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

[Rob]

On 1 July 2010 06:29, 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.

Hmm. If you can find some efficient way to handle these cases (maybe
via special-casing) then by all means implement it. It was avoided
because it complicated the code a lot to do overlapping in their way
to be able to handle these very strange and seemingly nonsensical
overlaps.

Are you saying that the spec's method of overlapping doesn't reduce
artifacting significantly for such overlaps?

Best regards,
Rob