JP2008092391A - Recording stream generating method and reproducing method thereof, recording device, and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate a recording stream suitable to simultaneous recording to a disk device and capable of having jitters suppressed when reproduced from a stream received from a transmission line on which reception time of a packet is randomly delayed behind transmission time and a stream received from a transmission line where no delay is generated. <P>SOLUTION: A recording stream generating method includes: receiving a first stream for a first transmission line; generating reference time for the recording stream from the detection timing of a packet as a constitution unit thereof; receiving a second stream for a second transmission line; correcting intervals of a packet string to the time series when transmitted according to transmission time included in the packet as the constitution unit thereof and the reference time; and multiplexing the first stream and the second stream having been corrected in the order of detection time of respective packet strings. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording stream generating method, a reproducing method thereof, a recording and reproducing apparatus.

  A recorder device has been developed that receives a digital broadcast that employs MPEG2-TS (Transport Stream) as a video and audio transmission method, records it on a disk recording medium, and reproduces the original video and audio information. On the other hand, recent recorder devices have connection interfaces with various external devices. For example, there are a serial interface that connects recorder devices one-to-one, and a LAN (Local Area Network) interface that enables connection to a network network to which a plurality of devices are connected. TCP (Transmission Control Protocol) and UDP (User Data Gram Protocol) are examples of communication protocols for data transmission between devices connected to a network. For transmission of video and audio information such as MPEG2-TS, it is important to transmit and receive data without interruption. Therefore, UDP is used which has less overhead during transmission and reception. See, for example, Non-Patent Document 1 for the recording method of MPEG2-TS on a disk recording medium, and refer to Non-Patent Document 2, for example, for UDP.

Nikkei Electronics 2003.7.21, pp.127-129 Nikkei Network 2002.4, pp.68-69

  Sources to be recorded in recorder equipment include not only digital broadcasts and received streams from external equipment connected to equipment on a one-to-one basis, but also transmission streams from network-connected equipment. It is expected to be used.

  When a stream transmitted via a network is congested with data transmission / reception on the network or via a network with a narrow transmission band, the reception time is chronologically related to the transmission time of the packets making up the stream. Randomly delays and causes jitter (problems such as unnatural video reproduction and inability to synchronize video and audio due to deviation in decoding time) when decoding the received stream.

  On the other hand, as a method for realizing multi-stream recording, there is a method of time-division multiplexing in units of packets constituting a stream for a plurality of channels according to the MPEG2-TS format. When multiplexing streams that are transmitted in digital broadcasting or the like that do not cause delays, when packets are time-division multiplexed and recorded as they are, jitter occurs at the time of playback stream switching, and smooth switching cannot be performed. There is.

  Accordingly, an object of the present invention is to provide a recording stream generation method, a playback method thereof, a recording and playback device, which solve the above-mentioned problems.

  A method for generating a recording stream that solves the above problem is to receive a first stream for a first transmission path, generate a reference time for the recording stream from a detection timing of a packet that is a constituent unit, and perform a second transmission. The second stream for the path is received, the transmission time included in the packet that is the structural unit, and the reference time, the interval of the packet sequence is corrected so as to be a time series at the time of transmission, the first stream, The problem is solved by multiplexing the packet streams in the order of detection times for the corrected second stream.

  In addition, the configuration of the recording apparatus that solves the above-described problem includes at least a first stream receiving unit for the first transmission path and a time generating unit that generates a reference time for the recording stream from the detection timing of the packet that is the unit A second stream receiving means for the second transmission line, a buffer means for temporarily holding the packet as its constituent unit, a timing generating means for generating an output timing for the packet sequence held in the buffer means, a first stream , Characterized in that there is provided a means for multiplexing each packet sequence for the second stream output from the buffer means, the timing generation means, from the transmission time included in the packets constituting the second stream and the reference time, The output timing is such that the packet sequence output from the buffer means becomes the time series interval at the time of sequence transmission. This can be solved by configuring a recording device that generates the recording.

