JP2002290910A - Multimedia information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce recorded information without stopping audio and video at a discontinuous part though there is an hourly discontinuous part. SOLUTION: When a separation processing part 14 detects the discontinuity of a time stamp PCR showing a system time and the discontinuity of a time stamp PTS showing a display time, the time stamp PCR showing the system time is set again. Concerning an audio decoder 15 and a video decoder 16, the control of display is stopped until the restoration of continuity, reproduction is performed according to throughput and when continuity is restored, the control of display and reproduction by comparing the display time and the system time is started again.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a terminal for receiving a multiplexed stream of multimedia information to which time stamp information is added and distributed by transmission of digital broadcasting or the like, and which performs recording and reproduction of the received information. The present invention relates to a media information recording / reproducing device.

[0002]

2. Description of the Related Art In digital broadcasting, when broadcasting a program based on multimedia information such as audio, video and data, each piece of media information in the program is packetized, and system time information / decoding is provided in the header of each packet. Time information
After adding time stamp information such as display time information,
A stream is generated by multiplexing each other, and this multiplexed stream is transmitted.

When a digital broadcast as described above is received to record and reproduce a broadcast program, the received multiplex stream is generally directly stored in an external storage device (memory, hard disk, DVD, or the like). . In the case of this recording method, at the time of reproduction, a multiplexed stream is read from an external storage device, a system time serving as a reference of time stamp information is determined, and audio / video separation and decoding of the multiplexed stream are performed based on the system time. And synchronous playback of video and audio.

In the case where a multiplex stream is transmitted in one direction as in a digital broadcasting system, a protocol including data retransmission such as TCP / IP used for data transfer of a computer network is not implemented. There is no guarantee that the received data will not contain errors. In particular, in the case of reception by a mobile unit, a burst-like error in which error correction cannot be performed frequently occurs due to the influence of multipath, fading, and the like. Continuity can occur.

[0005] When a temporal discontinuity occurs in the received stream as described above, a system time is created at the time of reproduction, and when the audio / video is synchronously reproduced, the system time becomes the reproduction time at the temporal discontinuity. Audio / video stops until it becomes. In the conventional recording / reproducing apparatus, since the received stream is recorded as it is, for example, when a burst error occurs for several seconds at the time of reception, the state of audio silence / video stop for several seconds also occurs during recording / reproducing. It will continue.

[0006]

As described above, in a conventional multimedia information recording / reproducing apparatus used for a receiving terminal by one-way transmission such as digital broadcasting, a received stream is recorded as it is. If a burst error for several seconds occurs at the time of reception, the state of audio silence / video stop for several seconds continues even during recording and reproduction.

[0007] The present invention solves the above-mentioned problem, and even if there is a temporal discontinuity in the recorded information, the voice / audio is recorded at the discontinuity.
It is an object of the present invention to provide a multimedia information recording / reproducing apparatus capable of reproducing a video without stopping.

[0008]

To achieve the above object, a multimedia information recording / reproducing apparatus according to the present invention comprises:
It has the following characteristic configuration.

(1) Used by a terminal for receiving a multiplexed stream of multimedia information to which at least a system time and a time stamp information for specifying a reproduction time of each piece of media information are added by transmission, In a multimedia information recording / reproducing apparatus for performing recording / reproduction of a recording buffer for transmitting a multiplexed stream from the recording buffer in response to a recording / reproduction instruction, a recording buffer for constantly storing a fixed amount of the received multiplexed stream and sending the multiplexed stream to the information recording unit. An information recording / reproducing unit for recording / reproducing, a reproducing buffer for accumulating and outputting a fixed amount of the multiplexed stream from the information recording / reproducing unit, and separating each media information from the multiplexed stream output from the reproducing buffer; A time stamp for specifying the system time and the reproduction time of each media information. A separation processing unit that separates the information, in the initial state of starting playback, and the system time setting unit for setting a system time based on the time stamp information for identifying the system time separated by the separation processing unit,
A media information playback instructing unit that instructs a playback time of each piece of media information from time stamp information for specifying a playback time of each piece of media information separated by the separation processing unit, and a piece of media information that is separated by the separation processing unit And a plurality of media information decoding units for outputting decode information when the playback time specified by the media information playback instruction unit matches the system time set by the system time setting unit. The separation processing unit monitors the temporal continuity of the reproduced multiplexed stream, and if there is a temporal discontinuity, the system time setting unit resets the system time based on the latest time stamp information. It is characterized by setting.

