[mythtv-commits] Ticket #7563: Upmixer uses wrong sample rate for IEC958

MythTV mythtv at cvs.mythtv.org
Sat Nov 14 08:57:59 UTC 2009


#7563: Upmixer uses wrong sample rate for IEC958
-----------------------------------+----------------------------------------
 Reporter:  anonymous              |        Owner:  jyavenard
     Type:  defect                 |       Status:  closed   
 Priority:  minor                  |    Milestone:  unknown  
Component:  MythTV - Audio Output  |      Version:  head     
 Severity:  medium                 |   Resolution:  invalid  
  Mlocked:  0                      |  
-----------------------------------+----------------------------------------
Changes (by jyavenard):

  * status:  new => closed
  * resolution:  => invalid


Comment:

 Alsa reports 44100 as being available ; and as your content is 44.1kHz,
 that's what it tried using... AC3 doesn't have to be 48kHz.

 44100 isn't an invalid sample rate for iec958.

 So here myth doesn't use the *wrong* sample rate. It uses what your card
 reports as being available.
 Yet, for some reasons ALSA uses 44.1kHz, you get 48kHz in return.

 Possible issues:
 -Alsa is broken for your device, try upgrading to a newer version
 -You haven't configured myth properly. Myth tries to open the "default"
 device. Make sure you have set the passthrough device properly and checked
 AC3 as being available

 This is what a proper ALSA driver would return when trying to play 44.1kHz
 audio with AC3 upmixing:
 {{{
 2009-11-14 12:52:55.239 DEnc: Init codecid=AC3, br=448000, sr=44100, ch=6
 2009-11-14 12:52:55.239 DigitalEncoder::Init fs=1536, bpf=12 ofb=18432
 2009-11-14 12:52:55.240 Opening audio device 'spdif'. ch 2(2) sr 44100
 (reenc 0)
 2009-11-14 12:52:55.240 Setting IEC958 status: non-audio
 2009-11-14 12:52:55.240 Opening ALSA audio device 'spdif'.
 2009-11-14 12:52:55.240 in SetParameters(format=2, channels=2, rate=44100,
 buffer_time=400000, period_time=25000)
 2009-11-14 12:52:55.281 AO: Audio fragment size: 6144
 2009-11-14 12:52:55.281 AO: create upmixer
 2009-11-14 12:52:55.281 AO: Create upmixer done with surround mode 2
 }}}

 In any cases, this is not a mythtv issue

-- 
Ticket URL: <http://svn.mythtv.org/trac/ticket/7563#comment:1>
MythTV <http://www.mythtv.org/>
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