[FFmpeg-devel] [PATCHv3 4/4] libavcodec: v4l2: add support for v4l2 mem2mem codecs

[Jorge Ramirez]

On 08/03/2017 01:53 AM, Mark Thompson wrote:
>> +    default:
>> +        return 0;
>> +    }
>> +
>> +    SET_V4L_EXT_CTRL(value, qmin, avctx->qmin, "minimum video quantizer scale");
>> +    SET_V4L_EXT_CTRL(value, qmax, avctx->qmax, "maximum video quantizer scale");
>> +
>> +    return 0;
>> +}
> This doesn't set extradata - you need to extract the codec global headers (such as H.264 SPS and PPS) at init time to be able to write correct files for some codecs (such as H.264) with muxers requiring global headers (such as MP4).  It kindof works without it, but the files created will not conform and will not be usable on some players.
>
ah that might explain some things (when I play back the encoded video 
the quality is pretty lousy)
is there already some code I can use as a reference? I might be out of 
my depth here so any help will be more than welcome