resize.cpp

著名的 helix realplayer 基于手机 symbian 系统的 播放器全套源代码

				tmp += (source_level << (FILT_COEFF_BITS + FILT_SCALE_BITS));
				tmp += (1U << (FILT_COEFF_BITS + FILT_SCALE_BITS - 1));
				tmp >>= (FILT_COEFF_BITS + FILT_SCALE_BITS);
				*tp = tmp;
				
				tp += src_pitch;
				pos += pos_inc;
				pos_int = pos >> POS_SCALE_BITS;
				line++;
			}
		}
	}

	if (dest_width == src_width)
	{
		// no horizontal resizing
		for (line = 0; line < dest_height; line++)
		{
			tp = buff + line * src_pitch;
			dp = dest + line * dest_pitch;

			for (pel = 0; pel < dest_width - 3; pel += 4)
			{
				dp[0] = CLIP_PEL(tp[0]);
				dp[1] = CLIP_PEL(tp[1]);
				dp[2] = CLIP_PEL(tp[2]);
				dp[3] = CLIP_PEL(tp[3]);
				dp += 4;
				tp += 4;
			}
			for (; pel < dest_width; pel++)
			{
				*dp = CLIP_PEL(*tp);
				dp ++;
				tp ++;
			}
		}
	}
	else if (dest_width == (src_width >> 1))
	{
		// decimate horizontally by 2

		int src_skip = src_pitch - src_width + 2;
		int dest_skip = dest_pitch - dest_width + 1;
		int a, b, c, d;

		tp = buff;
		dp = dest;

		for (line = 0; line < dest_height; line ++)
		{
			a = tp[0];
			b = a;
			c = tp[1];
			d = tp[2];

			b += c;
			a += d;
			b *= 9;
			b -= a;
			b += 7;
			b >>= 4;

			*dp = CLIP_PEL(b);

			tp += 2;
			dp ++;

			for (pel = 1; pel < dest_width - 1; pel++)
			{
				a = c;
				b = d;
				c = tp[1];
				d = tp[2];

				b += c;
				a += d;
				b *= 9;
				b -= a;
				b += 7;
				b >>= 4;

				*dp = CLIP_PEL(b);

				tp += 2;
				dp ++;
			}
			a = c;
			b = d;
			c = tp[1];
			d = c;

			b += c;
			a += d;
			b *= 9;
			b -= a;
			b += 7;
			b >>= 4;

			*dp = CLIP_PEL(b);

			tp += src_skip;
			dp += dest_skip;
		}
	}
	else
	{
		// horizonal filtering
		pos_inc = ((src_width << POS_SCALE_BITS) + (dest_width >> 1)) / (dest_width);
		pos_bgn = (pos_inc - (1 << POS_SCALE_BITS)) >> 1;
		filt_tab_inc = (FULL_PEL_INC * dest_width + (src_width >> 1)) / (src_width);
		if (filt_tab_inc > FULL_PEL_INC)
			filt_tab_inc = FULL_PEL_INC;
		filt_tap_num = (INT_FILT_SIZE - 1) / (filt_tab_inc << 1);
		filt_scale = ((dest_width << FILT_SCALE_BITS) + (src_width >> 1)) / (src_width);

		for (line = 0; line < dest_height; line++)
		{
			dp = dest + line * dest_pitch;
			
			pel = 0;
			pos = pos_bgn;
			pos_int = pos >> POS_SCALE_BITS;

			// Left edge pels
			while (pos_int < filt_tap_num)
			{
				tp = buff + line * src_pitch + pos_int;

#if USE_SOURCE_LEVEL
				source_level = *tp;
#endif
				tp -= filt_tap_num;

				filt_tab_ptr = int_filt_tab;
				filt_tab_ptr -= (filt_tab_inc * (pos & ((1L << POS_SCALE_BITS) - 1))) >> POS_SCALE_BITS;
				filt_tab_ptr += INT_FILT_CENTER - (filt_tap_num * filt_tab_inc);
				if (filt_tab_ptr < int_filt_tab)
				{
					tp ++;
					filt_tab_ptr += filt_tab_inc;
				}

				tmp = 0;
				while (filt_tab_ptr < int_filt_tab + INT_FILT_SIZE)
				{
					if (tp < buff)
						tmp += (*filt_tab_ptr) * (buff[line * src_pitch] - source_level);
					else
						tmp += (*filt_tab_ptr) * (*tp - source_level);
					tp++;
					filt_tab_ptr += filt_tab_inc;
				}
				tmp *= filt_scale;
				tmp += (source_level << (FILT_COEFF_BITS + FILT_SCALE_BITS));
				tmp += (1U << (FILT_COEFF_BITS + FILT_SCALE_BITS - 1));
				tmp >>= (FILT_COEFF_BITS + FILT_SCALE_BITS);
				*dp = CLIP_PEL(tmp);

				dp++;
				pos += pos_inc;
				pos_int = pos >> POS_SCALE_BITS;
				pel++;
			}
			// Center pels
			while (pos_int < src_width - filt_tap_num - 1)
			{
				tp = buff + line * src_pitch + pos_int;