  According to the present invention, it is possible to generate a recording stream suitable for simultaneous recording, and it is possible to suppress jitter that occurs when switching streams during reproduction.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a first embodiment of a recording stream generating method and reproducing method, recording and reproducing apparatus according to the present invention. In the figure, 1 is a transmission / reception unit that controls data transmission / reception between a plurality of devices connected on a network such as a LAN and this device according to the TCP / UDP communication protocol, and 2 is a transmission / reception unit on the network, TCP or UDP. A header analysis unit that analyzes information contained in the header part that constitutes the packet, 3 is a TS buffer that stores a TS (Transport Stream) packet sequence that is contained in the payload that constitutes the received UDP packet, and 4 is a header From the difference between the transmission time detected by the analysis unit 2 and the reference time in the device, it occurs during transmission through the network, and detects the delay that occurs between the packet sequence at the time of transmission and the packet sequence at the time of reception, Based on this, the timing generator 5 generates the output timing for the TS buffer 3, 5 receives the digital broadcast, and generates a full TS in which TS packet sequences for multiple channels are multiplexed. The broadcast receiving unit 6 is a TS selection unit that extracts a partial TS that is a packet sequence that includes only TS packets for the purpose of recording, playback, and 7 for the full TS, and 7 is output from the TS buffer 3. Control the time division multiplexing of the received packet sequence and the partial TS, further multiplex the time stamp for each packet sequence to be multiplexed, and the TS multiplexing unit for generating a recording stream, 8 generates the reference time in the device, In accordance with the detection timing of the partial TS in the TS selection unit 6 and the output timing to the TS buffer 3, a time generation unit that generates a time stamp for each packet sequence to be multiplexed, 9 is a data selection unit, 10 is a generated recording stream A write buffer 11 to be stored is a disk device corresponding to a magnetic disk device or an optical disk device.

  A recording stream generation method performed in the apparatus of FIG. 1 will be described with reference to FIGS. First, referring to FIG. 2, the full TS output from the broadcast receiving unit 5 and the partial TS generated by the TS selecting unit 6 will be described. Fig. 2 (a) shows PES packetization for video and audio streams (V1 ES, A1 ES) that have been compression-encoded for video and audio. These PES packets are further divided into 188-byte segments for video and audio. TS packets are generated by time division multiplexing of TS packets. FIG. 2B shows an example of a full TS, and shows generation of a full TS by time-division multiplexing TS packets for a plurality of channels (channels 1 and 2). In the full TS, TS packets including program (program) information and PSI for channels 1 and 2 are also multiplexed. The number of multiplexed channels can be multiplexed up to the maximum transfer rate that can be transmitted on the broadcast network. The broadcast receiving unit 5 performs a decoding process on the transmission signal from the broadcast network and outputs a full TS. FIG. 2C is an explanatory diagram of a partial TS output from the TS selection unit 6 and shows extraction of TS packets (V1, A1) for channel 1 as an example. On the other hand, in the TS selection unit 6, the program information is also included in the partial TS, corrected to only the program information for the selected channel 1 (PSI1), and multiplexed into the partial TS.

