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62 lines
2.3 KiB
C
62 lines
2.3 KiB
C
/**
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* TAV Encoder - EZBC (Embedded Zero Block Coding) Library
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*
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* Public API for EZBC entropy coding of wavelet coefficients.
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*/
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#ifndef TAV_ENCODER_EZBC_H
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#define TAV_ENCODER_EZBC_H
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#include <stdint.h>
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#include <stddef.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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// =============================================================================
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// EZBC Encoding
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// =============================================================================
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/**
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* EZBC encoding for a single channel.
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*
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* Implements binary tree embedded zero block coding for efficient storage
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* of sparse wavelet coefficients. Exploits coefficient sparsity through
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* hierarchical significance testing and progressive bitplane encoding.
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*
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* Algorithm:
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* 1. Find MSB bitplane from maximum absolute coefficient value
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* 2. Write header: MSB bitplane (8 bits), width (16 bits), height (16 bits)
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* 3. For each bitplane from MSB to 0:
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* a. Process insignificant blocks: check if they become significant
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* - Emit 0 if still insignificant, 1 if became significant
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* b. For newly significant blocks: recursively subdivide until 1x1
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* - Emit tree structure: 1=child is significant, 0=child insignificant
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* c. Emit sign bits for newly significant 1x1 coefficients (1=negative, 0=positive)
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* d. Process already-significant coefficients: emit refinement bits
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* - Emit bit at current bitplane for progressive reconstruction
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* 4. Return encoded bitstream
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*
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* Benefits:
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* - Exploits coefficient sparsity (typical: 86.9% zeros in luma, 97.8% in chroma)
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* - Progressive refinement from MSB to LSB
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* - Spatial clustering through quadtree decomposition
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* - No additional entropy coding needed (bitstream is already compressed)
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*
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* @param coeffs Input quantized coefficients (int16_t array)
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* @param count Number of coefficients (width × height)
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* @param width Frame width (must match coefficient array layout)
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* @param height Frame height (must match coefficient array layout)
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* @param output Output buffer pointer (allocated by this function, caller must free)
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* @return Encoded size in bytes (including header)
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*/
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size_t tav_encode_channel_ezbc(int16_t *coeffs, size_t count, int width, int height,
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uint8_t **output);
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#ifdef __cplusplus
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}
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#endif
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#endif // TAV_ENCODER_EZBC_H
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