In SRS Is it possible to Transcode with an FFMPEG -encoder that is not libx264?

Question

Is it possible to Transcode with an FFMPEG -encoder that is not libx264? I have a few scenarios where I want to use NVEC hardware accelerated encoding . Also transcoding streams to AV1 is desirable too for the network resiliency and lower bandwidth. Currently when I try to use another encoder than libx264 I get an error that says I must use Libx264. Is there a way around this?

Answer 1

SRS wrap the FFmpeg CLI and has a set of limitation about the params, for example, you could only use h.264 not h.265/av1 for video codec, because it simplify the usage of FFmpeg.

For example, the ingester/transcode config is bellow:

    ingest livestream {
        enabled      on;
        input {
            type    file;
            url     ./doc/source.200kbps.768x320.flv;
        }
        ffmpeg      ./objs/ffmpeg/bin/ffmpeg;
        engine {
            enabled          off;
            output          rtmp://127.0.0.1:[port]/live?vhost=[vhost]/livestream;
        }
    }

It equals to the FFmpeg CLI as demonstrated bellow:

./objs/ffmpeg/bin/ffmpeg -re -i ./doc/source.200kbps.768x320.flv \
  -c copy -f flv rtmp://127.0.0.1/live/livestream

You could find out the CLI in SRS log:

fored process, pid=76501, bin=./objs/ffmpeg/bin/ffmpeg, 
argv=./objs/ffmpeg/bin/ffmpeg -loglevel info -re -i 
./doc/source.200kbps.768x320.flv -vcodec copy -acodec copy -f flv 
-y rtmp://127.0.0.1:1935/live?vhost=__defaultVhost__/livestream

Rather than use the SRS ingest/transcode feature, you could run your FFmpeg CLI with any params you want, please read FFmpeg. It works like this:

OBS --RTMP--> SRS --hooks--> Your Backend Server
                                  +
                                  +--fork--> FFmpeg

Once you start a ffmpeg process, you could use libx265 or av1, to pull stream from SRS and transcode it, then publish it to SRS again.