I'd like to use restricted VBR (RC_RVBR) in the MPEG2VideoEncoder.
For unrestricted VBR I set rc_mode to RC_VBR, quant_vbr to certain values and bitrate to 0. Then
the output bitrate is variable, there's no restrictionn and the output quality/size depends on the quantizers (quant_vbr).
However when I try to achieve restricted VBR I set rc_mode to RC_RVBR, quant_vbr to certain
values and bitrate to the target limit (e.g. 6000000). But then the output bitrate is not restricted by the specified bitrate. On the other hand the output average bitrate is not close to the specified one either. It looks like the input bitrate is ignored.
According to the UMC documentation:
"Restricted VBR requires both bit rate and
quantizers to be set. This mode is similar to CBR but resulting bit rate is not greater than
the bit rate provided in parameters. The quantizer can be increased to decrease size of the
It is clear that the input bitrate is intended as a restriction (either peak or average bitrate) in restricted VBR.
So, do I have to set some other settings to achieve restricted VBR in the MPEG2VideoEncoder or this is not possible (not implemented) in the current version (IPP 6.x)?
If not implemented, can I increase the quantizers and resupply the input video frame again for
encoding until I get the required bitrate? Is this possible from the public interface of the MPEG2VideoEncoder or I have to modify the implementation in the UMC classes?