[opus] [Patch] Non-diegetic support for channel mapping 254
bitllama at google.com
Fri Apr 28 23:54:45 UTC 2017
sorry about that... extra lines... was it whitespace? If so, sorry about
On Fri, Apr 28, 2017 at 2:43 PM, Jean-Marc Valin <jmvalin at jmvalin.ca> wrote:
> Oops, looks like we both should have been more careful. The patch had
> some extra lines that shouldn't have been there.
> On 28/04/17 12:59 PM, Drew Allen wrote:
> > My apologies for the confusion, I think I have the mapping layout
> > correct in this patch.
> > Cheers!
> > On Tue, Apr 25, 2017 at 10:07 AM Jean-Marc Valin <jmvalin at jmvalin.ca
> > <mailto:jmvalin at jmvalin.ca>> wrote:
> > On 25/04/17 10:12 AM, Drew Allen wrote:
> > > We assume that the input file is ordered first by ACN ambisonic
> > channels
> > > followed by a (possible) stereo track, and we want to swap the
> > order for
> > > the API in order to couple the stereo for coding.
> > Well, if you look at section 5.1.1 of RFC7845:
> > The 'coupled stream
> > count' field indicates that the decoders for the first M Opus
> > streams are to be initialized for stereo (two-channel) output,
> > and the remaining (N - M) decoders are to be initialized for
> > (a single channel) only.
> > In other words, it says that in the file itself (regardless of what
> > do in the API), you need to have the stereo channels first, followed
> > the mono channels. Where the channels go in the API itself is another
> > question and you're free to put the non-diegetic stereo at the end
> > for that.
> > > The mapping code
> > > appears to be working on files I've tested it on so far.
> > Well, even if you get the mapping wrong, it's still going to work.
> > just that your non-diegetic stream will be made from two mono streams
> > and two of your directional channels will be coupled. That's one of
> > limitations of simple testing, since it's not going to catch these
> > of errors.
> > Jean-Marc
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