I get this error:

[mp4 @ 0x7fe854012400] Could not find tag for codec pcm_alaw in stream #1, codec not currently supported in container
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Stream mapping:
Stream #0:1 -> #0:0 (copy)
Stream #0:0 -> #0:1 (copy)
Last message repeated 1 times
Ok(Output { status: ExitStatus(ExitStatus(256)), stdout: "", stderr: "" })