in which a packet sequence is recorded, the demodulating means for demodulating the data read from the recording medium, and the error correction processing for the data from the demodulating means. A signal processing unit; a separating unit that extracts the one or an integer multiple of the frames from the packet and separates and extracts them in frame units; and a decoding process of the compression-coded audio data obtained from the separating unit in frame units. And a decoding unit for performing the frame unit during normal reproduction and special reproduction of the compression-encoded audio data. In playback apparatus of the compression-encoded audio data, wherein the compression-encoded audio data is configured to be supplied. 2. The packet has a header and compression-encoded audio data, the separating unit separates the header and the compression-encoded audio data, and the separated compression-encoded audio data is sent to the decoding unit. The compression-encoded audio data reproducing apparatus according to claim 1, wherein the reproducing apparatus supplies the compression-encoded audio data. 3. The compression-encoded audio data according to claim 2, wherein the separating means removes additional data such as padding packets and stuffing when the packet contains the additional data. Playback device. 4. The additional data is attached to the packet when the additional data is 8 bytes or more, and the additional data is attached in the packet when the additional data is 7 bytes or less. 4. The reproducing apparatus for compressed and encoded audio data according to claim 3, wherein 5. The reproduction apparatus for compressed and encoded audio data according to claim 2, wherein the header records management information of the compressed and encoded audio data. 6. The reproduction apparatus for compressed and encoded audio data according to claim 2, wherein the header records information indicating a type of the encoded and encoded audio data. 7. A fixed length 1 which is a physical reference data amount.
Sectors are defined as one packet, and compression-encoded audio data of multiple streams compressed so that decoding is possible in frame units is packetized, and each packet is completed by one or an integral multiple of that number of frames. A reproduction device for reproducing the compression-encoded audio data from a recording medium in which a packet sequence is recorded, the demodulation means for demodulating the data read from the recording medium, and the data from the demodulation means having an error. Signal processing means for performing correction processing; separation means for extracting the one or an integer multiple of frames from the packet and separating and extracting in frame units; and compression-coded audio data obtained by the separation means in frame units And a decoding means for performing a decoding process according to the above-mentioned method. When switching over beam, the reproducing apparatus of the compression-encoded audio data, wherein the compression-encoded audio data in the frame unit is characterized by being configured to be supplied. 8. The packet has a header and compression-encoded audio data, the separation means separates the header and the compression-encoded audio data, and the separated compression-encoded audio data is sent to the decoding means. The reproducing apparatus for compressed and encoded audio data according to claim 7, wherein the reproducing apparatus supplies the compressed and encoded audio data. 9. The compression-encoded audio data according to claim 8, wherein the separating means removes additional data such as padding packets and stuffing when the packet contains the additional data. Playback device. 10. The additional data is attached to the packet when the additional data is 8 bytes or more, and the additional data is attached to the packet when the additional data is 7 bytes or less. 10. The reproducing apparatus for compressed and encoded audio data according to claim 9, wherein. 11. The reproduction apparatus for compressed and encoded audio data according to claim 7, wherein the header records management information of the compressed and encoded audio data. 12. The reproducing apparatus for compressed and encoded audio data according to claim 7, wherein the header records information indicating a type of the encoded and encoded audio data.