libavcodec/alac.c File Reference

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

#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   2
Functions
static void	allocate_buffers (ALACContext *alac)
static int	alac_set_info (ALACContext *alac)
static int	decode_scalar (GetBitContext *gb, int k, int limit, int readsamplesize)
static void	bastardized_rice_decompress (ALACContext *alac, int32_t *output_buffer, int output_size, int readsamplesize, int rice_initialhistory, int rice_kmodifier, int rice_historymult, int rice_kmodifier_mask)
static int	sign_only (int v)
static void	predictor_decompress_fir_adapt (int32_t *error_buffer, int32_t *buffer_out, int output_size, int readsamplesize, int16_t *predictor_coef_table, int predictor_coef_num, int predictor_quantitization)
static void	reconstruct_stereo_16 (int32_t *buffer[MAX_CHANNELS], int16_t *buffer_out, int numchannels, int numsamples, uint8_t interlacing_shift, uint8_t interlacing_leftweight)
static void	decorrelate_stereo_24 (int32_t *buffer[MAX_CHANNELS], int32_t *buffer_out, int32_t *wasted_bits_buffer[MAX_CHANNELS], int wasted_bits, int numchannels, int numsamples, uint8_t interlacing_shift, uint8_t interlacing_leftweight)
static int	alac_decode_frame (AVCodecContext *avctx, void *outbuffer, int *outputsize, AVPacket *avpkt)
static av_cold int	alac_decode_init (AVCodecContext *avctx)
static av_cold int	alac_decode_close (AVCodecContext *avctx)
Variables
AVCodec	ff_alac_decoder

---

Detailed Description

ALAC (Apple Lossless Audio Codec) decoder.

Author:

2005 David Hammerton

For more information on the ALAC format, visit: http://crazney.net/programs/itunes/alac.html

Note: This decoder expects a 36- (0x24-)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: bytes 0-3 atom size (0x24), big-endian bytes 4-7 atom type ('alac', not the 'alac' tag from start of stsd) bytes 8-35 data bytes needed by decoder

Extradata: 32bit size 32bit tag (=alac) 32bit zero? 32bit max sample per frame 8bit ?? (zero?) 8bit sample size 8bit history mult 8bit initial history 8bit kmodifier 8bit channels? 16bit ?? 32bit max coded frame size 32bit bitrate? 32bit samplerate

Definition in file alac.c.

---

Define Documentation

#define ALAC_EXTRADATA_SIZE   36

Definition at line 61 of file alac.c.

Referenced by alac_decode_init(), and alac_encode_init().

#define MAX_CHANNELS   2

Definition at line 62 of file alac.c.

---

Function Documentation

static av_cold int alac_decode_close

(

AVCodecContext *

avctx

)

[static]

Definition at line 680 of file alac.c.

static int alac_decode_frame	(	AVCodecContext *	avctx,
		void *	outbuffer,
		int *	outputsize,
		AVPacket *	avpkt
	)			[static]

Definition at line 453 of file alac.c.

static av_cold int alac_decode_init

(

AVCodecContext *

avctx

)

[static]

Definition at line 660 of file alac.c.

static int alac_set_info

(

ALACContext *

alac

)

[static]

Definition at line 104 of file alac.c.

Referenced by alac_decode_init().

static void allocate_buffers

(

ALACContext *

alac

)

[static]

Definition at line 90 of file alac.c.

static void bastardized_rice_decompress	(	ALACContext *	alac,
		int32_t *	output_buffer,
		int	output_size,
		int	readsamplesize,
		int	rice_initialhistory,
		int	rice_kmodifier,
		int	rice_historymult,
		int	rice_kmodifier_mask
	)			[static]

Definition at line 166 of file alac.c.

Referenced by alac_decode_frame().

static int decode_scalar	(	GetBitContext *	gb,
		int	k,
		int	limit,
		int	readsamplesize
	)			[inline, static]

Definition at line 139 of file alac.c.

Referenced by bastardized_rice_decompress().

static void decorrelate_stereo_24	(	int32_t *	buffer[MAX_CHANNELS],
		int32_t *	buffer_out,
		int32_t *	wasted_bits_buffer[MAX_CHANNELS],
		int	wasted_bits,
		int	numchannels,
		int	numsamples,
		uint8_t	interlacing_shift,
		uint8_t	interlacing_leftweight
	)			[static]

Definition at line 403 of file alac.c.

Referenced by alac_decode_frame().

static void predictor_decompress_fir_adapt	(	int32_t *	error_buffer,
		int32_t *	buffer_out,
		int	output_size,
		int	readsamplesize,
		int16_t *	predictor_coef_table,
		int	predictor_coef_num,
		int	predictor_quantitization
	)			[static]

Definition at line 240 of file alac.c.

Referenced by alac_decode_frame().

static void reconstruct_stereo_16	(	int32_t *	buffer[MAX_CHANNELS],
		int16_t *	buffer_out,
		int	numchannels,
		int	numsamples,
		uint8_t	interlacing_shift,
		uint8_t	interlacing_leftweight
	)			[static]

Definition at line 363 of file alac.c.

Referenced by alac_decode_frame().

static int sign_only

(

int

v

)

[inline, static]

Definition at line 235 of file alac.c.

Referenced by predictor_decompress_fir_adapt().

---

Variable Documentation

AVCodec ff_alac_decoder

Initial value:

 {
    "alac",
    AVMEDIA_TYPE_AUDIO,
    CODEC_ID_ALAC,
    sizeof(ALACContext),
    alac_decode_init,
    NULL,
    alac_decode_close,
    alac_decode_frame,
    .long_name = NULL_IF_CONFIG_SMALL("ALAC (Apple Lossless Audio Codec)"),
}

Definition at line 694 of file alac.c.