[FFmpeg-user] Creating surround sound from mono wav files

[Moritz Barsnick]

On Sun, Dec 23, 2018 at 23:22:38 +0000, CherylJosie wrote:

> Yes thanks found a helpful site and got that far just after posting
> but I found the info on number of channels online not in the ffmpeg
> manual. I wasn't even sure what to look for so couldn't search the
> manual with a direct query.

Just by looking at the documentation for the amerge filter:

https://ffmpeg.org/ffmpeg-filters.html#amerge-1

This wiki page is also very practical, by the way:

https://trac.ffmpeg.org/wiki/AudioChannelManipulation

> I'm trying to do 7.0 but it's generating 6.1. I'll keep looking for the channel configuration instruction too i guess.

I believe ffmpeg is guessing the channel layout. The only trick I know
is to add the pan filter to the chain, where you can specify the output
layout:

$ ffmpeg [...] -af "[...],amerge=7,pan=7.0" [...]

But I have no idea whether it does exactly the right thing for you.
Worth a try.

> I could maybe add a blank LFE if I knew the syntax.

Wouldn't that give you eight channels?

> Syntax seems different for avlib than for ffmpeg and amerge is an
> avlib function apparently?

Not sure what you're trying to say. ffmpeg uses the av* libraries,
libavfilter is one of them. But the syntax of the command line options
for ffmpeg, the command line tool, is quite well documented.

> Getting there.

We'll get you there, no doubt. :-)

Cheers,
Moritz