[FFmpeg-user] mono or stereo? ffmpeg converts or phone?

[Moritz Barsnick]

On Mon, Apr 28, 2014 at 20:37:25 -0400, Sean Darcy wrote:

> 48000 bitrate with two channels, isn't that file size ~twice the file
> size of a mono 48000 bitrate?

No, not with compressed formats, unless your two audio channels carry
totally uncorrelated content. I'm saying compression can take advantage
of redundancies between the two channels.

And I don't agree with this concern of yours:

> My real question is: how does ffmpeg downmix 2 -> 1. I assume it
> doesn't just take one channel. Does it "average" in some way the two
> channels?
>
> I also assume whatever ffmpeg does, it does it better the android
> code on a phone doing it in realtime.

Downmixing stereo to mono is usually just an average (yes, there are
other approaches), and both the complexity and the required compute
power are negligible.

Moritz