[FFmpeg-devel] [Issue 664] [PATCH] Fix AAC PNS Scaling

Alex Converse alex.converse
Mon Oct 6 21:46:55 CEST 2008

On Tue, Sep 30, 2008 at 11:25 PM, Alex Converse <alex.converse at gmail.com> wrote:
> Hi,
> The attached patch should fix AAC PNS scaling [Issue 664]. It will not
> fix PNS conformance.

Here's a sightly updated patch (sqrtf instead of sqrt). The current
method of PNS will never conform because sample energy simpl doesn't
converge to it's mean fast enough. The spec explicitly states that PNS
should be normalized per band. Not doing it that way causes PNS-1
conformance to fail for 45 bands.

However with this patch there appears to be no audible difference
between the approaches. I don't know the ideal mean energy so I'm
using the sample mean energy for 1024 iterations of the LCG.

> [...]

Alex Converse
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