(2) The separation processing unit sequentially checks the continuity of each of the system time and time stamp information for specifying the reproduction time of each piece of media information, and detects temporal discontinuity of the reproduced multiplexed stream. Is detected.

(3) Each of the plurality of media information decoding units sequentially checks the continuity of the time stamp information for specifying the reproduction time, and notifies the separation processing unit when discontinuity is detected. The unit sequentially checks the continuity of the time stamp information for identifying the system time, and determines the temporal discontinuity of the reproduction multiplex stream from the inspection result and the discontinuity notification from the plurality of media information decoding units. It is characterized by detecting.

(4) The plurality of media information decoding units do not control the reproduction timing at least for a certain period when a temporal discontinuity of the reproduction multiplex stream occurs.

(5) The system time setting unit initializes a system clock specified by the time stamp information with a system clock generating unit that generates a system clock, and counts the system clock from the initial setting value. Generating a system time, wherein the separation processing unit resets the system time specified by the latest time stamp information when the discontinuity is detected, to the system time setting unit. .

(6) The information recording / reproducing unit includes an external recording media drive device, and writes or reads the multiplexed stream to or from an external recording medium.

That is, in the multimedia recording / reproducing apparatus having the above configuration, in the control of the system time when recording and reproducing the information including the error, after performing the initial setting, the recording information is reproduced and the time is reduced. When the discontinuity occurs, the decoding process of each media information is performed according to the progress of the process without checking the system time. At this time, the system time is re-extracted from the reproduction information and reset, thereby absorbing the time discontinuity. This solves the problem that the reproduction processing of each piece of media information stops at the discontinuous point until the system time reaches the reproduction time.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration in which a digital broadcast receiving apparatus is provided with a recording / reproducing unit as one embodiment of a multimedia recording / reproducing apparatus according to the present invention. In the apparatus shown in FIG. 1, a digital broadcast signal received by an antenna 11 is received and selected by a tuner 12, subjected to error correction and decoding by an error correction decoding unit (FEC) 13, and returned to a multiplexed stream of multimedia information. . The received multiplexed stream is separated into audio coded data and video coded data by a demultiplexing unit 14 in packet units.
5. Sent to the video decoder 16.

The separation processing section 14 outputs the header information of the audio packet and the video packet to the audio PTS extraction section 17 and the video PTS extraction section 18, respectively. These PTS extracting units 17 and 18 extract a PTS (Presentation Time Stamp: presentation time information) from the input header information and output the extracted PTS to the audio decoder 15 and the video decoder 16. Further, the separation processing unit 14 converts the input multiplexed stream from a PCR (Program Clock Re-
ference: time reference information) and this PCR
It is set in the R counter 19.

The PCR counter 19 is provided with a VCXO synchronized by the reproduction clock of the separation processor 14.
(Voltage-controlled crystal oscillator: usually 27 MHz) The system clock is set by counting the generated clock of 20 and counting up by the PCR value.
Supplied to The generated clock of the VCXO 20 is
A sampling clock for a DA (digital / analog) converter 21 which will be described later
It is used for synchronous control of the TSC encoder 22.

The audio decoder 15 compares the PTS extracted by the audio PTS extraction unit 17 with the system time, decodes the encoded audio data at the same timing, and reproduces and outputs the data. The reproduced output data is converted into an analog signal by the DA converter 21 and the analog signal is output from the speaker 2.
3 is reproduced. In the video decoder 16, the PTS extracted by the video PTS extraction unit 17 is also used.
Is compared with the system time, and the encoded video data is decoded at the coincident timing and reproduced and output. This reproduced output data is converted into a signal of the standard television system by the NTSC encoder 22 and displayed on the CRT 24.

With the above configuration, the audio / video synchronous reproduction of the received multiplex stream is performed. The recording / reproducing unit is configured as follows for the reception processing system.

First, the multiplexed stream input to the separation processing unit 14 is input to the recording buffer 31, and a constant amount is constantly stored. When recording start is instructed through a remote controller (not shown) or the like, the recording buffer 26
Are stored in an information recording unit 33 such as a memory, a hard disk, or a DVD managed by the host device 32. The information recording unit 33 may be an internal device of the receiving device or an external device.
If an external recording medium drive device capable of exchanging recording media is used, it is possible to solve the problem of recording capacity and the like.

When the host 32 is instructed to start reproduction, the multiplexed stream recorded in the information recording section 33 is read out in its original format in accordance with the instruction to start reproduction, and separated via the reproduction buffer 34. Output to the processing unit 14. In the separation processing unit 14 and thereafter, the reproduced multiplexed stream is handled in the same manner as the received multiplexed stream.

