[FFmpeg-trac] #8211(avformat:new): ffplay does'nt play mjpeg stream

FFmpeg trac at avcodec.org
Thu Mar 18 22:12:39 EET 2021

#8211: ffplay does'nt play mjpeg stream
             Reporter:  anhsoft      |                    Owner:
                 Type:  enhancement  |                   Status:  new
             Priority:  wish         |                Component:  avformat
              Version:  git-master   |               Resolution:
             Keywords:  rtsp mjpeg   |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |

Comment (by HappyCow):

 No, anhsoft is basically right.
 More or less the same results are obtained using ffmpeg/ffplay, VLC,
 GStreamer, OpenCV and its derivatives in Windows and Linux [32 bits and 64
 bits] (but not in Android)
 The frames are just partially decoded (the main top strip and sometimes
 other partial strips [when movement happens] either at the middle or at
 the bottom part of the image.
 This is a problem that seems it is plaguing the internet forums... as it
 happens with a broad range of devices [endoscope camera Ypc99, I-Spy mini
 tank, quite a few cheap drones, and some devices using v4l2rtspserver,
 The IjkPlayer does ok on android [where libijkffmpeg.so is just an
 specific ffmpeg build] but the other platforms fail to do the job.
 However, as far as I have traced it, all the decoding parameters and steps
 seem exactly identical [Stream #0:0, 21, 1/90000: Video: mjpeg, 1
 reference frame, yuvj420p(pc, bt470bg/unknown/unknown, center), 640x480
 [SAR 1:1 DAR 4:3], 0/1, 20 fps, 20 tbr, 90k tbn, 90k tbc] except when it
 comes to the marker=da buffer size estimation.
 The reason is unknown to me, but it does not seem to be related to any
 type of encryption, just some incompatibility with the calculation of
 buffer sizes (I guess)
 Even forcing some other types of codecs as mjpeg_qsv and other parameters
 you get quite similar results.

Ticket URL: <https://trac.ffmpeg.org/ticket/8211#comment:12>
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