Lambda File Format - 2020.2 English

The encoder uses lambda factors per QP value as bitrate as opposed to quality trade-off. By default, the encoder IP use internal lambda factors but it can also use user specified lambda factors. This feature is enabled when LambdaCtrlMode is set to LOAD_LDA and when a Lambdas.hex file is available in the working directory. Each line of Lambdas.hex contains one 32-bit hexadecimal value per QP values (that is 52 lines for QP in range [0...51]).

Each 32 bits word is split as follows:

Bit 7 to 0

Lambda factor for slice B

Bit 15 to 8

Lambda factor for slice P

Bit 23 to 16

Lambda factor for slice I

Bit 31 to 24

Lambda factor for the motion estimation block (this value shall be a power of two)

1 2 3 4
01010101 <-------QP 0
01010101 
01010101 
01010101 
01010101 
01010101 
01010101 
01010101 
01010101 
01010101 
01010101 
01010101 
01010101 
01010101 
01010101 
01020101 
02020202 
02020202 
… 
100b0a0e 
100c0b10 
200e0c12 
200f0e14 
20110f17 
20131119 
2015131d 
20181520 
401b1824 
401e1b28 
40221e2d 
40262133 
402a2539 
40302a40 
80352f48 
803c3551 
80433b5b <-------QP 51

1

Motion Estimation

2

Slice I

3

Slice P

4

Slice B