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"

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 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, 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)
static int	init_thread_copy (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:

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 (10) 8bit rice param limit (14) 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.

Macro Definition Documentation

#define ALAC_EXTRADATA_SIZE   36

Definition at line 61 of file alac.c.

Referenced by alac_decode_init().

Function Documentation

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

inlinestatic

Definition at line 86 of file alac.c.

Referenced by 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 108 of file alac.c.

Referenced by decode_element().

static int sign_only ( int  v )

inlinestatic

Definition at line 165 of file alac.c.

Referenced by 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 170 of file alac.c.

Referenced by decode_element().

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

static

Definition at line 233 of file alac.c.

Referenced by decode_element().

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 252 of file alac.c.

Referenced by decode_element().

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

static

Definition at line 262 of file alac.c.

Referenced by alac_decode_frame().

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

static

Definition at line 452 of file alac.c.

static av_cold int alac_decode_close ( AVCodecContext *  avctx )

static

Definition at line 511 of file alac.c.

Referenced by allocate_buffers().

static int allocate_buffers ( ALACContext *  alac )

static

Definition at line 526 of file alac.c.

Referenced by alac_decode_init(), and init_thread_copy().

static int alac_set_info ( ALACContext *  alac )

static

Definition at line 550 of file alac.c.

Referenced by alac_decode_init().

static av_cold int alac_decode_init ( AVCodecContext *  avctx )

static

Definition at line 581 of file alac.c.

static int init_thread_copy ( AVCodecContext *  avctx )

static

Definition at line 634 of file alac.c.

Variable Documentation

const AVOption options[]

static

Initial value:

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

Definition at line 641 of file alac.c.

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 648 of file alac.c.

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   = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,
    .priv_class     = &alac_class
}

Definition at line 655 of file alac.c.