JP2005026990A - Digital recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital recording and reproducing device which satisfactorily reproduces images regardless of the existence of errors in image data. <P>SOLUTION: It is detected whether a PES packet in contents data includes an error, and index data including an error flag showing a detection result are prepared. When contents data are to be reproduced, the index data are referred to so that the PES packet including an error is not reproduced. An I frame flag showing whether the PES packet includes intra-picture coded data and an offset indicating the relative position of the PES packet in the contents data are included in the index data, so that only I frames are reproduced to efficiently perform special reproduction like fast forwarding or fast rewinding. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital recording / reproducing apparatus for recording and reproducing content data including digital image data.
[0002]
[Prior art]
2. Description of the Related Art Digital recording / reproducing apparatuses that record and reproduce image data compressed by an MPEG (Moving Picture Experts Group) method are used.
In the MPEG system, a plurality of images are represented by GOP (Group of Pictures) including I frames (intra-picture encoded images), P frames (inter-picture predictive encoded images), and the like. The I frame is obtained by encoding image data by DCT (Discrete Cosine Transform) quantization. The P frame is obtained by encoding a difference between data predicted from past image data and current image data. The GOP is divided into PES (Packetized Elementary Stream) packets and transmitted, recorded, and the like. In order to reproduce the image data compressed by the MPEG method, the I frame is decoded, and the P frame or the like is decoded based on this. As a result, a plurality of image data is reproduced in time series.
In addition, a technique for smoothly performing fast-forward playback or the like by detecting a PES packet including an I frame and creating an index file is disclosed (see Patent Document 1).
[0003]
[Patent Document 1]
JP 2000-224543 A
[0004]
[Problems to be solved by the invention]
However, in the conventional digital recording / reproducing apparatus, when an error is mixed in image data, the image may not be reproduced satisfactorily. In particular, when there is an error in the data of the I frame, the disturbance of the image tends to increase.
The present invention has been made to solve such a problem, and an object of the present invention is to provide a digital recording / reproducing apparatus capable of satisfactorily reproducing an image even when an error is mixed in the image data.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a digital recording / reproducing apparatus according to the present invention provides a PES packet obtained by packetizing digital image data included in content data and subjected to intra-picture coding and inter-picture coding. An I frame detection unit for detecting whether or not data is included; an error detection unit for detecting whether or not the PES packet includes an error; and a relative position detection for detecting a relative position in the content data of the PES packet. Index data including an I frame flag representing a detection result by the I frame detection unit, an error flag representing an error detection result by the error detection unit, and an offset representing a detection result by the relative position detection unit And an index creation unit.
[0006]
Whether or not the PES packet in the content data includes an error is detected, and index data including an error flag indicating the detection result is created. For this reason, it is possible to prevent the PES packet including an error from being reproduced by referring to the index data when reproducing the content data. The index data includes an I frame flag indicating whether or not the PES packet includes intra-picture encoded data, and an offset indicating a relative position in the content data of the PES packet. For this reason, special reproduction such as fast forward and fast reverse can be efficiently performed by reproducing only the I frame.
[0007]
(1) Here, the error detection unit may detect whether or not the intra-picture encoded data includes an error.
Since intra-picture encoded data is data that is the basis of image reproduction, when this includes an error, the influence is greater than inter-picture encoded data. Therefore, the quality of the PES packet can be determined by checking only the encoded data in the picture.
[0008]
(2) The digital recording / reproducing apparatus may further include an index data storage unit that records the index data created by the index creation unit on a recording medium.
By recording the index data on a recording medium or the like, it is possible to efficiently reproduce the content data.
[0009]
(3) The digital recording / reproducing apparatus may further include a content data reproducing unit that reproduces content data based on the index data created by the index creating unit.
The content data using the index data can be efficiently reproduced.
[0010]
Here, the content data reproduction unit may reproduce the intra-picture encoded data based on the I frame flag.
By reproducing only the intra-picture encoded data (inter-picture encoded data or the like is excluded from reproduction), special reproduction such as fast forward and fast reverse can be performed efficiently.
[0011]
The content data reproducing unit may reproduce a PES packet that does not include an error based on the error flag.
