Video capture with pro mode configuration

[Indra Sapkota]

Greeting Developers,

I am working on a requirement which requires to capture video of fast moving objects. Reviewing existing camera api documentation and default camera app feature shipped with device, I found that they have a features where you manually set the shutter speed (SENSOR_EXPOSURE_TIME) and iso (SENSOR_SENSITIVITY) to reduce the blur on video frames. Which allow you to capture the high speed video with good resolutions.

With those assumption I started my prototype with camera-sample/camera2slowmotion google sample by updating previewRequestList and recordRequestList as,

// Disable Auto exposure mode and define own exposure-time and sensor-sensitivity

if (enableShutterSpeed) {
   set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_OFF)
   set(CaptureRequest.SENSOR_EXPOSURE_TIME,  25000L) // 1/4000
   set(CaptureRequest.SENSOR_SENSITIVITY,  3200) // 3200
}

With this addition lines of code, I could set the shutter speed and iso value that I want. But, I ran into couple of issues, where I need your advice and help.

Problems:

1. Compute ISO (SENSOR_SENSITIVITY ) for different lighting condition with respect to shutter speed (SENSOR_EXPOSURE_TIME)
   • Increased shutter speed, the sensor exposed to light is too less which cause the dark image, thus need to calculate the iso to accommodate. But `Auto Exposure` mode is disabled, so has to calculate the sensor sensitivity to set the brightness of image correctly.
2. Video recording FPS reduces to 30fps when disabling Auto Exposure mode (CONTROL_AE_MODE).
   
   • Even capture session is created for highspeed video recording at 240 fps, disabling auto-exposure mode reduces the video recording 30 fps.

Test Device:

1. Google Pixel 3XL

Hope to hear back from you!

Best Regards,
Indra