[pulseaudio-tickets] [PulseAudio] #837: A52 (ac3/Dolby Digital) encoding for SPDIF / Pulseaudio

[PulseAudio]

#837: A52 (ac3/Dolby Digital) encoding for SPDIF / Pulseaudio
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  Reporter:  mcarans  |       Owner:  lennart      
      Type:  defect   |      Status:  new          
 Milestone:           |   Component:  module-alsa-*
Resolution:           |    Keywords:               
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Comment(by coling):

 Due to the way PA drives the audio hardware (which is quite unlike almost
 every other alsa client) it needs the timing information returned from
 alsa to be accurate. This is one of the reasons PA adoption was generally
 problematic for many people as their drivers needed to be fixed.

 When I ran under plain alsa, speaker-test played each speaker's sample
 much quicker than it did under analog. With PA this was compressed much
 further to an almost inaudible chirp with underruns reported by PA.

 I didn't have time to look further than this. It could be that setting
 tsched=0 when loading the device would work fine, so you could try that
 but YMMV.

 Trying to discuss things with Raymond is not my favourite hobby as you'll
 see from our exchanges on the alsa mailing lists. It's very annoying as he
 does have valid points but cannot seem to express them in a constructive
 and logical manner.

 I think he's probably correct about the SNDRV_PCM_IOCTL_START failed error
 tho'. Not sure what to do other than ignore it tho' (I'm no alsa guru
 here). I'm not sure about the second point, but I would think if this is a
 limitation of the a52 plugin, then it should be fixed there. It could be
 that he's just describing what an "underrun" is generally, which is fine,
 but if the a52 plugin works different from other PCM plugins in this
 regard then I'd say it's probably the one to blame, but I really have no
 idea. The tsched=0 argument when loading the alsa-sink may work around
 this problem but I doubt it.

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Ticket URL: <http://pulseaudio.org/ticket/837#comment:8>
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