[Bug 667564] mpeg4videoparse: does not detect config data when VOP only stream is sent

GStreamer (bugzilla.gnome.org) bugzilla at gnome.org
Wed Jan 18 08:32:30 PST 2012


https://bugzilla.gnome.org/show_bug.cgi?id=667564
  GStreamer | gst-plugins-bad | git

--- Comment #1 from Marc Leeman <marc.leeman at gmail.com> 2012-01-18 16:32:27 UTC ---
In ffmpeg, this code is called for bad headers:
    if(s->time_increment_bits==0 || !(show_bits(gb,
s->time_increment_bits+1)&1)){
        av_log(s->avctx, AV_LOG_ERROR, "hmm, seems the headers are not
complete, trying to guess time_increment_bits\n");

        for(s->time_increment_bits=1 ;s->time_increment_bits<16;
s->time_increment_bits++){
            if (    s->pict_type == AV_PICTURE_TYPE_P
                || (s->pict_type == AV_PICTURE_TYPE_S &&
s->vol_sprite_usage==GMC_SPRITE)) {
                if((show_bits(gb, s->time_increment_bits+6)&0x37) == 0x30)
break;
            }else
                if((show_bits(gb, s->time_increment_bits+5)&0x1F) == 0x18)
break;
        }

        av_log(s->avctx, AV_LOG_ERROR, "my guess is %d bits
;)\n",s->time_increment_bits);
    }

GStreamer fails here (gst_mpeg4_parse_video_object_layer):
  READ_UINT8 (&br, video_object_layer_start_code, 8);
  if (!(video_object_layer_start_code >= GST_MPEG4_VIDEO_LAYER_FIRST &&
          video_object_layer_start_code <= GST_MPEG4_VIDEO_LAYER_LAST))
    goto wrong_start_code;

Adding header scanning (offset 1 byte)
0:00:00.139527614   874      0x1502f30 ERROR                 ffmpeg :0:: hmm,
seems the headers are not complete, trying to guess time_increment_bits
0:00:00.139653102   874      0x1502f30 ERROR                 ffmpeg :0:: my
guess is 5 bits ;)

should bring us a step closer.

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