The alac format info is from <a href="http://wiki.multimedia.cx/index.php?title=Apple_Lossless_Audio_Coding">http://wiki.multimedia.cx/index.php?title=Apple_Lossless_Audio_Coding</a><div><br></div><div>Test an alac file encoded by iTunes. The bitrate is correct. But test another alac file encoded by FFmpeg, the bitrate is 1411 kbps.</div>
<div><br></div><div>Found a link discussing this issue <a href="http://www.hydrogenaudio.org/forums/index.php?showtopic=76768">http://www.hydrogenaudio.org/forums/index.php?showtopic=76768</a></div><div>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.</div>
<div><br></div><div>Best Regards,</div><div>Frank Lai<br><br><div class="gmail_quote">2011/6/9 Lukáš Lalinský <span dir="ltr"><<a href="mailto:lalinsky@gmail.com">lalinsky@gmail.com</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div class="im">On Wed, Jun 8, 2011 at 6:45 PM, Frank Lai <<a href="mailto:frank.franklai@gmail.com">frank.franklai@gmail.com</a>> wrote:<br>
> Hi all,<br>
> The attached patch is for read properties from "alac" atom when the audio<br>
> codec in mp4 is ALAC.<br>
<br>
</div>Hi Frank,<br>
<br>
Thanks for the patch. It seems to work fine, except for bitrates. What<br>
is the source that you used for the format info? I've encoded a small<br>
file consisting only of silence and all applications report it to have<br>
3 kbps. Your code reports 1411 kpbs, which is what I get when I<br>
convert it to a wav file. Is it possible that it's the bitrate of the<br>
uncompressed audio data?<br>
<br>
Lukas<br>
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</blockquote></div><br></div>