Opened 4 years ago

Closed 4 years ago

#3743 closed enhancement (fixed)

mpeg2video decoder loses frames when progressive_sequence flag flips

Reported by: SianLiao Owned by:
Priority: normal Component: avcodec
Version: git-master Keywords: mpeg2video regression
Cc: Blocked By:
Blocking: Reproduced by developer: yes
Analyzed by developer: no

Description

Summary of the bug:

In mpeg2video streams where progressive_sequence flag flips, one-frame will be lost due to context reinitialized in mpeg_decode_postinit call

Without entering the initialization block the otherwise lost frame is decoded correctly.

(ffmpeg binary causes a duplicate frame in that position when decoding)

How to reproduce:

Decode an mpeg2 stream with progressive_sequence flipping

ffmpeg version 2.2.1 and prior

Attachments (1)

3743_mpeg_progressive_seq_flip.m2v (1.4 MB) - added by cehoyos 4 years ago.

Download all attachments as: .zip

Change History (6)

comment:1 Changed 4 years ago by cehoyos

Please test current FFmpeg git head and provide your failing command line (the command that doesn't produce the expected output) together with the complete, uncut console output and please upload a sample to make this a valid ticket.

comment:2 Changed 4 years ago by SianLiao

The file (too big to attach, 13 MB) is uploaded to upload.ffmpeg.org under filename 3743_mpeg_progressive_seq_flip.avi

Running ffmpeg decoder will cause "1 dup!", failing to decode a frame and therefore the frames 19 and 20 will be identical.

The frame otherwise is decodable, if no context reinit happens in the code as described above.

./ffmpeg -i 3743_mpeg_progressive_seq_flip.avi -loglevel verbose -y -an -f image2 "imgs/img_%05d.jpg"
ffmpeg version N-64226-g7e8fdf0 Copyright (c) 2000-2014 the FFmpeg developers
  built on Jun 26 2014 19:28:40 with Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
  configuration: --disable-optimizations --disable-stripping --enable-debug=3
  libavutil      52. 90.101 / 52. 90.101
  libavcodec     55. 68.100 / 55. 68.100
  libavformat    55. 44.100 / 55. 44.100
  libavdevice    55. 13.101 / 55. 13.101
  libavfilter     4.  9.100 /  4.  9.100
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 19.100 /  0. 19.100
Input #0, avi, from '3743_mpeg_progressive_seq_flip.avi':
  Metadata:
    encoder         : Lavf55.33.100
  Duration: 00:00:02.21, start: 0.000000, bitrate: 50237 kb/s
    Stream #0:0: Video: mpeg2video (4:2:2) (mpg2 / 0x3267706D), yuv422p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 51233 kb/s, 50 fps, 25 tbr, 50 tbn, 50 tbc
    Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 48000 Hz, mono, s16p, 64 kb/s
[graph 0 input from stream 0:0 @ 0x7fa7585003a0] w:1920 h:1080 pixfmt:yuv422p tb:1/50 fr:25/1 sar:1/1 sws_param:flags=2
[auto-inserted scaler 0 @ 0x7fa758500de0] w:iw h:ih flags:'0x4' interl:0
[format @ 0x7fa758500980] auto-inserting filter 'auto-inserted scaler 0' between the filter 'Parsed_null_0' and the filter 'format'
[swscaler @ 0x7fa759000600] deprecated pixel format used, make sure you did set range correctly
[auto-inserted scaler 0 @ 0x7fa758500de0] w:1920 h:1080 fmt:yuv422p sar:1/1 -> w:1920 h:1080 fmt:yuvj422p sar:1/1 flags:0x4
[image2 @ 0x7fa758825a00] Using AVStream.codec.time_base as a timebase hint to the muxer is deprecated. Set AVStream.time_base instead.
Output #0, image2, to 'imgs/img_%05d.jpg':
  Metadata:
    encoder         : Lavf55.44.100
    Stream #0:0: Video: mjpeg, yuvj422p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
    Metadata:
      encoder         : Lavc55.68.100 mjpeg
Stream mapping:
  Stream #0:0 -> #0:0 (mpeg2video (native) -> mjpeg (native))
Press [q] to stop, [?] for help
*** 1 dup!
*** 1 dup!9 fps=0.0 q=18.0 size=N/A time=00:00:00.36 bitrate=N/A dup=1 drop=0    
No more output streams to write to, finishing.:02.16 bitrate=N/A dup=2 drop=0    
frame=   56 fps= 20 q=24.8 Lsize=N/A time=00:00:02.24 bitrate=N/A dup=2 drop=0    
video:4148kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Input file #0 (3743_mpeg_progressive_seq_flip.avi):
  Input stream #0:0 (video): 55 packets read (13833108 bytes); 54 frames decoded; 
  Input stream #0:1 (audio): 31 packets read (5952 bytes); 
  Total: 86 packets (13839060 bytes) demuxed
Output file #0 (imgs/img_%05d.jpg):
  Output stream #0:0 (video): 56 frames encoded; 56 packets muxed (4247491 bytes); 
  Total: 56 packets (4247491 bytes) muxed

