[mythtv-users] Not getting Dolby Prologic out of s/pdif
adeffs.mythtv at gmail.com
Thu Mar 16 00:21:37 UTC 2006
On 3/15/06, Michael T. Dean <mtdean at thirdcontact.com> wrote:
> On 03/15/2006 10:41 AM, Jeff Clemens wrote:
> >That said, the redundant information necessary to allow prologic to work may
> >not make it through the compression process, its hard to say.
> That's what I had always heard, too, but Steve Adeff called me on it, so
> I did some research and found he's right--the Dolby Surround information
> should survive compression. Steve summed up the info in my, "I stand
> corrected" post in his reply to yours (use a high enough bitrate and
> you're OK), but in case you want the details, see
> http://www.gossamer-threads.com/lists/mythtv/users/188945#188945 .
when the mpeg group designed their audio compression algorithm they
made certain that DPL would survive. Of course they could only
guarantee it at a certain bitrate, but from what I understand they did
put algorithms in that were DPL smart so that they would not remove
any DPL information except when the bitrate made it necesary.
As well, from my understanding broadcast level DD encoding will never
remove DPL information as they always use a bitrate that won't affect
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