[FFmpeg-trac] #7355(avcodec:new): No MJPEG input with MMAL decoder

FFmpeg trac at avcodec.org
Mon Aug 13 17:39:03 EEST 2018


#7355: No MJPEG input with MMAL decoder
-------------------------------------+-------------------------------------
             Reporter:               |                     Type:
  Serveurperso                       |  enhancement
               Status:  new          |                 Priority:  normal
            Component:  avcodec      |                  Version:  git-
             Keywords:               |  master
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
-------------------------------------+-------------------------------------
 Can you add the MJPEG input to MMAL decoder ?

 https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/mmaldec.c

 Line 376 I can't see the MJPEG format :

     switch (avctx->codec_id) {
     case AV_CODEC_ID_MPEG2VIDEO:
         format_in->encoding = MMAL_ENCODING_MP2V;
         break;
     case AV_CODEC_ID_MPEG4:
         format_in->encoding = MMAL_ENCODING_MP4V;
         break;
     case AV_CODEC_ID_VC1:
         format_in->encoding = MMAL_ENCODING_WVC1;
         break;
     case AV_CODEC_ID_H264:
     default:
         format_in->encoding = MMAL_ENCODING_H264;
         break;
     }


 (From 6by9 on rpi-firmware)

 "The Pi supports hardware accelerated MJPEG via IL or MMAL, but FFMPEG
 doesn't.
 Having said that, the MMAL decoder would probably only need a half-dozen
 lines of code added to support it, mainly setting up format_in->encoding
 in ffmmal_init_decoder, and a FFMMAL_DEC definition at the end of the
 file. (libavcodec/mmaldec.c).
 I'm not sure how well FFMPEG differentiates between MJPEG and JPEG, so
 there may be minor issues. A couple of ffmpeg-dev list posts recently have
 been about adding some MJPEG codecs and were discussing it."


 I'm free to make any testing for you on my ready Raspberry PI + MJPEG
 capture hardware. I run 24/7 with FFMpeg git-master and raw YUYV but there
 is few USB2 bandwitch problem:(

 Thanks

--
Ticket URL: <https://trac.ffmpeg.org/ticket/7355>
FFmpeg <https://ffmpeg.org>
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