[mythtv-commits] Ticket #5473: audio out, PulseAudio

MythTV mythtv at cvs.mythtv.org
Fri Dec 26 17:43:30 UTC 2008

#5473: audio out, PulseAudio
 Reporter:  Alan Calvert <cal at graggrag.com>  |        Owner:  ijr    
     Type:  patch                            |       Status:  new    
 Priority:  minor                            |    Milestone:  unknown
Component:  mythtv                           |      Version:  head   
 Severity:  medium                           |   Resolution:         
  Mlocked:  0                                |  

Comment(by IntuitiveNipple):

 I've back-ported this patch to 0.21+fixess18722 (for Ubuntu Intrepid).
 Aside from the re-factoring required to deal with using QT3 rather than
 QT4, and the MythTV changes, I found a few issues some of which are not
 yet resolved:

 1. Mixed use of USE_PULSEAUDIO and USING_PULSEAUDIO confused things. I've
 used USING_PULSEAUDIO throughout.

 2. Mixer name needs to be "!PulseAudio:default" (not "!PulseAudio") in
 globalsettings.cpp !AudioOutputDevice():
 diff --git a/programs/mythfrontend/globalsettings.cpp
 index b1012d1..b8ff8cb 100644
 --- a/programs/mythfrontend/globalsettings.cpp
 +++ b/programs/mythfrontend/globalsettings.cpp
 @@ -168,6 +171,9 @@ static HostComboBox *MixerDevice()
      gc->addSelection("Windows:", "Windows:");
 +    gc->addSelection("PulseAudio:default", "PulseAudio:default");

      return gc;

 Not yet resolved:

 3. Matching the number of !PulseAudio channels. On a 7.1 channel audio
 system MythTV only outputs 5.1 maximum (doesn't output Side Left/Right).
 This looks to be easily fixable but I need to check before making changes.

 4. Occasional "!PulseAudio Error: stream buffer underflow" reports. No
 clues to the reason yet.

 5. Occasional bursts of static when changing to new channel (sounds like a
 16-bit sample getting out of step by 8 bits). This will sometimes self-
 correct (another 8 bits dropped would align the samples correctly again).

 6. Frequently audio is lost completely for long periods, with the report
 "NVP::!AddAudioData():p1: Audio buffer overflow, audio data lost!"

 7. Seemingly excessive CPU load by the pulseaudio process and
 mythtvfrontend.real when using !PulseAudio. I need to do more systematic
 comparisons before confirming this.

 I'll attach the current patch I'm using in Ubuntu Intrepid and update as I
 make progress with the discovered issues.

Ticket URL: <http://svn.mythtv.org/trac/ticket/5473#comment:14>
MythTV <http://www.mythtv.org/>

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