[Libav-user] Problems with some MXF file decoding

肖波 xiaobo_yc at 163.com
Thu Apr 26 09:41:43 CEST 2012


Hi All,
 
I found that the current git code have problems with decoding of some of my MXF files, but the libav-0.8.1 is OK.
 
Like the show_packets() in  "avproble.exe",I called the av_read_frame() function, and read the pts and dts of the file.It's all OK until the pts and dts value up to 14998(timestamp about 600 second);and then the video packet's dts and pts is always valued 14998, 14999, 15000 or 0x8000000000000000, but the audio packet's dts and pts value is all OK.
 
First I think maybe the way I called ffmpeg api is wrong, then I used the avprobe.exe like this:"avprobe.exe -show_packets myfile.mxf", and it have the same result,so I think there must be some bugs in the code source.
 
And I have interests in study the ffmpeg source code,anybody can tell me where maybe the problem is? Or help to fix the bug.
 
As showing in MediaInfo,the file format information is as follows:
General
Complete name                            : D:\myfile.mxf
Format                                   : MXF
Format profile                           : OP-1a
Format settings                          : Open / Incomplete
File size                                : 4.63 GiB
Duration                                 : 54mn 56s
Overall bit rate mode                    : Constant
Overall bit rate                         : 12.1 Mbps
Encoded date                             : 2011-12-14 09:46:46.708
Writing application                      : Omneon Inc. Omneon Media Subsystem 6.1.0.0.1
Writing library                          : Omneon Inc. Omneon Media Subsystem 6.1.0.0.1
Video
ID                                       : 2
Format                                   : MPEG Video
Format version                           : Version 2
Format profile                           : 4:2:2 at Main
Format settings, BVOP                    : Yes
Format settings, Matrix                  : Custom
Format_Settings_Wrapping                 : Frame
Duration                                 : 54mn 56s
Bit rate mode                            : Constant
Bit rate                                 : 10 000 Kbps
Width                                    : 720 pixels
Height                                   : 576 pixels
Display aspect ratio                     : 4:3
Frame rate                               : 25.000 fps
Standard                                 : PAL
Color space                              : YUV
Chroma subsampling                       : 4:2:2
Bit depth                                : 8 bits
Scan type                                : Interlaced
Scan order                               : Top Field First
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 0.965
Stream size                              : 3.84 GiB (83%)
Audio
ID                                       : 3
Format                                   : PCM
Format settings, Endianness              : Little
Format_Settings_Wrapping                 : Frame (BWF)
Duration                                 : 54mn 56s
Bit rate mode                            : Constant
Bit rate                                 : 1 536 Kbps
Channel(s)                               : 2 channels
Sampling rate                            : 48.0 KHz
Bit depth                                : 16 bits
Stream size                              : 604 MiB (13%)
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