What would be the correct way to use Exec or Transcode ffmpeg in SRS version of Windows 5.0.128

Question

i was doing tests in different ways, and i can't use the Exec or Transcode option, i highlight that I have copied the ffmpeg.exe in the objs folder. These are the codes I tried, and I attach the log errors.

exec {

enabled on;

publish ./objs/ffmpeg.exe -rtbufsize 10M -i rtmp://10.1.9.240/live/encoder  -vf scale=1080:720 -c:v libx264 -profile:v high -level 4.2 -preset fast -b:v 1500k -c:a aac -ac 2 -b:a 96k -f flv -y rtmp://10.1.9.240:1935/live/encoderlow/;

}

LOGS

[2023-01-04 10:05:46.410][WARN][1309][01568ctu][11] EXEC: Ignore error, code=3028(FFmpegFork)(Failed to fork FFmpeg trancoder process) : process start : vfork process failed, cli=./objs/ffmpeg.exe -rtbufsize 10M -i rtmp://10.1.9.240/live/encoder -vf scale=1080:720 -c:v libx264 -profile:v high -level 4.2 -preset fast -b:v 1500k -c:a aac -ac 2 -b:a 96k -f flv -y rtmp://10.1.9.240:1935/live/encoderlow/ thread [1309][01568ctu]: do_cycle() [./src/app/srs_app_ng_exec.cpp:108][errno=11] thread [1309][01568ctu]: start() [./src/app/srs_app_process.cpp:197][errno=11]

transcode {

    enabled     on;

    ffmpeg      ./objs/ffmpeg.exe;

    engine ff {

        enabled         on;

        vfilter {

        }

        vcodec          libx264;

        vthreads        4;

        vprofile        high;

        vpreset         fast;

        vbitrate        1500k;

        vparams {

        }

        acodec          libfdk_aac;

        aparams {

        }

        output          rtmp://127.0.0.1:[port]/[app]/[stream]_[engine]?vhost=[vhost];

    }

}

LOGS

[2023-01-04 11:04:45.295][WARN][1489][34r32764][11] Encoder: Ignore error, code=3028(FFmpegFork)(Failed to fork FFmpeg trancoder process) : ffmpeg start : vfork process failed, cli=./objs/ffmpeg.exe -f flv -i rtmp://127.0.0.1:1935/live?vhost=defaultVhost/encoder -vcodec libx264 -b:v 1500000 -threads 4 -profile:v high -preset fast -acodec libfdk_aac -f flv -y rtmp://127.0.0.1:1935/live/encoder_ff?vhost=defaultVhost 1 > ./objs/ffmpeg-encoder-defaultVhost-live-encoder-ff.log 2 > ./objs/ffmpeg-encoder-defaultVhost-live-encoder-ff.log thread [1489][34r32764]: do_cycle() [./src/app/srs_app_encoder.cpp:117][errno=11] thread [1489][34r32764]: start() [./src/app/srs_app_process.cpp:197][errno=11]

Answer 1

SRS windows use cygwin64, which is not support fork ffmpeg.exe process on win32, so it does not work for neither exec or transcode.

So you can try win64, which should work well with ffmpeg.exe.

However, there is a workaround, to start a ffmpeg.exe process to do transcode manually, for example:

./objs/ffmpeg.exe -f flv -i rtmp://127.0.0.1:1935/live/encoder \
  -vcodec libx264 -b:v 1500000 -threads 4 -profile:v high \
  -preset fast -acodec libfdk_aac -f flv \
  -y rtmp://127.0.0.1:1935/live/encoder_ff

Because SRS will do this for you, but it's not a good idea to let SRS to do this. Instead, you should use HTTP callback to hook the on_publish event, then start a FFmpeg process. Like this:

Client(OBS as such) --RTMP--> SRS ---HTTP-callback--> Go server
                               ^                          |
                               |                          V
                               ^--RTMP-- FFmpeg <--fork---+

Note: You should write a Go(or Nodejs or Python) server, for SRS to send HTTP request to, with the stream information, then fork new FFmpeg process to transcode RTMP stream, see HTTP Callback

The reason is quiet straight forward: To start and manage FFmpeg processes, we should use Go/Nodejs/Python backend server, but not C/C++ server like SRS or Nginx.

PS: Please remove the last slash of rtmp://10.1.9.240:1935/live/encoderlow/ to rtmp://10.1.9.240:1935/live/encoderlow because they are not the same URL for RTMP.