if (idx == 0 && !convert->pack_rgb) {
color_matrix_set_identity (&convert->to_YUV_matrix);
- compute_matrix_to_YUV (convert, &convert->to_YUV_matrix, FALSE);
- /* matrix is in 0..255 range, scale to pack bits */
+ /* When gamma remap is enabled, we do
+ * 1) converts to ARGB64 linear RGB
+ * - if input is 8bits, convert to ARGB and scaled to 16bits with gamma
+ * decoding at once
+ * - otherwise converted ARGB64 and gamma decoded
+ * 2) scale/convert etc,
+ * 3) and gamma encode
+ *
+ * So source data to the do_convert_to_YUV_lines() method is always
+ * ARGB64
+ *
+ * Then, if output unpack format is 8bits, setup_gamma_encode() will scale
+ * ARGB64 down to ARGB as a part of gamma encoding, otherwise it's still
+ * ARGB64
+ *
+ * Finally this to_YUV_matrix is applied. Since compute_matrix_to_YUV()
+ * expects [0, 1.0] range RGB as an input, scale down identity matrix
+ * to expected scale here, otherwise offset of the matrix would be
+ * very wrong
+ */
GST_DEBUG ("chain YUV convert");
scale = 1 << convert->pack_bits;
color_matrix_scale_components (&convert->to_YUV_matrix,
1 / (float) scale, 1 / (float) scale, 1 / (float) scale);
+
+ compute_matrix_to_YUV (convert, &convert->to_YUV_matrix, FALSE);
prepare_matrix (convert, &convert->to_YUV_matrix);
}
convert->current_format = convert->pack_format;