Downmixing Surround Flac to Stereo.

[Linux for blind general discussion]

Since the first two channels of a 5.1 audio stream are front-left
and front-right[1] all you need is to extract those channels.

Ffmpeg can do this. Here's what I concoct (untested) based
on some web advice.[2]

ffmpeg -i input.mkv -vn -c:a copy -ac 2 stereo.flac

-vn means don't take the video, -c:a copy means copy the
audio stream without decoding/re-encoding, -ac 2 means
take two audio channels. 

It's possible you might have to move the '-ac 2' earlier
in the command. Depending on position, options affect
either the input or output stream.

Let us know how it goes!

1.  https://en.wikipedia.org/wiki/5.1_surround_sound
2.  https://superuser.com/questions/1041858/converting-5-1-audio-to-stereo-and-keeping-both-tracks

joel

On Mon, Oct 16, 2017 at 11:18:05PM +0000, Linux for blind general discussion wrote:
> I recently downloaded a .mkv file with 5.1 audio encoded to flac and
> as I inteneded to listen to it on my Blaze ET, which doesn't support
> mkv files, I used mkvextract to extract the audio, producing a 1.1GB
> file with roughly a 90 minute runtime. Unfortunately, My Blaze ET
> apparently can't handle surround files and trying to play the flac in
> ogg123 seems to only be producing sound effects.
> 
> Can anyone suggest either a means of converting the surround flac file
> to stereo from the command line or suggest a lightweight command line
> flac player that can properly playback surround sound files through
> earphones?
> 
> -- 
> Sincerely,
> 
> Jeffery Wright
> President Emeritus, Nu Nu Chapter, Phi Theta Kappa.
> Former Secretary, Student Government Association, College of the Albemarle.
> 
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-- 
Joel Roth