libavcodec/alac.c File Reference

ALAC (Apple Lossless Audio Codec) decoder. More...

#include "libavutil/audioconvert.h"
#include "avcodec.h"
#include "get_bits.h"
#include "bytestream.h"
#include "unary.h"
#include "mathops.h"

Go to the source code of this file.

Data Structures

struct  ALACContext

Defines

#define ALAC_EXTRADATA_SIZE   36
#define MAX_CHANNELS   8

Enumerations

enum  RawDataBlockType {
  TYPE_SCE, TYPE_CPE, TYPE_CCE, TYPE_LFE,
  TYPE_DSE, TYPE_PCE, TYPE_FIL, TYPE_END,
  TYPE_SCE, TYPE_CPE, TYPE_CCE, TYPE_LFE,
  TYPE_DSE, TYPE_PCE, TYPE_FIL, TYPE_END
}

Functions

static unsigned int decode_scalar (GetBitContext *gb, int k, int bps)
static int rice_decompress (ALACContext *alac, int32_t *output_buffer, int nb_samples, int bps, int rice_history_mult)
static int sign_only (int v)
static void lpc_prediction (int32_t *error_buffer, int32_t *buffer_out, int nb_samples, int bps, int16_t *lpc_coefs, int lpc_order, int lpc_quant)
static void decorrelate_stereo (int32_t *buffer[2], int nb_samples, int decorr_shift, int decorr_left_weight)
static void append_extra_bits (int32_t *buffer[2], int32_t *extra_bits_buffer[2], int extra_bits, int channels, int nb_samples)
static int decode_element (AVCodecContext *avctx, void *data, int ch_index, int channels)
static int alac_decode_frame (AVCodecContext *avctx, void *data, int *got_frame_ptr, AVPacket *avpkt)
static av_cold int alac_decode_close (AVCodecContext *avctx)
static int allocate_buffers (ALACContext *alac)
static int alac_set_info (ALACContext *alac)
static av_cold int alac_decode_init (AVCodecContext *avctx)

Variables

static const uint8_t alac_channel_layout_offsets [8][8]
static const uint16_t alac_channel_layouts [8]
AVCodec ff_alac_decoder

Detailed Description

ALAC (Apple Lossless Audio Codec) decoder.

Author:
2005 David Hammerton
See also:
http://crazney.net/programs/itunes/alac.html
Note: This decoder expects a 36-byte QuickTime atom to be passed through the extradata[_size] fields. This atom is tacked onto the end of an 'alac' stsd atom and has the following format:

32bit atom size 32bit tag ("alac") 32bit tag version (0) 32bit samples per frame (used when not set explicitly in the frames) 8bit compatible version (0) 8bit sample size 8bit history mult (40) 8bit initial history (14) 8bit rice param limit (10) 8bit channels 16bit maxRun (255) 32bit max coded frame size (0 means unknown) 32bit average bitrate (0 means unknown) 32bit samplerate

Definition in file alac.c.

Define Documentation

#define ALAC_EXTRADATA_SIZE   36

Definition at line 55 of file alac.c.

Referenced by alac_decode_init(), and alac_encode_init().

#define MAX_CHANNELS   8

Definition at line 56 of file alac.c.

Enumeration Type Documentation

enum RawDataBlockType

Enumerator:
TYPE_SCE 
TYPE_CPE 
TYPE_CCE 
TYPE_LFE 
TYPE_DSE 
TYPE_PCE 
TYPE_FIL 
TYPE_END 
TYPE_SCE 
TYPE_CPE 
TYPE_CCE 
TYPE_LFE 
TYPE_DSE 
TYPE_PCE 
TYPE_FIL 
TYPE_END 

Definition at line 80 of file alac.c.

Function Documentation

static av_cold int alac_decode_close ( AVCodecContext *  avctx  )  [static]

Definition at line 527 of file alac.c.

Referenced by allocate_buffers().

static int alac_decode_frame ( AVCodecContext *  avctx,
void *  data,
int *  got_frame_ptr,
AVPacket *  avpkt 
) [static]

Definition at line 473 of file alac.c.

static av_cold int alac_decode_init ( AVCodecContext *  avctx  )  [static]

Definition at line 595 of file alac.c.

static int alac_set_info ( ALACContext *  alac  )  [static]

Definition at line 566 of file alac.c.

Referenced by alac_decode_init().

static int allocate_buffers ( ALACContext *  alac  )  [static]

Definition at line 542 of file alac.c.

static void append_extra_bits ( int32_t *  buffer[2],
int32_t *  extra_bits_buffer[2],
int  extra_bits,
int  channels,
int  nb_samples 
) [static]

Definition at line 280 of file alac.c.

Referenced by decode_element().

static int decode_element ( AVCodecContext *  avctx,
void *  data,
int  ch_index,
int  channels 
) [static]

Definition at line 290 of file alac.c.

Referenced by alac_decode_frame().

static unsigned int decode_scalar ( GetBitContext *  gb,
int  k,
int  bps 
) [inline, static]

Definition at line 114 of file alac.c.

Referenced by rice_decompress().

static void decorrelate_stereo ( int32_t *  buffer[2],
int  nb_samples,
int  decorr_shift,
int  decorr_left_weight 
) [static]

Definition at line 261 of file alac.c.

Referenced by decode_element().

static void lpc_prediction ( int32_t *  error_buffer,
int32_t *  buffer_out,
int  nb_samples,
int  bps,
int16_t *  lpc_coefs,
int  lpc_order,
int  lpc_quant 
) [static]

Definition at line 198 of file alac.c.

Referenced by decode_element().

static int rice_decompress ( ALACContext *  alac,
int32_t *  output_buffer,
int  nb_samples,
int  bps,
int  rice_history_mult 
) [static]

Definition at line 136 of file alac.c.

Referenced by decode_element().

static int sign_only ( int  v  )  [inline, static]

Definition at line 193 of file alac.c.

Referenced by lpc_prediction().

Variable Documentation

const uint8_t alac_channel_layout_offsets[8][8] [static]

Initial value:

 {
    { 0 },
    { 0, 1 },
    { 2, 0, 1 },
    { 2, 0, 1, 3 },
    { 2, 0, 1, 3, 4 },
    { 2, 0, 1, 4, 5, 3 },
    { 2, 0, 1, 4, 5, 6, 3 },
    { 2, 6, 7, 0, 1, 4, 5, 3 }
}

Definition at line 92 of file alac.c.

Referenced by alac_decode_frame().

const uint16_t alac_channel_layouts[8] [static]

Initial value:

 {
    AV_CH_LAYOUT_MONO,
    AV_CH_LAYOUT_STEREO,
    AV_CH_LAYOUT_SURROUND,
    AV_CH_LAYOUT_4POINT0,
    AV_CH_LAYOUT_5POINT0_BACK,
    AV_CH_LAYOUT_5POINT1_BACK,
    AV_CH_LAYOUT_6POINT1_BACK,
    AV_CH_LAYOUT_7POINT1_WIDE_BACK
}

Definition at line 103 of file alac.c.

Referenced by alac_decode_init().

AVCodec ff_alac_decoder

Initial value:

 {
    .name           = "alac",
    .type           = AVMEDIA_TYPE_AUDIO,
    .id             = AV_CODEC_ID_ALAC,
    .priv_data_size = sizeof(ALACContext),
    .init           = alac_decode_init,
    .close          = alac_decode_close,
    .decode         = alac_decode_frame,
    .capabilities   = CODEC_CAP_DR1,
    .long_name      = NULL_IF_CONFIG_SMALL("ALAC (Apple Lossless Audio Codec)"),
}

Definition at line 652 of file alac.c.

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