From 7659712749500d2307c24abb188766f8a96d87be Mon Sep 17 00:00:00 2001
From: John Van Sickle <john.vansickle@gmail.com>
Date: Wed, 6 Jan 2010 13:49:31 +0000
Subject: [PATCH] Fix entry on concatenating multiple yuv4mpegpipe streams.
patch by John Van Sickle, john.vansickle gmail com
Originally committed as revision 21033 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
doc/faq.texi | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/doc/faq.texi b/doc/faq.texi
index 97fa3931cd2..cf86616f9ed 100644
--- a/doc/faq.texi
+++ b/doc/faq.texi
@@ -316,6 +316,11 @@ ffmpeg -f mpeg -i - -sameq -vcodec mpeg4 -acodec libmp3lame output.avi
Similarly, the yuv4mpegpipe format, and the raw video, raw audio codecs also
allow concatenation, and the transcoding step is almost lossless.
+When using multiple yuv4mpegpipe(s), the first line needs to be discarded
+from all but the first stream. This can be accomplished by piping through
+@code{tail} as seen below. Note that when piping through @code{tail} you
+must use command grouping, @code{@{ ;@}}, to background properly.
+
For example, let's say we want to join two FLV files into an output.flv file:
@@ -329,7 +334,7 @@ mkfifo all.v
ffmpeg -i input1.flv -vn -f u16le -acodec pcm_s16le -ac 2 -ar 44100 - > temp1.a < /dev/null &
ffmpeg -i input2.flv -vn -f u16le -acodec pcm_s16le -ac 2 -ar 44100 - > temp2.a < /dev/null &
ffmpeg -i input1.flv -an -f yuv4mpegpipe - > temp1.v < /dev/null &
-ffmpeg -i input2.flv -an -f yuv4mpegpipe - > temp2.v < /dev/null &
+@{ ffmpeg -i input2.flv -an -f yuv4mpegpipe - < /dev/null | tail -n +2 > temp2.v ; @} &
cat temp1.a temp2.a > all.a &
cat temp1.v temp2.v > all.v &
ffmpeg -f u16le -acodec pcm_s16le -ac 2 -ar 44100 -i all.a \
--
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