[FFmpeg-user] In case of future deprecation, a backup of audio routing script shared for public servicing.

Sound Yuan soundyuanofficial at gmail.com
Tue Feb 12 01:42:27 EET 2019

Hi everyone,

I'm an amateurish sound artist and my personal English alias is Thomas. New
and nice to be with you.

Let us get to know my purpose here with one line of Windows script created
on my own:

ffmpeg -f dshow -rtbufsize 4 -i audio="Line 1 (Virtual Audio Cable)" -f
> dshow -rtbufsize 4 -i audio="Line 2 (Virtual Audio Cable)" -f dshow
> -rtbufsize 4 -i audio="Line 2 (Virtual Audio Cable)" -filter_complex
> "[0:a][1:a][2:a]amerge=inputs=3[a]" -map "[a]" -ar 48000 -vn -f wav - |
> ffmpeg -i - -filter_complex
> "channelmap=map=FL-BL|FR-BR|FC-FC|LFE-LFE|BL-FL|BR-FR:channel_layout=5.1"
> -vn -f wav -vol 1024 - | "C:\vlc-3.0.6\vlc.exe" - --prefetch-buffer-size=400

It may seem hard to understand, but it's on a budget PC so no additional
DACs considered for audio routing. What I intended to do was playing two
separated stereo audio outputs on the same 5.1 speaker configuration; Front
jack to a budget Philips stereo system 'MP3-Link', while rear jack to my

I once utilized Virtual Audio Cable and Audio Router to accomplish the
task, until found out VAC's built-in KS and MME audio redirection tools
could not work on my new Acer PC with a different model of Realtek codec -
It would just insist on outputting to front channels but not the rear's. So
after some research I found out FFMpeg capable of doing this through a
careful command-line design. The pro point over SoX (Sound eXchange) is
only because FFMpeg is more popular and pervasive in terms of end-user use
cases, otherwise a dedicated tool for sound manipulation is preferred.

Of course this method has some cons. First, there will be noticeable
delays. Second, sound choppy at times on Windows 10, a scenario I never
expected based on previous experiences with Windows 7. Third, we won't know
if this is going to work in the future as the system updates. So in the
very end of this submission, I'd like to know if there are already
equivalent applications similar to my script case, or the answer might be a
luxury VST plugin worthy of hundreds of dollars or some popular but
potentially unsafe programs? Would anyone like to help turn my initiative
into a real portable app coding idea?

If anyone find my story amusing (or confusing), do not hesitate to reply
for possible understandings. Thank you for your patience.

Best regards,
Thomas from Sound Yuan Studios

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