Hi x1tester62,
I think you are right. 1.5mbps can be the lowest bitrate for high motion case of 1080p30. In general, the bitrate is suggested to be ~10mbps for 1080p30 to get good quality. If all frames are quantized at 50 and it still cannot go below 1.5mbps, it hits the compression limit. For getting lower bitrate, we have to drop frames.
Please try
gst-launch-1.0 nvcamerasrc num-buffers=300 ! ‘video/x-raw(memory:NVMM),width=1920,height=1080,framerate=30/1,format=I420’ ! omxh264enc bitrate=500000 iframeinterval=60 temporal-tradeoff=2 ! qtmux ! filesink location=a.mp4
And below is the definition of all types
typedef enum NVX_ENCODE_VIDEOTEMPORALTRADEOFF{
NVX_ENCODE_VideoEncTemporalTradeoffLevel_DropNone= 0,
NVX_ENCODE_VideoEncTemporalTradeoffLevel_Drop1in5,
NVX_ENCODE_VideoEncTemporalTradeoffLevel_Drop1in3,
NVX_ENCODE_VideoEncTemporalTradeoffLevel_Drop1in2,
NVX_ENCODE_VideoEncTemporalTradeoffLevel_Drop2in3,
NVX_ENCODE_VideoEncTemporalTradeoffLevel_Force32 = 0x7FFFFFFF
} NVX_ENCODE_VIDEOTEMPORALTRADEOFF;
To check the quantization factor, please do
1 Extract h264 via yamb http://yamb.unite-video.com/
2 Decode h264 via JM decoder Karsten Suehring
(Download the source and compile)