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More => Old Versions => Media Center 16 (Development Ended) => Topic started by: ksvane on August 07, 2011, 02:42:49 am

Title: Labeled bitrate for HE-AAC files
Post by: ksvane on August 07, 2011, 02:42:49 am

The field [bitrate (labeled)] seems to show inaccurate values for HE-AAC files, in fact the displayed bitrate appears twice as big as the actual bitrate. Is this behaviour intentional? :-\ As I understand it, the sample rate of HE-AAC files is only half as big as the sample rate of the output (I think it's called spectral band replication?) I imagine this could be why the bitrate is somehow detected as twice its actual value (but I'm probably wrong).

Title: Re: Labeled bitrate for HE-AAC files
Post by: Matt on August 08, 2011, 01:22:28 pm

I don't seem to be able to reproduce this.

We're displaying the bitrate as found in the ESDS header of the MP4 container.

For the files I have, this value closely matches the bitrate you get by calculating manually (duration / bits).

Could you email a sample file to matt at jriver dot com?

Thanks.

Title: Re: Labeled bitrate for HE-AAC files
Post by: ksvane on August 08, 2011, 02:02:11 pm

done.

Title: Re: Labeled bitrate for HE-AAC files
Post by: Matt on August 09, 2011, 08:49:23 am

Thanks for the file.

It shows as "83" as the bitrate inside Media Center.  I think this is right.

If you take the file size divided by the duration:
2620438 bytes = 20964 kbit / 227 seconds = 92 kbit/sec

The numbers are a little different since the math above isn't subtracting the space in the file used for cover art, tags, etc.  So it should be a bit lower than 92, so 83 seems pretty reasonable.

Is this what you're seeing?  If not, does Update Library from Tags for the files help?

Title: Re: Labeled bitrate for HE-AAC files
Post by: ksvane on August 09, 2011, 09:36:11 am

Not quite what I'm seeing, no... here's a screenshot. The labeled bitrate stays roughly around 160 all the time.

(http://i1183.photobucket.com/albums/x479/KSvane/jriver.jpg)

Update library from tags makes no difference.

Title: Re: Labeled bitrate for HE-AAC files
Post by: Matt on August 09, 2011, 10:51:55 am

Ah, got it.

Coming soon:
Fixed: The bitrate displayed in the player area during playback could be double the actual bitrate for HE-AAC files.

Thanks.

Title: Re: Labeled bitrate for HE-AAC files
Post by: ksvane on August 09, 2011, 11:38:52 am

thanks! And sorry, perhaps I should have specified it was the text in the player area.