By excluding PES packets including errors from reproduction, it is possible to reproduce images favorably.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
FIG. 1 is a block diagram showing a digital recording / reproducing apparatus 10 according to an embodiment of the present invention. As shown in FIG. 1, the digital recording / reproducing apparatus 10 includes a recording medium 20, a recording apparatus 30, and a reproducing apparatus 40, and records and reproduces content data including image data and audio data.
[0013]
The recording medium 20 means a general recording medium such as a hard disk or a DVD (Digital Versatile Disc), and includes a content file storage area 21 and an index file storage area 22.
The content file storage area 21 is an area on the recording medium 20 that stores a content file including PES packets of audio (voice) and video (image). The index file storage area 22 is an area on the recording medium 20 that stores an index file corresponding to the content file stored in the content file storage area 21.
[0014]
The recording device 30 stores a content file including audio and video PES packets in the content file storage area 21 of the recording medium 20 and stores an index file in the index file storage area 22.
The recording apparatus 30 includes a reception unit 301, a selection unit 302, a demodulation / error correction detection unit 303, a demultiplexer 304, a content file storage unit 305, a PES header detection unit 306, an address counter 307, an I frame detection unit 308, and an I frame error. A detection unit 309, an index file creation unit 310, and an index file storage unit 311 are provided.
[0015]
The reception unit 301 has a reception antenna and receives a transmission signal that is multiplexed and transmitted from a broadcasting station.
The selection unit 302 is set with the service ID (program No.) of the program channel selected by the viewer, and the video / audio bitstream corresponding to the service ID is demodulated from the broadcast signal received by the reception unit 301. The data is output to the error correction detection unit 303. The service ID is input by an input device (not shown) (for example, a push button or a remote controller).
[0016]
The demodulation / error correction detection unit 303 performs demodulation and error correction of the bit stream input from the selection unit 302, converts it into a transport stream (TS) packet defined by the MPEG system, and outputs this to the demultiplexer 304. Output.
The demultiplexer 304 demultiplexes (separates) the audio and video PES packets of one program from the TS packets input from the demodulation / error correction detection unit 303 and outputs the PES packets. The output destination is the playback device 40 during normal use, and the playback device 40 and the content file storage unit 305 (further, the PES header detection unit 306 and the I frame detection unit 308) during recording (recording while displaying video). it can).
The content file storage unit 305 stores the audio and video PES packets input from the demultiplexer 304 in the content file storage area 21 as content files.
[0017]
The PES header detection unit 306 detects the PES header from the video PES packet input from the demultiplexer 304, and indexes the head address of the video PES packet included in the PES header and information on the PTS (Presentation Time Stamp). This is output to the file creation unit 310 and functions as a relative position detection unit. Here, PTS is time management information for reproduction output.
The address counter 307 measures the number of data of video PES packets when the PES header detection unit 306 detects the PES header.
[0018]
The I frame detection unit 308 detects an I frame (encoded data in the picture) from the video PES packet input from the demultiplexer 304, and an I frame flag representing the detection result is sent to the index file via the I frame detection unit 308. The data is output to the creation unit 310. The I frame detection unit 308 determines that an I frame is detected when “CI” and “I-VOP” are included in the video PES packet.
[0019]
The I frame error detection unit 309 performs I frame error detection from the video PES packet input from the I frame detection unit 308, and functions as an error detection unit. Then, the error flag as the detection result is output to the index file creation unit 310 together with the I frame flag input from the I frame detection unit 308.
As described above, the demodulated / error correction detecting unit 303 outputs a TS packet in which error correction has been performed, but a PES packet (particularly, an I frame) in which errors could not be corrected remains in the TS packet. There is a case. For this reason, the I frame error detection unit 309 performs error detection by checking predetermined items of the PES packet.
[0020]
FIG. 2 is a schematic diagram showing the data contents of the PES packet. Here, “PES_info_n” in (1) of FIG. 2 indicates parameters included in an ES (Elementary Stream) of a video including an nth (n = 1 to N) I frame. (2) represents details of “PES_info_1”, (3) represents details of “PES_info” in “PES_info_1”, and (4) represents details of “I_picture_info” in “PES_info_1”.
The I frame error detection unit 309 checks whether the validity of each parameter indicated by “PES_info_1” in FIG. 2A and the value of the PTS indicated by “PTS_info” in (3) are correct. As a result, an error flag corresponding to the I frame determined to be incorrect is output.
