[pulseaudio-discuss] RTP receiver problem, jumpy samplerate

[Nikolay Dvoeglazov]

Hello everyone,

I am struggling to make my simple RTP setup work correctly. I have one
sender and one receiver, both running the latest pulseaudio 0.9.15. Normal
"module-native-protocol-tcp" works fine with pulseaudio client (I am using
mplayer to test) running from the sender side, but when I start the
pulseaudio server on the sender side and start the receiver side, I have the
following output:

-------CUT-------
I: module-rtp-recv.c: New session 'PulseAudio RTP Stream on atom.splava.ru'
D: module-rtp-recv.c: Requesting rewind due to end of underrun
D: alsa-sink.c: Requested to rewind 65536 bytes.
D: alsa-sink.c: Limited to 37984 bytes.
D: alsa-sink.c: before: 9496
D: alsa-sink.c: after: 9496
D: alsa-sink.c: Rewound 37984 bytes.
D: sink.c: Processing rewind...
D: sink-input.c: Have to rewind 37984 bytes on render memblockq.
D: source.c: Processing rewind...
D: module-rtp-recv.c: Updating sample rate
D: module-rtp-recv.c: wi=2767821 ri=2663038
D: module-rtp-recv.c: Write index deviates by 270.23 ms, expected 500.00 ms
D: module-rtp-recv.c: Updated sampling rate to 42074 Hz.
I: alsa-sink.c: Underrun!
N: alsa-sink.c: Increasing wakeup watermark to 30.00 ms
D: module-rtp-recv.c: Requesting rewind due to end of underrun
D: alsa-sink.c: Requested to rewind 65532 bytes.
D: alsa-sink.c: Limited to 36228 bytes.
D: alsa-sink.c: before: 9057
D: alsa-sink.c: after: 9057
D: alsa-sink.c: Rewound 36228 bytes.
D: sink.c: Processing rewind...
D: sink-input.c: Have to rewind 36228 bytes on render memblockq.
D: source.c: Processing rewind...
D: module-rtp-recv.c: Updating sample rate
D: module-rtp-recv.c: wi=8146486 ri=7902267
D: module-rtp-recv.c: Write index deviates by 343.00 ms, expected 500.00 ms
D: module-rtp-recv.c: Updated sampling rate to 40690 Hz.
D: module-rtp-recv.c: Checking for dead streams ...
D: module-rtp-recv.c: Updating sample rate
D: module-rtp-recv.c: wi=13886477 ri=13267141
D: module-rtp-recv.c: Write index deviates by 842.90 ms, expected 500.00 ms
D: module-rtp-recv.c: Updated sampling rate to 43714 Hz.
D: module-rtp-recv.c: Updating sample rate
D: module-rtp-recv.c: wi=18010641 ri=17327172
D: module-rtp-recv.c: Write index deviates by 895.15 ms, expected 500.00 ms
D: module-rtp-recv.c: Updated sampling rate to 47199 Hz.
-------CUT-------

If I start feeding any source to the sender instance, I get sound on the
receiver side, but it stutters and, as the debugging messages say, plays at
the "updated" samplerate. The samplerate comes closer to ~70000 Hz in a
couple of minutes. Both machines run identical vanilla 2.6.29 kernels, I've
switched to RT kernels and back on both the sender and receiver with no
difference. I've also tried using different output sinks (JACK & ALSA) and
different sound cards. The machines are directly connected to each other via
100mbps LAN and nothing disrupts the network. I desperately need to get this
working and sincerely hope the experts can help out or point me in the right
direction!

Huge thanks in advance!

Nickie