Re: keeping bitrate during conversion

Michel Bardiaux wrote:
> astrograph GMX wrote:
> > hi,
> >
> > I am trying to convert .mp4 videos to .3gp, it works, but there is a 
> > big difference in bitrate between the original and the converted copy:
> >
> > ffmpeg -i media/470222.mp4 test3.3gp
> > ffmpeg version 0.4.9-pre1, build 4718, Copyright (c) 2000-2004 Fabrice 
> > Bellard
> >   built on Feb 28 2005 14:45:40, gcc: 3.2.3 20030502 (Red Hat Linux 
> > 3.2.3-49)
>
> This is very old. Please upgrade to CVS.

thank you for your quick response!! yes, I am aware of that, I ran into 
the problem that I wasn´t able to compile the current version of ffmpeg:

]$ make
make -C libavutil all
make[1]: Entering directory 
`/opt/qpass/mediaconverter/tools/ffmpeg/libavutil'
gcc -O3 -g -Wall -Wno-switch  -Wdeclaration-after-statement 
-DHAVE_AV_CONFIG_H -DBUILD_AVUTIL -I.. -D_FILE_OFFSET_BITS=64 
-D_LARGEFILE_SOURCE -D_GNU_SOURCE  -c -o mathematics.o mathematics.c
In file included from mathematics.c:24:
common.h:608: warning: static declaration of 'lrintf' follows non-static 
declaration
mathematics.c:132:7: warning: no newline at end of file
gcc -O3 -g -Wall -Wno-switch  -Wdeclaration-after-statement 
-DHAVE_AV_CONFIG_H -DBUILD_AVUTIL -I.. -D_FILE_OFFSET_BITS=64 
-D_LARGEFILE_SOURCE -D_GNU_SOURCE  -c -o rational.o rational.c
In file included from rational.c:30:
common.h:608: warning: static declaration of 'lrintf' follows non-static 
declaration
gcc -O3 -g -Wall -Wno-switch  -Wdeclaration-after-statement 
-DHAVE_AV_CONFIG_H -DBUILD_AVUTIL -I.. -D_FILE_OFFSET_BITS=64 
-D_LARGEFILE_SOURCE -D_GNU_SOURCE  -c -o intfloat_readwrite.o 
intfloat_readwrite.c
In file included from intfloat_readwrite.c:26:
common.h:608: warning: static declaration of 'lrintf' follows non-static 
declaration
gcc -O3 -g -Wall -Wno-switch  -Wdeclaration-after-statement 
-DHAVE_AV_CONFIG_H -DBUILD_AVUTIL -I.. -D_FILE_OFFSET_BITS=64 
-D_LARGEFILE_SOURCE -D_GNU_SOURCE  -c -o crc.o crc.c
In file included from crc.c:1:
common.h:608: warning: static declaration of 'lrintf' follows non-static 
declaration
rm -f libavutil.a
ar rc libavutil.a mathematics.o rational.o intfloat_readwrite.o crc.o
ranlib libavutil.a
make[1]: Leaving directory 
`/opt/qpass/mediaconverter/tools/ffmpeg/libavutil'
make -C libavcodec all
make[1]: Entering directory 
`/opt/qpass/mediaconverter/tools/ffmpeg/libavcodec'
gcc -O3 -g -Wall -Wno-switch  -Wdeclaration-after-statement 
-DHAVE_AV_CONFIG_H -I.. 
-I/opt/qpass/mediaconverter/tools/ffmpeg/libavutil 
-D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_GNU_SOURCE    -c -o 
bitstream.o bitstream.c
In file included from 
/opt/qpass/mediaconverter/tools/ffmpeg/libavutil/avutil.h:24,
                 from avcodec.h:14,
                 from bitstream.c:28:
/opt/qpass/mediaconverter/tools/ffmpeg/libavutil/common.h:608: warning: 
static declaration of 'lrintf' follows non-static declaration
gcc -O3 -g -Wall -Wno-switch  -Wdeclaration-after-statement 
-DHAVE_AV_CONFIG_H -I.. 
-I/opt/qpass/mediaconverter/tools/ffmpeg/libavutil 
-D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_GNU_SOURCE    -c -o 
utils.o utils.c
In file included from 
/opt/qpass/mediaconverter/tools/ffmpeg/libavutil/avutil.h:24,
                 from avcodec.h:14,
                 from utils.c:27:
/opt/qpass/mediaconverter/tools/ffmpeg/libavutil/common.h:608: warning: 
static declaration of 'lrintf' follows non-static declaration
utils.c: In function `avcodec_string':
utils.c:1093: warning: implicit declaration of function `_snprintf'
utils.c: In function `av_tempfile':
utils.c:1375: error: `_O_RDWR' undeclared (first use in this function)
utils.c:1375: error: (Each undeclared identifier is reported only once
utils.c:1375: error: for each function it appears in.)
utils.c:1375: error: `_O_BINARY' undeclared (first use in this function)
utils.c:1375: error: `_O_CREAT' undeclared (first use in this function)
make[1]: *** [utils.o] Error 1
make[1]: Leaving directory 
`/opt/qpass/mediaconverter/tools/ffmpeg/libavcodec'
make: *** [lib] Error 2

