[FFmpeg-trac] #3743(avcodec:new): mpeg2video decoder loses frames when progressive_sequence flag flips

[FFmpeg]

#3743: mpeg2video decoder loses frames when progressive_sequence flag flips
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             Reporter:  SianLiao  |                     Type:  defect
               Status:  new       |                 Priority:  normal
            Component:  avcodec   |                  Version:  git-master
             Keywords:  mpeg      |               Blocked By:
             Blocking:            |  Reproduced by developer:  0
Analyzed by developer:  0         |
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 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
 }}}

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Ticket URL: <https://trac.ffmpeg.org/ticket/3743>
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