JP3641051B2 - Packetized data processing apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a packetized data processing apparatus and method for appropriately processing a desired packet when various types of packetized data arrive together.
[0002]
[Prior art]
In recent years, when data transmission or data recording / reproduction is performed, data is compressed and transmitted, or recording / reproduction is performed. Conventionally, when a data compression standard is determined, data transmission, data recording, and reproduction are performed based on the compression standard. However, recently, with the advancement of transmission technology and the spread of product distribution channels, various standards of compressed data and encoded data have been mixed nearby.
[0003]
[Problems to be solved by the invention]
In order to obtain the various data as described above, it is burdensome for the user to prepare an individual decoder according to each standard.
Therefore, according to the present invention, main data divided by a frame having a data length that does not conform to the data length standard of the data portion constituting the packet serving as a basic packet for transmission or recording / playback is allocated to the data portion of the packet. Even so, an object of the present invention is to provide a packetized data processing apparatus and method which can reliably obtain the synchronization state of the main data and can effectively use the packets.
[0004]
It is an object of the present invention to provide a packetized data processing apparatus and method capable of reliably obtaining frame synchronization of the audio data when the main data of the packet is audio data of a linear PCM system in particular. .
[0005]
[Means for Solving the Problems]
According to the present invention, one packet includes a header part and a data part, and main data is allocated to each data part of the packet sequence of such a packet, and the frame length of the main data is different from the data part length. There is a case where the main data for one frame is arranged across packets, and the header portion includes a first indicating the start of the main data frame in the packet in which the header portion exists. An access unit pointer is included, and a presentation time stamp indicating when the main data in the packet is output from the memory is included, and an input unit to which the packet string is input, and the first access pointer From the time of detection to the time of detecting the next first access pointer The main data amount detecting means for measuring the main data amount, the frame length information holding means for acquiring in advance information indicating the frame length of the main data, and the main data amount obtained by the data amount detecting means are the frame length information. It is determined whether it is an integer multiple of the data amount corresponding to the frame length obtained by the holding means. If it is an integer multiple, the main data is determined to be continuous, and if it is not an integer multiple, the main data Is determined to be discontinuous, and if the determination result of the determination means is the continuity, reading of the memory is continued, and if it is discontinuous, the presentation time stamp and the internal reference time Resynchronizing means for setting the time when reading from the memory is started when a match with the information is obtained .
[0006]
According to the present invention, one packet includes a header part and a data part, and main data is allocated to each data part of the packet sequence of such a packet. The frame length of the main data is the data part length. The main data for one frame may be arranged across different packets with different frame lengths, and the header portion indicates the start of the frame of the main data in the packet in which the header portion exists A first access unit pointer is included, and a presentation time stamp indicating when the main data in the packet is output from the memory is included, and the step of capturing the packet sequence, processing the packet sequence, From the time when the first access pointer is detected, the next first access pointer is detected. Measuring the amount of main data up to the point of detecting the data, obtaining in advance frame length information indicating the frame length of one frame of the main data, and the amount of main data corresponding to the frame length information Determining whether the data amount is an integer multiple, and determining that the main data is continuous if it is an integer multiple, and determining that the main data is discontinuous if it is not an integer multiple; When the determination result of the determination step is the continuity, the reading of the memory is continued, and when the determination result is discontinuous, the time when the presentation time stamp matches the internal reference time information is obtained. A step of starting reading from the memory.
[0007]
By the above means and steps, the main data is divided into frames having a data length that does not conform to the data length standard of the data portion constituting the basic packet for transmission or recording / reproduction, and the data portion of the packet is Even if it is assigned, the packet can be used effectively by ensuring the synchronization state of the main data.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a packetized data processing apparatus according to an embodiment of the present invention. Specifically, the packetized data processing apparatus is incorporated in an optical disk reproducing apparatus. FIG. 2 shows an example of a packet sequence of audio data recorded on an optical disc played back by an optical disc playback apparatus.
