Hi
I want to set the bitrate of my webcam (HP Envy laptop). ./v4l2-ctl
--all gives me following:
Driver Info (not using libv4l2):
Driver name : uvcvideo
Card type : HP Truevision HD
Bus info : usb-0000:00:1d.0-1.3
Driver version: 4.4.24
Capabilities : 0x84200001
Video Capture
Streaming
Extended Pix Format
Device Capabilities
Device Caps : 0x04200001
Video Capture
Streaming
Extended Pix Format
Priority: 2
Video input : 0 (Camera 1: ok)
Format Video Capture:
Width/Height : 1280/720
Pixel Format : 'MJPG'
Field : None
Bytes per Line : 0
Size Image : 1843789
Colorspace : sRGB
Transfer Function : Default
YCbCr Encoding : Default
Quantization : Default
Flags :
Crop Capability Video Capture:
Bounds : Left 0, Top 0, Width 1280, Height 720
Default : Left 0, Top 0, Width 1280, Height 720
Pixel Aspect: 1/1
Selection: crop_default, Left 0, Top 0, Width 1280, Height 720
Selection: crop_bounds, Left 0, Top 0, Width 1280, Height 720
Streaming Parameters Video Capture:
Capabilities : timeperframe
Frames per second: 30.000 (30/1)
Read buffers : 0
brightness (int) : min=-64 max=64 step=1
default=0 value=0
contrast (int) : min=0 max=64 step=1
default=32 value=32
saturation (int) : min=0 max=128 step=1
default=64 value=64
hue (int) : min=-40 max=40 step=1
default=0 value=0
white_balance_temperature_auto (bool) : default=1 value=1
gamma (int) : min=72 max=500 step=1
default=100 value=100
gain (int) : min=0 max=100 step=1
default=0 value=0
power_line_frequency (menu) : min=0 max=2 default=2 value=2
white_balance_temperature (int) : min=2800 max=6500 step=1
default=4000 value=4000 flags=inactive
sharpness (int) : min=0 max=5 step=1 default=0 value=0
backlight_compensation (int) : min=0 max=1 step=1 default=0 value=0
exposure_auto (menu) : min=0 max=3 default=3 value=3
exposure_absolute (int) : min=10 max=2500 step=1
default=156 value=156 flags=inactive
exposure_auto_priority (bool) : default=0 value=1
I don't see MPEG related options here. Does it mean that MPEG is not
supported by the webcam? I also tried following function to query
V4L2_CTRL_CLASS_MPEG options.
static void show_mpeg_controls(int fd, int show_menus)
{
const unsigned next_fl = V4L2_CTRL_FLAG_NEXT_CTRL | V4L2_CTRL_CLASS_MPEG;
struct v4l2_query_ext_ctrl qctrl;
int id;
memset(&qctrl, 0, sizeof(qctrl));
qctrl.id = next_fl;
while (query_ext_ctrl_ioctl(fd, qctrl) == 0) {
if (V4L2_CTRL_ID2CLASS(qctrl.id) != V4L2_CTRL_CLASS_MPEG)
break;
print_control(fd, qctrl, show_menus);
qctrl.id |= next_fl;
}
}
It wouldn't print anything. Could you please advise me what is wrong
here? I'm new to V4L2. Looking forward to your suggestions.
Many thanks
Tamim
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