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

Taha Ansari mtaha.ansari at gmail.com
Mon Jun 24 12:07:47 CEST 2013

Hi Carl,

On your suggestion, I downloaded latest available build from Zeranoe site:
ffmpeg-20130623-git-c329713-win32. I had some trouble getting my code to
run with latest build, but finally was able to do so.

I had to make following additions:

inside open_audio_input():

        // Set up SWR context once you've got codec information
        swr = swr_alloc();
        av_opt_set_int(swr, "in_channel_layout",
codec_ctx_audio->channel_layout, 0);
        av_opt_set_int(swr, "out_channel_layout",
codec_ctx_audio->channel_layout,  0);
        av_opt_set_int(swr, "in_sample_rate",
codec_ctx_audio->sample_rate, 0);
        av_opt_set_int(swr, "out_sample_rate",
codec_ctx_audio->sample_rate, 0);
        av_opt_set_sample_fmt(swr, "in_sample_fmt",  AV_SAMPLE_FMT_S16P, 0);
        av_opt_set_sample_fmt(swr, "out_sample_fmt", AV_SAMPLE_FMT_S16,  0);

inside decode_packet():

                    swr_convert( swr, audio_dst_data,
decoded_frame->nb_samples, (const uint8_t**) decoded_frame->extended_data,
decoded_frame->nb_samples );

inside add_audio_stream():

    c->sample_fmt  = AV_SAMPLE_FMT_S16;
    c->bit_rate    = audio_bit_rate;
    c->sample_rate = audio_sample_rate;
    c->channels    = audio_channels;

Then, all things started working, but the output was identical to previous
behavior (plays faster, and ends on same time: on about 65th second).

I tried changing output format from AV_SAMPLE_FMT_S16 to AV_SAMPLE_FMT_FLTP
(inside above relevant functions), but it fails inside avcodec_open2(),
giving me -22 return value.

Any ideas how to fix this?

Thanks for your time...

On Mon, Jun 24, 2013 at 11:26 AM, Taha Ansari <mtaha.ansari at gmail.com>wrote:

> Hi Carl,
> You are right, last working build I downloaded from Zeranoe FFmpeg builds
> was from a long time ago. If you suggest I can always get the latest
> working build from there, but! the point is: even for this old version of
> FFmpeg, command line "ffmpeg.exe -i test.mp3 test.mp4" converts the file
> just fine, so there is obviously something wrong with my code...
> Still, if you suggest I get latest build from there, well, I can do it as
> well!
> Kindly, could you guide further based on above facts?
> On Mon, Jun 24, 2013 at 11:04 AM, Carl Eugen Hoyos <cehoyos at ag.or.at>wrote:
>> Taha Ansari <mtaha.ansari at ...> writes:
>> > ffprobe version N-47062-g26c531c Copyright (c) 2007-2012
>> This looks outdated.
>> The aac decoder of current git head outputs FLTP iirc.
>> Carl Eugen
>> _______________________________________________
>> Libav-user mailing list
>> Libav-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/libav-user
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