Add support for Rec.709 encoding and inverse encoding.
Reported-by: Tim Harvey <thar...@gateworks.com>
Signed-off-by: Steve Longerbeam <slongerb...@gmail.com>
---
Changes in v5:
- moved API changes to a previous patch.
- moved CSC coeff calc to new function calc_csc_coeffs().
Changes in v4:
- fix compile error.
Chnges in v3:
- none.
Changes in v2:
- only return "Unsupported YCbCr encoding" error if inf != outf,
since if inf == outf, the identity matrix can be used. Reported
by Tim Harvey.
---
drivers/gpu/ipu-v3/ipu-ic.c | 63 ++++++++++++++++++++++++++++++++-----
1 file changed, 56 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/ipu-v3/ipu-ic.c b/drivers/gpu/ipu-v3/ipu-ic.c
index c4048c921801..1460901af9b5 100644
--- a/drivers/gpu/ipu-v3/ipu-ic.c
+++ b/drivers/gpu/ipu-v3/ipu-ic.c
@@ -214,6 +214,23 @@ static const struct ic_encode_coeff ic_encode_identity = {
.scale = 2,
};
+/*
+ * REC.709 encoding from RGB full range to YUV full range:
+ *
+ * Y = .2126 * R + .7152 * G + .0722 * B
+ * U = -.1146 * R - .3854 * G + .5000 * B + 128
+ * V = .5000 * R - .4542 * G - .0458 * B + 128
+ */
+static const struct ic_encode_coeff ic_encode_rgb2ycbcr_709 = {
+ .coeff = {
+ { 54, 183, 19 },
+ { 483, 413, 128 },
+ { 128, 396, 500 },
+ },
+ .offset = { 0, 512, 512 },
+ .scale = 1,
+};
+
/*
* Inverse BT.601 encoding from YUV full range to RGB full range:
*
@@ -237,11 +254,35 @@ static const struct ic_encode_coeff
ic_encode_ycbcr2rgb_601 = {
.scale = 2,
};
+/*
+ * Inverse REC.709 encoding from YUV full range to RGB full range:
+ *
+ * R = 1. * Y + 0 * (Cb - 128) + 1.5748 * (Cr - 128)
+ * G = 1. * Y - .1873 * (Cb - 128) - .4681 * (Cr - 128)
+ * B = 1. * Y + 1.8556 * (Cb - 128) + 0 * (Cr - 128)
+ *
+ * equivalently (factoring out the offsets):
+ *
+ * R = 1. * Y + 0 * Cb + 1.5748 * Cr - 201.574
+ * G = 1. * Y - .1873 * Cb - .4681 * Cr + 83.891
+ * B = 1. * Y + 1.8556 * Cb + 0 * Cr - 237.517
+ */
+static const struct ic_encode_coeff ic_encode_ycbcr2rgb_709 = {
+ .coeff = {
+ { 128, 0, 202 },
+ { 128, 488, 452 },
+ { 128, 238, 0 },
+ },
+ .offset = { -403, 168, -475 },
+ .scale = 2,
+};
+
static int calc_csc_coeffs(struct ipu_ic_priv *priv,
struct ic_encode_coeff *coeff_out,
const struct ipu_ic_colorspace *in,
const struct ipu_ic_colorspace *out)
{
+ const struct ic_encode_coeff *encode_coeff;
bool inverse_encode;
if (in->colorspace != out->colorspace) {
@@ -249,11 +290,6 @@ static int calc_csc_coeffs(struct ipu_ic_priv *priv,
return -ENOTSUPP;
}
- if (out->enc != V4L2_YCBCR_ENC_601) {
- dev_err(priv->ipu->dev, "Only BT.601 encoding supported\n");
- return -ENOTSUPP;
- }
-
if ((in->cs == IPUV3_COLORSPACE_YUV &&
in->quant != V4L2_QUANTIZATION_FULL_RANGE) ||
(out->cs == IPUV3_COLORSPACE_YUV &&
@@ -278,8 +314,21 @@ static int calc_csc_coeffs(struct ipu_ic_priv *priv,
inverse_encode = (in->cs == IPUV3_COLORSPACE_YUV);
- *coeff_out = inverse_encode ?
- ic_encode_ycbcr2rgb_601 : ic_encode_rgb2ycbcr_601;
+ switch (out->enc) {
+ case V4L2_YCBCR_ENC_601:
+ encode_coeff = inverse_encode ?
+ &ic_encode_ycbcr2rgb_601 : &ic_encode_rgb2ycbcr_601;
+ break;
+ case V4L2_YCBCR_ENC_709:
+ encode_coeff = inverse_encode ?
+ &ic_encode_ycbcr2rgb_709 : &ic_encode_rgb2ycbcr_709;
+ break;
+ default:
+ dev_err(priv->ipu->dev, "Unsupported YCbCr encoding\n");
+ return -ENOTSUPP;
+ }
+
+ *coeff_out = *encode_coeff;
return 0;
}
--
2.17.1
