JP2005026854A - Digital recording and reproducing device and reproduction rate control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the buffer of an MPEG (Motion Picture Experts Group) decoder from overflowing and underflowing by allowing reproduction at a reproduction rate coinciding with a recording rate even when a transport stream via a LAN (Local Area Network) is recorded. <P>SOLUTION: The I/F section 102 of a recording device extracts a PCR (Port Control Register) packet in the transport stream, acquires a PCR value, and obtains the number of packets between the PCR packets. The I/F section 102 of the recording device calculates the transfer rate of the transport stream from the number of packets and the PCR value between the PCR packets to prepare a management table describing the values, recording the values and the transport stream of contents to be recorded. In reproduction, controlling the reproduction rate by referring to the management table allows the reproduction at the reproduction rate coinciding with the recording rate. Thus, the buffer in a decoding section 111 is prevented from overflowing or underflowing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital recording / reproducing apparatus and a reproduction rate control method suitable for recording a transport stream received via a local area network or the like.
[0002]
[Prior art]
In recent years, digital broadcasting has been started, and apparatuses for recording digital broadcasting signals as bit streams have been commercialized. In digital broadcasting, the MPEG2 system is adopted. MPEG2 is designed to transmit transmission data in units of packets in order to facilitate time division multiplexing of a plurality of images, sounds, data, and the like. One packet is composed of the same type of data, and an identification signal indicating the type of data is added to each packet. In the MPEG2 standard, a signal is transmitted by a transport stream (TS) having a transport packet (TS packet) having a length of 188 bytes as a transmission unit.
[0003]
The digital recording device extracts and records a stream of a desired program from the transmitted transport stream. As such a digital recording apparatus, for example, there is an apparatus using a disk medium such as a hard disk as a recording medium.
[0004]
By the way, the MPEG2 stream employs a variable length code, and the code amount of the stream necessary for displaying the part differs for each part of the content. Therefore, even if it is transmitted at a fixed rate, the amount of code required to display the content at normal speed differs for each part of the content, and the MPEG decoder does not provide a buffer so that a stream overflow or underflow does not occur. It is necessary to prepare.
[0005]
When playing back a transport stream (MPEG2-TS) recorded on a recording medium such as a hard disk, the playback rate of the transport stream is controlled so that the MPEG decoder buffer does not overflow or underflow. However, it is necessary to send a transport stream to the MPEG decoder.
[0006]
For this control, conventionally, one of the following two methods has been adopted. That is, in the first method, when recording a transport stream, the digital recording / reproducing apparatus adds a time stamp as arrival time information to the head of each input TS packet. The digital recording / reproducing apparatus controls the transmission timing of each TS packet with reference to the added time stamp when reproducing and transferring to the MPEG decoder.
[0007]
On the other hand, in the second method, the digital recording / reproducing apparatus records the number of recorded packets and the recording time as management information at regular time intervals or at specific packet intervals when the transport stream is recorded. The digital recording / reproducing apparatus calculates the stream rate value based on the relationship between the number of recorded packets and the recording time, and controls the rate during reproduction.
[0008]
For example, Patent Document 1 discloses a method of storing a recording amount and time for each picture and calculating a bit rate for each picture from these data.
[0009]
However, these methods are based on the premise that a stream necessary for displaying content at a normal speed is transmitted (hereinafter referred to as real-time transmission) in accordance with the display of the content as a whole. That is, the digital recording / reproducing apparatus not only transmits in real time at the time of reproduction as described above, but also records the stream transmitted in real time at the time of recording. It becomes.
[0010]
For example, as in the case of directly receiving and recording a stream transmitted from a broadcasting station, the recording rate and the stream reproduction rate need to be the same.
[0011]
However, in recent years, it has been considered that a digital recording / reproducing apparatus is provided with a LAN (local area network) interface and the digital recording / reproducing apparatus records a stream transferred via the LAN. Such transfer of the stream via the LAN may not be real-time transmission. In this case, the playback rate cannot be controlled by the first or second method described above.
