[pulseaudio-discuss] Audio degradation and Underruns when changing sinks on a 'live stream'

[Colin Guthrie]

[Please create a new message rather than replying next time as it messes
up the threading :)]

Hiya


'Twas brillig, and Alejandro Gonzalez at 01/06/11 00:17 did gyre and gimble:
> Hi there, 
> 
> I'm new to PA so please forgive me if what I said have no much sense.
> 
> I'm using PA 0.9.22 + UCM patches from Margarita Olaya in an Ubuntu
> Maverik FS. And I have an alsa UCM profile that sets the playback
> controls and define 2 devices (Headset and Handset), so I can manually
> change between these two profiles using gnome-sound-preferences. PA
> shows them as different profiles Playback__Handset and
> Playback__Headset.
> 
> The issue is that if I change profiles on a 'live stream' the audio is
> correctly routed every time, but after a couple of tries it starts to
> get distorted and I can see a lot of buffer underruns and 'Requested to
> rewind'. 
> 
> I know there is a 'module-rescue-streams' that does the stream
> 're-routing' when the sink it is playing at dies, and this is exactly
> what happens when I do change profiles, the old-sink is deleted and a
> new sink is created, both have the same properties but a different name
> and each one set different alsa controls. 
> 
> D: sink.c: Processing rewind...
> D: sink-input.c: Have to rewind 208 bytes on render memblockq.
> D: sink-input.c: Have to rewind 184 bytes on implementor.
> D: source.c: Processing rewind...
> E: protocol-native.c: handle_seek: 0 -- 1
> D: protocol-native.c: Requesting rewind due to rewrite.
> D: alsa-sink.c: Requested to rewind 1360 bytes.
> D: alsa-sink.c: Limited to 1360 bytes.
> D: alsa-sink.c: before: 170
> D: alsa-sink.c: after: 170
> D: alsa-sink.c: Rewound 1360 bytes.
> D: sink.c: Processing rewind...
> D: sink-input.c: Have to rewind 1360 bytes on render memblockq.
> D: sink-input.c: Have to rewind 1256 bytes on implementor.
> 
> 
> I'm playing the file with a simple gstreamer pipeline:
> 
> gst-launch playbin2
> uri=file:///home/ubuntu/DaftPunk_Homework_AroundTheWorld.mp3
> 
> So my questions are:
> Can I fix the 'Underruns' increasing the default latency or buffer size?
> if so, Can I do this through a configuration parameter in
> default.pa/daemon.conf/client.conf?
> 
> Or is this 'on-the-fly' sink change simply not supported?
> and the 'module-rescue-streams' is not really a feature but a 'security
> harness'?

It very much should work as you expect, but somewhere along the lines
something is messing up :s

I'm not sure of the top of my head but I just wanted to reply to you to
let you know that the move itself should not be affecting underruns etc.

Can I ask if you are using the 0.9.22 vanilla or the patches from
"stable-queue" git branch (in particular David's "Fighting Rewinds"
patches)? I would very much recommend using stable-queue. Also there are
corresponding patches in David's set to the GST side too. I'd first
ensure you have all of these patches installed to see if this helps your
situation.

Cheers

Col

-- 

Colin Guthrie
gmane(at)colin.guthr.ie
http://colin.guthr.ie/

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