[mythtv-users] AAC 5.1 decode and analog playback

Mark Fink marksfink at yahoo.com
Thu Nov 22 01:09:41 UTC 2007

Thanks for your feedback.  No offense, but it does seem like more work (to me at least) to change encoding format and parameters based on movie content.  I'd rather just have one "standard" way of doing it where I can pop the DVD in the drive, run a script, come back several hours later and its done, with little thought beyond that, even if the movie content does not necessarily require the quality encode.  However, in saying that, I do not mean to depreciate your way of doing things -- I love the MythTV DIY approach because it gives individuals flexibility to manage things as they like.

That said, based on everything I've read, with no experience on it, there seems to be consensus that H.264/AAC are high-quality, broadly-supported formats, except that home theatre receivers cannot decode AAC streams (though perhaps they will someday).  And until I get more experience on it, I am happy to base decisions on that consensus for the time being.  And I didn't see anything in your response that would refute this, just that not all movies would require it.

In any case, I may find that Divx and/or Xvid are simply easier (time/effort) than H.264, especially for standard DVD content, which is all I am dealing with now.  However, it seems a certainty I will be moving to 1080p/i Blu-Ray content in due time and would rather have a library of consistent file formats than a mix of Divx and H.264, not that its that big a deal, but I always prefer consistency when possible, so why not start with H.264 now?

Since writing my first post, I found that ac3filter is for Windows only, not Linux, so I have ruled that out as a means of playback for AAC encoded audio.  I have not found similar software for Linux.  I am thinking it is moot anyway, since delivering the discrete 5.1 channels to the receiver via analog is probably a better way to go (short of using Divx or Xvid).  If I tested it out and found that audio playback was significantly better with Divx/Xvid with the original AC3 audio, that would become a compelling reason for me to go with Divx/Xvid.

But before I go any further, do you (or anyone) see any "gotcha" with decoding an AAC 5.1 soundtrack on the HTPC (with MythVideo, mplayer, or xine) and delivering the discrete 5.1 channels via analog RCA connections to the receiver (which has the requisite 5.1 RCA inputs)?  I suppose I should check my assumptions and be sure this configuration is even possible/workable.  I think it is, but...if not, let me know!

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