[0012]
[Patent Document 1]
JP 2002-185920 A
[0013]
[Problems to be solved by the invention]
As described above, in the conventional digital recording / reproducing apparatus described above, it is possible to control the reproduction rate without overflowing or underflowing the buffer of the MPEG decoder only when a stream transmitted in real time is recorded. When a stream that is not transmitted in real time, such as a stream, is recorded, the reproduction rate cannot be controlled.
[0014]
The present invention has been made in view of such problems, and provides a digital recording / reproducing apparatus and a reproduction rate control method capable of reliably controlling a reproduction rate even when a stream that is not transmitted in real time is recorded. The purpose is to do.
[0015]
[Means for Solving the Problems]
The digital recording / reproducing apparatus according to the present invention receives an encoded stream into which an encoded stream in which a plurality of contents are multiplexed and into which a packet including time information of the stream is inserted at a predetermined packet interval is input. Extracting means for separating and extracting an encoded stream of a predetermined content from the encoded stream; and time information detecting means for extracting the packet including the time information from the encoded stream extracted by the extracting means and detecting the time information A code amount detection unit for detecting a code amount of a stream between packets including the time information among the encoded streams extracted by the extraction unit; and the time information detected by the time information detection unit and the code amount detection unit Management table creation means for creating a management table including information on the code amount detected by the The extraction means Bull is obtained by including a recording means for recording with the extracted coded stream.
[0016]
In the present invention, a plurality of contents are multiplexed in the encoded stream, and the extraction means separates and extracts only the encoded stream of the predetermined content. A packet including time information in the extracted encoded stream is detected by the time information detection means. The code amount detection means detects the code amount of the stream between packets including time information. The stream transfer rate at the packet interval including the time information can be determined from the code amount of the stream between the packets including the time information and the time information detected from the packet including the time information. The management table creation means creates a management table including time information detected by the time information detection means and information on the code amount detected by the code amount detection means, and the recording means encodes the management table extracted by the extraction means. Record with stream. Thereby, at the time of reproduction, reproduction at a reproduction rate corresponding to the transfer rate at the time of recording, that is, the recording rate is enabled.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a digital recording / reproducing apparatus according to an embodiment of the present invention.
[0018]
In this embodiment, a recording amount and a PCR (Program Clock Reference) value are held for each PCR packet, and the bit rate for each PCR packet is calculated from these data, thereby enabling control of the reproduction rate. It is a thing.
[0019]
In FIG. 1, an MPEG2 standard transport stream is input to an input terminal 100. The transport stream corresponds to a multi-program, and a packet of a desired program can be selected from a plurality of programs transmitted in a time division manner at the time of decoding. For this selection, a transport packet (TS packet) is transmitted with a link level header (Link Level Header) added before a payload (Payload) for transmitting information. Of the 188 bytes of the transport packet, 4 bytes are a link level header.
[0020]
In the link level header, a synchronization byte (sync_byte) is arranged at the head, and thereafter, an error indicator (transport packed error indicator) indicating the presence or absence of a bit error, a unit start indication (PES packet start indicator) indicating the start of a PES packet, and a packet Transport packet priority indicating transport importance, packet identification information PID (packet identification), scrambling control indicating scramble (sport scrambling control), adaptation field control indicating payload, etc. field control) It constituted a cyclic counter that indicates the continuity of the PID (continuity counter) are sequentially arranged.
[0021]
The transport stream from the input terminal 100 is input to the recording device I / F unit 102 of the recording / reproducing unit 110. The recording / reproducing unit 110 includes an STC counter 101, a recording device I / F unit 102, and a recording medium 103. The recording device I / F unit 102 serving as an extraction unit demultiplexes the transport stream, extracts only the packets corresponding to the PID designated by the user, and outputs the packets. The output of the recording apparatus I / F unit 102 is a partial transport stream (partial transport stream), and this output is supplied to the recording medium 103. The recording device I / F unit 102 outputs the input transport stream as it is to the decoder unit 111 or outputs the reproduction stream from the recording medium 103 to the decoder unit 111.
