Whether bitrate could be changed when the RateControlMethod is set to 'MFX_RATECONTROL_CBR'

[Di_L_Intel]

Hello,

On Ivy Bridge Desktop platform with Win7 pro OS, initialize an encoder based on version 1.11 MSDK, its RateControlMethod is set to MFX_RATECONTROL_CBR', and its resolution is set to 720p or 1080p.
Following that, the encoder is reset to set a new bitrate value for its parameter 'mfxVideoParam.mfx.TargetKbps', and the new value could be higher or lower than the original one. But the resetting process will fail with an error code -14 of 'incompatible video parameters'.
If the RateControlMethod is set to 'MFX_RATECONTROL_VBR', the resetting process will succeed.
I would like to confirm whether the bitrate value of 'mfxVideoParam.mfx.TargetKbps' could not be changed when the RateControlMethod is set to 'MFX_RATECONTROL_CBR', or it is our own code's error which causes the failture of the resetting process.

Best Regards,

Rudy
 

[Harshdeep_B_Intel · Accepted solution]

Hi Di,

When the  RateControlMethod is set to MFX_RATECONTROL_CBR, this means it is set to constant bitrate/constant value,  when rateControlMethod is set to 'MFX_RATECONTROL_VBR' means ratecontrol is set to variable bitrate. So when we set a new bit rate value for mfxVideoParam.mfx.TargetKbps, ratecontrolmethod has to be set to MFX_RATECONTROL_VBR. RateControlmethod when set to MFX_RATECONTROL_CBR , mfxVideoParam.mfx.TargetKbps cannot be changed as doing that will result in error. The error you are see is due to allocating wrong video parameters. Please further refer to mediasdk manual on other video parameters. 

[Di_L_Intel]

Hi Harsh,

Thanks a lot.

Rudy