[0021]
The index file creation unit 310 creates an index file corresponding to the video PES packet (content data) based on each information input from the PES header detection unit 306 and the I frame error detection unit 309.
The index file storage unit 311 stores the index file created by the index file creation unit 310 in the index file storage area 22.
[0022]
FIG. 3 is a schematic diagram illustrating an example of an index file created by the index file creation unit 310. In the index file, an I frame flag, an error flag, and an offset are recorded in order corresponding to each PES packet.
Here, the I frame flag is information that is output from the I frame detection unit 308 and indicates the presence or absence of an I frame in the PES packet. It is “1” when there is an I frame (CI + I−VOP is included), and “0” when there is no I frame (CI + I−VOP is not included).
The error flag is information output from the I frame error detection unit 309 and indicating the presence or absence of an error in each I frame. It is “1” when an error is included, and “0” when no error is included.
The offset is information representing the position of the PES packet from the beginning of the content file in bytes. The offset is created by the index file creation unit 310 based on the information of the head address of the PES packet output from the PES header detection unit 306.
[0023]
The playback device 40 plays back the content file stored in the content file storage area 21 based on the index file stored in the index file storage area 22 of the recording medium 20.
The playback device 40 includes a user interface control unit 401, an index file reading unit 402, a content file reading unit 403, a playback mode control unit 404, a PES packet buffer 405, an A / V decoder 406, an image decoding unit 407, a monitor 408, and audio decoding. 409 and speaker 410 are provided.
[0024]
The user interface control unit 401 outputs a playback command for normal playback or special playback (fast forward, fast reverse, etc.) input by the user to the playback mode control unit 404. The reproduction command is input using an input device (not shown) (for example, a push button or a remote controller).
[0025]
The index file reading unit 402 reads the index file from the index file storage area 22 according to an instruction from the playback mode control unit 404 and outputs the index file to the playback mode control unit 404.
The content file reading unit 403 extracts audio and video PES packets from the content file storage area 21 in accordance with an instruction from the playback mode control unit 404 and outputs them to the PES packet buffer 405.
[0026]
When a normal playback command is input from the user interface control unit 401, the playback mode control unit 404 instructs the content file reading unit 403 to transfer data from the content file storage area 21 in accordance with the free capacity of the PES packet buffer 405. To do.
Also, when a special playback command is input from the user interface control unit 401, the playback mode control unit 404 transfers data from the content file storage area 21 based on the index file obtained from the index file reading unit 402. The reading unit 403 is instructed.
[0027]
The PES packet buffer 405 receives the request signal from the A / V decoder 406 and outputs the input PES packet data to the A / V decoder 406. The input source of the PES packet data is the demultiplexer 304 during normal use and recording, and the content file reading unit 403 during reproduction.
[0028]
The A / V decoder 406 decodes the input audio and video PES packet data, and outputs the video data to the image decoding unit 407 and the audio data to the audio decoding unit 409, respectively.
The image decoding unit 407 converts the video data received from the A / V decoder 406 into a television output signal and outputs it to the monitor 408.
The audio decoding unit 409 converts the audio data received from the A / V decoder 406 into an analog signal and outputs the analog signal to the speaker 410.
[0029]
(Operation of the digital recording / reproducing apparatus 10)
Next, the operation of the digital recording / reproducing apparatus 10 will be described.
A. In normal use, the case of viewing a broadcast as it is first will be described.
The broadcast signal received from the broadcast station by the reception antenna is output to the selection unit 302 via the reception unit 301. The selection unit 302 selects a video / audio bit stream corresponding to the service ID of the program channel set from the broadcast signal.
[0030]
The demodulation / error correction detection unit 303 performs demodulation and error correction of the bit stream input from the selection unit 302 and converts the bit stream into TS packets. The demultiplexer 304 separates and outputs the audio and video PES packets of one program from the TS packets.
The audio and video PES packets are decoded by the A / V decoder 406 via the PES packet buffer 405, and the video data is output to the image decoding unit 407 and the audio data is output to the audio decoding unit 409. As a result, the broadcast can be viewed through the monitor 408 and the speaker 410.
[0031]
B. Consider a case where image data received from a broadcasting station at the time of recording is recorded on the recording medium 20 as a content file.