[0022]
The recording medium 103 records a file composed of a partial transport stream demultiplexed by the recording device I / F unit 102. Only the desired program of the PID designated by the user is recorded on the recording medium 103.
[0023]
The decoding unit 111 includes a TS decoder 104, an STC counter 105, a video decoder 106, and an audio decoder 107. The TS decoding unit 104 depackets the stream input from the recording apparatus I / F unit 102 into section data, video, audio data, and the like.
[0024]
In the MPEG2 standard, each stream such as video data and audio data is transmitted by an elementary stream (ES). A header is added to the ES to form a PES (Peketized Elementary Stream Packet) packet. Since the PES packet is relatively large, it is transmitted by a plurality of transport packet payloads. The TS decoder 104 receives video and audio packets corresponding to the PID designated by the user, generates video and audio PES data from the payload data of the transport packet, gives the video PES data to the video decoder 106, and outputs the audio PES. Data is supplied to the audio decoder 107. The TS decoder 104 includes a buffer for temporarily storing the stream.
[0025]
Also, the TS decoder 104 outputs the PCR value described in the transport stream input from the recording device I / F unit 102 to the STC counter 105. The STC counter 105 reproduces the time clock on the transmission side based on the PCR. The STC counter 105 outputs the count value STC to the video and audio decoders 106 and 107.
[0026]
The video decoder 106 and the audio decoder 107 decode the input video packet and audio packet, respectively, and output the decoded video and audio signals to the outside. In this case, the video and audio decoders 106 and 107 compare the STC and time information in the stream, perform decoding time control, and realize a reproduction operation while synchronizing the video and audio.
[0027]
In the present embodiment, in the recording mode, the recording apparatus I / F unit 102 extracts a packet of a PID designated for recording based on a user operation, outputs a bit stream to the recording medium 103, and performs PCR. A packet is extracted to obtain a PCR value. In other words, the recording device I / F unit 102 serving as a time information detection unit, a code amount detection unit, and a management table creation unit creates management table data based on the acquired PCR values. Further, the recording device I / F unit 102 as a recording unit records the number of transport stream packets transferred to the recording medium in the management table every time the PCR packet is extracted. Then, the recording device I / F unit 102 calculates the rate value of the stream between the PCR packets from the difference value of the PCR between the PCR packets and the number of transfer packets between the PCR packets, and records it in the management table. It has become.
[0028]
FIG. 2 is an explanatory diagram showing an example of the management table.
[0029]
FIG. 2 shows the number of recorded packets, the PCR value, and the calculated bit rate. As described above, PCR packets are inserted at predetermined packet intervals, and their values provide a time reference on the transmission side. In the example of FIG. 2, the PCR packet is extracted at the fourth packet from the first packet record, and the PCR value is 0x3EBEC062. Then, the next PCR packet is extracted at the 476th packet from the first record, indicating that the PCR value is 0x3EBECAEC.
[0030]
The recording device I / F unit 102 calculates the transfer bit rate (recording rate) RATEn of the recording stream by the following equation (1).
[0031]
RATEn = (mn) × 188 × 8 / {(PCRm−PCRn) / 90k} (1)
Equation (1) indicates the stream rate value from the number n of transfer packets (record packets) to (m−1), and PCRm and PCRn are the PCR values of the packets with transfer numbers m and n, respectively.
[0032]
The recording apparatus I / F unit 102 describes the calculated recording stream rate value in pairs with the number of transfer packets and the PCR value for each PCR packet extraction. Then, the recording device I / F unit 102 is configured to record the created management table data on the recording medium 103.
[0033]
Furthermore, in the present embodiment, the recording device I / F unit 102 reads the management table at the time of reproduction, and outputs the reproduction stream to the decoding unit 111 at a transfer rate based on the description of the management table. Yes. In this case, the recording apparatus I / F unit 102 gives the PCR packet in the reproduction stream to the STC counter 101. The STC counter 101 reproduces the time clock on the transmission side with reference to the PCR, and gives the STC as the count value to the recording device I / F unit 102 so that the reproduction speed can be controlled. .
