[FFmpeg-user] Direct Show issue?

Justin Slauson justin.slauson at gmail.com
Mon Jun 24 23:36:53 CEST 2013

I have a problem that I believe has to do with directshow. I changed
libavformat\rtp.c to have a few custom payload types due to a device I am
trying to stream to.

Problem: capturing directly from dshow and multi-casting via rtp results in
many dropped packets. (tagged as too old via audio device log)

Other info: Whenever I capture from dshow to a file, the quality is
perfect. From a file, I can stream to multicast and it is played without an
issue. If I stream to a multicast ip, use a second version of ffmpeg to
catch the stream and rebroadcast to the correct ip without re-encoding, the
device plays the stream without issue.

I've tested this on the pcm_s16le entry that I added and the default ulaw
protocol entry. It is successfully sending as the right payload type.

Here's the command (i've tried so many variations and changes) that I use
to stream from dshow:
ffmpeg -loglevel debug -f dshow -c:a pcm_s16le -ac 1 -ar 22050 -vn -i
audio="Line In (USB Multi-Channel Audi" -c:a copy -f rtp "rtp://"

Any help would be appreciated!

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