On Fri, 2019-02-08 at 17:47 -0800, Steve Longerbeam wrote:
quoted hunk ↗ jump to hunk
Pass v4l2 encoding enum to the ipu_ic task init functions, and add
support for the BT.709 encoding and inverse encoding matrices.
Reported-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
---
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 | 71 +++++++++++++++++++--
drivers/gpu/ipu-v3/ipu-image-convert.c | 1 +
drivers/staging/media/imx/imx-ic-prpencvf.c | 4 +-
include/video/imx-ipu-v3.h | 5 +-
4 files changed, 71 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/ipu-v3/ipu-ic.c b/drivers/gpu/ipu-v3/ipu-ic.c
index e459615a49a1..c5f83d7e357f 100644
--- a/drivers/gpu/ipu-v3/ipu-ic.c
+++ b/drivers/gpu/ipu-v3/ipu-ic.c
@@ -212,6 +212,23 @@ static const struct ic_csc_params ic_csc_identity = {
.scale = 2,
};
+/*
+ * BT.709 encoding from RGB full range to YUV limited range:
+ *
+ * Y = R * .2126 + G * .7152 + B * .0722;
+ * U = R * -.1146 + G * -.3854 + B * .5000 + 128.;
+ * V = R * .5000 + G * -.4542 + B * -.0458 + 128.;
This is a conversion to YUV full range. Limited range should be:
Y R * .1826 + G * .6142 + B * .0620 + 16;
U = R * -.1007 + G * -.3385 + B * .4392 + 128;
V R * .4392 + G * -.3990 + B * -.0402 + 128;
quoted hunk ↗ jump to hunk
+ */
+static const struct ic_csc_params ic_csc_rgb2ycbcr_bt709 = {
+ .coeff = {
+ { 54, 183, 18 },
+ { 483, 413, 128 },
+ { 128, 396, 500 },
+ },
+ .offset = { 0, 512, 512 },
+ .scale = 1,
+};
+
/*
* Inverse BT.601 encoding from YUV limited range to RGB full range:
*@@ -229,12 +246,31 @@ static const struct ic_csc_params ic_csc_ycbcr2rgb_bt601 = {
.scale = 2,
};
+/*
+ * Inverse BT.709 encoding from YUV limited range to RGB full range:
+ *
+ * R = (1. * (Y - 16)) + (1.5748 * (Cr - 128));
+ * G = (1. * (Y - 16)) - (0.1873 * (Cb - 128)) - (0.4681 * (Cr - 128));
+ * B = (1. * (Y - 16)) + (1.8556 * (Cb - 128);
The coefficients look like full range again, conversion from limited
range YUV should look like:
R = (1.1644 * (Y - 16)) + (1.7927 * (Cr - 128));
G = (1.1644 * (Y - 16)) - (0.2132 * (Cb - 128)) - (0.5329 * (Cr - 128));
B = (1.1644 * (Y - 16)) + (2.1124 * (Cb - 128);
quoted hunk ↗ jump to hunk
+ */
+static const struct ic_csc_params ic_csc_ycbcr2rgb_bt709 = {
+ .coeff = {
+ { 128, 0, 202 },
+ { 128, 488, 452 },
+ { 128, 238, 0 },
+ },
+ .offset = { -435, 136, -507 },
+ .scale = 2,
+};
+
static int init_csc(struct ipu_ic *ic,
enum ipu_color_space inf,
enum ipu_color_space outf,
+ enum v4l2_ycbcr_encoding encoding,
Should we support YUV BT.601 <-> YUV REC.709 conversions? That would
require separate encodings for input and output. Also, this might be a
good time to think about adding quantization range parameters as well.
regards
Philipp