mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-10-07 19:22:15 +00:00
alpha: Refactor chroma keying into a single function
This reduces code duplication once we add support for more color formats.
This commit is contained in:
Sebastian Dröge
parent
cccfeaa59c
commit
f7ba12513e
1 changed files with 102 additions and 168 deletions
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@ -456,17 +456,94 @@ gst_alpha_set_i420 (guint8 * src, guint8 * dest, gint width, gint height,
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}
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}
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/* based on http://www.cs.utah.edu/~michael/chroma/
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*/
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static inline gint
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chroma_keying_yuv (gint a, gint * y, guint ny, gint * u,
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gint * v, gint cr, gint cb, gint smin, gint smax, guint8 accept_angle_tg,
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guint8 accept_angle_ctg, guint8 one_over_kc, guint8 kfgy_scale, gint8 kg,
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gfloat noise_level)
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{
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gint tmp, tmp1;
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gint x1, y1;
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gint x, z;
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gint b_alpha;
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for (tmp = 0; tmp < ny; tmp++) {
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/* too dark or too bright, keep alpha */
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if (y[tmp] < smin || y[tmp] > smax)
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return a;
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}
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/* Convert foreground to XZ coords where X direction is defined by
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the key color */
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tmp = ((*u) * cb + (*v) * cr) >> 7;
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x = CLAMP (tmp, -128, 127);
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tmp = ((*v) * cb - (*u) * cr) >> 7;
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z = CLAMP (tmp, -128, 127);
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/* WARNING: accept angle should never be set greater than "somewhat less
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than 90 degrees" to avoid dealing with negative/infinite tg. In reality,
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80 degrees should be enough if foreground is reasonable. If this seems
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to be a problem, go to alternative ways of checking point position
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(scalar product or line equations). This angle should not be too small
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either to avoid infinite ctg (used to suppress foreground without use of
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division) */
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tmp = (x * accept_angle_tg) >> 4;
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tmp = MIN (tmp, 127);
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if (abs (z) > tmp) {
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/* keep foreground Kfg = 0 */
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return a;
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}
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/* Compute Kfg (implicitly) and Kbg, suppress foreground in XZ coord
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according to Kfg */
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tmp = (z * accept_angle_ctg) >> 4;
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tmp = CLAMP (tmp, -128, 127);
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x1 = abs (tmp);
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y1 = z;
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tmp1 = x - x1;
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tmp1 = MAX (tmp1, 0);
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b_alpha = (tmp1 * one_over_kc) / 2;
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b_alpha = 255 - CLAMP (b_alpha, 0, 255);
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b_alpha = (a * b_alpha) >> 8;
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tmp = (tmp1 * kfgy_scale) >> 4;
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tmp1 = MIN (tmp, 255);
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for (tmp = 0; tmp < ny; tmp++)
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y[tmp] = (y[tmp] < tmp1) ? 0 : y[tmp] - tmp1;
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/* Convert suppressed foreground back to CbCr */
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tmp = (x1 * cb - y1 * cr) >> 7;
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*u = CLAMP (tmp, -128, 127);
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tmp = (x1 * cr + y1 * cb) >> 7;
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*v = CLAMP (tmp, -128, 127);
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/* Deal with noise. For now, a circle around the key color with
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radius of noise_level treated as exact key color. Introduces
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sharp transitions.