[0009]
The processing apparatus of FIG. 1 will be described. A packet sequence is supplied to the input terminal 11. This packet sequence is picked up and demodulated from an optical disc, for example, and one packet corresponds to one pack, and one pack includes an audio pack, a video pack, a sub-picture pack, a control information pack, and the like. Is input to the input terminal 11 in a time-sharing manner. These pack sequences are separated by audio packet, video packet, sub-picture packet, and control information packet with reference to the packet header in the data separation unit 12.
[0010]
Here, the packet sequence will be described with reference to FIG.
FIG. 2 shows a data sequence in which an audio signal is modulated by the linear PCM method, and shows frame-based main data and packet-based data in which this frame-based main data is allocated to the data portion of the packet sequence. .
[0011]
Looking at the packet structure, one packet is composed of a header part and a data part. Main data is allocated to each data portion of the packet sequence of such a packet. Here, the frame length of the main data is a frame length different from the data length of the data portion, and there is a case where the main data for one frame is arranged across the packets. In the example of the figure, the frame F3 and the frame F4 are arranged across the packets.
[0012]
The header portion includes a first access unit pinter indicating the start of the main data frame of the data portion in the packet in which the header portion exists, and information related to the main data frame length (audio data information). Audio data information).
[0013]
The first access unit pointer indicates the start position of the main data in the packet by the data count number. Therefore, in the example of FIG. 2, the packet PCK1 indicates the start position of the frame F2, and the packet PCK2 indicates the start position of the frame F4. In the case of PCK3, the start position of the frame F5 is shown.
[0014]
The audio data information indicates the number of quantization bits of the main data, the number of samples in the packet, the frequency, and the like, and the amount of data (frame length) in the frame can be obtained by calculating such information.
[0015]
In addition, a presentation time stamp (PTS) is described in the header portion, and this PTS indicates time information to be output by decoding main data in the packet. This PTS is compared with the clock information in the playback apparatus, and when they match, the data output of the frame corresponding to the PTS is executed. The clock information is obtained from a counter in the apparatus, and this counter is reset or timed by the time stamp of the control information packet included in the reproduction packet and outputs absolute time information.
[0016]
Returning to FIG.
The audio packet is supplied to a first access unit pointer extraction unit 21 and a data count start unit 22 that constitute the main data amount detection unit 20. The data number count output from the data number count start unit 22 is input to the data number count end unit 23. The pointer extraction unit 21 counts the number of data according to the content of the first access unit pointer, and outputs a pointer signal when the main data frame start position of the packet is reached, and the reset terminal and the data number of the data number count start unit 22 This is given to the latch input terminal of the count end unit 23. Accordingly, the data count start unit 22 counts the data amount of F2 of the packet PCK1 and F3 straddling to the PCK2, for example, as illustrated in the example of FIG.
[0017]
The data number count end unit 23 latches the output data of the data number count start unit 22 when a pointer signal is given from the pointer extraction unit 21. Therefore, the data number counting end unit 23 obtains a numerical value A that is an integral multiple of the data amount of one frame of main data.
[0018]
On the other hand, the audio packet is supplied to an audio data information extraction unit 31 constituting a frame length detection unit 30 that obtains the frame length of the main data. The audio data information extraction unit 31 extracts the audio data information described in FIG. 2 and supplies it to the frame length information output unit 32. The frame length information output unit 32 calculates the frame length (data amount) for one frame and outputs the frame length information B.
[0019]
The numerical value A which is an integral multiple of the data amount of one frame of main data output from the data count counting unit 23 and the frame length information B of one frame output from the frame length information output unit 32 are determined. It is input to the continuous state determination unit 40 as a means.
[0020]
The continuous state determination unit 40 determines whether or not the main data amount obtained by the data amount detection unit 20 is an integer multiple of the data amount corresponding to the frame length obtained by the frame length detection unit 30. If there is, the main data is determined to be continuous, and if it is not an integer, it is determined that the main data is discontinuous and the determination output is obtained.
