diff options
| author | Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2021-10-30 10:46:09 +0100 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2021-10-30 10:46:09 +0100 |
| commit | 1d00c48a42a86d46bc61cbe66a7eec0aeaedab61 (patch) | |
| tree | 7a0177a529e62294579c1c06da2f38a196da61d9 | |
| parent | a0921e28bc5c05010f5666a9f6817b91b36a3544 (diff) | |
| download | v4l-utils-1d00c48a42a86d46bc61cbe66a7eec0aeaedab61.tar.gz | |
v4l2grab: use BT.709 by default on YUV conversion
This is more commonly found those days. Yet, the right approach
would be, instead, to add full support for colorspace. So,
add a note there, while keeping the BT.601 table too.
As the hole idea of v4l2grab is to do quick tests, let's
keep using an integer arithimetic, as this should be faster.
Yet, let's improve its precision.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
| -rw-r--r-- | contrib/test/v4l2grab.c | 31 |
1 files changed, 25 insertions, 6 deletions
diff --git a/contrib/test/v4l2grab.c b/contrib/test/v4l2grab.c index 70b29da3..1f4a0988 100644 --- a/contrib/test/v4l2grab.c +++ b/contrib/test/v4l2grab.c @@ -217,7 +217,7 @@ static void copy_two_pixels(uint32_t fourcc, case V4L2_PIX_FMT_UYVY: case V4L2_PIX_FMT_YVYU: case V4L2_PIX_FMT_VYUY: - int y_off, u_off, u, v; + int32_t y_off, u_off, u, v; y_off = (fourcc == V4L2_PIX_FMT_YUYV || fourcc == V4L2_PIX_FMT_YVYU) ? 0 : 1; u_off = (fourcc == V4L2_PIX_FMT_YUYV || fourcc == V4L2_PIX_FMT_UYVY) ? 0 : 1; @@ -226,11 +226,30 @@ static void copy_two_pixels(uint32_t fourcc, v = src[1 - y_off][1 - u_off] - 128; for (i = 0; i < 2; i++) { - int y = src[i][y_off] - 16; - - *(*dst)++ = CLAMP((298 * y + 409 * v + 128) >> 8); - *(*dst)++ = CLAMP((298 * y - 100 * u - 208 * v + 128) >> 8); - *(*dst)++ = CLAMP((298 * y + 516 * u + 128) >> 8); + int32_t y = src[i][y_off] - 16; +#if 0 + /* TODO: add colorspace check logic */ + + /* + * ITU-R BT.601 matrix: + * R = 1.164 * y + 0.0 * u + 1.596 * v + * G = 1.164 * y + -0.392 * u + -0.813 * v + * B = 1.164 * y + 2.017 * u + 0.0 * v + */ + *(*dst)++ = CLAMP((76284 * y + 104595 * v + 32768) >> 16); + *(*dst)++ = CLAMP((76284 * y - 25690 * u - 53281 * v + 32768) >> 16); + *(*dst)++ = CLAMP((76284 * y + 132186 * u + 32768) >> 16); +#else + /* + * ITU-R BT.709 matrix: + * R = 1.164 * y + 0.0 * u + 1.793 * v + * G = 1.164 * y + -0.213 * u + -0.533 * v + * B = 1.164 * y + 2.112 * u + 0.0 * v + */ + *(*dst)++ = CLAMP((76284 * y + 117506 * v + 32768) >> 16); + *(*dst)++ = CLAMP((76284 * y - 13959 * u - 34931 * v + 32768) >> 16); + *(*dst)++ = CLAMP((76284 * y + 138412 * u + 32768) >> 16); +#endif } break; default: |