[FFmpeg-devel] Review request - ra288.{c,h} ra144.{c,h}

Vitor Sessak vitor1001
Sat Sep 13 21:48:46 CEST 2008


Michael Niedermayer wrote:
> On Sat, Sep 13, 2008 at 07:07:26PM +0200, Vitor Sessak wrote:
>> Michael Niedermayer wrote:
>>> On Fri, Sep 05, 2008 at 12:23:58AM +0200, Vitor Sessak wrote:
>>>> Vitor Sessak wrote:
> [...]
>>> [...]
>>>> static void colmult(float *tgt, const float *m1, const float *m2, int n)
>>>> {
>>>>     while (n--)
>>>>         *tgt++ = *m1++ * *m2++;
>>>> }
>>> such function is commonly called apply_window() in other codecs
>>>> static void decode(RA288Context *ractx, float gain, int cb_coef)
>>>> {
>>>>     int i, j;
>>>>     double sumsum;
>>>>     float sum, buffer[5];
>>>>     float *block = ractx->sp_block + 36; // Current block
>>>>
>>>>     memmove(ractx->sp_block, ractx->sp_block + 5, 
>>>> 36*sizeof(*ractx->sp_block));
>>>>
>>>>     for (i=0; i < 5; i++) {
>>>>         block[i] = 0.;
>>>>         for (j=0; j < 36; j++)
>>>>             block[i] -= block[i-1-j]*ractx->sp_lpc[j];
>>>>     }
>>>>
>>>>     /* block 46 of G.728 spec */
>>>>     sum = 32.;
>>>>     for (i=0; i < 10; i++)
>>>>         sum -= ractx->gain_block[9-i] * ractx->gain_lpc[i];
>>>>
>>>>     /* block 47 of G.728 spec */
>>>>     sum = av_clipf(sum, 0, 60);
>>>>
>>>>     /* block 48 of G.728 spec */
>>>>     sumsum = exp(sum * 0.1151292546497) * gain; /* pow(10.0,sum/20)*gain 
>>>> */
>>>>
>>>>     for (i=0; i < 5; i++)
>>>>         buffer[i] = codetable[cb_coef][i] * sumsum;
>>>>
>>>>     sum = scalar_product_float(buffer, buffer, 5) / 5;
>>>>
>>>>     sum = FFMAX(sum, 1);
>>>>
>>>>     /* shift and store */
>>>>     memmove(ractx->gain_block, ractx->gain_block + 1,
>>>>             9 * sizeof(*ractx->gain_block));
>>>>
>>>>     ractx->gain_block[9] = 10 * log10(sum) - 32;
>>>>
>>>>     for (i=1; i < 5; i++)
>>>>         for (j=i-1; j >= 0; j--)
>>>>             buffer[i] -= ractx->sp_lpc[i-j-1] * buffer[j];
>>>>
>>>>     /* output */
>>>>     for (i=0; i < 5; i++)
>>>>         block[i] = av_clipf(block[i] + buffer[i], -4095, 4095);
>>> can the buffer values be stored in block and sp_lpc applied over both
>>> in one pass instead of this 2 pass and add-clip thing?
>> I can't apply sp_lpc to buffer+block, so I need two buffers...
> 
> What i was thinking about was:
> 
>     /* block 46 of G.728 spec */
>     sum = 32.;
>     for (i=0; i < 10; i++)
>         sum -= gain_block[9-i] * ractx->gain_lpc[i];
> 
>     /* block 47 of G.728 spec */
>     sum = av_clipf(sum, 0, 60);
> 
>     /* block 48 of G.728 spec */
>     sumsum = exp(sum * 0.1151292546497) * gain; /* pow(10.0,sum/20)*gain */
> 
>     for (i=0; i < 5; i++)
>         buffer[i] = codetable[cb_coef][i] * sumsum * (1./2048.);
> 
>     sum = scalar_product_float(buffer, buffer, 5) / 5;
> 
>     sum = FFMAX(sum, 1);
> 
>     /* shift and store */
>     memmove(gain_block, gain_block + 1, 9 * sizeof(*gain_block));
> 
>     gain_block[9] = 10 * log10(sum) - 32;
> 
>     for (i=0; i < 5; i++) {
>         block[i] = buffer[i];

Here you are overwriting the value of block[i] (while previous code used 
this value).

>         for (j=0; j < 36; j++)
>             block[i] -= block[i-1-j]*ractx->sp_lpc[j];
>     }
> 
>     /* output */
>     for (i=0; i < 5; i++)
>         block[i] = av_clipf(block[i], -4095, 4095);
> 
> am i missing a proble in this?
> 
> 
> 
>>> [...]
>>>> static int ra288_decode_frame(AVCodecContext * avctx, void *data,
>>>>                               int *data_size, const uint8_t * buf,
>>>>                               int buf_size)
>>>> {
>>>>     int16_t *out = data;
>>>>     int i, j;
>>>>     RA288Context *ractx = avctx->priv_data;
>>>>     GetBitContext gb;
>>>>
>>>>     if (buf_size < avctx->block_align) {
>>>>         av_log(avctx, AV_LOG_ERROR,
>>>>                "Error! Input buffer is too small [%d<%d]\n",
>>>>                buf_size, avctx->block_align);
>>>>         return 0;
>>>>     }
>>>>
>>>>     if (*data_size < 32*5*2)
>>>>         return -1;
>>>>
>>>>     init_get_bits(&gb, buf, avctx->block_align * 8);
>>>>
>>>>     for (i=0; i < 32; i++) {
>>>>         float gain = amptable[get_bits(&gb, 3)];
>>>>         int cb_coef = get_bits(&gb, 6 + (i&1));
>>>>
>>>>         decode(ractx, gain, cb_coef);
>>>>
>>>>         for (j=0; j < 5; j++)
>>>>             *(out++) = 8 * ractx->sp_block[36 + j];
>>> if float output works already, then this could output floats, if not then
>>> this could use lrintf()
>> I've tried the float output (with the attached patch) and it didn't work. 
> 
> ok
> 
> 
>> Using lrint() changes slightly the output (PSNR about 99), is it expected?
> 
> yes, it does round differently (=more correctly)

Too correct maybe. PSNR to binary decoder with SVN:

stddev:    0.15 PSNR:112.70 bytes:   990720/  1013760
stddev:    0.04 PSNR:122.74 bytes:   368640/   368640
stddev:    0.07 PSNR:118.84 bytes:   460800/   458752
stddev:    0.31 PSNR:106.24 bytes:  6451200/  6451200

Using lrint()

stddev:    0.70 PSNR: 99.33 bytes:   990720/  1013760
stddev:    0.70 PSNR: 99.35 bytes:   368640/   368640
stddev:    0.70 PSNR: 99.35 bytes:   460800/   458752
stddev:    0.75 PSNR: 98.76 bytes:  6451200/  6451200

-Vitor




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