Re: [PATCH v4 3/4] gpu: ipu-v3: ipu-ic: Add support for BT.709 encoding
From: Philipp Zabel <p.zabel@pengutronix.de>
Date: 2019-02-11 10:12:43
Also in:
dri-devel, linux-media, lkml
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);
+ */
+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