#if USE_SOURCE_LEVEL
				source_level = *tp;
#endif
				tp -= filt_tap_num;

				filt_tab_ptr = int_filt_tab;
				filt_tab_ptr -= (filt_tab_inc * (pos & ((1L << POS_SCALE_BITS) - 1))) >> POS_SCALE_BITS;
				filt_tab_ptr += INT_FILT_CENTER - (filt_tap_num * filt_tab_inc);
				if (filt_tab_ptr < int_filt_tab)
				{
					tp ++;
					filt_tab_ptr += filt_tab_inc;
				}

				// There are at least 4 taps...
				tmp = (*filt_tab_ptr) * (tp[0] - source_level);
				filt_tab_ptr += filt_tab_inc;
				tmp += (*filt_tab_ptr) * (tp[1] - source_level);
				filt_tab_ptr += filt_tab_inc;
				tmp += (*filt_tab_ptr) * (tp[2] - source_level);
				filt_tab_ptr += filt_tab_inc;
				tmp += (*filt_tab_ptr) * (tp[3] - source_level);
				filt_tab_ptr += filt_tab_inc;

				tp += 4;
				
				// Remaining taps...
				while (filt_tab_ptr < int_filt_tab + INT_FILT_SIZE)
				{
					tmp += (*filt_tab_ptr) * (*tp - source_level);
					tp++;
					filt_tab_ptr += filt_tab_inc;
				}
				tmp *= filt_scale;
				tmp += (source_level << (FILT_COEFF_BITS + FILT_SCALE_BITS));
				tmp += (1U << (FILT_COEFF_BITS + FILT_SCALE_BITS - 1));
				tmp >>= (FILT_COEFF_BITS + FILT_SCALE_BITS);

				*dp = CLIP_PEL(tmp);

				dp++;
				pos += pos_inc;
				pos_int = pos >> POS_SCALE_BITS;
				pel++;
			}
			// Right edge pels
			while (pel < dest_width)
			{
				tp = buff + line * src_pitch + pos_int;

#if USE_SOURCE_LEVEL
				source_level = *tp;
#endif
				tp -= filt_tap_num;

				filt_tab_ptr = int_filt_tab;
				filt_tab_ptr -= (filt_tab_inc * (pos & ((1L << POS_SCALE_BITS) - 1))) >> POS_SCALE_BITS;
				filt_tab_ptr += INT_FILT_CENTER - (filt_tap_num * filt_tab_inc);
				if (filt_tab_ptr < int_filt_tab)
				{
					tp ++;
					filt_tab_ptr += filt_tab_inc;
				}

				tmp = 0;
				while (filt_tab_ptr < int_filt_tab + INT_FILT_SIZE)
				{
					if (tp >= buff + line * src_pitch + src_width)
						tmp += (*filt_tab_ptr) * (buff[line * src_pitch + src_width - 1] - source_level);
					else
						tmp += (*filt_tab_ptr) * (*tp - source_level);
					tp++;
					filt_tab_ptr += filt_tab_inc;
				}
				tmp *= filt_scale;
				tmp += (source_level << (FILT_COEFF_BITS + FILT_SCALE_BITS));
				tmp += (1U << (FILT_COEFF_BITS + FILT_SCALE_BITS - 1));
				tmp >>= (FILT_COEFF_BITS + FILT_SCALE_BITS);
				*dp = CLIP_PEL(tmp);

				dp++;
				pos += pos_inc;
				pos_int = pos >> POS_SCALE_BITS;
				pel++;
			}
		}
	}
}

	
/* 12-19-98 02:36am, written by Yuriy A. Reznik, [e-mail] */

#define TOTAL_SCALE_BITS    16  /* precision of inverse coordinate mapping */
#define COEF_SCALE_BITS     3   /* actual grid used to select scale coeffs */

