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

[Vitor Sessak]

Loren Merritt wrote:
> On Mon, 18 Jan 2010, Vitor Sessak wrote:
> 
>> + data[i    ] =   COS(s,n,i) * val1 + SIN(s,n,i) * val2;
>> + data[i + 1] =   SIN(s,n,i) * val1 - COS(s,n,i) * val2;
> 
> data aliases costab, so the SIN/COS loads will be duplicated.

Done.

>> + float tmp1 = data[i        ] * (1./n);
>> + float tmp2 = data[n - i - 1] * (1./n);
>> + float sin1 = 0.5/SIN(s,n,2*i+1);
> 
> division?

I don't see how it is avoidable, I've tried a LUT and it is slower.

>> +typedef struct {
>> +    int nbits;
>> +    int inverse;
>> +    FFTSample *data;
>> +    RDFTContext rdft;
>> +    const float *costab
>> +} DCTContext;
> 
> libavcodec/dsputil.h:902: warning: no semicolon at end of struct or union

Fixed.

New version attached with the above changes, indentation nits and added 
myself to the copyright.

-Vitor
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