So i have this code:

command = [self.ffmpegl,
                    '-f', 'dshow',
                    '-i','audio=Microphone (Webcam C170)',
                    '-f', 's16le',
                    '-acodec', 'libmp3lame',
                    '-']

which runs in python along with pipes, using subprocess, for those who didnt get it from above -  so in short:
ffmpeg.exe -f dshow -i audio="My mic" -f s161e -acodec libmp3lame -

the last '-' part is for piping
i get output on the stdout with the pipe, but i send "q\n" through stdin pipe to stop recording after 10 seconds.

When i do that, i get:

Press [q] to stop, [?] for help
av_interleaved_write_frame(): Invalid argument
size=     100kB time=00:00:06.33 bitrate= 128.7kbits/s
video:0kB audio:100kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%
Conversion failed!

Any idea what i should do?