[FFmpeg-trac] #6629(avdevice:new): Assertion failed when specifying h264 format on v4l2 device that does NOT support h264

[FFmpeg]

#6629: Assertion failed when specifying h264 format on v4l2 device that does NOT
support h264
-------------------------------------+-------------------------------------
             Reporter:  Mr-Dave      |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:  avdevice     |                  Version:  git-
             Keywords:  avdevice     |  master
  v4l2 input_format                  |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:
 When opening the format context to a v4l2 device and have specified a
 format which the device does NOT support, the avformat_open_input
 assertion fails.

 How to reproduce:
 Sample code using a device that does NOT support h264
 {{{
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>

 #include <libavformat/avformat.h>
 #include <libavdevice/avdevice.h>
 #include <libavutil/avutil.h>

 int main (int argc, const char **argv) {

     AVFormatContext *format_context;
     AVDictionary *opts = 0;

     int  retcd;
     char errstr[128];
     char optfmt[8];

     av_register_all();
     avcodec_register_all();
     avformat_network_init();
     avdevice_register_all();

     format_context = avformat_alloc_context();
     format_context->iformat = av_find_input_format("video4linux2");

     sprintf(optfmt, "%s","h264");
     av_dict_set(&opts, "input_format", optfmt, 0);

     retcd = avformat_open_input(&format_context, "/dev/video0", NULL,
 &opts);
     fprintf(stderr,"Format context is open: \n");
     if (retcd < 0){
         av_strerror(retcd, errstr, sizeof(errstr));
         fprintf(stderr,"error opening file: %s \n",errstr);
         av_dict_free(&opts);
         return -1;
     }

     fprintf(stderr,"Device is open: \n");

     avformat_close_input(&format_context);

     return 0;
 }
 }}}
 Output:
 {{{
 ./sample
 [video4linux2,v4l2 @ 0x3d4a420] Cannot find a proper format for codec
 'h264' (id 28), pixel format 'none' (id -1)
 Assertion *codec_id != AV_CODEC_ID_NONE failed at libavdevice/v4l2.c:808
 Aborted (core dumped)
 }}}

 Expected result:

 avformat_open_input would return a error code.

 ffmpeg version:
 {{{
 /home/dave/ffmpeg_33/bin/ffmpeg
 ffmpeg version 3.3 Copyright (c) 2000-2017 the FFmpeg developers
   built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609
   configuration: --prefix=/home/dave/ffmpeg_33 --pkg-config-flags=--static
 --extra-cflags=-I/home/dave/ffmpeg_33/include --extra-
 ldflags=-L/home/dave/ffmpeg_33/lib --bindir=/home/dave/ffmpeg_33/bin
 --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype
 --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis
 --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree
   libavutil      55. 58.100 / 55. 58.100
   libavcodec     57. 89.100 / 57. 89.100
   libavformat    57. 71.100 / 57. 71.100
   libavdevice    57.  6.100 / 57.  6.100
   libavfilter     6. 82.100 /  6. 82.100
   libswscale      4.  6.100 /  4.  6.100
   libswresample   2.  7.100 /  2.  7.100
   libpostproc    54.  5.100 / 54.  5.100
 Hyper fast Audio and Video encoder
 usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options]
 outfile}...
 }}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6629>
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