alac.c File Reference

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

#include <inttypes.h>
#include "libavutil/channel_layout.h"
#include "libavutil/opt.h"
#include "avcodec.h"
#include "get_bits.h"
#include "bytestream.h"
#include "internal.h"
#include "thread.h"
#include "unary.h"
#include "mathops.h"
#include "alac_data.h"
#include "alacdsp.h"

Go to the source code of this file.

Data Structures
struct	ALACContext

Macros
#define	ALAC_EXTRADATA_SIZE   36

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 int	decode_element (AVCodecContext *avctx, AVFrame *frame, 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 AVOption	options []
static const AVClass	alac_class
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:

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

Definition in file alac.c.

Macro Definition Documentation

ALAC_EXTRADATA_SIZE

#define ALAC_EXTRADATA_SIZE   36

Definition at line 62 of file alac.c.

Referenced by alac_decode_init().

Function Documentation

decode_scalar()

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

inlinestatic

Definition at line 90 of file alac.c.

Referenced by rice_decompress().

rice_decompress()

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

static

Definition at line 112 of file alac.c.

Referenced by decode_element().

sign_only()

static int sign_only ( int  v )

inlinestatic

Definition at line 169 of file alac.c.

Referenced by lpc_prediction().

lpc_prediction()

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 174 of file alac.c.

Referenced by decode_element().

decode_element()

static int decode_element ( AVCodecContext *  avctx, AVFrame *  frame, int  ch_index, int  channels  )

static

Definition at line 237 of file alac.c.

Referenced by alac_decode_frame().

alac_decode_frame()

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

static

Definition at line 412 of file alac.c.

alac_decode_close()

static av_cold int alac_decode_close ( AVCodecContext *  avctx )

static

Definition at line 471 of file alac.c.

Referenced by allocate_buffers().

allocate_buffers()

static int allocate_buffers ( ALACContext *  alac )

static

Definition at line 486 of file alac.c.

Referenced by alac_decode_init().

alac_set_info()

static int alac_set_info ( ALACContext *  alac )

static

Definition at line 516 of file alac.c.

Referenced by alac_decode_init().

alac_decode_init()

static av_cold int alac_decode_init ( AVCodecContext *  avctx )

static

Definition at line 547 of file alac.c.

Variable Documentation

options

const AVOption options[]

static

Initial value:

= {
    { "extra_bits_bug", "Force non-standard decoding process",
      0x42, AV_OPT_TYPE_BOOL, { .i64 = 0 },
      0, 1, AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM },
    { NULL },
}

Definition at line 611 of file alac.c.

alac_class

const AVClass alac_class

static

Initial value:

= {
    .class_name = "alac",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
}

Definition at line 618 of file alac.c.

ff_alac_decoder

AVCodec ff_alac_decoder

Initial value:

= {
    .name           = "alac",
    .long_name      = NULL_IF_CONFIG_SMALL("ALAC (Apple Lossless Audio Codec)"),
    .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,
    .init_thread_copy = ONLY_IF_THREADS_ENABLED(init_thread_copy),
    .capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
    .priv_class     = &alac_class
}

Definition at line 625 of file alac.c.