[0034]
Next, the operation of the embodiment configured as described above will be described with reference to the flowcharts of FIGS.
[0035]
First, the operation during recording will be described. FIG. 3 shows an operation flow during recording of the recording apparatus I / F unit 102.
[0036]
In step 201 of FIG. 3, the recording apparatus I / F unit 102 first determines whether or not the input packet input from the input terminal 100 matches a desired video PID to be recorded. Packets to be recorded include PCR packets and various control packets in addition to video and audio packets desired by the user.
[0037]
Step 201 is repeatedly executed until a packet to be recorded is input. In step 201, when the PID of the input packet matches the PID of the packet to be recorded, it is determined whether or not the next packet to be recorded has a PCR value, that is, whether it is a PCR packet (step). 202). If the packet to be recorded is not a PCR packet, the process proceeds to step 204 to transfer the packet to be recorded to the recording medium 103 for recording.
[0038]
If it is determined in step 202 that the packet to be recorded is a PCR packet, a management table is created / updated in step 203. That is, the recording device I / F unit 102 first records the PCR value in the management table data. Next, by this time, the number of transport stream packets transferred to the recording medium 103 is recorded in the management table data. Then, the rate value of the stream between PCR packets is calculated from the difference value of PCR between PCR packets and the number of transfer packets between PCR packets, and is recorded in the management table data.
[0039]
Next, in step 204, the recording apparatus I / F unit 102 transfers the PCR packet to the recording medium 103 for recording.
[0040]
Thus, in the present embodiment, at the time of recording, the bit rate (recording rate) of the transport stream to be recorded can be accurately obtained for each PCR packet transfer for each content to be recorded.
[0041]
Next, the operation during reproduction will be described. FIG. 4 shows an operation flow of the recording apparatus I / F unit 102 during reproduction.
[0042]
At the time of reproduction, the recording apparatus I / F unit 102 sets the stream rate value described in the management table as a reproduction rate value RATEplay that serves as a reference for reproduction, and a fixed rate (RATEout) that is larger than the maximum value of the reproduction rate value RATEplay. Then, the playback stream from the recording medium 103 is output to the decoding unit 111. Then, the recording apparatus I / F unit 102 controls the transfer of the reproduction packet at the fixed rate RATEout and the transfer of the null packet, and performs PCR so that the actual transfer rate matches the recording rate (reproduction rate value RATEplay). Control every packet.
[0043]
In step 401 in FIG. 4, the recording apparatus I / F unit 102 captures a packet (TS packet) reproduced from the recording medium 103. Next, in step 402, it is determined whether or not the fetched TS packet is a PCR packet (step 402). If it is determined in step 402 that the playback packet is a PCR packet, the recording device I / F unit 102 acquires the rate value RATEplay of the stream from this PCR packet to the next PCR packet from the management table (step 403). Thus, until the next PCR packet is input, reproduction / transfer using the read rate value RATEplay is performed. That is, in step 404, the recording apparatus I / F unit 102 initializes an internal variable γ used for rate control, which will be described later, to 0, and the packet determined to be a PCR packet in step 402 is the first PCR packet after starting reproduction. Whether or not (step 405).
[0044]
Assume that the packet determined to be a PCR packet is the first PCR packet after the start of reproduction. In this case, the recording apparatus I / F unit 102 holds the difference value between the STC counter value of the STC counter 101 and the PCR value of the PCR packet in the internal variable β (step 406), and decodes the PCR packet. 111 (step 407), and the process returns to step 401. The STC counter 101 outputs the count value STC to the recording apparatus I / F unit 102. Thereby, it is possible to determine whether or not the transfer timing of the PCR packet is appropriate at the time of subsequent reproduction of the PCR packet.
