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Old 25th April 2015, 10:35   #44  |  Link
hello_hello
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Join Date: Mar 2011
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Quote:
Originally Posted by Ghitulescu View Post
Here's one example
Lots of quatropfonic albums are encoded as 4.0 or 4.1.
I had a bit of a look through your thread. It seems to indicate what I suspected, that many/most hardware players/decoders aren't going to be happy with those formats either. I guess applying the same logic that's been applied to AAC here it means hardware players aren't adequate for multi-channel audio either.

While I was messing around trying to create 2.1ch/3.1ch/4.1ch AAC audio yesterday I kept wondering to myself why I was bothering as if I had audio in those formats and I was wanting to re-encode it, I'd probably convert it to another format in the process? I see you thought the same thing. For ffdshow users it'd be easy enough to enable it's mixer filter and decode via DirectShow. I assume it'd be possible to convert from one multi-channel format to another using Avisynth, but I just added the Matrix Mixer DSP to foobar2000's conversion chain.

In this case I reduced the centre channel by 60dB (that seems to be the maximum) reduced the over-all gain by 60dB (for a total of -120dB), and I boosted all the other channels by 60dB to compensate. If the input had been 4.1 channel there'd be no centre channel to turn down to nothing, but you could always duplicate the LFE channel in the centre channel at -60b to create a centre channel with nothing in it that way.

Once that was done it was simply a matter of opening a 5.1ch file (because I've got no 4.1ch files) and converting it directly to 5.1ch AAC..... to simulate converting 4.1ch directly to 5.1ch AAC with a silent centre channel. All that intermediate wave file creating and editing and exporting and converting seems like it's something to be avoided if possible.


Last edited by hello_hello; 25th April 2015 at 18:51.
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