diff options
| -rw-r--r-- | drivers/media/video/bt8xx/bttv-vbi.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/drivers/media/video/bt8xx/bttv-vbi.c b/drivers/media/video/bt8xx/bttv-vbi.c index 8c9f0f7cf46..63676e7bd63 100644 --- a/drivers/media/video/bt8xx/bttv-vbi.c +++ b/drivers/media/video/bt8xx/bttv-vbi.c @@ -31,11 +31,16 @@ #include <asm/io.h> #include "bttvp.h" -/* Offset from line sync pulse leading edge (0H) in 1 / sampling_rate: - bt8x8 /HRESET pulse starts at 0H and has length 64 / fCLKx1 (E|O_VTC - HSFMT = 0). VBI_HDELAY (always 0) is an offset from the trailing edge - of /HRESET in 1 / fCLKx1, and the sampling_rate tvnorm->Fsc is fCLKx2. */ -#define VBI_OFFSET ((64 + 0) * 2) +/* Offset from line sync pulse leading edge (0H) to start of VBI capture, + in fCLKx2 pixels. According to the datasheet, VBI capture starts + VBI_HDELAY fCLKx1 pixels from the tailing edgeof /HRESET, and /HRESET + is 64 fCLKx1 pixels wide. VBI_HDELAY is set to 0, so this should be + (64 + 0) * 2 = 128 fCLKx2 pixels. But it's not! The datasheet is + Just Plain Wrong. The real value appears to be different for + different revisions of the bt8x8 chips, and to be affected by the + horizontal scaling factor. Experimentally, the value is measured + to be about 244. */ +#define VBI_OFFSET 244 #define VBI_DEFLINES 16 #define VBI_MAXLINES 32 |