bug for calculating target bits in rate control in case of TemporalSubsampleRatio not equals to one

[liye0713]

In case of rate control is enabled, the sequence target bits is calculated from the given target rate.During the conversion from target rate to target bits, the frame rate should be considered. In VTM, the frame rate is constrained to be an integer number. So in case of temporal subsample ratio, the frame rate is divided and then rounded from the original value:

(int)((double)m_iFrameRate / m_temporalSubsampleRatio + 0.5)

Right now, the target rate is set as the actually coded rate when the sequence is coded in QP 22, 27,32,37 with rate control disabled. When using the actually coded bits to calculate the actual rate, the frame rate is regarded as float number not int. In case of this inconsistency, the target bits set for rate control will be largely different from the actually coded bits.

[liye0713]

patch of the 'source' directory after setting the frame rate as double format in case of rate control