[linux-uvc-devel] Cant't change exposure_absolute

[Maurice H. <mau...@gm...>]

Hello,

I try to get fluid (let's say > 10fps) with SQ11 (cheap chinese webcam) on
a Raspberry Pi 4 running on Raspbian. The cool thing is that the uvc driver
works fine and I can recompile it from sources (e.g to solve this problem;
if needed).

The other cool thing is that I get fluid display with Logitech C920 cam
with Python + Opencv, or qv4l2 or ffmpeg, whatever (30fps) using the uvc
driver too.

The bad thing is that with the SQ11 I only get 2-3 fps when the cam move
rapidly, but I get high fps (10fps) when the cam is steady (no joke !)

I can reproduce this slow FPS on the C920 with setting exposure_absolute to
extra high value (e.g > 2000), so my idea was to set exposure_absolute=300
for the SQ11 but this parameter seems to be locked or not accessible (see
below).

So is there any possibility to make the picture fluid ?
Btw, the thing comes from the driver or Rpi, not the cam, because I can
get fluid image on Windows7.

Thanks in advance,

Maurice, BELGIUM

v4l2-ctl --list-ctrls
                     brightness 0x00980900 (int)    : min=0 max=255 step=1
default=128 value=128
                       contrast 0x00980901 (int)    : min=0 max=255 step=1
default=128 value=128
                     saturation 0x00980902 (int)    : min=0 max=255 step=1
default=128 value=128
                            hue 0x00980903 (int)    : min=-256 max=-32513
step=1 default=-32640 value=128
 white_balance_temperature_auto 0x0098090c (bool)   : default=0 value=0
    white_balance_red_component 0x0098090e (int)    : min=0 max=255 step=0
default=128 value=128
   white_balance_blue_component 0x0098090f (int)    : min=0 max=255 step=1
default=128 value=128
                          gamma 0x00980910 (int)    : min=0 max=255 step=10
default=128 value=128
                           gain 0x00980913 (int)    : min=0 max=255 step=1
default=128 value=128
           power_line_frequency 0x00980918 (menu)   : min=0 max=2 default=0
value=0
                       hue_auto 0x00980919 (bool)   : default=0 value=0
      white_balance_temperature 0x0098091a (int)    : min=0 max=255 step=1
default=128 value=128
                      sharpness 0x0098091b (int)    : min=0 max=255 step=1
default=128 value=128
         backlight_compensation 0x0098091c (int)    : min=0 max=255 step=1
default=128 value=128
                  exposure_auto 0x009a0901 (menu)   : min=0 max=3 default=0
value=0
              exposure_absolute 0x009a0902 (int)    : min=0 max=0 step=0
default=0 value=0 flags=inactive
         exposure_auto_priority 0x009a0903 (bool)   : default=0 value=0
                   pan_absolute 0x009a0908 (int)    : min=0 max=0 step=0
default=0 value=0
                  tilt_absolute 0x009a0909 (int)    : min=0 max=0 step=0
default=0 value=0
                 focus_absolute 0x009a090a (int)    : min=0 max=0 step=0
default=0 value=0
                     focus_auto 0x009a090c (bool)   : default=0 value=0
                  zoom_absolute 0x009a090d (int)    : min=0 max=0 step=0
default=0 value=0
                zoom_continuous 0x009a090f (int)    : min=0 max=0 step=0
default=0 value=0 flags=write-only
                        privacy 0x009a0910 (bool)   : default=0 value=0
                  iris_absolute 0x009a0911 (int)    : min=0 max=0 step=0
default=0 value=0
                  iris_relative 0x009a0912 (int)    : min=0 max=0 step=0
default=0 value=0 flags=write-only
                      pan_speed 0x009a0920 (int)    : min=0 max=0 step=0
default=0 value=0
                     tilt_speed 0x009a0921 (int)    : min=0 max=0 step=0
default=0 value=0