any idea what could be causing this?

thx

Phil

> > Input #0, mov,mp4,m4a,3gp, from 'media/470222.mp4':
> >   Duration: 00:00:30.0, bitrate: 80 kb/s
> >   Stream #0.0: Video: mpeg4, 176x144, 12.00 fps
> >   Stream #0.1: Audio: amr_nb, 8000 Hz, mono
> > Output #0, 3gp, to 'test3.3gp':
> >   Stream #0.0: Video: h263, 176x144, 12.00 fps, q=2-31, 200 kb/s
>
> Normal, 200kb/s is the default bitrate for the ffmpeg command line app.
>
> >   Stream #0.1: Audio: amr_nb, 8000 Hz, mono, 64 kb/s
> > Stream mapping:
> >   Stream #0.0 -> #0.0
> >   Stream #0.1 -> #0.1
> > Press [q] to stop encoding
> > [h263 @ 0x443014]warning, cliping 1 dct coefficents to -127..127
> > ...<snip/>...
> > [h263 @ 0x443014]warning, cliping 1 dct coefficents to -127..127
> > frame=  360 q=2.0 Lsize=     846kB time=30.0 bitrate= 231.0kbits/s
> > video:789kB audio:47kB global headers:0kB muxing overhead 1.184066%
> >
> > of course I can set the bitrate parameters manually:
> >
> > ffmpeg -i media/470222.mp4 -b 50 -ab 10 test4.3gp
> > ffmpeg version 0.4.9-pre1, build 4718, Copyright (c) 2000-2004 Fabrice 
> > Bellard
> >   built on Feb 28 2005 14:45:40, gcc: 3.2.3 20030502 (Red Hat Linux 
> > 3.2.3-49)
> > Input #0, mov,mp4,m4a,3gp, from 'media/470222.mp4':
> >   Duration: 00:00:30.0, bitrate: 80 kb/s
> >   Stream #0.0: Video: mpeg4, 176x144, 12.00 fps
> >   Stream #0.1: Audio: amr_nb, 8000 Hz, mono
> > Output #0, 3gp, to 'test4.3gp':
> >   Stream #0.0: Video: h263, 176x144, 12.00 fps, q=2-31, 50 kb/s
> >   Stream #0.1: Audio: amr_nb, 8000 Hz, mono, 10 kb/s
> > Stream mapping:
> >   Stream #0.0 -> #0.0
> >   Stream #0.1 -> #0.1
> > Press [q] to stop encoding
> > [h263 @ 0x351014]warning, cliping 1 dct coefficents to -127..127
> > [h263 @ 0x351014]warning, cliping 1 dct coefficents to -127..127
> > frame=  360 q=4.4 Lsize=     324kB time=30.0 bitrate=  88.6kbits/s
> > video:275kB audio:40kB global headers:0kB muxing overhead 3.161163%
> >
> > question 1: is there a way to tell ffmpeg to keep the (overall) 
> > bitrate from the original?
>
> No.
>
> > question 2: is there a command which returns the bitrate(s) for a 
> > specific file?
>
> No.
>
> > thx
> >
> > Phil
> >
> > _______________________________________________
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