[Ffmpeg-devel] using apiexample.c

[Riccardo Zanella]

Michel Bardiaux ha scritto:
> Riccardo Zanella wrote:
>> Hello,
>>
>> I'm using apiexample.c to learn how to encode video.
>> I want to be able to set the bitrate, so i think I have to modify
>> this line:
>>
>> c->bit_rate = 400000;
>>
>> where c is AVCodecContext*.
>>
>> But it seems it doesn't work: the bitrate of the output stream isn't
>> affected by the modification.
> 
> How do you know that? What does ffmpeg -i say about your output file?

If i compile and run apiexample.c with:

c->bit_rate = 400000;

FFmpeg version SVN-rUNKNOWN, Copyright (c) 2000-2004 Fabrice Bellard
   configuration:  --shlibdir=/usr/lib64 --prefix=/usr 
--mandir=/usr/share/man --libdir=/usr/lib64 --enable-shared 
--enable-mp3lame --enable-libogg --enable-vorbis --enable-faad 
--enable-faac --enable-xvid --enable-a52 --enable-x264 --enable-pp 
--enable-gpl --enable-gprof --enable-amr_nb --enable-amr_wb
   libavutil version: 49.0.0
   libavcodec version: 51.11.0
   libavformat version: 50.5.0
   built on Aug 18 2006 12:56:43, gcc: 4.0.2 20050901 (prerelease) (SUSE 
Linux)
Input #0, mpegvideo, from 'test.mpg':
   Duration: 00:00:00.0, start: 0.000000, bitrate: -2147483 kb/s
   Stream #0.0: Video: mpeg1video, yuv420p, 352x288, 104857 kb/s, 25.00 
fps(r)
Must supply at least one output file

If i compile and run apiexample.c with:

c->bit_rate = 800000;

FFmpeg version SVN-rUNKNOWN, Copyright (c) 2000-2004 Fabrice Bellard
   configuration:  --shlibdir=/usr/lib64 --prefix=/usr 
--mandir=/usr/share/man --libdir=/usr/lib64 --enable-shared 
--enable-mp3lame --enable-libogg --enable-vorbis --enable-faad 
--enable-faac --enable-xvid --enable-a52 --enable-x264 --enable-pp 
--enable-gpl --enable-gprof --enable-amr_nb --enable-amr_wb
   libavutil version: 49.0.0
   libavcodec version: 51.11.0
   libavformat version: 50.5.0
   built on Aug 18 2006 12:56:43, gcc: 4.0.2 20050901 (prerelease) (SUSE 
Linux)
Input #0, mpegvideo, from 'test.mpg':
   Duration: 00:00:00.0, start: 0.000000, bitrate: -2147483 kb/s
   Stream #0.0: Video: mpeg1video, yuv420p, 352x288, 104857 kb/s, 25.00 
fps(r)
Must supply at least one output file

By the way, the two output files provided have the same size:

ricky at MAN-10-16-2-180:~/Lavoro/libffwrap2/apiexample/test>ls -l *.mpg
-rw-r--r--  1 ricky users 94786 2006-11-13 12:42 test4.mpg
-rw-r--r--  1 ricky users 94786 2006-11-14 12:06 test8.mpg

where
test4.mpg  has  c->bit_rate = 400000
test8.mpg  has  c->bit_rate = 800000

> BTW this belongs on ffmpeg-user, not here.

Yes, you are right, but in the other list no one has responded.

I'm using SUSE 10.0 on athlon64, gcc version 4.0.2 20050901 (prerelease) 
(SUSE Linux)