X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavcodec%2Fac3.h;h=cbbb71821be842ee760dd0181a95447f9d45dd76;hb=47146dfbf6bca94dd0706b4313cc5e26edaf18d4;hp=28c7f03956f6f0ae3ec558bf1ad3737b7df8c473;hpb=050aa8b9bca6a2c29e1c4c914e05aca49007f1d7;p=ffmpeg diff --git a/libavcodec/ac3.h b/libavcodec/ac3.h index 28c7f03956f..cbbb71821be 100644 --- a/libavcodec/ac3.h +++ b/libavcodec/ac3.h @@ -1,5 +1,5 @@ /* - * Common code between AC3 encoder and decoder + * Common code between the AC-3 encoder and decoder * Copyright (c) 2000, 2001, 2002 Fabrice Bellard. * * This file is part of FFmpeg. @@ -21,13 +21,18 @@ /** * @file ac3.h - * Common code between AC3 encoder and decoder. + * Common code between the AC-3 encoder and decoder. */ +#ifndef AVCODEC_AC3_H +#define AVCODEC_AC3_H + +#include "ac3tab.h" + #define AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */ #define AC3_MAX_CHANNELS 6 /* including LFE channel */ -#define NB_BLOCKS 6 /* number of PCM blocks inside an AC3 frame */ +#define NB_BLOCKS 6 /* number of PCM blocks inside an AC-3 frame */ #define AC3_FRAME_SIZE (NB_BLOCKS * 256) /* exponent encoding strategy */ @@ -38,28 +43,144 @@ #define EXP_D25 2 #define EXP_D45 3 +/** Delta bit allocation strategy */ +typedef enum { + DBA_REUSE = 0, + DBA_NEW, + DBA_NONE, + DBA_RESERVED +} AC3DeltaStrategy; + +/** Channel mode (audio coding mode) */ +typedef enum { + AC3_CHMODE_DUALMONO = 0, + AC3_CHMODE_MONO, + AC3_CHMODE_STEREO, + AC3_CHMODE_3F, + AC3_CHMODE_2F1R, + AC3_CHMODE_3F1R, + AC3_CHMODE_2F2R, + AC3_CHMODE_3F2R +} AC3ChannelMode; + typedef struct AC3BitAllocParameters { - int fscod; /* frequency */ - int halfratecod; - int sgain, sdecay, fdecay, dbknee, floor; - int cplfleak, cplsleak; + int sr_code; + int sr_shift; + int slow_gain, slow_decay, fast_decay, db_per_bit, floor; + int cpl_fast_leak, cpl_slow_leak; } AC3BitAllocParameters; -extern uint16_t ff_ac3_frame_sizes[38][3]; -extern const uint8_t ff_ac3_channels[8]; -extern const uint16_t ff_ac3_freqs[3]; -extern const uint16_t ff_ac3_bitratetab[19]; -extern const int16_t ff_ac3_window[256]; -extern const uint8_t ff_sdecaytab[4]; -extern const uint8_t ff_fdecaytab[4]; -extern const uint16_t ff_sgaintab[4]; -extern const uint16_t ff_dbkneetab[4]; -extern const int16_t ff_floortab[8]; -extern const uint16_t ff_fgaintab[8]; +/** + * @struct AC3HeaderInfo + * Coded AC-3 header values up to the lfeon element, plus derived values. + */ +typedef struct { + /** @defgroup coded Coded elements + * @{ + */ + uint16_t sync_word; + uint16_t crc1; + uint8_t sr_code; + uint8_t bitstream_id; + uint8_t channel_mode; + uint8_t lfe_on; + uint8_t frame_type; + int substreamid; ///< substream identification + int center_mix_level; ///< Center mix level index + int surround_mix_level; ///< Surround mix level index + uint16_t channel_map; + int num_blocks; ///< number of audio blocks + /** @} */ + + /** @defgroup derived Derived values + * @{ + */ + uint8_t sr_shift; + uint16_t sample_rate; + uint32_t bit_rate; + uint8_t channels; + uint16_t frame_size; + /** @} */ +} AC3HeaderInfo; + +typedef enum { + EAC3_FRAME_TYPE_INDEPENDENT = 0, + EAC3_FRAME_TYPE_DEPENDENT, + EAC3_FRAME_TYPE_AC3_CONVERT, + EAC3_FRAME_TYPE_RESERVED +} EAC3FrameType; void ac3_common_init(void); + +/** + * Calculates the log power-spectral density of the input signal. + * This gives a rough estimate of signal power in the frequency domain by using + * the spectral envelope (exponents). The psd is also separately grouped + * into critical bands for use in the calculating the masking curve. + * 128 units in psd = -6 dB. The dbknee parameter in AC3BitAllocParameters + * determines the reference level. + * + * @param[in] exp frequency coefficient exponents + * @param[in] start starting bin location + * @param[in] end ending bin location + * @param[out] psd signal power for each frequency bin + * @param[out] band_psd signal power for each critical band + */ +void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd, + int16_t *band_psd); + +/** + * Calculates the masking curve. + * First, the excitation is calculated using parameters in \p s and the signal + * power in each critical band. The excitation is compared with a predefined + * hearing threshold table to produce the masking curve. If delta bit + * allocation information is provided, it is used for adjusting the masking + * curve, usually to give a closer match to a better psychoacoustic model. + * + * @param[in] s adjustable bit allocation parameters + * @param[in] band_psd signal power for each critical band + * @param[in] start starting bin location + * @param[in] end ending bin location + * @param[in] fast_gain fast gain (estimated signal-to-mask ratio) + * @param[in] is_lfe whether or not the channel being processed is the LFE + * @param[in] dba_mode delta bit allocation mode (none, reuse, or new) + * @param[in] dba_nsegs number of delta segments + * @param[in] dba_offsets location offsets for each segment + * @param[in] dba_lengths length of each segment + * @param[in] dba_values delta bit allocation for each segment + * @param[out] mask calculated masking curve + * @return returns 0 for success, non-zero for error + */ +int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd, + int start, int end, int fast_gain, int is_lfe, + int dba_mode, int dba_nsegs, uint8_t *dba_offsets, + uint8_t *dba_lengths, uint8_t *dba_values, + int16_t *mask); + +/** + * Calculates bit allocation pointers. + * The SNR is the difference between the masking curve and the signal. AC-3 + * uses this value for each frequency bin to allocate bits. The \p snroffset + * parameter is a global adjustment to the SNR for all bins. + * + * @param[in] mask masking curve + * @param[in] psd signal power for each frequency bin + * @param[in] start starting bin location + * @param[in] end ending bin location + * @param[in] snr_offset SNR adjustment + * @param[in] floor noise floor + * @param[in] bap_tab look-up table for bit allocation pointers + * @param[out] bap bit allocation pointers + */ +void ff_ac3_bit_alloc_calc_bap(int16_t *mask, int16_t *psd, int start, int end, + int snr_offset, int floor, + const uint8_t *bap_tab, uint8_t *bap); + void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap, int8_t *exp, int start, int end, - int snroffset, int fgain, int is_lfe, - int deltbae,int deltnseg, - uint8_t *deltoffst, uint8_t *deltlen, uint8_t *deltba); + int snr_offset, int fast_gain, int is_lfe, + int dba_mode, int dba_nsegs, + uint8_t *dba_offsets, uint8_t *dba_lengths, + uint8_t *dba_values); + +#endif /* AVCODEC_AC3_H */