[Libav-user] Conversion from mp3 to aac/mp4 container problem

[Taha Ansari]

Hi everyone!

I am trying to get this puzzle solved, but no success so far. Can anyone
please guide me further?

Thanks in advance for your time!


On Fri, Jun 21, 2013 at 3:28 PM, Taha Ansari <mtaha.ansari at gmail.com> wrote:

>
>
>
> On Fri, Jun 21, 2013 at 3:06 PM, Carl Eugen Hoyos <cehoyos at ag.or.at>wrote:
>
>> Taha Ansari <mtaha.ansari at ...> writes:
>>
>> > I have run this application with existing mp4
>> > files as input, and it properly extracts audio,
>> > and encodes to mp4 (audio only:AAC), or even
>> > directly in AAC format (i.e. test.aac also
>> > works). But when I tried running it on mp3
>> > files, output clip plays faster than it should
>> > be (a clip of 1:12 seconds plays back till
>> > 1:05 seconds only, and is also noisy).
>>
>> I did not look at your code but did you consider
>> that the AAC decoder outputs AV_SAMPLE_FMT_FLTP
>> and the MP3 decoder signed 16 bit values (I
>> believe you can request planar or not)?
>>
>> Carl Eugen
>>
>> _______________________________________________
>> Libav-user mailing list
>> Libav-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/libav-user
>>
>
> Hi Carl!
>
> As a matter of fact, I never knew about this, till now. In fact, when I
> was probing the two files, I got s16 indication, so I thought they were
> similar, maybe:
>
>
> ----------------------------------------------------------------------------------------------------
> FFprobe from test.mp3 (input file):
>
> ----------------------------------------------------------------------------------------------------
> ffprobe version N-47062-g26c531c Copyright (c) 2007-2012 the FFmpeg
> developers
>   built on Nov 25 2012 12:23:20 with gcc 4.7.2 (GCC)
>   configuration: --disable-static --enable-shared --enable-gpl
> --enable-version3
>  --disable-pthreads --enable-runtime-cpudetect --enable-avisynth
> --enable-bzlib
> --enable-frei0r --enable-libass --enable-libopencore-amrnb
> --enable-libopencore-
> amrwb --enable-libfreetype --enable-libgsm --enable-libmp3lame
> --enable-libnut -
> -enable-libopenjpeg --enable-libopus --enable-librtmp
> --enable-libschroedinger -
> -enable-libspeex --enable-libtheora --enable-libutvideo
> --enable-libvo-aacenc --
> enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264
> --enab
> le-libxavs --enable-libxvid --enable-zlib
>   libavutil      52.  9.100 / 52.  9.100
>   libavcodec     54. 77.100 / 54. 77.100
>   libavformat    54. 37.100 / 54. 37.100
>   libavdevice    54.  3.100 / 54.  3.100
>   libavfilter     3. 23.102 /  3. 23.102
>   libswscale      2.  1.102 /  2.  1.102
>   libswresample   0. 17.101 /  0. 17.101
>   libpostproc    52.  2.100 / 52.  2.100
> [mp3 @ 007b2a60] max_analyze_duration 5000000 reached at 5015510
> Input #0, mp3, from 'test.mp3':
>   Metadata:
>     major_brand     : isom
>     minor_version   : 512
>     compatible_brands: isomiso2avc1mp41
>     encoder         : Lavf54.37.100
>   Duration: 00:01:12.67, start: 0.000000, bitrate: 128 kb/s
>     Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16, 128 kb/s
>
> ----------------------------------------------------------------------------------------------------
>
>
> ----------------------------------------------------------------------------------------------------
> FFprobe from test.mp4 (converted file):
>
> ----------------------------------------------------------------------------------------------------
>
> ffprobe version N-47062-g26c531c Copyright (c) 2007-2012 the FFmpeg
> developers
>   built on Nov 25 2012 12:23:20 with gcc 4.7.2 (GCC)
>   configuration: --disable-static --enable-shared --enable-gpl
> --enable-version3
>  --disable-pthreads --enable-runtime-cpudetect --enable-avisynth
> --enable-bzlib
> --enable-frei0r --enable-libass --enable-libopencore-amrnb
> --enable-libopencore-
> amrwb --enable-libfreetype --enable-libgsm --enable-libmp3lame
> --enable-libnut -
> -enable-libopenjpeg --enable-libopus --enable-librtmp
> --enable-libschroedinger -
> -enable-libspeex --enable-libtheora --enable-libutvideo
> --enable-libvo-aacenc --
> enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264
> --enab
> le-libxavs --enable-libxvid --enable-zlib
>   libavutil      52.  9.100 / 52.  9.100
>   libavcodec     54. 77.100 / 54. 77.100
>   libavformat    54. 37.100 / 54. 37.100
>   libavdevice    54.  3.100 / 54.  3.100
>   libavfilter     3. 23.102 /  3. 23.102
>   libswscale      2.  1.102 /  2.  1.102
>   libswresample   0. 17.101 /  0. 17.101
>   libpostproc    52.  2.100 / 52.  2.100
> Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test.mp4':
>   Metadata:
>     major_brand     : isom
>     minor_version   : 512
>     compatible_brands: isomiso2mp41
>     encoder         : Lavf54.37.100
>   Duration: 00:01:04.62, start: 0.000000, bitrate: 129 kb/s
>     Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo,
> s16, 128
>  kb/s
>     Metadata:
>       handler_name    : SoundHandler
>
> ----------------------------------------------------------------------------------------------------
>
> Hence the reason I was supplying:
>
> c->sample_fmt  = AV_SAMPLE_FMT_S16; (in add_audio_stream() function).
>
> If I'm not wasting too much of your time, can you please guide how I can
> co relate the two formats, pragmatically?
>
> Thanks for your time!
>
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