That is, in the demultiplexing section 14, the reproduced multiplexed stream is separated into audio coded data and video coded data.
5. Sent to the video decoder 16. Then, the PTSs extracted by the audio PTS extraction unit 17 and the video PTS extraction unit 18 are decoded at a timing that matches the system time generated from the PCR in the reproduced multiplex stream,
Playback output.

Here, the synchronous playback of audio and video is performed by using P
The CR is extracted, the system time at the time of reproduction is determined by the PCR counter unit 19, and the synchronous display of audio and video is performed by a video PTS and an audio PTS that define the display time included in the audio information and video information of the multiplexed stream. And the system time based on the PCR.

As a method of controlling the system time, a PCR first extracted from the multiplexed stream is set, and thereafter control is not performed (for example, a control voltage value applied to the VCXO 20 of 27 MHz is not changed), By writing the reproduction data into the reproduction buffer 28 at a rate, control may be performed in the same manner as in normal broadcast reception.

In the above configuration, a process of reproducing recorded information will be described below with reference to FIGS. FIG.
FIG. 3 shows a stream configuration on the time axis when there is no temporal discontinuity during reproduction, and FIG. 3 shows a case where a temporal discontinuity occurs during reproduction.

First, the recording information (multiplexed stream) is input to the reproduction buffer 34 when the reproduction of the recording information is started. After that, the separation processing unit 14 separates the audio coded data, the video coded data, and the time stamp (PCR) that specifies the system time from the multiplexed stream, and the PTS extraction units 17 and 18 specify the audio / video display time. Extract the time stamp (PTS).

Subsequently, a time stamp PCR defining the system time detected first is set in the PCR counter section 19 expressing the system time, and a fixed value Vconst is set as a control voltage of the VCXO 20. That is, P
The CR counter unit 19 uses this value as the initial value of the system time at the time of reproducing the recorded information, and automatically counts up at the frequency of the VCXO 20 given the fixed voltage value Vconst.

The audio coded data and the video coded data separated by the separation processing unit 14 are input to the audio decoder 15 and the video decoder 16, respectively, and at the same time, the display times (PTS) associated with the PTS extraction units 17 and 18 are respectively. ) Is also notified. Audio decoder 1
5. The video decoder 16 decodes the respective information and outputs the decoded data when the display time at which the system time is notified is reached. As a result, the audio / video synchronous reproduction is realized, and the audio decoded data and the video decoded data are converted into the DA converter 21 and the NTSC encoder 22 respectively.
Is sent to the speaker 23 and the CRT 24 via the, and is provided to the user as actual audio / video.

The above processing is normally performed when the reproduced information does not have a temporal discontinuity as shown in FIG. 2, but a temporal discontinuity occurs in the reproduced information. System time and audio playback time,
Video playback time cannot be matched. Therefore, FIG.
As shown in (1), when the occurrence of temporal discontinuity is detected, the system time is reset.

The temporal discontinuity of the reproduced information is determined by the continuity of the time stamp PCR indicating the system time in the multiplexed stream and the time indicating the reproduction time in the separation processing unit 14, or the audio decoder 15 and the video decoder 16. The determination is made by sequentially checking the continuity of the stamp PTS. When the continuity check of the time stamp PTS is performed only by the audio decoder 15 and the video decoder 16, the detection result is notified to the separation processing unit 14.

Upon detecting the discontinuity of the time stamp PCR indicating the system time and the discontinuity of the time stamp PTS indicating the display time, the separation processing unit 14 sets the time stamp PCR indicating the system time again. . In the audio decoder 15 and the video decoder 16, the display control is stopped until the continuity is restored.
Playback is performed in accordance with the processing capacity, and when the continuity is restored, the control of display playback by comparing the display time with the system time is restarted.

Therefore, in the multimedia recording / reproducing apparatus having the above configuration, in the control of the system time when recording and reproducing the information including the error, after the initial setting, the recorded information is reproduced, and the time discontinuity is caused. If this occurs, the audio / video decoding process can be performed without checking the system time, and the system time can be re-extracted from the reproduction information and reset to absorb the time discontinuity. . As a result, it is possible to solve the problem that the audio / video is stopped at the discontinuous point until the system time reaches the reproduction time.

