[pulseaudio-discuss] 'clicks' in audio and rtp troubles

[Lennart Poettering]

On Mon, 28.05.07 23:44, joysn at gmx.net (joysn at gmx.net) wrote:

> > Hmm, this probably means you're running a really awful non-"preempt"
> > kernel whith a large HZ. Last time I looked Ubuntu shipped a shitty
> > kernel like that. Dunno if they still do. You might want to change
> > that.
> 
> i use a vanilla kernel with Ingo Molnars RT patch:
> Linux joysn 2.6.21-rt8 #1 PREEMPT RT

That doesn't sound too bad. ;-)

> > Also, a VLC client with minor modifications should be able to pick up
> > the SAP announcements. (i.e. just replacing the multicasting address
> > to listen on -- ideally that address should be configurable. maybe it
> > is time to file a feature request bug for vlc for this)
> 
> hm. vlc 0.8.6 has a configurable mcast address for SAP. the playlists
> also 'see' the stream but when i try to connect to ist vlc reports:
> 
> live555 error: Nothing to play for rtsp://v=0
> o=chris 3389376985 0 IN IP4 192.168.0.3
> s=PulseAudio RTP Stream on joysn
> c=IN IP4 225.0.0.1
> t=3389376985 0
> a=recvonly
> m=audio 554 RTP/AVP 10
> a=rtpmap:10 L16/44100/2
> a=type:broadcast
> 
> main error: no suitable access module for `sdp://v=0
> o=chris 3389376985 0 IN IP4 192.168.0.3
> s=PulseAudio RTP Stream on joysn
> c=IN IP4 225.0.0.1
> t=3389376985 0
> a=recvonly
> m=audio 554 RTP/AVP 10
> a=rtpmap:10 L16/44100/2
> a=type:broadcast

Hmm. Those are very strange URLs, don't you think?

Seems VLCs SDP parsing is not compatible with PAs SDP generation. Or
maybe VLC is just not able to deal with S16BE audio data?

I think you should discuss this with the VLC people. (This looks like
a VLC issue to me, although I wouldn't rule out that PA is the
evildoer here.)

> ok. i'll try to modify wireshark to use a audio decoder lib and route
> the results to an available audio device ;-)
> i played with mplayer, but annot figure out the syntax for the rtp 
> stream? rtp://225.0.0.1?

You should pass the RTP port number as well. PA randomizes the RTP port number
on each call (which is a good thing when SAP is used). If you
want to use RTP without SAP/SDP you need to use a fixed port number by passing
port=46000 or similar to module-rtp-send.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4