[FFmpeg-user] Question about mp3 bit rate mode

[DopeLabs]

In your earlier console output for both commands...

>> size=    2344kB time=00:05:00.01 bitrate=  64.0kbits/s speed= 128x 

>> size=    2344kB time=00:05:00.01 bitrate=  64.0kbits/s speed= 134x    

What method are you using to 'verify' the length?

What is the ffprobe output for each of those files?



> On Jan 30, 2017, at 8:23 13AM, 桃源老師 <xanadu6291 at dream.jp> wrote:
> 
> In Addition...
> 
>> 2017/01/30 11:54 A.M. 桃源老師 <xanadu6291<at>dream.jp> wrote:
>> 
>> Hello ffmpeg experts...
>> 
>> I have question about mp3 bit rate mode.  
>> 
>> When I run the following command, the resulting duration.mp3 is VBR.  I have confirmed it's bit rate mode with mediainfo, mpg123, and SinkuSuperLite (on Windows).
>> 
>> $ ffmpeg -f lavfi -i sine=d=300 duration.mp3
>> ffmpeg version N-83152-gf7e9275 Copyright (c) 2000-2017 the FFmpeg developers
>> built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
>> configuration: --prefix=/Volumes/ffmpeg_compile --pkg-config-flags=--static --disable-ffserver --enable-gpl --enable-version3 --enable-nonfree --enable-libmp3lame --enable-libfdk-aac --enable-libvo-amrwbenc --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvorbis --enable-libspeex --enable-libopus --enable-libgsm --enable-libtwolame --enable-libsoxr --enable-libwavpack --enable-libmodplug --enable-libopenjpeg --enable-libwebp --enable-libtheora --enable-libx264 --enable-libopenh264 --enable-libx265 --enable-libxvid --enable-libvpx --enable-libxavs --enable-libfreetype --enable-fontconfig --enable-libfribidi --enable-libass --enable-libbluray --enable-libvidstab --enable-libschroedinger --enable-libsnappy --enable-libzmq
>> libavutil      55. 43.100 / 55. 43.100
>> libavcodec     57. 74.100 / 57. 74.100
>> libavformat    57. 62.100 / 57. 62.100
>> libavdevice    57.  2.100 / 57.  2.100
>> libavfilter     6. 69.100 /  6. 69.100
>> libswscale      4.  3.101 /  4.  3.101
>> libswresample   2.  4.100 /  2.  4.100
>> libpostproc    54.  2.100 / 54.  2.100
>> Input #0, lavfi, from 'sine=d=300':
>> Duration: N/A, start: 0.000000, bitrate: 705 kb/s
>>   Stream #0:0: Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
>> Output #0, mp3, to 'duration.mp3':
>> Metadata:
>>   TSSE            : Lavf57.62.100
>>   Stream #0:0: Audio: mp3 (libmp3lame), 44100 Hz, mono, s16p
>>   Metadata:
>>     encoder         : Lavc57.74.100 libmp3lame
>> Stream mapping:
>> Stream #0:0 -> #0:0 (pcm_s16le (native) -> mp3 (libmp3lame))
>> Press [q] to stop, [?] for help
>> size=    2344kB time=00:05:00.01 bitrate=  64.0kbits/s speed= 128x    
>> video:0kB audio:2344kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.009457%
>> 
>> And when I run the following command, the resulting duration.mp3 is CBR.  Confirmed with same program as above.
>> 
>> $ ffmpeg -f lavfi -i sine=d=300 -write_xing 0 duration.mp3
>> ffmpeg version N-83152-gf7e9275 Copyright (c) 2000-2017 the FFmpeg developers
>> built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
>> configuration: --prefix=/Volumes/ffmpeg_compile --pkg-config-flags=--static --disable-ffserver --enable-gpl --enable-version3 --enable-nonfree --enable-libmp3lame --enable-libfdk-aac --enable-libvo-amrwbenc --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvorbis --enable-libspeex --enable-libopus --enable-libgsm --enable-libtwolame --enable-libsoxr --enable-libwavpack --enable-libmodplug --enable-libopenjpeg --enable-libwebp --enable-libtheora --enable-libx264 --enable-libopenh264 --enable-libx265 --enable-libxvid --enable-libvpx --enable-libxavs --enable-libfreetype --enable-fontconfig --enable-libfribidi --enable-libass --enable-libbluray --enable-libvidstab --enable-libschroedinger --enable-libsnappy --enable-libzmq
>> libavutil      55. 43.100 / 55. 43.100
>> libavcodec     57. 74.100 / 57. 74.100
>> libavformat    57. 62.100 / 57. 62.100
>> libavdevice    57.  2.100 / 57.  2.100
>> libavfilter     6. 69.100 /  6. 69.100
>> libswscale      4.  3.101 /  4.  3.101
>> libswresample   2.  4.100 /  2.  4.100
>> libpostproc    54.  2.100 / 54.  2.100
>> Input #0, lavfi, from 'sine=d=300':
>> Duration: N/A, start: 0.000000, bitrate: 705 kb/s
>>   Stream #0:0: Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
>> File 'duration.mp3' already exists. Overwrite ? [y/N] y
>> Output #0, mp3, to 'duration.mp3':
>> Metadata:
>>   TSSE            : Lavf57.62.100
>>   Stream #0:0: Audio: mp3 (libmp3lame), 44100 Hz, mono, s16p
>>   Metadata:
>>     encoder         : Lavc57.74.100 libmp3lame
>> Stream mapping:
>> Stream #0:0 -> #0:0 (pcm_s16le (native) -> mp3 (libmp3lame))
>> Press [q] to stop, [?] for help
>> size=    2344kB time=00:05:00.01 bitrate=  64.0kbits/s speed= 134x    
>> video:0kB audio:2344kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.001875%
> 
> The command which produces VBR mp3 file, "$ ffmpeg -f lavfi -i sine=d=300 duration.mp3"'s duration is 5:43 on Mac and is 5:01 on Windows.
> 
> The command which produces CBR mp3 file, "$ ffmpeg -f lavfi -i sine=d=300 -write_xing 0 duration.mp3"'s duration is 5:00 on Mac/Win.
> 
> So the issue of wrong duration is not only on Mac but also on Win, I think...
> 
> 
> Best Regards,
> 
> 
> Miya aka Tougen-Roushi_______________________________________________
> ffmpeg-user mailing list
> ffmpeg-user at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
> 
> To unsubscribe, visit link above, or email
> ffmpeg-user-request at ffmpeg.org with subject "unsubscribe".