On 06/20/2018 01:54 AM, Philipp Zabel wrote:
Hi Steve,
On Tue, 2018-06-19 at 18:30 -0700, Steve Longerbeam wrote:
I've found some time to diagnose the behavior of interweave with B/T line
swapping (to support interlaced-bt) with planar formats.
There are a couple problems (one known and one unknown):
1. This requires 32 pixel alignment to meet the IDMAC 8-byte alignment
of the planar U/V buffer offsets, and 32 pixel alignment precludes
capturing raw NTSC/PAL at 720 pixel line stride.
What needs to be aligned to multiples of 32 pixels?
I thought 8 pixel width alignment should be good enough for NV12/NV16,
for which luma and chroma strides are equal to the width in pixels, and
16 pixel alignment for YUV420/YVU420/YUV422P, where chroma stride is
half the width in pixels.
I see where the problem is now. I was basing my mistaken 32 pixel
alignment from a read of the U_OFFSET/V_OFFSET macros in
ipu-cpmem.c:
u_offset = pix->width * pix->height + pix->width * y / 4 + x / 2
But you can probably see the bug now. This does not produce
a correct offset for odd values of y. It should read:
u_offset = pix->width * pix->height + pix->width * (y / 2) / 2 + x / 2
With that fix, interweave line swap with planar 4:2:0 is working now.
That includes YUV420, YVU420, and NV12.
NV16 is also working after programming SLUV with double
the chroma line stride.
2. Even with 32 pixel aligned frames, for example by using the prpenc scaler
to generate 704 pixel strides from 720, the colors are still wrong when
capturing interlaced-bt.
As a side note, we can't properly scale seq-tb/bt direct input from the
CSI vertically with the IC, as the bottom line of the first field will
be blended with the top line of the second field...
I thought for sure this must be because we
also
need to double the SLUV line strides in addition to doubling SLY
line stride.
But I tried this and the results are that it works only for YUV
4:2:2. For 4:2:0
it causes system hard lockups. (Aside note: interweave without line
swap
apparently has never worked for 4:2:2, even when doubling SLUV, so it's
quite bizarre to me why 4:2:2 interweave _with_ line swap _does_ work
after doubling SLUV).
When you say 4:2:2 you only mean YUV422P, not NV16 or YUYV/UYVY ?
Correct, I meant planar YUV422P.
For these reasons I think we should disallow interlaced-bt with planar
formats.
Does that include NV12/NV16? Capturing to NV12 could be desirable if at
all possible, because the result can be encoded by the CODA. The other
formats are bandwidth inefficient anyway.
Never mind, I found the bug described above in the U_OFFSET/V_OFFSET
macros.
In summary, at this point all planar formats are working with interlaced
bt and tb, except for YUV422P.
Steve