[0021]
When the continuity of the main data is determined using the data amount, the count value A of data that is an integral multiple of one frame is output from the data count counting unit 23, and the frame length information output unit 32 A count value B of data for one frame is output. At this time, the continuous state determination unit 40 determines that there is continuity when A / B is divisible by a predetermined error range. Of course, there is also continuity when A / B is divisible correctly.
[0022]
In addition, the continuity of the main data can be determined using the timing pulse. In this case, the count value A is counted with a stable clock to obtain a timing pulse A1 that has been counted. This pulse is obtained at a period of 1 / integer multiple of the frame period of the main data. On the other hand, the frame length information output 32 outputs a pulse B1 of one frame period by operating a counter based on the audio data information and in synchronization with the packet header. Here, the continuous state determination unit 40 can determine whether the main data has continuity by determining whether the timings of the pulse A1 and the pulse B1 match or are maintained in a predetermined phase relationship. .
[0023]
The reason for determining whether there is continuity of the main data as described above is as follows.
That is, when the packet sequence is recorded on a recording medium, it may be partially lost due to scratches or pride. In addition, some parts may be lost due to disturbance when transmitted. In such a case, since the data is not reliable, it is necessary to display or discard the fact. In the case of audio data, if the missing part is reproduced as it is, it is output as noise. Therefore, it is possible to detect the loss and perform the mute process.
[0024]
In the embodiment described above, it is determined whether or not the main data is continuous. If a determination output indicating that the main data is discontinuous is obtained, it is possible that the audio and video that can be reproduced are out of synchronization. Therefore, it is necessary to re-synchronize audio packets in synchronization with the absolute time.
[0025]
In FIG. 3, the output timing of the audio information is corrected in order to obtain synchronization between the decoded output of the video information and the sub-picture information and the decoded output of the audio information using the above-described continuous / discontinuous determination output. The device is shown.
[0026]
That is, the audio packet separated by the data separation unit 12 is input to the continuity determination unit 100 and also input to the PTS detection unit 52 via the switch 51. The PTS detector 52 detects the presentation time stamp and supplies it to one input terminal of the comparator 53. Count information and absolute reference time information from the time stamp counter 54 are input to the other input terminal of the comparator 53. The time stamp counter 54 generates continuous reference time information as a reference in the apparatus based on time information (presentation time stamp) included in the control information.
[0027]
When the reference time information matches the PTS from the PTS detection unit 52, the comparator 53 outputs the matching pulse to the FIFO memory unit 55. In the FIFO memory unit 55, main data (audio data) is detected and written in units of frames by the frame detection unit 56. Main data and frame unit information of the data (data count value indicating a frame delimiter, that is, an integer multiple of the frame data number) are supplied from the frame detection unit 56 to the FIFO memory unit 55. Here, when a coincidence pulse is given from the comparator 53, data reading is started from the head of the frame based on the frame unit information. As a result, the audio data is output as data synchronized with the reference time in the apparatus, and can be synchronized with the video.
[0028]
Here, the continuity determination unit 100 is the determination unit described with reference to FIG. 1 and obtains a determination output as to whether or not the frames of main data that are audio data are continuous. This determination output is used to turn on / off the switch 51. Normally, the switch 51 is turned off when the frames are continuous. At this time, the main data that has passed through the frame detection unit 56 is written into the FIFO memory unit 55 and read out at a predetermined data rate.
[0029]
However, when the continuity determination unit 100 detects discontinuity of the main data, the switch 51 is turned on. Then, the PTS is read again, and the main data is controlled to synchronize with the reference time in a predetermined relationship. This operation is executed for a certain period or until a predetermined number of coincidence pulses are obtained from the comparator 53, for example.
