Raspistill fullscreen preview with valid aspect ratio on composite PAL 16:9 display

Question

Software: raspbian, hardware: Pi model B 512 with camera board

Display: rear view car display, PAL composite input, 480x272 resolution, 16:9 aspect ratio

Goal: I'd like to shot still images with raspistill then show it on the screen - with valid 16:9 ratio at both stages (camera preview and final image). I know PAL is 4:3 only, I'd like to push anamorphic signal from Pi and let display scale it to target width/height proprtions.

What I'm able to do: if I switch display to 4:3 ratio, use raspistill to shot and fbi to show works as expected, but display has black bars on left and right edge.

Problem: If I switch display to widened 16:9 mode, I'm unable to convince raspistill to do 16:9 fullscreen image preview (which would be too tall on assumed 4:3 display but OK on widened display).

When I use sdtv_aspect=3 mode switch in config.txt, nothing changes in raspistill preview no matter what options I use. It has either 16:9 image preview with black bars on top and bottom (therefore deformed on widened display) or fullscreen 4:3 preview (also deformed on widened display) but not both (expected fullscreen preview of 16:9 image).

With sdtv_aspect=3 the fbi image viewer adds extra black bars to displayed 4:3 image which effectively cancels widening done in display (expected effect). Raspistill ignores sdtv_aspect.

I have tried to disable overscan or define 480x272 framebuffer, without luck.

Answer 1

I was not aware of the -roi switch.

For the record: with PAL screen widened from 4:3 to 16:9, following line results with valid-ratio preview of half screen width & full screen height picture, which is then shown on the screen. Proportions are valid thanks to using 75% of sensor height.

sudo raspistill -vf -w 1296 -h 1944 -o out.jpg -fp -p 0,0,720,576 -v -vf -roi '0,0.125,1,0.75' \
&& sudo fbi -T 1 out.jpg[/code]

Switch sdtv_aspect is not active in config.txt, only sdtv_mode=2 is present.

My current framebuffer info (gathered from ssh session if it matters):

pi@raspberrypi ~ $ fbset
mode "656x512"
    geometry 656 512 656 512 16
    timings 0 0 0 0 0 0 0
    rgba 5/11,6/5,5/0,0/16
endmode

pi@raspberrypi ~ $ tvservice -s
state 0x80001 [PAL 4:3], 720x576 @ 50Hz, interlaced

EDIT: issue below was fixed with Jan2014 firmware update.

Interesting catch: when ROI width is 1 (like -roi '0,0.125,1,0.75'), height change is ignored. When ROI width is slightly decreased (-roi '0,0.125,0.999,0.75'), all parameters are honored. This issue was observed with codebase from November 2013.