Changed 4 years ago by cehoyos

comment:3 Changed 4 years ago by cehoyos

  • Keywords mpeg2video regression added; mpeg removed
  • Priority changed from normal to important
  • Reproduced by developer set
  • Status changed from new to open

Regression since 0127b861
The attached sample outputs four frames for older FFmpeg versions, the third frame is missing since that change.

$ ffmpeg -vsync 0 -i 3743_mpeg_progressive_seq_flip.m2v -f framecrc -
ffmpeg version N-64228-g057d270 Copyright (c) 2000-2014 the FFmpeg developers
  built on Jun 26 2014 20:00:52 with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl
  libavutil      52. 90.101 / 52. 90.101
  libavcodec     55. 68.100 / 55. 68.100
  libavformat    55. 44.100 / 55. 44.100
  libavdevice    55. 13.101 / 55. 13.101
  libavfilter     4.  9.100 /  4.  9.100
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 19.100 /  0. 19.100
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mpegvideo, from '3743_mpeg_progressive_seq_flip.m2v':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: mpeg2video (4:2:2), yuv422p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], max. 50000 kb/s, 25 fps, 25 tbr, 1200k tbn, 50 tbc
[framecrc @ 0x2430060] Using AVStream.codec.time_base as a timebase hint to the muxer is deprecated. Set AVStream.time_base instead.
#software: Lavf55.44.100
#tb 0: 1/25
Output #0, framecrc, to 'pipe:':
  Metadata:
    encoder         : Lavf55.44.100
    Stream #0:0: Video: rawvideo (Y42B / 0x42323459), yuv422p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
    Metadata:
      encoder         : Lavc55.68.100 rawvideo
Stream mapping:
  Stream #0:0 -> #0:0 (mpeg2video (native) -> rawvideo (native))
Press [q] to stop, [?] for help
0,          3,          3,        1,  4147200, 0x4af40956
0,          4,          4,        1,  4147200, 0x468d0927
0,          6,          6,        1,  4147200, 0x32961317
frame=    3 fps=0.0 q=0.0 Lsize=       0kB time=00:00:00.28 bitrate=   6.0kbits/s
video:12150kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

comment:4 Changed 4 years ago by michael

  • Priority changed from important to normal
  • Type changed from defect to enhancement

the progressive sequence flag isnt allowed to change in mpeg, thus this is a bug in the used encoder.

Where is this file from ?

mpeg2:
In repeat sequence headers all of  the  data  elements  with  the  permitted
exception    of     those     defining     the     quantisation     matrices
(load_intra_quantiser_matrix,      load_non_intra_quantiser_matrix       and
optionally  intra_quantiser_matrix  and  non_intra_quantiser_matrix)   shall
have the same values as in  the  first  sequence  header.  The  quantisation
matrices may be redefined each time that a sequence  header  occurs  in  the
bitstream (Note  that  quantisation  matrices  may  also  be  updated  using
quant_matrix_extension()).
All of the data elements in the sequence_extension() that follows  a  repeat
sequence_header()  shall  have   the   same   values   as   in   the   first
sequence_extension().
If a sequence_scalable_extension() occurs after the first  sequence_header()
all    subsequent    sequence    headers    shall     be     followed     by
sequence_scalable_extension() in which all data elements are the same as  in
the    first    sequence_scalable_extension().

comment:5 Changed 4 years ago by michael

  • Resolution set to fixed
  • Status changed from open to closed
Note: See TracTickets for help on using tickets.