[0030]
Therefore, in this case, the FIFO memory unit 55 includes a memory control unit including a function for determining a coincidence pulse and counting a predetermined number of times, and a memory control function for performing automatic writing and reading affected by the coincidence pulse when the predetermined number of times is counted. It shall be included. The memory control unit receives the frame synchronization signal from the frame detection unit 56, performs writing / reading in units of frames, and manages the write / read addresses and data in units of frames. Thereby, reading can be started in units of frames when the previous coincidence pulse is obtained.
[0031]
FIG. 4 shows a specific configuration example of the frame detection unit 56 described above.
The audio packet separated by the data separation unit 12 is supplied to the first access unit pointer extraction unit 21, the audio data information extraction unit 31, and the data count start unit 22. The output of the data count start unit 22 is input to the frame synchronization detection unit 61. The frame synchronization detection unit 61 may be substantially the same as the data count counting unit 23 shown in FIG.
[0032]
An imming signal indicating the start timing of the main data frame in the packet is supplied from the first access unit pointer extraction unit 21 to the data count start unit 22 and the frame synchronization detection unit 61, respectively. As a result, the frame synchronization detection unit 61 latches the data count number at the frame break. This count value is an integral multiple of the frame length (the number of frame data).
[0033]
The output of the previous audio data information extraction unit 31 is supplied to the frame length information extraction unit 32. The audio data information extraction unit 31 extracts the audio data information described in FIG. 2 and supplies it to the frame length information output unit 32. The frame length information output unit 32 calculates the frame length (data amount) for one frame and outputs the frame length information. This frame length information is supplied to the window generator 62. The window generation unit 62 generates a frame period window pulse using the frame length information (the number of data for one frame).
[0034]
At the timing of this window pulse, the previous count value is output as a frame synchronization signal.
The memory control unit that uses the frame synchronization signal performs the following use, for example. When writing main data to the FIFO memory 55, if the frame synchronization signal indicates a count value that is an integral multiple of the data value for one frame, the write start address of the memory is reset to a predetermined address. This is because a lot of data is written in the FIFO memory 55. On the contrary, when the frame synchronization signal is equal to a specific value, for example, a data value for one frame, the current write address is incremented to be written continuously. This is because there is a margin even if data is continuously written in the memory 55.
[0035]
When the frame synchronization signal indicates a count value that is an integer multiple of the data value for one frame, for example, referring to FIG. 2, the count of the data number (F2, F3 minutes) is terminated until F4 of the packet PCK2. Next, immediately before the data count of F4 is newly started. When the frame synchronization signal is equal to a specific value, for example, the data value for one frame, it is immediately before the count of the number of data of F4 is finished and the data count of F5 of the packet PCK3 is newly started.
[0036]
FIG. 5 shows another embodiment of the present invention.
In the embodiment of FIG. 3, a switch 57 is further added. The switch 57 is a switch that determines whether or not to use the frame continuity / discontinuity determination signal output from the continuity determination unit 100. The other parts are the same as those in the embodiment of FIG. 3, so the same reference numerals as those in FIG. In the case of this embodiment, for example, in the optical disc playback apparatus, whether the video pack and the audio pack are recorded on the optical disc being played back, or whether only the audio pack is described Is identified by the system control unit 58. This identification can be easily performed by the system control unit 58 reading and determining the control information pack (see FIG. 1). The system control unit 58 outputs a control signal for turning on and off the switch 57. If the optical disc being played back records only audio, the switch 57 is turned off.
[0037]
This is because, according to this embodiment, when a disc on which only audio is recorded is reproduced, it is not necessary to establish frame synchronization. This is because if the frame synchronization is taken when data is lost, the sound breaks off, and especially in the case of music, the sound breaks off. In such a case, it is preferable to attenuate the audio output when discontinuity is detected or to perform a muting process. On the other hand, when playing back an optical disc on which video and audio are recorded, if the audio is delayed and the video and timing do not meet, the video is unnatural and it is unnatural. It is better to process.
