[mythtv-users] ALSA:surround51 with MythTV 0.24

[Jean-Yves Avenard]

Hi

On 7 March 2011 07:00, Achim Hofmann <news at achim-hofmann.com> wrote:

> In my MythBox there's a VIA Technologies, Inc. VT8233/A/8235/8237 AC97
> Audio Controller (rev 60). This is the output of `aplay -L`:
>
> null
>    Discard all samples (playback) or generate zero samples (capture)
> default:CARD=V8237
>    VIA 8237, VIA 8237
>    Default Audio Device
> front:CARD=V8237,DEV=0
>    VIA 8237, VIA 8237
>    Front speakers
> surround40:CARD=V8237,DEV=0
>    VIA 8237, VIA 8237
>    4.0 Surround output to Front and Rear speakers
> surround41:CARD=V8237,DEV=0
>    VIA 8237, VIA 8237
>    4.1 Surround output to Front, Rear and Subwoofer speakers
> surround50:CARD=V8237,DEV=0
>    VIA 8237, VIA 8237
>    5.0 Surround output to Front, Center and Rear speakers
> surround51:CARD=V8237,DEV=0
>    VIA 8237, VIA 8237
>    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
> iec958:CARD=V8237,DEV=0
>    VIA 8237, VIA 8237
>    IEC958 (S/PDIF) Digital Audio Output
>
> When set to ALSA:surround51:CARD=V8237,DEV=0 and playing a movie, the
> following error appears in mythfrondend.log:
>
> 2011-03-06 12:31:18.479 AFD Warning: ScanATSCCaptionStreams() called
> with no PMT
> 2011-03-06 12:31:18.480 AFD: Opened codec 0xb3c04a0, id(MPEG2VIDEO)
> type(Video)
> 2011-03-06 12:31:18.480 AFD: codec AC3 has 6 channels
> 2011-03-06 12:31:18.481 AFD: Opened codec 0xb387cb0, id(AC3) type(Audio)
> 2011-03-06 12:31:18.607 AO: Opening audio device
> 'surround51:CARD=V8237,DEV=0' ch 6(6) sr 48000 sf signed 16 bit reenc 0
> 2011-03-06 12:31:18.617 ALSA, Error: Error opening
> /proc/asound/card0/pcm1p/sub0/prealloc. Fix reading permissions.
> 2011-03-06 12:31:18.617 ALSA, Error: Unable to sufficiently increase
> ALSA hardware buffer size - underruns are likely
> 2011-03-06 12:31:18.635 AudioPlayer: Enabling Audio
>
> The audio sounds heavy scratched.

Interesting.

Never seen ALSA allocation that folder before.

> So there's no folder called "pcm1p". I've no idea why MythTV tries to
> handle with it?

Because that's where ALSA points to:
card 0 , 1st PCM, sub-device 0

>
> By the way: Using mplayer with the ALSA surround51 pcm device still
> works fine. Only using the MythTV internal player makes trouble.

I'm working on another fix for other type of weird audio card ; I will
include this in it.

Jean-Yves