[mythtv-users] MythTV + AC3 question

[William Munson]

Drew Bernat wrote:
> With everything set up and (mostly) working, I've turned to getting my 
> HDTV-recorded programs (via a PCHDTV-5500) to output using AC3. I 
> looked through the archives and found a thread with similar symptoms 
> to mine, but no resolution. 
>
> The setup:
>
> PCHDTV-5500 recorded programs
> NForce 4 sound, ALSA, snd_intel_hda module (the MSI 6150 motherboard)
> MythTV internal player (mplayer et. al. work at this point). 
> MythTV WIKI asoundrc file (in /etc/asound.conf)
>
> I've tried the following configurations with the included results. I'm 
> wondering if this seems familiar to anyone:
>
> Sound output = ALSA:spdif or ALSA:iec958
>   - ALSA complains about a nonexistent device (?)
>
> ALSA:hw:0.2 (the IEC958 output) or plughw:0.2
>   - "AC3 passthrough" checked: static on all speakers
>   - "AC3 passthrough" unchecked: overdriven audio out of right front 
> channel only; I can hear the program, but it sounds like a blown speaker. 
>
> ALSA:hw:0 or plughw:0
>   - "AC3 passthrough" checked: no sound
>   - "AC3 passthrough" unchecked: sound, but it's being decoded by Myth 
> and coming out on analog + digital
>
>
> When I was using hw:0.2 and "AC3 passthrough" checked it appeared as 
> though Myth was still using an internal decoder:
>
> 2006-08-24 05:22:52.810 AFD: Looking for decoder for MPEG2VIDEO
> 2006-08-24 05:22:52.834 AFD: Opened codec 0x7d5e50, id(MPEG2VIDEO) 
> type(Video)
> 2006-08-24 05:22:52.874 AFD: Stream #1, has id 0x84 codec id AC3, type 
> Audio at
> 0x0x79b390
> 2006-08-24 05:22:52.909 AFD: Looking for decoder for AC3
> 2006-08-24 05:22:52.927 AFD: Opened codec 0x7c8e70, id(AC3) type(Audio)
>
>
> Has anyone had a similar problem and managed to get it worked out? The 
> oddest thing to me is the overdriven output on the right front channel 
> - I'm not familiar with anything that would cause such symptoms. 
>
The lack of sound devices is most likely your problem. Depending on how 
you update your system you might want to install the alsa-devices package.