/*
 * Interpolate image.
 * Use:
 *  void interpolate_x (
 *       unsigned char *dest, int dest_width, int dest_height, int dest_pitch,
 *       unsigned char *src,  int src_width,  int src_height,  int src_pitch);
 */
static void  /** G2H263Codec:: NEVER make this function a class method!!!! */
interpolate_ii (
    unsigned char *dest, int dest_width, int dest_height, int dest_pitch,
    unsigned char *src,  int src_width,  int src_height,  int src_pitch)
{
    /* scaled row/column counters, limits, & increment values: */
    int src_x, src_y;
    int src_x_inc = ((src_width << TOTAL_SCALE_BITS) + dest_width / 2) / dest_width;
    int src_y_inc = ((src_height << TOTAL_SCALE_BITS) + dest_height / 2) / dest_height;
    int src_x_max = (src_width - 1) << TOTAL_SCALE_BITS;
    int src_y_max = (src_height - 1) << TOTAL_SCALE_BITS;
    int src_x_end = src_x_inc * dest_width;
    int src_y_end = src_y_inc * dest_height;
	int src_x_bgn = (src_width < dest_width)?(0):((src_x_inc  - (1 << TOTAL_SCALE_BITS)) >> 1);
	int src_y_bgn = (src_height < dest_height)?(0):((src_y_inc - (1 << TOTAL_SCALE_BITS)) >> 1);

	src_x_bgn = 0;
	src_y_bgn = 0;

    /* source/destination pointers: */
    unsigned char *s1, *s2, *d1 = dest;

    /* perform interpolation by inverse mapping from destination to source: */
    for (src_y = src_y_bgn; src_y < src_y_max; src_y += src_y_inc) {

        /* map row: */
        int src_y_i = src_y >> TOTAL_SCALE_BITS;
        int q       = (src_y >> (TOTAL_SCALE_BITS - COEF_SCALE_BITS)) & ((1U << COEF_SCALE_BITS) - 1);

        /* get source row pointers: */
        s1 = src + src_y_i * src_pitch;
        s2 = s1 + src_pitch;

        src_x = src_x_bgn;
        do {
            register int src_x_i, p;
            register unsigned int a, b, c;

            /* get first pixel: */
            src_x_i = src_x >> TOTAL_SCALE_BITS;
            p = (src_x >> (TOTAL_SCALE_BITS - COEF_SCALE_BITS)) & ((1U << COEF_SCALE_BITS) - 1);
            /* load 4 pixels in 2 registers: */
            a = (s2 [src_x_i] << 16) + s1 [src_x_i]; 
            c = (s2 [src_x_i + 1] << 16) + s1 [src_x_i + 1]; 
            /* perform 1st horisontal projection: */
            a = (a << COEF_SCALE_BITS) + p * (c - a);

            src_x  += src_x_inc;	/* 1! */

            /* get second pixel: */
            src_x_i = src_x >> TOTAL_SCALE_BITS;
            p = (src_x >> (TOTAL_SCALE_BITS - COEF_SCALE_BITS)) & ((1U << COEF_SCALE_BITS) - 1);
            /* load 4 pixels in 2 registers: */
            b = (s2 [src_x_i] << 16) + s1 [src_x_i]; 
            c = (s2 [src_x_i + 1] << 16) + s1 [src_x_i + 1]; 
            /* perform 2nd horisontal projection: */
            b = (b << COEF_SCALE_BITS) + p * (c - b);

            /* repack & perform vertical projection: */
            c = a;
            a = (a & 0xFFFF) + (b << 16);
            b = (b & 0xFFFF0000) + ((unsigned int)c >> 16);
            a = (a << COEF_SCALE_BITS) + q * (b - a);
            
            /* store pixels: */
            *d1++ = (unsigned int)a >> 2 * COEF_SCALE_BITS;
            *d1++ = (unsigned int)a >> (16 + 2 * COEF_SCALE_BITS);

            src_x  += src_x_inc;	/* 2! */

        } while (src_x < src_x_max);

        /* last pixels: */
        {
            int a = s1 [src_width - 1];
            int c = s2 [src_width - 1];
            a = (unsigned int)((a << COEF_SCALE_BITS) + q * (c - a)) >> COEF_SCALE_BITS;

            for (; src_x < src_x_end; src_x += src_x_inc)
                *d1++ = a;
        }

        d1 = (dest += dest_pitch);
    }

    /* last rows: */
    for (; src_y < src_y_end; src_y += src_y_inc) {

        s1 = src + (src_height-1) * src_pitch;

        for (src_x = 0; src_x < src_x_max; src_x += src_x_inc) {

            int src_x_i = src_x >> TOTAL_SCALE_BITS;
            int p       = (src_x >> (TOTAL_SCALE_BITS - COEF_SCALE_BITS)) & ((1U << COEF_SCALE_BITS) - 1);

            /* get four pixels: */
            int a = s1 [src_x_i];
            int b = s1 [src_x_i + 1];

            /* compute the interpolated pixel value: */
            a = (a << COEF_SCALE_BITS) + p * (b - a);

            *d1++ = (unsigned int)a >> COEF_SCALE_BITS;
        }

        /* last delta_x pixels: */
        for (; src_x < src_x_end; src_x += src_x_inc)
            *d1++ = s1 [src_width - 1];

        d1 = (dest += dest_pitch);
    }
}