  Next, in FIG. 3, the structure of the transmission packet transmitted through the network and received by the transmission / reception unit 1, the storage of the packet sequence in the TS buffer 3, and the output of the packet sequence according to the output timing from the timing generation unit 4 The control will be described. FIGS. 3A and 3B show configuration examples of TCP packets and UDP packets, which are communication units on the network. In Fig. 3 (a) and (b), each packet contains information used for data transmission control according to the IP packet header, TCP, and UDP communication protocols given as individual address information for each device connected to the network. It consists of a stored TCP packet header, UDP packet header, and payload for storing transmission data. A plurality of TS packets are stored in the payload of a UDP packet suitable for video and audio stream transmission. For example, a plurality of TS packets including PSI generated by the method described in FIGS. 2 (a) and 2 (c) are stored. In addition, a sequence number is provided as a means for confirming the loss of UDP packets during transmission. The header analyzer 2 checks the sequence number every time a UDP packet is received and detects the loss of the packet by detecting the missing number. To do. On the other hand, the UDP packet to be transmitted including the TS packet passes through the network traffic congestion state or the narrow bandwidth network network, so that the UDP packet sequence of the device side is different from the UDP packet sequence of the transmission side device. There may be a random delay between the two. In this case, jitter occurs when video and audio information is decoded for the TS packet sequence transmitted by the received UDP packet. A transmission time is added to the header portion of the UDF packet for the purpose of detecting a delay occurring in transmission / reception of such a packet sequence.

  FIG. 3 (c) is an example for explaining the occurrence of a random delay when a UDP packet is transmitted through a network, and the payload (from the TS buffer 3 is corrected for the received UDP packet sequence while correcting the delay. An example of timing control in which a plurality of TS packet sequences) are output and the packet intervals at the time of transmission are time-sequentially shown. In the figure, the transmission delay in a network where a sufficient transmission band is secured for convenience is assumed to be zero.

In order to correct the delay of the received packet sequence, the read timing of the received packet sequence stored from the TS buffer 3 is controlled and output so as to be time-sequentially spaced from the packet sequence at the time of transmission. The timing for controlling the output is generated by comparing the transmission time generated by the timing generation unit 4 and detected by the header analysis unit 2 with the reference time of the entire apparatus generated by the time generation unit 8. In the figure, for example, the transmission times of UDP packets U3 and U4 at the time of transmission are t5 and t7, respectively, but the times at the time of reception are t6 and t10, respectively, and Δt (Δt is a unit in time series) Time), Δt × 2 delay occurs. The timing generation unit 4 generates an output timing for correcting a delay for each packet.
The delay correction method will be described in detail. In the figure, for example, within the finite range of U1 and U8 where the transmission / reception time difference is 0, the reception of U4 is based on U4 with the maximum time difference (Δt × 2) The TS buffer 3 output delay Δt × n (n is a positive integer) with respect to time is corrected by delaying U1 and U8 with a time difference of 0 by Δt × (n + 2). Similarly, U2, U3, U5, U6, and U7 are delayed by Δt × (n + 1) based on U4. In addition, when packet reception with a time difference of 0 is not performed for a long time, the maximum time difference is detected, for example, until the reception of a packet with a time difference of 1 or within the range of packet strings that can be stored in the TS buffer, and the output timing Can also be generated.

  On the other hand, the time stamp generated by the time generation unit 8 and the time stamp for the output of the TS buffer 3 adopts the time corresponding to the output timing, so that it is delayed from the time at the time of packet transmission by the time required for delay correction by the TS buffer. In the figure, t1 ′ after Δt × (n + 2) delay corresponds to the packet transmitted and received at time t1. However, the packet sequence at the time of reception is the same interval in time series as the packet sequence at the time of transmission.

  Further, in FIG. 4, the TS packet output from the TS buffer 3, the TS multiplexing of the partial TS, and the multiplexing of the time stamp generated by the time generation unit 8 will be described. The time generation unit 8 multiplexes the time information corresponding to the output timing of the TS buffer 3 and the detection timing of TS packets constituting the partial TS. In the example of FIG. 4, the output timing of the TS buffer 3 and the partial TS are output in the time series shown in the figure, but each TS packet multiplexed in the TS multiplexing unit 7 is multiplexed so as to correspond to the time stamp, and the disk device 11 A recording stream for is generated. A time stamp for a common time series is given to packet sequences received from different transmission paths. When the recorded stream generated by the method described above is played back, the reference time synchronization process accompanying the switching of the playback stream is easily performed in the middle, and the disturbance of video and audio at the time of switching is suppressed. The generated recording stream is transferred to the write buffer 10 and transferred to the disk device 11 and recorded for each writing unit (sector).

