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| author | Lou Logan <lou@lrcd.com> | 2012-06-21 09:43:33 -0800 |
|---|---|---|
| committer | Michael Niedermayer <michaelni@gmx.at> | 2012-06-22 01:36:14 +0200 |
| commit | cdb94139cccfa1434c9c6d7901ea571fd4569184 (patch) | |
| tree | 5652678bb337980599b41382fda5de372487257a | |
| parent | 87dced8074cf83e74e69d7dee725c8d62601c4e8 (diff) | |
| download | ffmpeg-cdb94139cccfa1434c9c6d7901ea571fd4569184.tar.gz | |
doc/faq: Update video joining examples
-same_quant is not designed to convert between quantizer scales, AFAIK.
Add example using concat protocol.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
| -rw-r--r-- | doc/faq.texi | 32 |
1 files changed, 20 insertions, 12 deletions
diff --git a/doc/faq.texi b/doc/faq.texi index 5f371a4546..da44adbb94 100644 --- a/doc/faq.texi +++ b/doc/faq.texi @@ -222,26 +222,34 @@ equally humble @code{copy} under Windows), and finally transcoding back to your format of choice. @example -ffmpeg -i input1.avi -same_quant intermediate1.mpg -ffmpeg -i input2.avi -same_quant intermediate2.mpg +ffmpeg -i input1.avi -qscale:v 1 intermediate1.mpg +ffmpeg -i input2.avi -qscale:v 1 intermediate2.mpg cat intermediate1.mpg intermediate2.mpg > intermediate_all.mpg -ffmpeg -i intermediate_all.mpg -same_quant output.avi +ffmpeg -i intermediate_all.mpg -qscale:v 2 output.avi @end example -Notice that you should either use @code{-same_quant} or set a reasonably high -bitrate for your intermediate and output files, if you want to preserve -video quality. +Additionally, you can use the @code{concat} protocol instead of @code{cat} or +@code{copy} which will avoid creation of a potentially huge intermediate file. -Also notice that you may avoid the huge intermediate files by taking advantage -of named pipes, should your platform support it: +@example +ffmpeg -i input1.avi -qscale:v 1 intermediate1.mpg +ffmpeg -i input2.avi -qscale:v 1 intermediate2.mpg +ffmpeg -i concat:"intermediate1.mpg|intermediate2.mpg" -c copy intermediate_all.mpg +ffmpeg -i intermediate_all.mpg -qscale:v 2 output.avi +@end example + +Note that you may need to escape the character "|" which is special for many +shells. + +Another option is usage of named pipes, should your platform support it: @example mkfifo intermediate1.mpg mkfifo intermediate2.mpg -ffmpeg -i input1.avi -same_quant -y intermediate1.mpg < /dev/null & -ffmpeg -i input2.avi -same_quant -y intermediate2.mpg < /dev/null & +ffmpeg -i input1.avi -qscale:v 1 -y intermediate1.mpg < /dev/null & +ffmpeg -i input2.avi -qscale:v 1 -y intermediate2.mpg < /dev/null & cat intermediate1.mpg intermediate2.mpg |\ -ffmpeg -f mpeg -i - -same_quant -c:v mpeg4 -acodec libmp3lame output.avi +ffmpeg -f mpeg -i - -qscale:v 2 -c:v mpeg4 -acodec libmp3lame -q:a 4 output.avi @end example Similarly, the yuv4mpegpipe format, and the raw video, raw audio codecs also @@ -268,7 +276,7 @@ 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 \ -f yuv4mpegpipe -i all.v \ - -same_quant -y output.flv + -qscale:v 2 -y output.flv rm temp[12].[av] all.[av] @end example |