[FFmpeg-devel] [PATCH] als in mp4

[Jai Menon]

On 3/21/09, Alex Converse <alex.converse at gmail.com> wrote:
> On Sat, Mar 21, 2009 at 1:50 AM, Jai Menon <jmenon86 at gmail.com> wrote:
>  >
>  > Hi,
>  >
>  > Attached :
>  >
>  > 1) demux als streams from mp4, als codec id and minor lavc version bump
>  > 2) mux als in to mp4, add isomedia type
>  >
>  > --
>  > Regards,
>  >
>  > Jai
>  >
>
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>
>
> > Index: libavformat/mov.c
>  > ===================================================================
>  > --- libavformat/mov.c    (revision 18065)
>  > +++ libavformat/mov.c    (working copy)
>  > @@ -426,6 +426,11 @@
>  >                                           st->codec->extradata_size);
>  >                  if (cfg.chan_config > 7)
>  >                      return -1;
>  > +                if(cfg.object_type == 36) {
>
> > +                    st->codec->codec_id = CODEC_ID_MP4ALS;
>  > +                    st->codec->codec_type = CODEC_TYPE_AUDIO;
>
> > +                    return 0;
>  > +                }
>  >                  st->codec->channels = ff_mpeg4audio_channels[cfg.chan_config];
>  >                 if (cfg.object_type == 29 && cfg.sampling_index < 3) // old mp3on4
>  >                     st->codec->sample_rate = ff_mpa_freq_tab[cfg.sampling_index];
>
>
> I hope this isn't too bikeshedy but can this be made part of the
>  codec_get_id section below.

It can and it should be. But as i said, the reference codec does not
write the channel config correctly. So some if(codec_id != MP4ALS)
will still be required. So it will still look like a hack ;)

>  Also why do we skip out on setting the sample_rate, is it wrong / inaccurate?

Samplerate value is correct, just that i have never seen it differ
from value stored in stsd :)
But, you are correct, we should store samplerate value specified in
the audio config object.

>  Otherwise good work,

any ideas btw on how to do this cleanly. i'm assuming you have already
looked into this at some point :)

>  Alex Converse

-- 
Regards,

Jai