[0038]
FIG. 6 further shows the internal configuration of the FIFO memory unit 55.
Data is supplied to the memory unit 211. The address generation unit 212 generates a write address and a read address and supplies them to the memory unit 211. Here, the state of the write address is monitored by the fixed amount capture detection unit 213. Then, the fixed amount capturing detection unit 213 detects the fact that a predetermined amount or more of data has been captured in the memory unit 211 and then performs a reading process. The reason for this control is that if data is read out due to a predetermined write / read time when input data is missing, repeated underflow may occur in the output buffer and the audio may be harsh. Because. This process is effective when only the audio information is recorded and the disc is reproduced.
[0039]
In the above description, the frame length (data amount) for one frame is transmitted while being included in the header portion, and there is a dedicated frame length detection portion. However, the frame length information may be recorded in the management information area of the disc, and may be grasped and held by the system control unit as control information at the start of disc playback. If the disc to be played back or the incoming signal is known, it may be stored in advance accordingly.
[0040]
In the above description, an example in which the present invention is applied to an optical disk reproducing apparatus has been described. However, the recording medium may be a signal from various media such as a magnetic disk and a magnetic tape, and may be wireless or wired. It can also be used sufficiently for packet elementary streams sent through the transmission path.
[0041]
That is, as shown in FIG. 7, a recording signal is picked up by a pickup 63 from a medium such as an optical disk (magnetic disk) 61 or a magnetic tape 62, and a signal demodulated by a demodulator 64 is packetized data as described above. In some cases, the present invention can be applied effectively. The separation unit 65 separates the packet and supplies it to the decoder 66. The decoder 66 does not include a FIFO memory as described above. The packet is input to the continuity processing unit 67. The continuity processing unit 67 is a part that performs continuity / discontinuity determination as described above, and performs PTS re-acquisition.
[0042]
Furthermore, the present invention is not limited to the above-described embodiment, and various modifications can be made. Of course, the blocks shown in FIGS. 1 and 3 to 6 may be configured as software processing blocks by using a plurality of digital signal processors.
[0043]
【The invention's effect】
As described above, according to the present invention, the main data divided by the frames having the data length that does not conform to the data length standard of the data portion constituting the basic packet for transmission or recording / reproduction is the above-mentioned Even if it is assigned to the data portion of the packet, the synchronization state of the main data is reliably obtained so that the packet can be used effectively.
[0044]
Also, the present invention ensures that frame synchronization of the audio data can be reliably obtained when the main data of the packet is particularly audio data of linear PCM system.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a packet elementary stream according to the present invention.
FIG. 3 is a diagram showing another embodiment of the present invention.
FIG. 4 is a view showing still another embodiment of the present invention.
FIG. 5 is a view showing still another embodiment of the present invention.
FIG. 6 is a diagram showing another embodiment of the memory unit according to the present invention.
FIG. 7 is a diagram showing an application example of the present invention.
[Explanation of symbols]
12: Data separation unit,
21 ... First access unit pointer extraction unit 22 ... Data number count start unit 23 ... Data number count end unit 31 ... Audio data information extraction unit 32 ... Frame length information extraction unit 40 ... Continuous state determination units 51, 57 ... Switch 52 ... PTS Capture unit 53... Comparator 54. Time stamp counter 55... FIFO memory unit 56... Frame detection unit 58... System control unit 100 ... Continuous determination unit 61. Frame synchronization detection unit 62.

