[FFmpeg-devel] [PATCH 2/3] Indeo 5 decoder: common DSP functions

Maxim max_pole
Sat Jan 9 01:01:34 CET 2010


Michael Niedermayer schrieb:
> On Sun, Jan 03, 2010 at 12:56:36PM +0200, Kostya wrote:
> [...]
>   
>> void ff_ivi_recompose53(const IVIPlaneDesc *plane, uint8_t *dst,
>>                         const int dst_pitch, const int num_bands)
>> {
>>     int             x, y, indx;
>>     int32_t         p0, p1, p2, p3, tmp0, tmp1, tmp2;
>>     int32_t         b0_1, b0_2, b1_1, b1_2, b1_3, b2_1, b2_2, b2_3, b2_4, b2_5, b2_6;
>>     int32_t         b3_1, b3_2, b3_3, b3_4, b3_5, b3_6, b3_7, b3_8, b3_9;
>>     uint32_t        pitch, back_pitch;
>>     const IDWTELEM *b0_ptr, *b1_ptr, *b2_ptr, *b3_ptr;
>>
>>     /* all bands should have the same pitch */
>>     pitch = plane->bands[0].pitch;
>>
>>     /* pixels at the position "y-1" will be set to pixels at the "y" for the 1st iteration */
>>     back_pitch = 0;
>>
>>     /* get pointers to the wavelet bands */
>>     b0_ptr = plane->bands[0].buf;
>>     b1_ptr = plane->bands[1].buf;
>>     b2_ptr = plane->bands[2].buf;
>>     b3_ptr = plane->bands[3].buf;
>>
>>     for (y = 0; y < plane->height; y += 2) {
>>         /* load storage variables with values */
>>         if (num_bands > 0) {
>>             b0_1 = b0_ptr[0];
>>             b0_2 = b0_ptr[pitch];
>>         }
>>
>>         if (num_bands > 1) {
>>             b1_1 = b1_ptr[back_pitch];
>>             b1_2 = b1_ptr[0];
>>             b1_3 = b1_1 - b1_2*6 + b1_ptr[pitch];
>>         }
>>
>>         if (num_bands > 2) {
>>             b2_2 = b2_ptr[0];     // b2[x,  y  ]
>>             b2_3 = b2_2;          // b2[x+1,y  ] = b2[x,y]
>>             b2_5 = b2_ptr[pitch]; // b2[x  ,y+1]
>>             b2_6 = b2_5;          // b2[x+1,y+1] = b2[x,y+1]
>>         }
>>
>>         if (num_bands > 3) {
>>             b3_2 = b3_ptr[back_pitch]; // b3[x  ,y-1]
>>             b3_3 = b3_2;               // b3[x+1,y-1] = b3[x  ,y-1]
>>             b3_5 = b3_ptr[0];          // b3[x  ,y  ]
>>             b3_6 = b3_5;               // b3[x+1,y  ] = b3[x  ,y  ]
>>             b3_8 = b3_2 - b3_5*6 + b3_ptr[pitch];
>>             b3_9 = b3_8;
>>         }
>>
>>         for (x = 0, indx = 0; x < plane->width; x+=2, indx++) {
>>             /* some values calculated in the previous iterations can */
>>             /* be reused in the next ones, so do appropriate copying */
>>             b2_1 = b2_2; // b2[x-1,y  ] = b2[x,  y  ]
>>             b2_2 = b2_3; // b2[x  ,y  ] = b2[x+1,y  ]
>>             b2_4 = b2_5; // b2[x-1,y+1] = b2[x  ,y+1]
>>             b2_5 = b2_6; // b2[x  ,y+1] = b2[x+1,y+1]
>>             b3_1 = b3_2; // b3[x-1,y-1] = b3[x  ,y-1]
>>             b3_2 = b3_3; // b3[x  ,y-1] = b3[x+1,y-1]
>>             b3_4 = b3_5; // b3[x-1,y  ] = b3[x  ,y  ]
>>             b3_5 = b3_6; // b3[x  ,y  ] = b3[x+1,y  ]
>>             b3_7 = b3_8; // vert_HPF(x-1)
>>             b3_8 = b3_9; // vert_HPF(x  )
>>
>>             p0 = p1 = p2 = p3 = 0;
>>
>>             /* process the LL-band by applying LPF both vertically and horizontally */
>>             if (num_bands > 0) {
>>                 tmp0 = b0_1;
>>                 tmp2 = b0_2;
>>                 b0_1 = b0_ptr[indx+1];
