Instead of using two tables to estimate the temporal decimation
factor, use a formula. This allows to get the closest fps, with
sounds better than the current tables.
Compile-tested only.
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>
[media] tw686x: cleanup the fps estimation code
There are some issues with the old code:
1) it uses two static tables;
2) some values for 50Hz standards are wrong;
3) it doesn't store the real framerate.
This patch fixes the above issues.
Compile-tested only.
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>
-
v3: Patch v2 were actually a diff patch against PATCH v1. Fold the two patches in one.
PS.: With this patch, it should be easy to add support for
VIDIOC_G_PARM and VIDIOC_S_PARM, as vc->fps will now store the
real frame rate, with should be used when returning from those
functions.
---
drivers/media/pci/tw686x/tw686x-video.c | 110 +++++++++++++++++++++-----------
1 file changed, 73 insertions(+), 37 deletions(-)
diff --git a/drivers/media/pci/tw686x/tw686x-video.c b/drivers/media/pci/tw686x/tw686x-video.c
index 253e10823ba3..b247a7b4ddd8 100644
--- a/drivers/media/pci/tw686x/tw686x-video.c
+++ b/drivers/media/pci/tw686x/tw686x-video.c
@@ -43,53 +43,89 @@ static const struct tw686x_format formats[] = {
}
};
-static unsigned int tw686x_fields_map(v4l2_std_id std, unsigned int fps)
+static const unsigned int fps_map[15] = {
+ /*
+ * bit 31 enables selecting the field control register
+ * bits 0-29 are a bitmask with fields that will be output.
+ * For NTSC (and PAL-M, PAL-60), all 30 bits are used.
+ * For other PAL standards, only the first 25 bits are used.
+ */
+ 0x00000000, /* output all fields */
+ 0x80000006, /* 2 fps (60Hz), 2 fps (50Hz) */
+ 0x80018006, /* 4 fps (60Hz), 4 fps (50Hz) */
+ 0x80618006, /* 6 fps (60Hz), 6 fps (50Hz) */
+ 0x81818186, /* 8 fps (60Hz), 8 fps (50Hz) */
+ 0x86186186, /* 10 fps (60Hz), 8 fps (50Hz) */
+ 0x86619866, /* 12 fps (60Hz), 10 fps (50Hz) */
+ 0x86666666, /* 14 fps (60Hz), 12 fps (50Hz) */
+ 0x9999999e, /* 16 fps (60Hz), 14 fps (50Hz) */
+ 0x99e6799e, /* 18 fps (60Hz), 16 fps (50Hz) */
+ 0x9e79e79e, /* 20 fps (60Hz), 16 fps (50Hz) */
+ 0x9e7e7e7e, /* 22 fps (60Hz), 18 fps (50Hz) */
+ 0x9fe7f9fe, /* 24 fps (60Hz), 20 fps (50Hz) */
+ 0x9ffe7ffe, /* 26 fps (60Hz), 22 fps (50Hz) */
+ 0x9ffffffe, /* 28 fps (60Hz), 24 fps (50Hz) */
+};
+
+static unsigned int tw686x_real_fps(unsigned int index, unsigned int max_fps)
+{
+ unsigned int i, bits, c = 0;
+
+ if (!index || index >= ARRAY_SIZE(fps_map))
+ return max_fps;
+
+ bits = fps_map[index];
+ for (i = 0; i < max_fps; i++)
+ if ((1 << i) & bits)
+ c++;
+
+ return c;
+}
+
+static unsigned int tw686x_fps_idx(unsigned int fps, unsigned int max_fps)
{
- static const unsigned int map[15] = {
- 0x00000000, 0x00000001, 0x00004001, 0x00104001, 0x00404041,
- 0x01041041, 0x01104411, 0x01111111, 0x04444445, 0x04511445,
- 0x05145145, 0x05151515, 0x05515455, 0x05551555, 0x05555555
- };
-
- static const unsigned int std_625_50[26] = {
- 0, 1, 1, 2, 3, 3, 4, 4, 5, 5, 6, 7, 7,
- 8, 8, 9, 10, 10, 11, 11, 12, 13, 13, 14, 14, 0
- };
-
- static const unsigned int std_525_60[31] = {
- 0, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7,
- 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 0, 0
- };
-
- unsigned int i;
-
- if (std & V4L2_STD_525_60) {
- if (fps >= ARRAY_SIZE(std_525_60))
- fps = 30;
- i = std_525_60[fps];
- } else {
- if (fps >= ARRAY_SIZE(std_625_50))
- fps = 25;
- i = std_625_50[fps];
- }
-
- return map[i];
+ unsigned int idx, real_fps;
+ int delta;
+
+ /* First guess */
+ idx = (12 + 15 * fps) / max_fps;
+
+ /* Minimal possible framerate is 2 frames per second */
+ if (!idx)
+ return 1;
+
+ /* Check if the difference is bigger than abs(1) and adjust */
+ real_fps = tw686x_real_fps(idx, max_fps);
+ delta = real_fps - fps;
+ if (delta < -1)
+ idx++;
+ else if (delta > 1)
+ idx--;
+
+ /* Max framerate */
+ if (idx >= 15)
+ return 0;
+
+ return idx;
}
static void tw686x_set_framerate(struct tw686x_video_channel *vc,
unsigned int fps)
{
- unsigned int map;
+ unsigned int i, max_fps;
if (vc->fps == fps)
return;
- map = tw686x_fields_map(vc->video_standard, fps) << 1;
- map |= map << 1;
- if (map > 0)
- map |= BIT(31);
- reg_write(vc->dev, VIDEO_FIELD_CTRL[vc->ch], map);
- vc->fps = fps;
+ if (vc->video_standard & V4L2_STD_525_60)
+ max_fps = 30;
+ else
+ max_fps = 25;
+
+ i = tw686x_fps_idx(fps, max_fps);
+
+ reg_write(vc->dev, VIDEO_FIELD_CTRL[vc->ch], fps_map[i]);
+ vc->fps = tw686x_real_fps(i, max_fps);
}
static const struct tw686x_format *format_by_fourcc(unsigned int fourcc)
--
2.5.5
--
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