10bit dynamic range

[mattipee]

Hi, this might be of interest.

I've been playing with the ov534 linux kernel module to add gamma, framerates <1fps, etc, and used your register initialisation routines to get raw output working.

By setting DSP_Ctrl4[0], video format to RAW10 and framesize to 0x017700, I've managed to capture 10bit raw.

Four pixels every five bytes, with the lsb's packed into the fifth byte:
11111111 22222222 33333333 44444444 44332211

[cdoty]

Is the mode limited to 320x240?

[mattipee]

Is the mode limited to 320x240?

I've only tried 640x480, which works.

[bakercp]

@cdoty What settings were you using to get < 1fps?

[mattipee]

Suggest opening another issue for frame rates. I don't know how accurate these values are in terms of the actual resultant frame rate, but for VGA I currently have:

...
{2, 0x09, 0x01, 0x02},
{1, 0x18, 0x01, 0x02},
{0.9, 0x31, 0x81, 0x09},
{0.8, 0x2e, 0x41, 0x07},
{0.7, 0x3d, 0x41, 0x06},
{0.6, 0x18, 0x01, 0x04},
{0.5, 0x31, 0x01, 0x02},
{0.4, 0x2e, 0x01, 0x03},
{0.3, 0x31, 0x01, 0x04},
{0.2, 0x2b, 0x01, 0x08},
{0.1, 0x3f, 0x01, 0x0a}

Note that the type of fps has to change. In the kernel module, I had to modify gspca.h/c and include fixed values for numerator/denominator also.

[mattipee]

Can anyone confirm if 10bit works for them?

[bakercp]

Thanks for those entries @mattipee -- I hope to try 10-bit in the next few days -- if / when I do, I'll report back.

[mattipee]

I don't know what downstream support you'll have for 10-bit, but 8-bit conversion is as simple as dropping every 5th byte - you might test by checking for non-null before you drop. Alternatively, 10-bit to 16bit is relatively easy too, you can left-align the relevant bits from the 5th byte and pad with 0s to create each low-byte. You may already appreciate all of that, but I expect you'll need to implement one or the other. Good luck, @bakercp.

Here's a snippet for reference:

#define OUTPUT_FORMAT 0x03
#define VIDEO_FORMAT 0x10
#define FRAMESIZE_1 0x01
#define FRAMESIZE_2 0x77
#define FRAMESIZE_3 0x00
#define PIX_FMT V4L2_PIX_FMT_SGRBG10P
#define BYTES_PER_LINE (640*1.25)
#define SIZE_IMAGE (640*480*1.25)

You could also use:

#define OUTPUT_FORMAT 0x03
#define VIDEO_FORMAT 0x20
#define FRAMESIZE_1 0x02
#define FRAMESIZE_2 0x58
#define FRAMESIZE_3 0x00
#define PIX_FMT V4L2_PIX_FMT_SGRBG10
#define BYTES_PER_LINE (640*2)
#define SIZE_IMAGE (640*480*2)

But note that (from memory), the 10 bits are right aligned.

[mattipee]

@bakercp

...with the most important change of course being from:

{ 0x67, 0x02 },

to:

{ 0x67, 0x03 }, // set DSP_Ctrl4[0]