Claims (8)

One packet is composed of a header part and a data part, and main data is allocated to each data part of the packet sequence of such a packet, and the frame length of the main data is different from the data part length. In some cases, one frame of main data is arranged across packets, and the header portion includes a first access unit pointer that indicates the start of the main data frame in the packet in which the header portion exists. A presentation time stamp indicating when the main data in the packet is output from the memory,
An input unit to which the packet sequence is input;
Main data amount detecting means for measuring the amount of main data from the time when the first access pointer is detected to the time when the next first access pointer is detected;
Frame length information holding means for acquiring in advance information indicating the frame length of the main data;
It is determined whether the main data amount obtained by the main data amount detection means is an integer multiple of the data amount corresponding to the frame length obtained by the frame length information holding means. Is determined to be continuous, and when it is not an integer multiple, a determination means for determining that the main data is discontinuous;
When the determination result of the determination means is the continuity, reading of the memory is continued, and when the determination result is discontinuous, the time when the presentation time stamp matches the internal reference time information is obtained. And a resynchronizing means for starting reading from the packetized data processing apparatus. One packet is composed of a header part and a data part, and main data is allocated to each data part of the packet sequence of such a packet, and the frame length of the main data is different from the data part length. The main data for one frame may be arranged across packets, and the header part includes a first access unit pointer indicating the start of the frame of the main data in the packet in which the header part exists. , Including information indicating the frame length of the main data, and including a presentation time stamp indicating the time when the main data in the packet is output from the memory,
An input unit to which the packet sequence is input;
Main data amount detecting means for measuring the amount of main data from the time when the first access pointer is detected to the time when the next first access pointer is detected;
Frame length detection means for obtaining the frame length of the main data included in the packet sequence of the input unit using information indicating the frame length of the main data;
The main amount of data obtained in the main data amount detecting means determines whether an integer multiple of the data amount corresponding to a frame length obtained by the frame length detecting means, wherein the main data if the integral multiple If it is determined that there is continuity and is not an integer multiple, determination means for determining that the main data is discontinuous;
When the determination result of the determination means is the continuity, reading of the memory is continued, and when the determination result is discontinuous, the time when the presentation time stamp matches the internal reference time information is obtained. And a resynchronizing means for starting reading from the packetized data processing apparatus.   The packetized data processing apparatus according to claim 1 or 2, wherein the packet sequence includes a packet sequence related to audio and a packet sequence related to video, and the main data is data related to audio. . The packet sequence includes a packet sequence related to audio and a packet sequence related to video,
3. The packetized data processing apparatus according to claim 1, further comprising means for stopping the determination operation of the determination means when only the packet sequence relating to the audio is supplied to the input unit. The packet sequence includes a packet sequence related to audio and a packet sequence related to video,
When the memory for storing the main data of the packet sequence related to the audio and whether or not a certain amount or more of the main data is captured are determined and it is determined that a certain amount or more is captured 3. The packetized data processing apparatus according to claim 1, further comprising: means for reading data in the memory only. The packet sequence includes a packet sequence related to audio and a packet sequence related to video,
3. The packetized data processing according to claim 1, further comprising means for turning on the determination means when the packet sequence related to audio and the packet sequence related to video are supplied to the input unit. apparatus. The packet sequence includes a packet sequence related to audio and a packet sequence related to video,
3. The packetized data processing apparatus according to claim 1, wherein the data portion of the packet sequence related to audio is linear PCM audio data. One packet is composed of a header part and a data part, and main data is allocated to each data part of the packet sequence of such a packet, and the frame length of the main data is different from the data part length. In some cases, one frame of main data is arranged across packets, and the header portion includes a first access unit pointer that indicates the start of the main data frame in the packet in which the header portion exists. A presentation time stamp indicating when the main data in the packet is output from the memory,
Capturing the packet sequence;
Processing the packet sequence and measuring the amount of main data from the time when the first access pointer is detected to the time when the next first access pointer is detected;
Obtaining in advance frame length information indicating a frame length of one frame of the main data;
It is determined whether the main data amount is an integer multiple of the data amount corresponding to the frame length information. If the main data amount is an integer multiple, the main data is determined to be continuous. Determining that the main data is discontinuous;
When the determination result of the determination step is the continuity, the reading of the memory is continued, and when the determination result is discontinuous, the time when the presentation time stamp matches the internal reference time information is obtained. A method for processing packetized data, comprising: a step of starting reading from a packet.

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