  In FIG. 4, when the TS buffer 3 output and the time stamp for the partial TS are the same time, one common time stamp is given, but even at the same time, a time stamp is given to each TS packet from each transmission path. It is also possible.

  Further, the data selection unit 9 selects transmission / reception unit 1 and header analysis unit 2 to directly transfer the data for the payload to the write buffer 10 in the case of TCP packet detection, and TS multiplexing unit in the case of UDP packet detection. Select the recording stream from 7. Also for the TS multiplexing unit 7, a source to be multiplexed can be selected. By controlling the multiplex selection signal, the TS buffer 3 output or the selection of only the partial TS and the generation of the multiplex stream are controlled. The time stamp is also added according to the selection of the TS multiplexing unit 7 according to the selection status.

  The TS selection unit 6 performs conversion from a full TS to a partial TS for recording / playback channels. However, it is possible that the number of selectable channels is plural or the full TS is output to the TS multiplexing unit 7 as it is. . Also in this case, time stamps are generated and multiplexed according to the detection timing of the selected TS packet.

  In the TS multiplexing unit 7, the streams to be multiplexed are limited so as to be equal to or lower than the transfer rate to the disk device 11. For example, when full TS recording occupies the vicinity of the upper limit of the transfer rate, it is conceivable that the transmission / reception unit 1 restricts reception from the network, or the TS multiplexing unit 7 does not perform multiplexing.

  The apparatus of FIG. 1 can also support recording of a recording stream in which streams from a plurality of devices connected to a network are transmitted in a time division multiplexed manner. The header analysis unit 2 in FIG. 1 detects the packet transmission time for each stream from the analysis of the transmission packet header for each of the plurality of streams A and B, and the TS buffer 3 stores the packets for the streams A and B. The timing generation unit generates a buffer output timing for each stream, thereby absorbing a random delay generated when each stream is received, and correcting the original time series interval. Subsequent processing is the same as that of the first embodiment, and a description thereof is omitted.

  FIG. 5 is a block diagram showing an embodiment of the recording stream generating method and reproducing method, recording and reproducing apparatus of the present invention. The description of the constituent elements corresponding to the reference numerals overlapping with those in FIG. 1 is omitted. Reference numeral 11 denotes a disk recording device in which a stream based on the recording stream generation method described in the first embodiment is recorded. For example, a TS of multiple channels transmitted via the broadcast network and the network described in FIG. Packets and time stamps are recorded. 12 is a read buffer for temporarily accumulating the recording stream reproduced from the disk device 11, 13 is identification and separation of multiple channel streams included in the recording stream, and time stamp detection for each multiplexed TS packet Stream identifiers 14 and 15 are stream buffers A and B for temporarily accumulating TS packets for each channel separated by the stream identifier 13, and two channels are provided here as an example. 16 is an output selection unit that selects an output destination for the two-channel streams A and B, and 17 is a stream that decodes video and audio to the output TS packet from the output selection unit 16 and outputs it to a display, a speaker, etc. A decoding unit 18 is a packet generation unit that performs UDP packetization by adding a TS packet from the output selection unit 16, a transmission time, and the like. See Figure 3 (b) for UDP packets.

  A reproduction method performed in the apparatus of FIG. 5 will be described with reference to FIG. 5 and 6, the read buffer 12 stores data for the playback stream from the disk device 11 in the format of FIG. 6 (a). The playback stream is based on the recording stream generation method shown in FIGS. In response to the playback stream output from the read buffer 12, the stream identification unit 13 separates streams A and B while identifying TS packets included in the playback stream, and stores them in the stream buffers A and B, respectively. FIG. 6B shows TS packets stored in the stream buffers A and B, and the streams U1 to U8 and T1 to T9 multiplexed when the recording stream is generated are separated. On the other hand, time stamps (t1 ′ to t5 ′, t7 ′, t10 ′ to t14 ′, t17 ′ to t18 ′) that are multiplexed in the reproduction stream and are the packet reproduction times of each channel are also detected. The timing generation unit 4 generates a reference time in the apparatus of FIG. 5 according to the detected time stamp, and also generates output timings A and B for the stream buffers A and B. FIG. 6 (c) shows the output of the stream buffers A and B at the output timings A and B in time series, and TS packets for the streams A and B separated by the time with respect to the detected time stamp are output. .

