[FFmpeg-user] the out mp3 file is shorter than the .caf file

[notedit]

hi lou and Carl Eugen:


i install the ffmpeg from from git repo, the ffmpeg version info is:

root at li493-104:/tmp# ffmpeg -version
ffmpeg version N-46149-g4b7f34a
built on Oct 31 2012 11:04:31 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
configuration: --enable-gpl --enable-version3 --enable-nonfree
--enable-postproc --enable-libass --enable-libfreetype --enable-libmp3lame
--enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg
--enable-openssl --enable-libschroedinger --enable-libspeex
--enable-libtheora --enable-libvo-aacenc --enable-libvorbis --enable-libvpx
--enable-libx264 --enable-libxvid --enable-libilbc --prefix=/usr/local
libavutil      52.  1.100 / 52.  1.100
libavcodec     54. 69.100 / 54. 69.100
libavformat    54. 35.100 / 54. 35.100
libavdevice    54.  3.100 / 54.  3.100
libavfilter     3. 20.109 /  3. 20.109
libswscale      2.  1.101 /  2.  1.  0
libswresample   0. 16.100 /  0. 16.100
libpostproc    52.  1.100 / 52.  0.  0


the ilbc-in-caf file is produced from our iphone app. then we need to
transcoding
it to mp3 file.

this is the out info:


/usr/local/bin/ffmpeg -acodec ilbc -i 0000xc.caf -ab 16k  0000xc.mp3

[caf @ 0x8827460] Estimating duration from bitrate, this may be inaccurate
Guessed Channel Layout for  Input Stream #0.0 : mono
Input #0, caf, from '0000xc.caf':
  Duration: 00:00:05.23, start: 0.000000, bitrate: 15 kb/s
    Stream #0:0: Audio: ilbc (ilbc / 0x63626C69), 8000 Hz, mono, s16, 15
kb/s
Output #0, mp3, to '0000xc.mp3':
  Metadata:
    TSSE            : Lavf54.35.100
    Stream #0:0: Audio: mp3, 8000 Hz, mono, s16p, 16 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (libilbc -> libmp3lame)
Press [q] to stop, [?] for help
0000xc.caf: Input/output error
size=       7kB time=00:00:03.10 bitrate=  17.4kbits/s
video:0kB audio:6kB subtitle:0 global headers:0kB muxing overhead 3.873457%


the caf file in the attachment



   刘连响

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2012/11/18 notedit <notedit at gmail.com>

> hi,
>
> when i use the ffmpeg to transcoding a ilbc encoding caf file to a mp3
> file.  the out mp3 file is shorter than the caf file.
> the command is:/usr/local/bin/ffmpeg -acodec ilbc -i xxx.caf -ab 16k
> xxxx.mp3 .
>
> anyone knows the answer?
>
> thx
>
>
>
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