[0045]
That is, if the recording apparatus I / F unit 102 determines in step 405 that the packet is the second or subsequent PCR packet, the STC counter value of the STC counter 101 and the internal variable β (hereinafter also referred to as a difference value β). It is determined whether or not the value obtained by adding) is larger than the PCR value of this PCR packet (step 408). When the sum of the count value STC and the internal variable β is smaller than the PCR value of the regenerated PCR packet, the time given by the regenerated PCR packet is later than the time given by the count value STC. Thus, it can be determined that this PCR packet has not reached the transfer time.
[0046]
That is, if the count value (STC101) + difference value β of the STC counter 101 is smaller than the PCR value of the PCR packet in step 408, the recording apparatus I / F unit 102 still has time to transfer this PCR packet. It is determined that it is not, the null packet is transferred to the decoding unit 111 (step 409), and the process returns to step 408.
[0047]
On the other hand, if it is determined in step 408 that the STC101 + difference value β is larger than the PCR value of the PCR packet to be determined, the time to be transferred for this PCR packet has passed. The I / F unit 102 rewrites the PCR value with the sum of the STC counter value of the STC counter 101 and the difference value β in order to reduce the jitter of the PCR value, and then transfers the PCR packet to the decoding unit 111. (Step 410), the process returns to Step 401.
[0048]
If the TS packet reproduced from the recording medium 103 is a packet other than the PCR packet, the process proceeds from step 402 to step 411, and the reproduction rate RATEplay and output rate of the stream in the current section recorded in the management table. Packet transfer control is performed using RATEout.
[0049]
That is, first, a value obtained by adding the internal variable γ of the initial value 0 and the stream rate RATEplay is held in the internal variable γ (step 411), and it is determined whether the internal variable γ is larger than the output rate RATEout (step 411). 412).
[0050]
If the recording apparatus I / F unit 102 determines in step 412 that the internal variable γ is smaller than the output rate RATEout, the recording device I / F unit 102 transfers a null packet to the decoding unit 111 in order to keep the stream rate at RATEplay ( In step 413), the process returns to step 411.
[0051]
On the other hand, when it is determined in step 412 that the internal variable γ is larger than the output rate RATEout, the recording apparatus I / F unit 102 holds the difference value between the internal variable γ and the output rate RATEout in the internal variable γ ( Step 414), the packet acquired in Step 401 is transferred to the TS decoding unit 104 (Step 415), and the process returns to Step 401.
[0052]
By repeating the above operation, the playback stream can be output to the decoding unit 111 at a rate corresponding to the playback rate of the recorded stream.
[0053]
With respect to the decoding unit 111, a case where the transport stream input via the input terminal 100 is decoded as it is to view the content, and a case where the stream reproduced from the recording medium 103 is decoded and the content is viewed Both perform the same operation.
[0054]
The TS decoder 104 generates video and audio PES data based on payload data of a plurality of transport packets from the input reproduction packet. Video PES data is supplied to the video decoder 106, and audio PES data is supplied to the audio decoder 107. On the other hand, the STC counter 105 is provided with the PCR separated and extracted by the TS decoder 104. When the input packet first matches the PID of the PCR, the value is loaded into the STC counter 105 and the counter value is set. The STC counter 105 obtains an STC serving as a time clock, and outputs this STC to the video decoder 106 and the audio decoder 107.
[0055]
The video decoder 106 and the audio decoder 107 decode the input video and audio PES data by controlling the decoding time based on the time information in the input stream and the STC. The audio signal from the audio decoder 107 is supplied to a speaker (not shown), and the audio signal from the video decoder 106 is supplied to a monitor (not shown). In this way, the content reproduced from the recording medium 103 can be viewed.
[0056]
A decoding packet is input to the decoding unit 111 by real-time transmission in which a reproduction stream is transmitted at the same rate as when recording, and the buffer in the TS decoder 104 does not overflow or underflow.
[0057]
As described above, in this embodiment, PCR is referred to when a stream is recorded, the rate value between PCR packets is calculated from the PCR difference value and the number of recorded packets, and management data in which the stream rate value is recorded is created. As a result, it is possible to control the stream rate with reference to the rate value of the management data when the stream is played back.