  On the other hand, the stream identification unit converts the multiplexed stream into a single stream and transfers the stream to the write buffer 10 as a cache stream. For example, a TS packet and a time stamp for stream A are output as a cache stream. The disk device records the cache stream accumulated in the write buffer 10 between recording stream transfers to the read buffer 12. Conversion from a multiple stream to a single stream is performed using reproduction of a recording stream. There may be a case where a plurality of write buffers 10 are provided, and conversion to a plurality of single streams and recording on a disk device may be considered. The recording of the cache stream is not limited to the apparatus configuration of FIG. 5, and it may be supplied to a separately provided disk device and write buffer.

  Each stream output in a time-series manner according to the detected time stamp is output to the transfer destination via the output selection unit 16. For example, the stream B is output to the stream decoding unit 17, in which the payload constituting the TS packet is detected, PES header analysis, video and audio ES are restored, decompressed, and output to the display and the speaker. On the other hand, the stream A is output to the packet generation unit 18, and the packet generation unit configures the TS packets constituting the stream A in a plurality of units as a UDP packet payload and generates a UDP packet header. The transmission time included in the UDP packet header is generated based on time information for the output timing A. Finally, the stream A is transmitted to the receiving device in the transmission / reception unit 1 via the network.

  Note that the read buffer 12 shown in FIG. 5 may be shared with the write buffer shown in FIG. 1, and the stream buffer may be a single buffer. Considering the case where output timings A and B occur simultaneously for the stream buffer, buffer access is time-divided and assigned to multiple channels, and the TS packet output for multiple channels is completed within the basic time Δt of the time stamp. It is also possible to use a speed buffer.

  In addition, when the playback stream is transmitted to the network, it is conceivable that the playback stream is directly transferred from the read buffer 12 to the packet generation unit 18, or the single stream detected by the stream identification unit and the time stamp for the stream are transferred. . In this case, it is considered that data is handled instead of a stream transmitted at time series intervals according to the time stamp, and a TCP packet is generated and transmitted.

FIG. 3 is an explanatory diagram of a recording apparatus according to the present invention. Explanatory drawing of full TS and partial TS generation in a broadcasting network. Explanatory drawing about the structure of the transmission unit of a network, and the delay at the time of reception. Explanatory drawing of recording stream production | generation. Explanatory drawing of the reproducing | regenerating apparatus with respect to the produced | generated recording stream. Explanatory drawing of the process performed before stream reproduction | regeneration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transmission / reception part, 2 ... Header analysis part, 3 ... TS buffer, 4 ... Timing generation part, 5 ... Broadcast reception part, 6 ... TS selection part, 7 ... TS multiplexing part, 8 ... Time generation part, 9 ... Data selection , 10 ... Write buffer, 11 ... Disk device, 12 ... Read buffer, 13 ... Stream identification unit, 14 ... Stream buffer A, 15 ... Stream buffer B, 16 ... Output selection unit, 17 ... Stream decoding unit, 18 ... Packet Generator.

