coda: Unable to use encoder video_bitrate

["Frédéric Sureau" <frederic.sureau@vodalys.com>]

Hi

I am trying to use the coda encoder through Gstreamer on an iMX6-based 
board.

I use the (rebased and slightly modified) gstv4l2h264enc plugin from:
https://github.com/hizukiayaka/gst-plugins-good

This pipeline works fine:
gst-launch-1.0 -vvv v4l2src device=/dev/video4 ! 
"video/x-raw,width=1280,height=720" ! videoconvert ! v4l2video0h264enc ! 
h264parse ! mp4mux ! filesink location=test.mp4

When encoder has no bitrate param set (default=0), video encoding works 
well, but bitrate reaches ~2.5Mbps

When I try to set the bitrate with whatever value like 100,000 or 
1,000,000, the encoder produces video with bitrate around 480kbps and a 
very poor quality.

Here is the gstreamer pipeline I use with bitrate set:
gst-launch-1.0 -vvv v4l2src device=/dev/video4 ! 
"video/x-raw,width=1280,height=720" ! videoconvert ! v4l2video0h264enc 
extra-controls="controls,video_bitrate=1000000;" ! h264parse ! mp4mux ! 
filesink location=test.mp4

The video_bitrate control seems to be correctly passed to the driver by 
GStreamer since I can see the VIDIOC_S_CTRL call.

Any idea ?

Thanks
Fred