AcoSail/kernel_optimize_test
8
0
Fork 0
forked from luck/tmp_suning_uos_patched
Code Pull Requests Activity

V4L/DVB: sh_mobile_ceu_camera.c: update documentation to reflect the new cropping

Browse Source 
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Guennadi Liakhovetski 2010-03-23 11:42:32 -03:00 committed by Mauro Carvalho Chehab
parent ab56d5eb58
commit f7fc97adb1
1 changed files with 31 additions and 49 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

80
Documentation/video4linux/sh_mobile_ceu_camera.txt
View File

@ -17,18 +17,18 @@ Generic scaling / cropping scheme
-2-- -\
| --\
| --\
+-5-- -\ -- -3--
| ---\
| --- -4-- -\
| -\
| - -6--
+-5-- . -- -3-- -\
| `... -\
| `... -4-- . - -7..
| `.
| `. .6--
|
| - -6'-
| -/
| --- -4'- -/
| ---/
+-5'- -/
| -- -3'-
| . .6'-
| .´
| ... -4'- .´
| ...´ - -7'.
+-5'- .´ -/
| -- -3'- -/
| --/
| --/
-2'- -/
@ -36,7 +36,11 @@ Generic scaling / cropping scheme
|
-1'-
Produced by user requests:
In the above chart minuses and slashes represent "real" data amounts, points and
accents represent "useful" data, basically, CEU scaled amd cropped output,
mapped back onto the client's source plane.
Such a configuration can be produced by user requests:
S_CROP(left / top = (5) - (1), width / height = (5') - (5))
S_FMT(width / height = (6') - (6))
@ -106,52 +110,30 @@ window:
S_CROP
------
If old scale applied to new crop is invalid produce nearest new scale possible
The API at http://v4l2spec.bytesex.org/spec/x1904.htm says:
1. Calculate current combined scales.
"...specification does not define an origin or units. However by convention
drivers should horizontally count unscaled samples relative to 0H."
scale_comb = (((4') - (4)) / ((6') - (6))) * (((2') - (2)) / ((3') - (3)))
We choose to follow the advise and interpret cropping units as client input
pixels.
2. Apply iterative sensor S_CROP for new input window.
Cropping is performed in the following 6 steps:
3. If old combined scales applied to new crop produce an impossible user window,
adjust scales to produce nearest possible window.
1. Request exactly user rectangle from the sensor.
width_u_out = ((5') - (5)) / scale_comb
2. If smaller - iterate until a larger one is obtained. Result: sensor cropped
to 2 : 2', target crop 5 : 5', current output format 6' - 6.
if (width_u_out > max)
scale_comb = ((5') - (5)) / max;
else if (width_u_out < min)
scale_comb = ((5') - (5)) / min;
3. In the previous step the sensor has tried to preserve its output frame as
good as possible, but it could have changed. Retrieve it again.
4. Issue G_CROP to retrieve actual input window.
4. Sensor scaled to 3 : 3'. Sensor's scale is (2' - 2) / (3' - 3). Calculate
intermediate window: 4' - 4 = (5' - 5) * (3' - 3) / (2' - 2)
5. Using actual input window and calculated combined scales calculate sensor
target output window.
5. Calculate and apply host scale = (6' - 6) / (4' - 4)
width_s_out = ((3') - (3)) = ((2') - (2)) / scale_comb
6. Apply iterative S_FMT for new sensor target output window.
7. Issue G_FMT to retrieve the actual sensor output window.
8. Calculate sensor scales.
scale_s = ((3') - (3)) / ((2') - (2))
9. Calculate sensor output subwindow to be cropped on CEU by applying sensor
scales to the requested window.
width_ceu = ((5') - (5)) / scale_s
10. Use CEU cropping for above calculated window.
11. Calculate CEU scales from sensor scales from results of (10) and user window
from (3)
scale_ceu = calc_scale(((5') - (5)), &width_u_out)
12. Apply CEU scales.
6. Calculate and apply host crop: 6 - 7 = (5 - 2) * (6' - 6) / (5' - 5)
--
Author: Guennadi Liakhovetski <g.liakhovetski@gmx.de>