[0058]
The information necessary to obtain the stream rate value is only the PCR value and the number of recorded packets. Therefore, not only when the broadcast signal is recorded in real time, but also when the broadcast signal is recorded in non-real time via the LAN. It is possible to create management data in which stream rate values are recorded, and perform real-time transmission during playback.
[0059]
Also, the management data recording the stream rate value does not necessarily have to be performed when the stream is recorded. For example, with respect to a stream that has already been recorded, the number of PCR packets and the difference value between the PCRs may be analyzed to create management data that records the stream rate value.
[0060]
【The invention's effect】
As described above, according to the present invention, even when a stream that is not transmitted in real time is recorded, the reproduction rate can be reliably controlled.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a digital recording / reproducing apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing an example of a management table.
FIG. 3 is a flowchart for explaining the operation of the embodiment;
FIG. 4 is a flowchart for explaining the operation of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 ... STC counter, 102 ... Recording apparatus I / F part, 103 ... Recording medium, 110 ... Recording / reproducing part, 111 ... Decoding part

Claims (6)

An encoded stream in which a plurality of contents are multiplexed and into which a packet including time information of the stream is inserted at a predetermined packet interval is input, and the encoded stream of the predetermined content is input from the input encoded stream Extraction means for separating and extracting
Time information detecting means for extracting the packet including the time information from the encoded stream extracted by the extracting means and detecting the time information;
A code amount detection unit for detecting a code amount of a stream between packets including the time information among the encoded streams extracted by the extraction unit;
A management table creating means for creating a management table including the time information detected by the time information detecting means and the information of the code amount detected by the code amount detecting means;
A digital recording / reproducing apparatus comprising: recording means for recording the management table together with the encoded stream extracted by the extracting means. Extraction means for separating and extracting a transport stream of predetermined content from a transport stream in which a plurality of contents are multiplexed;
Time information detection means for extracting a PCR packet from the transport stream extracted by the extraction means and detecting a PCR value;
Code amount detection means for detecting the code amount of a stream between PCR packets in the transport stream extracted by the extraction means;
A management table creating means for creating a management table including information on the PCR value detected by the time information detecting means and the code amount detected by the code amount detecting means;
A digital recording / reproducing apparatus comprising: recording means for recording the management table together with the transport stream extracted by the extracting means. 3. The digital recording / reproducing apparatus according to claim 1, wherein the code amount detection means uses the number of packets in the stream as the code amount. Further comprising transfer rate calculation means for calculating the transfer rate of the stream extracted by the extraction means based on the time information detected by the time information detection means and the code amount information detected by the code amount detection means;
3. The digital recording / reproducing apparatus according to claim 1, wherein the management table creating unit creates a management table including information on the transfer rate calculated by the transfer rate calculating unit. 5. The reproduction apparatus according to claim 1, further comprising reproduction means for performing reproduction control at a reproduction rate based on information in the management table created by the management table creation means when playing back the stream recorded by the recording means. A digital recording / reproducing apparatus according to any one of the above. An encoded stream in which a plurality of contents are multiplexed and into which a packet including time information of the stream is inserted at a predetermined packet interval is input, and the encoded stream of the predetermined content is input from the input encoded stream Extraction procedure to separate and extract,
A time information detection procedure for detecting the time information by extracting a packet including the time information from the encoded stream extracted by the extraction procedure;
A code amount detection procedure for detecting a code amount of a stream between packets including the time information among the encoded streams extracted by the extraction procedure;
A management table creation procedure for creating a management table including information on the time information detected by the time information detection procedure and the code amount detected by the code amount detection procedure;
A recording procedure for recording the management table together with the encoded stream extracted by the extraction procedure;
A playback rate control method comprising: a playback procedure for controlling playback of a stream recorded in the recording procedure at a playback rate based on information in the management table created in the management table creation procedure.

Images