[MPlayer-DOCS] [PATCH] update -channels to match observed behavior

[Corey Hickey]

Rich Felker wrote:
> On Fri, Sep 02, 2005 at 03:07:34AM -0700, Corey Hickey wrote:
> 
>>Maybe a reasonable compromise would be to automatically use -af
>>channels=2 _unless_ -channels (or -af channels) is specified on the
>>command line or config file. In that case it's up to the user to make
>>sure the output channels are correct.
> 
> 
> Just fix the af init code to auto-load af_channels (at the END of the
> chain) if the output device does not support the number of channels
> requested. HOWEVER: it's probably wrong anyway, since the first 2
> channels are usually not L/R.

They aren't? I was under the impression (from testing AC3 5.1) that the
usual channel order is:

0 - left front
1 - right front
2 - left rear
3 - right rear
4 - center front
5 - subwoofer

I haven't been able to find many sample files, though. If other files
typically have a different channel order I'd like to document it. Dang.
I just made a 6-channel ogg with oggenc -C 6 and it came out:

0 - left rear
1 - right rear
2 - center front
3 - subwoofer
4 - left front
5 - right front

Is that correct or is that a bug?

Can anybody who reads this please provide me some links to sample files?
If I'm to have any hope of documenting channel order I need to see
what's out there and I'm having trouble finding any with google.

I agree that truncating to two channels isn't a great solution, though,
even if the channel order were standard. It'll still sound really wrong
unless at the very least the center channel is mixed with left front and
right front. The best solution would be for all audio codecs to be able
to downmix to two channels from whatever numbers of channels that format
supports. liba52 does, and that probably covers 99% of the files. vorbis
and pcm don't. For lack of being able to find samples I don't know about
any others.

-Corey