[FFmpeg-devel] [RFC] AAC nonmeaningful window sequences

Alex Converse alex.converse
Mon Jul 12 20:27:30 CEST 2010


On Thu, Jul 1, 2010 at 12:29 AM, Alex Converse <alex.converse at gmail.com> wrote:
> For a long time we've spammed a warning and ignored the spec when an
> AAC non-meaningful window transition is encountered (e.g. ONLY_LONG ->
> SHORT[1], oddly we don't warn about the reverse) The authors have made
> it clear that non-meaningful window transitions should be handled
> naively. They even included some non-meaningful transition test
> vectors (al03*). When asked to clarify they have stuck to this
> position[2].
>
> We do a fancier fixup where we force windows to match. (e.g. ONLY_LONG
> -> SHORT becomes START ->SHORT). Still I get bug-reports about this.
> Most people see the warning and hear an artifact but not and artifact
> in comparison to the spec's method and report a bug. I'm wondering if
> we should remove the warning, make the warning consistent, or
> implement the transitions as the spec requires.
>

The warning has been removed. The code continues to use our fancier
(and simpler when optimized) non-spec transition in these cases.



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