Module quantization 

Quantization and rate control for MP3 encoding

This module implements the quantization loop that controls the trade-off between audio quality and bitrate by adjusting quantization step sizes and managing the bit reservoir.

The implementation strictly follows the shine reference implementation in ref/shine/src/lib/l3loop.c

Functions

bigv_tab_select

Select Huffman code tables for bigvalues regions Corresponds to bigv_tab_select() in l3loop.c

calc_runlen

Calculate run length encoding information Corresponds to calc_runlen() in l3loop.c

count1_bitcount

Count bits for count1 region Corresponds to count1_bitcount() in l3loop.c

count_bit

Count the number of bits necessary to code the subregion Corresponds to count_bit() in l3loop.c

ix_max

Calculate maximum value in range

labs

Absolute value function (matches shine labs)

mulr

Multiply with rounding and 32-bit right shift (matches shine mulr)

mulsr

Multiplication macros matching shine’s mult_noarch_gcc.h These implement fixed-point arithmetic operations

part2_length

Calculate part2 length (scalefactors) Corresponds to part2_length() in l3loop.c

quantize

Quantize MDCT coefficients Corresponds to quantize() in l3loop.c

quantize_with_l3loop

Helper function to avoid borrowing conflicts

shine_inner_loop

Inner loop: find optimal quantization step size for given scalefactors Corresponds to shine_inner_loop() in l3loop.c

shine_iteration_loop

Main iteration loop for encoding Corresponds to shine_iteration_loop() in l3loop.c

shine_loop_initialise

Initialize quantization loop tables Corresponds to shine_loop_initialise() in l3loop.c

shine_outer_loop

Outer loop: controls masking conditions and computes best scalefac and global gain Corresponds to shine_outer_loop() in l3loop.c

subdivide

Subdivide big values region into regions for different Huffman tables Corresponds to subdivide() in l3loop.c

subdivide_with_samplerate

Helper function to subdivide without borrowing conflicts