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| author | Andy Walls <awalls@radix.net> | 2009-11-10 03:55:30 +0100 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2009-12-05 21:41:52 +0100 |
| commit | 22dce188ef3e1e058ceabe3b3072640d7568f764 (patch) | |
| tree | 6a5ee29e5b7cdf9125bea7456c8de75ab0861b92 /drivers/media/video/cx18/cx18-driver.h | |
| parent | V4L/DVB (13429): cx18: Add Memory Descriptor List (MDL) layer to buffer handling (diff) | |
| download | linux-22dce188ef3e1e058ceabe3b3072640d7568f764.tar.xz linux-22dce188ef3e1e058ceabe3b3072640d7568f764.zip | |
V4L/DVB (13430): cx18: Fix YUV capture so that encoder passes a single frame per transfer
Fix YUV capture such that the encoder will pass one frame per transfer. This
will allow the application to maintain frame alignment when a transfer from
the encoder is missed due to high system latency in service the CX23418 IRQ.
Also force YUV buffer sizes to be specified in multiples of 33.75 kB, the
smalled amount of buffer sizes need to store a complete set of HM12 4:2:0
macroblocks specifying 32 lines of the frame. A full 60Hz/525 line
screen requires 15 * 33.75 kB per frame and a full 50Hz/625 line screen
requires 18 * 33.75 kB per frame so the default buffer size is 3 * 33.75 kB,
requiring exactly 5 or 6 buffers per MDL respectively. The bytes needed per
frame and hence MDL need not be the bytes in an integer number of buffers.
However, if frame artifacts are seen with scaled screen sizes, the YUV buffer
size can be set 34 kB (33.75 kB) to get rid of the artifacts at the cost of more
copies between the kernel and userspace.
Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'drivers/media/video/cx18/cx18-driver.h')
| -rw-r--r-- | drivers/media/video/cx18/cx18-driver.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/media/video/cx18/cx18-driver.h b/drivers/media/video/cx18/cx18-driver.h index bed8bcc65411..5c78b014dbc0 100644 --- a/drivers/media/video/cx18/cx18-driver.h +++ b/drivers/media/video/cx18/cx18-driver.h @@ -120,11 +120,16 @@ /* Maximum firmware DMA buffers per stream */ #define CX18_MAX_FW_MDLS_PER_STREAM 63 +/* YUV buffer sizes in bytes to ensure integer # of frames per buffer */ +#define CX18_UNIT_ENC_YUV_BUFSIZE (720 * 32 * 3 / 2) /* bytes */ +#define CX18_625_LINE_ENC_YUV_BUFSIZE (CX18_UNIT_ENC_YUV_BUFSIZE * 576/32) +#define CX18_525_LINE_ENC_YUV_BUFSIZE (CX18_UNIT_ENC_YUV_BUFSIZE * 480/32) + /* DMA buffer, default size in kB allocated */ #define CX18_DEFAULT_ENC_TS_BUFSIZE 32 #define CX18_DEFAULT_ENC_MPG_BUFSIZE 32 #define CX18_DEFAULT_ENC_IDX_BUFSIZE 32 -#define CX18_DEFAULT_ENC_YUV_BUFSIZE 128 +#define CX18_DEFAULT_ENC_YUV_BUFSIZE (CX18_UNIT_ENC_YUV_BUFSIZE * 3 / 1024 + 1) /* Default VBI bufsize based on standards supported by card tuner for now */ #define CX18_DEFAULT_ENC_PCM_BUFSIZE 4 |