[FFmpeg-trac] #3229(avcodec:open): ffplay shows bad images

[FFmpeg]

#3229: ffplay shows bad images
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             Reporter:  hxuanyu     |                    Owner:
                 Type:  defect      |                   Status:  open
             Priority:  normal      |                Component:  avcodec
              Version:  git-master  |               Resolution:
             Keywords:  mjpeg       |               Blocked By:
             Blocking:              |  Reproduced by developer:  1
Analyzed by developer:  0           |
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Changes (by ami_stuff):

 * cc: ami_stuff@… (added)


Comment:

 It's a problem with fields' order.

 This quick hack fixes it:

 libavcoedec/mjpegdec.c:

 {{{
     if (avctx->field_order == AV_FIELD_BB) { /* quicktime icefloe 019 */
         s->interlace_polarity = 1;           /* bottom field first */
         av_log(avctx, AV_LOG_DEBUG, "bottom field first\n");
     }
     if (avctx->codec->id == AV_CODEC_ID_AMV)
         s->flipped = 1;

 +        s->interlace_polarity = 1;

     return 0;
 }}}

 Also WMP plays the file correctly.

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Ticket URL: <https://trac.ffmpeg.org/ticket/3229#comment:3>
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