Claims (10)

A recording stream suitable for recording on a recording medium is generated from a stream that is received via a first transmission path in which random time-series delay does not occur in packet transmission units and a second transmission path in which delay occurs. A method,
The first stream for the first transmission path is received, and the reference time for the recording stream is generated from the detection timing of the packet that is the structural unit,
The second stream for the second transmission path is received, the transmission time included in the packet that is the structural unit, and from the reference time, the interval of the packet sequence is corrected so as to be a time series at the time of transmission,
Recording stream generation method, wherein multiplexing is performed in order of detection time of each packet sequence for the first stream and the corrected second stream The recording stream generation method according to claim 1,
When multiplexing the first stream and the corrected second stream,
For the first stream, the reference time for the packet detection,
A recording stream generating method, wherein the reference time for the corrected packet sequence is multiplexed for the second stream. The recording stream generation method according to claim 1,
In the first stream, packets for M channels (M is a positive number) are time-division multiplexed,
A recording stream generating method, comprising: detecting a packet sequence for a recording target N channel (N is a positive number and M ≧ N) for a first stream. The recording stream generation method according to claim 1,
In the second stream, m-channel packet sequences transmitted from m devices (m is a positive number and m ≧ 1) connected to the second transmission path are time-division multiplexed.
A recording stream generation method, comprising: correcting each packet sequence of m channels from a transmission time included in an m channel packet sequence and the reference time so as to be a time series at the time of transmission. A recording stream suitable for recording on a recording medium is generated from a stream that is received via a first transmission path in which random time-series delay does not occur in packet transmission units and a second transmission path in which delay occurs. A recording device,
at least,
First stream receiving means for the first transmission path;
Time generation means for generating a reference time for the recording stream from the detection timing of the packet which is the structural unit;
Second stream receiving means for the second transmission path;
A buffer means for temporarily holding a packet which is the structural unit;
Timing generation means for generating output timing for the packet sequence held in the buffer means;
The first stream, characterized by providing a means for multiplexing each packet sequence for the second stream output from the buffer means,
The timing generation means generates an output timing from the transmission time included in the packets constituting the second stream and the reference time so that the packet string output from the buffer means becomes a time series interval at the time of string transmission. A recording apparatus. In the recording apparatus according to claim 5,
The multiplexing means, when multiplexing the first stream and the stream output from the buffer means,
For the first stream, the reference time for the packet detection,
A recording apparatus for multiplexing the reference time with respect to the output timing of the buffer means for the second stream. In the recording apparatus according to claim 5,
In the first stream, packets for M channels (M is a positive number) are time-division multiplexed,
A recording apparatus comprising: means for detecting a packet sequence for a recording target N channel (N is a positive number and M ≧ N) for a first stream. In the recording apparatus according to claim 5,
In the second stream, m-channel packet sequences transmitted from m devices (m is a positive number and m ≧ 1) connected to the second transmission path are time-division multiplexed.
The recording apparatus according to claim 1, wherein the timing generation unit generates an output timing for each packet sequence of the m channel from a transmission time included in the packet sequence of the m channel and the reference time. A reproduction method for a multiplexed stream multiplexed on a packet basis and recorded on a recording medium,
While separating each stream from the reproduced multiple streams,
Detect the playback time information of the packet sequence that makes up each stream,
A stream reproduction method, wherein a packet sequence for a target stream is transmitted in synchronization with a reproduction time for the packet sequence, and simultaneously transmitted including reproduction time information. An apparatus for reproducing a multiplexed stream multiplexed on a packet basis and recorded on a recording medium,
at least,
Playback means for playing back multiple streams from a recording medium;
At the same time as separating the nuclear stream from the regenerated multiple streams,
Separating means for detecting reproduction time information for a packet sequence constituting each stream;
Buffer means for temporarily storing each separated packet sequence;
Timing generation means for controlling the output of each packet sequence from the buffer means and generating timing synchronized with the detected reproduction time;
A unit for generating a transmission unit of a packet sequence in a transmission path and comprising means for controlling transmission / reception of the packet sequence,
The buffer means outputs a packet sequence according to the timing,
The transmission / reception means outputs a packet sequence to the transmission path and includes reproduction time information in a transmission unit.

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