These are standard features used for encoding video, as seen with encoders available in other processors we use.
There should be an option to switch between constant bit rate (CBR) and variable bit rate (VBR).
With VBR, the quality is allowed to vary by adjusting the quantization parameter (QP)
The minimum QP setting specifies a minimum quality since higher QP degrades quality.
It is not possible to adjust the desired quality / bitrate. If this were available, we might be able to utilise the encoder. As it stands, the encoder is pretty much non-configurable.
What method does the encoder use for rate control:
Variable Bit Rate
Constant Bit Rate?
The reason for asking is because the encoder does not appear to:
Prevent the bit rate overshooting the desired bitrate (by over 50%)
Drop the bit rate sufficiently if the source is static
I tested 2 above by using the same camera pointing at a plain wall for a static image. I used a GStreamer pipeline with amlvenc and compared this with an equivalent pipeline using x264 for encoding. Both were configured to encode to a resolution of 1280x720 and set to a bitrate of 1200kbps.
amlvenc produced a stream at around 800 to 1000 kbps, whereas
x264 produced a stream at 80 to 100 kbps.
On other hardware that we use, Intel vaapih264enc, Rockchip mpph264enc, or anything using v4l2h264enc, the settings can be adjusted to align closely with the output of x264.
We are hoping to migrate to this board, but the uncontrollable encoder is problematic