[PATCH v8 4/5] gpu: ipu-v3: ipu-ic-csc: Add support for Rec.709 encoding

Steve Longerbeam
2019-05-22T01:03:37Z

Add support for Rec.709 encoding and inverse encoding.

Reported-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
---
Changes in v7:
- moved CSC tables to new module ipu-ic-csc.c.
- express negative coefficients as true signed int's, for better
readability.
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-csc.c | 139 ++++++++++++++++++++++++++++++--
1 file changed, 134 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/ipu-v3/ipu-ic-csc.c b/drivers/gpu/ipu-v3/ipu-ic-csc.c
index 8e9150b1d668..09e94aa12c40 100644
--- a/drivers/gpu/ipu-v3/ipu-ic-csc.c
+++ b/drivers/gpu/ipu-v3/ipu-ic-csc.c
@@ -230,14 +230,133 @@ static const struct ipu_ic_csc_params *yuv2rgb_601[] = {
&yuvl2rgbl_601,
};

+/*
+ * 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 ipu_ic_csc_params rgbf2yuvf_709 = {
+ .coeff = {
+ { 54, 183, 19 },
+ { -29, -99, 128 },
+ { 128, -116, -12 },
+ },
+ .offset = { 0, 512, 512 },
+ .scale = 1,
+};
+
+/* Rec.709 RGB full-range to YUV limited-range */
+static const struct ipu_ic_csc_params rgbf2yuvl_709 = {
+ .coeff = {
+ { 47, 157, 16, },
+ { -26, -87, 112, },
+ { 112, -102, -10, },
+ },
+ .offset = { 64, 512, 512, },
+ .scale = 1,
+ .sat = true,
+};
+
+/* Rec.709 RGB limited-range to YUV full-range */
+static const struct ipu_ic_csc_params rgbl2yuvf_709 = {
+ .coeff = {
+ { 63, 213, 22, },
+ { -34, -115, 149, },
+ { 149, -135, -14, },
+ },
+ .offset = { -75, 512, 512, },
+ .scale = 1,
+};
+
+/* Rec.709 RGB limited-range to YUV limited-range */
+static const struct ipu_ic_csc_params rgbl2yuvl_709 = {
+ .coeff = {
+ { 54, 183, 18, },
+ { -30, -101, 131, },
+ { 131, -119, -12, },
+ },
+ .offset = { 0, 512, 512, },
+ .scale = 1,
+ .sat = true,
+};
+
+/*
+ * 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 ipu_ic_csc_params yuvf2rgbf_709 = {
+ .coeff = {
+ { 128, 0, 202 },
+ { 128, -24, -60 },
+ { 128, 238, 0 },
+ },
+ .offset = { -403, 168, -475 },
+ .scale = 2,
+};
+
+/* Rec.709 YUV full-range to RGB limited-range */
+static const struct ipu_ic_csc_params yuvf2rgbl_709 = {
+ .coeff = {
+ { 110, 0, 173, },
+ { 110, -21, -51, },
+ { 110, 204, 0, },
+ },
+ .offset = { -314, 176, -376, },
+ .scale = 2,
+};
+
+/* Rec.709 YUV limited-range to RGB full-range */
+static const struct ipu_ic_csc_params yuvl2rgbf_709 = {
+ .coeff = {
+ { 75, 0, 115, },
+ { 75, -14, -34, },
+ { 75, 135, 0, },
+ },
+ .offset = { -248, 77, -289, },
+ .scale = 3,
+};
+
+/* Rec.709 YUV limited-range to RGB limited-range */
+static const struct ipu_ic_csc_params yuvl2rgbl_709 = {
+ .coeff = {
+ { 128, 0, 197, },
+ { 128, -23, -59, },
+ { 128, 232, 0, },
+ },
+ .offset = { -394, 164, -464, },
+ .scale = 2,
+};
+
+static const struct ipu_ic_csc_params *rgb2yuv_709[] = {
+ &rgbf2yuvf_709,
+ &rgbf2yuvl_709,
+ &rgbl2yuvf_709,
+ &rgbl2yuvl_709,
+};
+
+static const struct ipu_ic_csc_params *yuv2rgb_709[] = {
+ &yuvf2rgbf_709,
+ &yuvf2rgbl_709,
+ &yuvl2rgbf_709,
+ &yuvl2rgbl_709,
+};
+
static int calc_csc_coeffs(struct ipu_ic_csc *csc)
{
const struct ipu_ic_csc_params **params_tbl;
int tbl_idx;

- if (csc->out_cs.enc != V4L2_YCBCR_ENC_601)
- return -ENOTSUPP;
-
tbl_idx = (QUANT_MAP(csc->in_cs.quant) << 1) |
QUANT_MAP(csc->out_cs.quant);

@@ -250,8 +369,18 @@ static int calc_csc_coeffs(struct ipu_ic_csc *csc)

/* YUV <-> RGB encoding is required */

- params_tbl = (csc->in_cs.cs == IPUV3_COLORSPACE_YUV) ?
- yuv2rgb_601 : rgb2yuv_601;
+ switch (csc->out_cs.enc) {
+ case V4L2_YCBCR_ENC_601:
+ params_tbl = (csc->in_cs.cs == IPUV3_COLORSPACE_YUV) ?
+ yuv2rgb_601 : rgb2yuv_601;
+ break;
+ case V4L2_YCBCR_ENC_709:
+ params_tbl = (csc->in_cs.cs == IPUV3_COLORSPACE_YUV) ?
+ yuv2rgb_709 : rgb2yuv_709;
+ break;
+ default:
+ return -ENOTSUPP;
+ }

csc->params = *params_tbl[tbl_idx];

--
2.17.1