[FFmpeg-devel] [PATCH] 1D DCT for dsputil

[Alex Converse]

On Tue, Dec 22, 2009 at 8:04 PM, Alex Converse <alex.converse at gmail.com> wrote:
> On Tue, Dec 22, 2009 at 6:25 AM, ?<pross at xvid.org> wrote:
>> On Mon, Dec 21, 2009 at 02:02:00PM -0500, Daniel Verkamp wrote:
>>> Hi,
>>>
>>> In an effort to get at least some parts of the Bink patch committed, I
>>> am splitting it into separable pieces.
>>>
>>> This is a one-dimensional floating-point DCT used by Bink audio. ?The
>>> actual code was written by Peter Ross.
>>>
>>> The comments I myself have about this code:
>>> - Should it be using math.h cos()/sin() or some lookup table approach?
>>> - Can there be a test written? (I don't know enough about the math
>>> involved to write a sane test...)
>>
>> Thanks for taking the time to split the patch.
>>
>> Note that the algorithm here is inefficient. It requires a 2*N FFT,
>> whereas there are ways of achieving this with 1*N FFT. Michael posted
>> some info on this many months ago.
>>
>
> I had a 1-D 1*N DCT but it generated the transpose (i.e.
> uninterleaved). I can dig it up when I come back from xmas holiday if
> you are interested.
>

As promised...
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