We are working on a product based on APQ8016E (SD410c) and Linaro platform.
We have an query regarding venus encoders.
We’ve found no solution for is that with frame_level_rate_control_enable=1 (adaptive bitrate, the default), first frames of stream, especially first and maybe second I-frame, are overquantized. In the ffprobe file - after looking at all the I-frames (pict_type=I) and pkt_size.
the sizes are 3.6KB, 4.0KB, 23.6KB, 33.4KB, 34.1KB, 34.5KB, 34.9KB, 35.3KB, …
The first 2 I-frames are way too small, and the third one is somewhat small too, meaning that the first 2-3 GOPs (which might be several seconds…) have awful quality.
We think it’s due to the computation of current bitrate during stream start. Given FPS and target bitrate, the encoder might think that the first I-frame is too large and will violate bitrate constraint. Thus it increases quantization - while in reality it isn’t needed since I-frame is followed by many P-frames which are smaller. This might be related to H264 buffer size being too small (it’s not exposed as a parameter).
Please help to resolve this.
Parth Y Shah