Properties of ALAC in mp4

[Anton Sergunov]

Size/duration? :)
09.06.2011 0:41 пользователь "Frank Lai" <frank.franklai at gmail.com> написал:
> The alac format info is from
> http://wiki.multimedia.cx/index.php?title=Apple_Lossless_Audio_Coding
>
> Test an alac file encoded by iTunes. The bitrate is correct. But test
> another alac file encoded by FFmpeg, the bitrate is 1411 kbps.
>
> Found a link discussing this issue
> http://www.hydrogenaudio.org/forums/index.php?showtopic=76768
> Looks like FFmpeg did not fill the bitrate value correctly. But other
> applications (except iTunes) can report the correct bitrate, so there
should
> be another way to calculate the bitrate.
>
> Best Regards,
> Frank Lai
>
> 2011/6/9 Lukáš Lalinský <lalinsky at gmail.com>
>
>> On Wed, Jun 8, 2011 at 6:45 PM, Frank Lai <frank.franklai at gmail.com>
>> wrote:
>> > Hi all,
>> > The attached patch is for read properties from "alac" atom when the
audio
>> > codec in mp4 is ALAC.
>>
>> Hi Frank,
>>
>> Thanks for the patch. It seems to work fine, except for bitrates. What
>> is the source that you used for the format info? I've encoded a small
>> file consisting only of silence and all applications report it to have
>> 3 kbps. Your code reports 1411 kpbs, which is what I get when I
>> convert it to a wav file. Is it possible that it's the bitrate of the
>> uncompressed audio data?
>>
>> Lukas
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>> taglib-devel at kde.org
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>>
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