[mythtv] [mythtv-commits] Ticket #6395: AVFormatDecoder Language/codec detection improvements

Robert McNamara robert.mcnamara at gmail.com
Sat Mar 28 06:16:48 UTC 2009


On Fri, Mar 27, 2009 at 11:10 PM, George Nassas <gnassas at mac.com> wrote:
> On 28-Mar-09, at 1:55 AM, Robert McNamara wrote:
>
>> DTS-HD MA is not yet broken out as a seperate codec in
>> libavcodec/format.
>
> Oh OK, I didn't know that part. What twigged me was the possibility of
> TrueHD's AC3 core overriding a DTS track which I wouldn't want. Of course
> you're right it's unlikely both formats would ever be on one disc. Sounds
> great (no pun intended).
>
> - George
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TrueHD is a codec unto itself with no relation to AC3.  It's actually
MLP (Meridian Lossless Packing) with a higher allowable bitrate and
more extensive metadata.  Blu-ray *does* allow muxing a THD and AC3
stream onto a single PID, but Libavformat has no way of handling that
yet so it's a moot point so far.  Tt's being worked on, though, and
will present the THD and AC3 codecs as two different streams even
though they're on the same PID, so the current logic would still work.

I have some thoughts on how to properly hunt the Blu ray audio tracks
as support for them improves, but we'll cross that bridge when we come
to it.

Robert


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