The operation contents of the reception unit 301, the selection unit 302, and the demodulation / error correction detection unit 303 during the recording are the same as those during normal use. That is, the video / audio bit stream corresponding to the service ID of the program channel is selected from the received broadcast signal.
[0032]
(1) Content file recording The demultiplexer 304 separates and outputs audio and video PES packets as in normal use, but a content file storage unit 305 is added to the output destination. As a result, the content file including the PES packet is recorded in the content file storage area 21.
Since the PES packet is also output to the PES packet buffer 405, the broadcast can be viewed through the monitor 408 and the speaker 410 as in normal use.
[0033]
(2) Creation and recording of index file In parallel with recording of the content file, creation and recording of an index file are performed by the index file creation unit 310 and the index file storage unit 311.
Prior to creation of the index file, the following processing is performed. That is, the I frame detection unit detects an I frame from the video PES packet and outputs an I frame flag. The I frame error detection unit 309 detects an error in the detected I frame and outputs an error flag. Also, the PES header detection unit detects the PES header from the input video PES packet, and outputs the start address of the video PES packet included in the PES header. The index file creation unit 310 converts the head address into an offset converted from the head of the content file.
[0034]
The index file creation unit 310 generates an index file from these I frame flag, error flag, and offset, and the index file storage unit 311 stores the index file in the index file storage area 22.
[0035]
C. Consider a case where a content file recorded on the recording medium 20 during playback is played back.
In this case, the reproduction speed (normal speed, fast forward) and the reproduction direction (forward direction, reverse direction) are determined by the reproduction command input from the user interface control unit 401. Normal playback is forward playback at normal speed, and playback other than this is special playback.
[0036]
In accordance with the designation of the playback state, the index file reading unit 402 reads the index file from the index file storage region 22 and the content file reading unit 403 reads the content data from the content file storage region 21 in parallel.
[0037]
(1) The reproduction mode control unit 404 controls the reading direction and reading speed of the index file by the index file reading unit 402 in accordance with an index file reading / playing command.
In the case of forward reproduction, the index file is read from the beginning to the end, and in the case of reverse reproduction, the index file is read from the end to the beginning. When the image is reproduced at a speed higher than the normal speed, the index file is read at a high speed accordingly.
However, the reading of the index file does not necessarily correspond to the playback direction and speed of the content file represented by the playback command. For example, if a buffer that temporarily holds the contents of the index file is used, the index file can be read without depending on the contents of the reproduction command.
[0038]
(2) Reading and playback of content file The playback mode control unit 404 controls reading of content data by the content file reading unit 403 in accordance with the read index file. By reading the content file according to the index file, it is possible to prevent disturbance of the reproduced image and facilitate fast-forward reproduction.
[0039]
By reproducing an image based on an I frame having no error (not using an I frame having an error), it is possible to prevent the reproduced image from being disturbed. For example, in the index file shown in FIG. 3, reproduction is performed in the order of numbers 1, 2, 4, 5, 14, 16, and 17, and PES packets with numbers in the middle can not be used for image reproduction.
In this example, only an I frame (I frame flag: 1) with no error (error flag: 0) is used for reproduction. By not using an errored I frame (error flag: 1) for reproduction, it is possible to prevent reproduction of a defective image. The reason why the PES packet not including the I frame is not used for image reproduction is to facilitate fast-forwarding.
Normally, if an incorrect I frame is played back, the image is displayed broken, or in the worst case, it is not displayed and the display is interrupted. However, since the incorrect I frame is not played back, the image display is interrupted without breaking the image. Content can be fast-forwarded.
[0040]
When fast-forwarding is not performed, it is possible to use not only an error-free (error flag: 0) I frame (I frame flag: 1) but also a PES packet including a subsequent P frame or the like for image reproduction. It is. For example, with the index file shown in FIG. 3, playback is performed in the order of numbers 1 to 9 and 14 to 17, and PES packets (P frames, etc.) that do not include I frames existing between error-free I frames are played back. Available.
[0041]
In addition, it is easy to increase the playback speed by thinning out the I frames.
FIG. 4 is a schematic diagram showing the relationship between the playback speed and the extraction of “CI + I−VOP” data (thinning out I frames).