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*/
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tmp = z * z + (x - kg) * (x - kg);
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tmp = MIN (tmp, 0xffff);
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if (tmp < noise_level * noise_level)
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b_alpha = 0;
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return b_alpha;
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}
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static void
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gst_alpha_chroma_key_ayuv (guint8 * src, guint8 * dest, gint width, gint height,
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GstAlpha * alpha)
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{
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gint b_alpha;
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guint8 *src1;
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guint8 *dest1;
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gint i, j;
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gint x, z, u, v, y, a;
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gint tmp, tmp1;
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gint x1, y1;
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gint a, y, u, v;
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gint smin, smax;
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smin = 128 - alpha->black_sensitivity;
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@ -482,78 +559,14 @@ gst_alpha_chroma_key_ayuv (guint8 * src, guint8 * dest, gint width, gint height,
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u = *src1++ - 128;
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v = *src1++ - 128;
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if (y < smin || y > smax) {
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/* too dark or too bright, keep alpha */
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b_alpha = a;
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} else {
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/* Convert foreground to XZ coords where X direction is defined by
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the key color */
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tmp = ((short) u * alpha->cb + (short) v * alpha->cr) >> 7;
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x = CLAMP (tmp, -128, 127);
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tmp = ((short) v * alpha->cb - (short) u * alpha->cr) >> 7;
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z = CLAMP (tmp, -128, 127);
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/* WARNING: accept angle should never be set greater than "somewhat less
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than 90 degrees" to avoid dealing with negative/infinite tg. In reality,
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80 degrees should be enough if foreground is reasonable. If this seems
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to be a problem, go to alternative ways of checking point position
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(scalar product or line equations). This angle should not be too small
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either to avoid infinite ctg (used to suppress foreground without use of
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division) */
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tmp = ((short) (x) * alpha->accept_angle_tg) >> 4;
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tmp = MIN (tmp, 127);
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if (abs (z) > tmp) {
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/* keep foreground Kfg = 0 */
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b_alpha = a;
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} else {
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/* Compute Kfg (implicitly) and Kbg, suppress foreground in XZ coord
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according to Kfg */
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tmp = ((short) (z) * alpha->accept_angle_ctg) >> 4;
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tmp = CLAMP (tmp, -128, 127);
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x1 = abs (tmp);
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y1 = z;
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tmp1 = x - x1;
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tmp1 = MAX (tmp1, 0);
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b_alpha = (((unsigned char) (tmp1) *
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(unsigned short) (alpha->one_over_kc)) / 2);
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b_alpha = 255 - CLAMP (b_alpha, 0, 255);
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b_alpha = (a * b_alpha) >> 8;
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tmp = ((unsigned short) (tmp1) * alpha->kfgy_scale) >> 4;
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tmp1 = MIN (tmp, 255);
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tmp = y - tmp1;
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y = MAX (tmp, 0);
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/* Convert suppressed foreground back to CbCr */
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tmp = ((char) (x1) * (short) (alpha->cb) -
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(char) (y1) * (short) (alpha->cr)) >> 7;
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u = CLAMP (tmp, -128, 127);
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tmp = ((char) (x1) * (short) (alpha->cr) +
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(char) (y1) * (short) (alpha->cb)) >> 7;
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v = CLAMP (tmp, -128, 127);
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/* Deal with noise. For now, a circle around the key color with
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radius of noise_level treated as exact key color. Introduces
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sharp transitions.
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*/
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tmp = z * (short) (z) + (x - alpha->kg) * (short) (x - alpha->kg);
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tmp = MIN (tmp, 0xffff);
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if (tmp < alpha->noise_level * alpha->noise_level) {
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b_alpha = 0;
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}
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}
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}
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a = chroma_keying_yuv (a, &y, 1, &u, &v, alpha->cr, alpha->cb,
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smin, smax, alpha->accept_angle_tg, alpha->accept_angle_ctg,
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alpha->one_over_kc, alpha->kfgy_scale, alpha->kg, alpha->noise_level);
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u += 128;
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v += 128;
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*dest1++ = b_alpha;
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*dest1++ = a;
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*dest1++ = y;
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*dest1++ = u;
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*dest1++ = v;
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@ -561,15 +574,12 @@ gst_alpha_chroma_key_ayuv (guint8 * src, guint8 * dest, gint width, gint height,
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}
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}
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static void
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static inline void
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gst_alpha_chromakey_row_i420 (GstAlpha * alpha, guint8 * dest1, guint8 * dest2,
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guint8 * srcY1, guint8 * srcY2, guint8 * srcU, guint8 * srcV, gint width)
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{
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gint xpos;
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gint b_alpha;
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gint x, z, u, v, y11, y12, y21, y22, a;
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gint tmp, tmp1;
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gint x1, y1;
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gint a, a2, y[4], u, v;
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gint smin, smax;
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a = 255 * alpha->alpha;
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@ -577,115 +587,40 @@ gst_alpha_chromakey_row_i420 (GstAlpha * alpha, guint8 * dest1, guint8 * dest2,
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smax = 128 + alpha->white_sensitivity;
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for (xpos = 0; xpos < width / 2; xpos++) {
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y11 = *srcY1++;
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y12 = *srcY1++;
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y21 = *srcY2++;
