If you kill ffmpeg process it will exit with code 255 (easily reproducible in the terminal)

[mp4 @ 0x7fe98400dc00] track 1: could not find tag, codec not currently supported in container This means that pcm_mulaw is not allowed in the MP4 output container format. Your choices are: Use a different output container format ffmpeg -i input -codec copy output.mkv Or re-encode the audio ffmpeg -i input -c:v copy -c:a aac output.mp4

Encode the audio to a supported format, such as AAC by replacing -acodec copy with -c:a aac, or use a more flexible output container format that does support pcm_alaw, such as MOV or MKV.

This is telling you not that the codec is missing, but that it is not compatible with the MP4 format. You can fix this issue by using a different audio codec. ffmpeg -i P1010989.MOV -vcodec copy -acodec aac -strict -2 -b:a 384k out.mp4

The command: ffmpeg -i rtsp://@192.168.241.1:62156 -acodec copy -vcodec copy c:/abc.mp4 will not do transcoding and dump the file for you in an mp4.

FFmpeg itself is composed of several libraries that can be used individually, and outside of FFmpeg, for instance in integrating parts of FFmpeg into your own program.

Compile with pthreads and make sure to specify the number of threads you want to use with the -threads cmdline parameter