bitrate control, How to make the bandwidth not fluctuate wildly and the image is clear

[王恒]

When I use x265 to encode live video stream, I need the encoder output a keyframe every 10 seconds, The bitrate I set is 1.5M. But when the encoder output keyframe, the bandwidth will fluctuate to 5M, or even 10M，Then I use the vbvBufferSize and vbvMaxBitrate parameters to limit the fluctuation of the bitrate, This modification causes the keyframe to become unclear. H264 does not have this problem. How should I set x265 parameters, How to make the bandwidth not fluctuate wildly and the image is clear

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_x265_params->keyframeMax = -1;

_x265_params->rc.bitrate = 1500;
_x265_params->rc.rateControlMode = X265_RC_ABR;

_x265_params->rc.vbvBufferSize = 1.5 * 1500;
_x265_params->rc.vbvMaxBitrate = 1500;

[王恒]

The bandwidth fluctuation of H264 is like this

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