Runtime encoder control updates

This driver update allows live bitrate changes and on-demand IDR insertion to be applied while the encoder is already streaming, avoiding STREAMOFF/STREAMON cycles. If nothing is configured in userspace, the encoder now defaults to CBR at 8 Mbit/s.

Supported runtime controls

• V4L2_CID_MPEG_VIDEO_BITRATE – apply a new target bitrate during streaming.
• V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME – request an immediate IDR.
• V4L2_CID_VSI_FORCE_IDR – driver-private button that mirrors the standard force keyframe control.

Example usage

# Update bitrate without restarting the pipeline
v4l2-ctl -d /dev/videoX --set-ctrl=video_bitrate=8000000

# Force an IDR while streaming
v4l2-ctl -d /dev/videoX --set-ctrl=video_force_key_frame=1
# Or using the private IDR button
v4l2-ctl -d /dev/videoX --set-ctrl=vsi_force_idr=1

GStreamer pipelines that keep streaming (e.g. using v4l2src or v4l2h264enc) benefit automatically; the driver pushes updates to the firmware without requiring a pipeline restart.

Notes

• Runtime updates reuse the existing daemon/firmware UPDATE_INFO command path.
• Firmware is expected to honor bitrate and IDR updates mid-stream; no userspace changes are required.