Format of Multicast RTP stream

[jolouis]

I ran into the same choppy audio when streaming from PulseAudio in Linux. After a whole lot of fighting and packet tracing I finally came to the conclusion that the packets being sent out were too big for the Yealink phones to handle properly. I set the MTU to 300 instead of the default and instantly everything was clear no more problems.

Not sure how you do it with vlc, but something like --mtu=300 would seem to be correct to add to your command line somewhere:
https://forum.videolan.org/viewtopic.php?t=95549

(05-24-2015 12:29 AM)srcurtis Wrote:  Hi

I'm trying to output a pre-recorded wav file to Yealink phones via vlc and RTP Multicast and am experiencing choppy audio.

Phones are T38G's and T42G's configured for PCMU.

When not using vlc and originating the stream from a Yealink phone, multicast from a phone to other phones gives a crystal clear stream.

Using vlc I am transcoding as follows:

--sout "#transcode{acodec=ulaw,ab=16,samplerate=8000,channels=1}:rtp{dst=224.0.1.201,por​t-audio=5439}"

The audio plays but is very choppy.

I'm at a loss as to what I am doing wrong and am questioning the format of the audio stream.

Any help would be much appreciated.

Thanks

Steve