>>                 b0_2 = b0_ptr[pitch+indx+1];
>>                 tmp1 = tmp0 + b0_1;
>>
>>                 p0 =  tmp0 << 4;
>>                 p1 =  tmp1 << 3;
>>                 p2 = (tmp0 + tmp2) << 3;
>>                 p3 = (tmp1 + tmp2 + b0_2) << 2;
>>             }
>>
>>             /* process the HL-band by applying HPF vertically and LPF horizontally */
>>             if (num_bands > 1) {
>>                 tmp0 = b1_2;
>>                 tmp1 = b1_1;
>>                 b1_2 = b1_ptr[indx+1];
>>                 b1_1 = b1_ptr[back_pitch+indx+1];
>>
>>                 tmp2 = tmp1 - tmp0*6 + b1_3;
>>                 b1_3 = b1_1 - b1_2*6 + b1_ptr[pitch+indx+1];
>>
>>                 p0 += (tmp0 + tmp1) << 3;
>>                 p1 += (tmp0 + tmp1 + b1_1 + b1_2) << 2;
>>                 p2 +=  tmp2 << 2;
>>                 p3 += (tmp2 + b1_3) << 1;
>>             }
>>
>>             /* process the LH-band by applying LPF vertically and HPF horizontally */
>>             if (num_bands > 2) {
>>                 b2_3 = b2_ptr[indx+1];
>>                 b2_6 = b2_ptr[pitch+indx+1];
>>
>>                 tmp0 = b2_1 + b2_2;
>>                 tmp1 = b2_1 - b2_2*6 + b2_3;
>>
>>                 p0 += tmp0 << 3;
>>                 p1 += tmp1 << 2;
>>                 p2 += (tmp0 + b2_4 + b2_5) << 2;
>>                 p3 += (tmp1 + b2_4 - b2_5*6 + b2_6) << 1;
>>             }
>>
>>             /* process the HH-band by applying HPF both vertically and horizontally */
>>             if (num_bands > 3) {
>>                 b3_6 = b3_ptr[indx+1];            // b3[x+1,y  ]
>>                 b3_3 = b3_ptr[back_pitch+indx+1]; // b3[x+1,y-1]
>>
>>                 tmp0 = b3_1 + b3_4;
>>                 tmp1 = b3_2 + b3_5;
>>                 tmp2 = b3_3 + b3_6;
>>
>>                 b3_9 = b3_3 - b3_6*6 + b3_ptr[pitch+indx+1];
>>
>>                 p0 += (tmp0 + tmp1) << 2;
>>                 p1 += (tmp0 - tmp1*6 + tmp2) << 1;
>>                 p2 += (b3_7 + b3_8) << 1;
>>                 p3 +=  b3_7 - b3_8*6 + b3_9;
>>             }
>>
>>             /* output four pixels */
>>             dst[x]             = av_clip_uint8((p0 >> 6) + 128);
>>             dst[x+1]           = av_clip_uint8((p1 >> 6) + 128);
>>             dst[dst_pitch+x]   = av_clip_uint8((p2 >> 6) + 128);
>>             dst[dst_pitch+x+1] = av_clip_uint8((p3 >> 6) + 128);
>>         }// for x
>>
>>         dst += dst_pitch << 1;
>>
>>         back_pitch = -pitch;
>>
>>         b0_ptr += pitch;
>>         b1_ptr += pitch;
>>         b2_ptr += pitch;
>>         b3_ptr += pitch;
>>     }
>> }
>>     
>
> is this mess faster than some more readable variant?
>   

It resembles the original code and was include for testing purposes!
Xanim/Mac indeo5 binaries contain really buggy code for this function :-(
My intention was to reuse the snow's compose53i code at the end! So I
suggest to split that code out of the snow's source and place it into a
separate file. BTW JPEG2000 uses the same wavelet. Once thing required
is a scale step for indeo5 HPF coefficients. Maybe that could be
incorporated into the code...

Regards
maxim



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