[mythtv] Software AC3 decoding when watching TV

htpc htpc at treblid.dyndns.org
Thu Dec 9 03:55:22 UTC 2004


Sighz, this is very frustrating!! I have posted no less than 3 posts over 40 days at both mythtv-dev and mythtv-users asking about software AC3 decoding and got zilch replies. I searched the gossamer threads using various search combinations but found no answers. I had patiently waited for some kind soul to shed some light on this issue but none came forward.

Can somebody please, please tell me whether software AC3 decoding support is working in Myth in the first place? i.e. when the audio stream is in surround sound, decode it inside the computer and pass out the 5.1 channels via the sound card's 3 analog outputs. I have surround sound in MythVideo, but not when watching live HDTV. Whenever I set a surround sound APID in my channel info, all I hear are cracks, snaps and pops over the 3 analog outputs (note, I am not using the DVB 2.1 patch for this).

Is this feature lacking in MythTV itself, or is it because of some configuration error that I've made? Is surround sound part of the DVB patch? As mentioned I am more than willing to try and implement this feature, still it takes time for me to understand how sound is implemented in Myth, so I welcome any help/tips/suggestions to point me in the right direction.

Again, say something to me - abuse, flame, curses, anything to put me on the right track.

The community help for MythTV is amazing, but somehow lacking when it comes to surround sound for TV, sighz.


Regards.

htpc wrote:

>Dear all,
>
>Does MythTV support software AC3 decoding when watching TV with AC3 APIDs for the DVB-T format? (damn these acronyms) Everybody seem to output AC3 via digital out but I prefer an all-in-one solution (mainly becoz I can't afford to buy a receiver).
>
>Are they any technical issues that makes software AC3 decoding impossible for Myth? libavcodec appears to have ac3 decoder support. (not sure whether that is the AC3 for DVB-T or the a52 for ATSC, or whatever).
>
>I am a C++/QT programmer (although a lousy one) by trade but it still takes time for me to look through the source and get the big picture, thus I appreciate any tips/pointers/references/help to help me start working on this feature.
>
>Some more questions:
>1) Is A52 == Dolby Digital == AC3?
>2) Is it right that the AC3 audio on DVB-T doesn't have a proper AC3 header?
>
>I'm sorry if all this have been discussed before, but I can't seem to find a definite answer or solution for this topic on Gossamer Threads, so I'm starting a new one.
>
>
>Regards.
>
>
>
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