From 9aaa70a845fe8eb26b3d2e264958b8586150d76b Mon Sep 17 00:00:00 2001 From: Nicolas George Date: Tue, 24 Jan 2012 12:42:20 +0100 Subject: faq: document af_aconvert quirks using lavfi. --- doc/faq.texi | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'doc/faq.texi') diff --git a/doc/faq.texi b/doc/faq.texi index bd88da3568..3fda98eb8d 100644 --- a/doc/faq.texi +++ b/doc/faq.texi @@ -292,6 +292,24 @@ The solution is to apply the @option{-profile} option to the video stream only by using @url{http://ffmpeg.org/ffmpeg.html#Stream-specifiers-1, Stream specifiers}. Appending @code{:v} to it will do exactly that. +@section Using @option{-f lavfi}, audio becomes mono for no apparent reason. + +Use @option{-dumpgraph -} to find out exactly where the channel layout is +lost. + +Most likely, it is through @code{auto-inserted aconvert}. Try to understand +why the converting filter was needed at that place. + +Just before the output is a lilely place, as @option{-f lavfi} currently +only support packed S16. + +Then insert the correct @code{aconvert} explicitly in the filter graph, +specifying the exact format. + +@example +aconvert=s16:stereo:packed +@end example + @chapter Development @section Are there examples illustrating how to use the FFmpeg libraries, particularly libavcodec and libavformat? -- cgit v1.2.3