[0035]

As described above, according to the present invention, even if there is a temporal discontinuity in the recorded information, voice /
It is possible to provide a multimedia information recording / reproducing apparatus capable of reproducing a video without stopping.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration in a case where a recording / reproducing unit is mounted on a digital broadcast receiving apparatus as one embodiment of a multimedia recording / reproducing apparatus according to the present invention.

FIG. 2 is a diagram showing a stream configuration on a time axis when there is no temporal discontinuity during reproduction in the embodiment.

FIG. 3 is a diagram showing a stream configuration on a time axis when a temporal discontinuity occurs during reproduction in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Antenna 12 ... Tuner 13 ... Error correction decoding part (FEC) 14 ... Separation processing part 15 ... Audio decoder 16 ... Video decoder 17 ... Audio PTS extraction part 18 ... Video PTS extraction part 19 ... PCR counter part 20 ... VCXO (voltage) Control crystal oscillator 21 DA (digital / analog) converter 22 NTSC encoder 23 Speaker 24 CRT 31 Recording buffer 32 Host device 33 Information recording unit 34 Reproduction buffer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 7/08 H04N 7/08 Z 7/081 F-term (Reference) 5C052 AA01 AA16 AB03 CC06 CC11 DD04 DD06 5C053 FA20 GA11 GB06 GB11 GB21 HA33 JA03 JA22 KA04 KA06 KA18 LA06 LA07 5C063 AA01 AB03 AB05 AC01 AC05 AC10 CA11 CA14 CA20 DA07 DA13 5D044 AB05 AB07 BC01 BC04 CC04 DE39 DE83 EF03 FG10 FG18 GK08

Claims (6)

[Claims] 1. A terminal for receiving a multiplexed stream of multimedia information, which is distributed by transmission and added with at least system time and time stamp information for specifying a reproduction time of each piece of media information. In a multimedia information recording / reproducing apparatus for performing recording / reproduction, a recording buffer for constantly storing a predetermined amount of the received multiplexed stream and sending the multiplexed stream to the information recording unit, and recording a multiplexed stream from the recording buffer in response to a recording / reproduction instruction. An information recording / reproducing unit to be reproduced; a reproducing buffer for accumulating and outputting a fixed amount of a multiplexed stream from the information recording / reproducing unit; and separating each media information from the multiplexed stream output from the reproducing buffer; System time,
A separation processing unit that separates time stamp information for specifying a reproduction time of each piece of media information; and a time stamp information for specifying the system time separated by the separation processing unit in an initial state of reproduction start. A system time setting unit that sets a system time based on the media information reproduction instruction unit that indicates a reproduction time of each piece of media information from time stamp information for specifying a reproduction time of each piece of media information separated by the separation processing unit And decoding each media information separated by the separation processing unit separately, and decoding when the playback time specified by the media information playback instruction unit matches the system time set by the system time setting unit. And a plurality of media information decoding units for outputting information, wherein the separation processing unit includes the reproduction multiplex stream. Multimedia time recording that monitors the time continuity of the system and, when there is a time discontinuity, causes the system time setting unit to reset the system time based on the latest time stamp information. Playback device. 2. The separation processing unit sequentially checks the continuity of each of the system time and time stamp information for specifying a reproduction time of each piece of media information, and detects a temporal discontinuity of the reproduction multiplexed stream. 2. The multimedia information recording / reproducing apparatus according to claim 1, wherein the multimedia information is detected. 3. The plurality of media information decoding units,
The continuity of the time stamp information for specifying the reproduction time is sequentially inspected, and when the discontinuity is detected, the continuity is notified to the separation processing unit. 2. The multimedia information according to claim 1, wherein continuity is sequentially inspected, and temporal discontinuity of the reproduced multiplex stream is detected from the inspection result and a discontinuity notification from the plurality of media information decoding units. Recording and playback device. 4. The plurality of media information decoding units,
2. The multimedia information recording / reproducing apparatus according to claim 1, wherein when a temporal discontinuity of the reproduced multiplex stream occurs, the reproduction timing is not controlled for at least a certain period. 5. The system time setting section, wherein: a system clock generating section for generating a system clock; and a system time specified by the time stamp information are initialized, and the system clock is counted from the initial set value. Generating a system time, the separation processing unit, the system time setting unit,
2. The multimedia information recording / reproducing apparatus according to claim 1, wherein the system time specified by the latest time stamp information is reset when discontinuity is detected. 6. The multimedia information recording / reproducing apparatus according to claim 1, wherein the information recording / reproducing unit includes an external recording medium drive device, and writes or reads the multiplexed stream to / from an external recording medium. apparatus.