[FFmpeg-user] Has the syntax changed for audio remapping in ffmpeg 3.0?

Moritz Barsnick barsnick at gmx.net
Tue Feb 16 00:59:24 CET 2016

Hi sat,
I may have a solution below. Long shot though.

On Tue, Feb 16, 2016 at 00:27:56 +0100, satelliteviewer at gmx.ca wrote:
> see if maybe ffmpeg 3.0 fixed that, but instead what I found after
> installing ffmpeg 3.0 (using the stable static build of ffmpeg 3.0
> from http://johnvansickle.com/ffmpeg/ which is where I've always
> gotten my ffmpeg builds) is that now it passes the video, but I get
> no audio on the channel in question at all.

Does that site provide older *and* recent git builds, so that you could
iterate through to see when it stopped working? I guess that would be
too much of a hassle for you, judging from the below.

> If anyone can enlighten me as to why this no longer works in ffmpeg
> 3.0 I would very much appreciate it.

There's probably really meaningful info in the console output. ;-)

> I cannot show you ffmpeg's output because it is not being run from a
> command prompt, so I don't see any output and since this is a live
> stream rather than a file I don't even think there is any way I could
> see any output from ffmpeg.

Using the "-report" option will let ffmpeg create files named
ffmpeg-YYYYMMDD-HHMMSS.log in the "current" directory. Perhaps you
could create and grab those.

> pipe:///usr/local/bin/ffmpeg -loglevel fatal -i -c:v copy -c:s copy -c:d copy -c:t copy -filter_complex +[0:1][0:2][0:3]amerge=inputs=3,pan=5.1|FL=c0|FR=c1|FC=c2|LFE=c3|BL=c4|BR=c5 -c:a eac3 -f mpegts pipe:1

I have an idea what the issue could be though!
It may be this recent commit:
It changes the format of the output MPEG-TS w.r.t. E-AC3 audio (which
you are using). If you add "-mpegts_flags system_b", it should revert
the behavior.

Please see if that helps. It's a wild guess.

(BTW, if that's it, then that's something we probably could *not* have
seen from the console logs. ;-))


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