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y22 = *srcY2++;
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y[0] = *srcY1++;
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y[1] = *srcY1++;
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y[2] = *srcY2++;
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y[3] = *srcY2++;
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u = *srcU++ - 128;
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v = *srcV++ - 128;
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if (y11 < smin || y11 > smax ||
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y12 < smin || y12 > smax ||
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y21 < smin || y21 > smax || y22 < smin || y22 > smax) {
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/* too dark or too bright, make opaque */
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b_alpha = 255;
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} else {
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/* Convert foreground to XZ coords where X direction is defined by
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the key color */
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tmp = ((short) u * alpha->cb + (short) v * alpha->cr) >> 7;
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x = CLAMP (tmp, -128, 127);
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tmp = ((short) v * alpha->cb - (short) u * alpha->cr) >> 7;
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z = CLAMP (tmp, -128, 127);
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/* WARNING: accept angle should never be set greater than "somewhat less
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than 90 degrees" to avoid dealing with negative/infinite tg. In reality,
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80 degrees should be enough if foreground is reasonable. If this seems
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to be a problem, go to alternative ways of checking point position
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(scalar product or line equations). This angle should not be too small
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either to avoid infinite ctg (used to suppress foreground without use of
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division) */
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tmp = ((short) (x) * alpha->accept_angle_tg) >> 4;
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tmp = MIN (tmp, 127);
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if (abs (z) > tmp) {
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/* keep foreground Kfg = 0 */
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b_alpha = 255;
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} else {
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/* Compute Kfg (implicitly) and Kbg, suppress foreground in XZ coord
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according to Kfg */
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tmp = ((short) (z) * alpha->accept_angle_ctg) >> 4;
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tmp = CLAMP (tmp, -128, 127);
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x1 = abs (tmp);
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y1 = z;
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tmp1 = x - x1;
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tmp1 = MAX (tmp1, 0);
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b_alpha = (((unsigned char) (tmp1) *
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(unsigned short) (alpha->one_over_kc)) / 2);
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b_alpha = 255 - CLAMP (b_alpha, 0, 255);
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b_alpha = (a * b_alpha) >> 8;
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tmp = ((unsigned short) (tmp1) * alpha->kfgy_scale) >> 4;
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tmp1 = MIN (tmp, 255);
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tmp = y11 - tmp1;
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y11 = MAX (tmp, 0);
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tmp = y12 - tmp1;
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y12 = MAX (tmp, 0);
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tmp = y21 - tmp1;
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y21 = MAX (tmp, 0);
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tmp = y22 - tmp1;
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y22 = MAX (tmp, 0);
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/* Convert suppressed foreground back to CbCr */
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tmp = ((char) (x1) * (short) (alpha->cb) -
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(char) (y1) * (short) (alpha->cr)) >> 7;
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u = CLAMP (tmp, -128, 127);
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tmp = ((char) (x1) * (short) (alpha->cr) +
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(char) (y1) * (short) (alpha->cb)) >> 7;
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v = CLAMP (tmp, -128, 127);
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/* Deal with noise. For now, a circle around the key color with
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radius of noise_level treated as exact key color. Introduces
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sharp transitions.
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*/
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tmp = z * (short) (z) + (x - alpha->kg) * (short) (x - alpha->kg);
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tmp = MIN (tmp, 0xffff);
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if (tmp < alpha->noise_level * alpha->noise_level) {
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/* Uncomment this if you want total suppression within the noise circle */
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b_alpha = 0;
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}
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}
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}
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a2 = chroma_keying_yuv (a, y, 4, &u, &v, alpha->cr, alpha->cb, smin,
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smax, alpha->accept_angle_tg, alpha->accept_angle_ctg,
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alpha->one_over_kc, alpha->kfgy_scale, alpha->kg, alpha->noise_level);
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u += 128;
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v += 128;
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*dest1++ = b_alpha;
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*dest1++ = y11;
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*dest1++ = a2;
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*dest1++ = y[0];
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*dest1++ = u;
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*dest1++ = v;
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*dest1++ = b_alpha;
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*dest1++ = y12;
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*dest1++ = a2;
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*dest1++ = y[1];
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*dest1++ = u;
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*dest1++ = v;
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*dest2++ = b_alpha;
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*dest2++ = y21;
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*dest2++ = a2;
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*dest2++ = y[2];
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*dest2++ = u;
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*dest2++ = v;
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*dest2++ = b_alpha;
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*dest2++ = y22;
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*dest2++ = a2;
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*dest2++ = y[3];
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*dest2++ = u;
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*dest2++ = v;
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}
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}
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/* based on http://www.cs.utah.edu/~michael/chroma/
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*/
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static void
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gst_alpha_chroma_key_i420 (guint8 * src, guint8 * dest, gint width, gint height,
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GstAlpha * alpha)
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@ -718,7 +653,6 @@ gst_alpha_chroma_key_i420 (guint8 * src, guint8 * dest, gint width, gint height,
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src_y_stride *= 2;
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for (ypos = 0; ypos < height / 2; ypos++) {
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gst_alpha_chromakey_row_i420 (alpha, dest1, dest2,
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srcY1, srcY2, srcU, srcV, width);
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