In the normal playback shown in FIG. 4 (1), images are played back including P frames other than I frames, and a large number of images are played back over time, thereby making it possible to play back moving images with smooth motion. .
On the other hand, in the fast-forward 1 of (2), “CI + I−VOP” corresponding to the I frame is extracted to easily realize fast-forward and fast-reverse. Further, in the fast forward 2 of (3), “CI + I−VOP” (I frame) corresponding to the I frame is thinned out and extracted, so that fast forward / fast reverse with higher speed can be easily realized.
[0042]
Such thinning out of I frames can be performed, for example, by reducing PES files to which 1 is assigned as an I frame flag when creating an index file. In addition, the I frame may not be thinned out on the index file, and the I frame used for reproduction during the reproduction may be thinned out.
[0043]
When such I frame decimation is performed, if there is an error in the I frame, the I frame is skipped and reproduced.
FIGS. 5A to 5C are schematic diagrams showing the relationship between an I-frame error in fast-forwarding and the playback state. In the figure, “◯” represents an I frame having no error, and “X” represents an I frame having an error.
FIG. 5A shows a case where there is no error in the I frame, and reproduction is performed by thinning out every other I frame. (B) shows a case where there is an error in the I frame, and the I frame having the error is skipped and reproduced. (C) shows a case where a plurality of I frames having errors continue, and images are reproduced by skipping to I frames having no errors.
FIGS. 6A to 6C are schematic diagrams showing the relationship between the error of the I frame and the playback state in fast reverse. “O” indicates an I frame without an error, and “X” indicates an I frame with an error. Similar to FIG. 5, an I frame with an error is skipped, and an image is reproduced using only an I frame without an error.
[0044]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a digital recording / reproducing apparatus capable of satisfactorily reproducing an image even when an error is mixed in the image data.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a digital recording / reproducing apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic diagram showing data contents of a PES packet.
FIG. 3 is a schematic diagram illustrating an example of an index file created by an index file creation unit.
FIG. 4 is a schematic diagram showing a relationship between reproduction speed and I frame thinning.
FIG. 5 is a schematic diagram showing a relationship between an I-frame error and a reproduction state in fast-forwarding.
FIG. 6 is a schematic diagram showing a relationship between an I-frame error and a reproduction state in fast reverse.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Digital recording / reproducing apparatus, 20 ... Recording medium, 21 ... Content file storage area, 22 ... Index file storage area, 30 ... Recording apparatus, 40 ... Playback apparatus, 301 ... Reception part, 302 ... Selection part, 303 ... Error correction detection unit 304. Demultiplexer 305 Content file storage unit 306 PES header detection unit 307 Address counter 308 I frame detection unit 309 I frame error detection unit 310 Index file creation unit 311 ... Index file storage unit 401 ... User interface control unit 402 ... Index file reading unit 403 ... Content file reading unit 404 ... Playback mode control unit 405 ... PES packet buffer 406 ... A / V decoder 407 ... Image decoding unit, 4 8 ... monitor, 409 ... audio decoding section, 410 ... speaker

Claims (6)

An I frame detection unit that detects whether or not a PES packet that is packetized digital image data that is included in content data and that has been subjected to intra-picture encoding and inter-picture encoding includes intra-picture encoded data;
An error detection unit for detecting whether the PES packet includes an error;
A relative position detector for detecting a relative position in the content data of the PES packet;
Index creation unit that creates index data including an I frame flag that represents a detection result by the I frame detection unit, an error flag that represents an error detection result by the error detection unit, and an offset that represents a detection result by the relative position detection unit When,
A digital recording / reproducing apparatus comprising: 2. The digital recording / reproducing apparatus according to claim 1, wherein the error detection unit detects whether or not the intra-picture encoded data includes an error. An index data storage unit for recording the index data created by the index creation unit on a recording medium;
The digital recording / reproducing apparatus according to claim 1, further comprising: The digital recording / reproducing apparatus according to claim 1, further comprising a content data reproducing unit that reproduces content data based on the index data created by the index creating unit. 5. The digital recording / reproducing apparatus according to claim 4, wherein the content data reproducing unit reproduces intra-picture encoded data based on the I frame flag. 5. The digital recording / reproducing apparatus according to claim 4, wherein the content data reproducing unit reproduces a PES packet not including an error based on the error flag.

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