[FFmpeg-devel] [PATCH] aacenc: Correct spreading calculation in the 3GPP psymodel.

Nathan Caldwell saintdev
Sun Oct 31 07:09:42 CET 2010

On Sat, Oct 30, 2010 at 3:27 PM, Nathan Caldwell <saintdev at gmail.com> wrote:
> Spreading is currently being calculated incorrectly. We were
> multiplying the previous band
> threshold by the lower spreading factor, and the next band by the
> higher spreading
> factor. Also, the first spreading loop was using the spreading factor for the
> previous band, instead of the spreading factor for the current band.
> I've found this fix to be most noticeable in the Tom's Diner sample.
> ---
> ?libavcodec/aacpsy.c | ? ?4 ++--
> ?1 files changed, 2 insertions(+), 2 deletions(-)

I'm not so sure this is correct now. The constants for calculating the
spreading factors seem to be reversed from what they should be (which
I hadn't noticed). So it appears what we are currently doing is
correct. I think I may need to do more investigation on this, because
it did noticeably help the Tom's Diner sample.

-Nathan Caldwell

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