Downmixing Surround Flac to Stereo.

[Linux for blind general discussion]

Yes, this is what I do all the time with mkv files. I have created a
couple scripts, e.g.

<begin code>
#!/bin/bash
#Use ffmpeg to extract 16bit to audio.wav
#One argument is input file
ffmpeg -i "$1" -acodec pcm_s16le -ac 2 audio.wav
</end code

>From there I can "flac -best" or "oggenc -q 10" or whatever.

I generally play via mplayer, which will handle mkv perfectly well, by
the way.

Janina

Linux for blind general discussion writes:
> 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.
> > 
> > _______________________________________________
> > Blinux-list mailing list
> > Blinux-list at redhat.com
> > https://www.redhat.com/mailman/listinfo/blinux-list
> 
> -- 
> Joel Roth
>   
> 
> _______________________________________________
> Blinux-list mailing list
> Blinux-list at redhat.com
> https://www.redhat.com/mailman/listinfo/blinux-list

-- 

Janina Sajka,	Phone:	+1.443.300.2200
			sip:janina at asterisk.rednote.net
		Email:	janina at rednote.net

Linux Foundation Fellow
Executive Chair, Accessibility Workgroup:	http://a11y.org

The World Wide Web Consortium (W3C), Web Accessibility Initiative (WAI)
Chair, Accessible Platform Architectures	http://www.w3.org/wai/apa