wmadec.c File Reference

WMA compatible decoder. More...

#include "libavutil/attributes.h"
#include "libavutil/ffmath.h"
#include "avcodec.h"
#include "internal.h"
#include "wma.h"

Go to the source code of this file.

Macros
#define	EXPVLCBITS   8
#define	EXPMAX   ((19 + EXPVLCBITS - 1) / EXPVLCBITS)
#define	HGAINVLCBITS   9
#define	HGAINMAX   ((13 + HGAINVLCBITS - 1) / HGAINVLCBITS)

Functions
static void	wma_lsp_to_curve_init (WMACodecContext *s, int frame_len)
static av_cold int	wma_decode_init (AVCodecContext *avctx)
static float	pow_m1_4 (WMACodecContext *s, float x)
	compute x^-0.25 with an exponent and mantissa table. More...
static void	wma_lsp_to_curve (WMACodecContext *s, float *out, float *val_max_ptr, int n, float *lsp)
	NOTE: We use the same code as Vorbis here. More...
static void	decode_exp_lsp (WMACodecContext *s, int ch)
	decode exponents coded with LSP coefficients (same idea as Vorbis) More...
static int	decode_exp_vlc (WMACodecContext *s, int ch)
	decode exponents coded with VLC codes More...
static void	wma_window (WMACodecContext *s, float *out)
	Apply MDCT window and add into output. More...
static int	wma_decode_block (WMACodecContext *s)
static int	wma_decode_frame (WMACodecContext *s, float **samples, int samples_offset)
static int	wma_decode_superframe (AVCodecContext *avctx, void *data, int *got_frame_ptr, AVPacket *avpkt)
static av_cold void	flush (AVCodecContext *avctx)

Variables
static const float	pow_tab []
	pow(10, i / 16.0) for i in -60..95 More...

Detailed Description

WMA compatible decoder.

This decoder handles Microsoft Windows Media Audio data, versions 1 & 2. WMA v1 is identified by audio format 0x160 in Microsoft media files (ASF/AVI/WAV). WMA v2 is identified by audio format 0x161.

To use this decoder, a calling application must supply the extra data bytes provided with the WMA data. These are the extra, codec-specific bytes at the end of a WAVEFORMATEX data structure. Transmit these bytes to the decoder using the extradata[_size] fields in AVCodecContext. There should be 4 extra bytes for v1 data and 6 extra bytes for v2 data.

Definition in file wmadec.c.

Macro Definition Documentation

EXPVLCBITS

#define EXPVLCBITS   8

Definition at line 43 of file wmadec.c.

Referenced by decode_exp_vlc(), and wma_decode_init().

EXPMAX

#define EXPMAX   ((19 + EXPVLCBITS - 1) / EXPVLCBITS)

Definition at line 44 of file wmadec.c.

Referenced by decode_exp_vlc().

HGAINVLCBITS

#define HGAINVLCBITS   9

Definition at line 46 of file wmadec.c.

Referenced by wma_decode_block(), and wma_decode_init().

HGAINMAX

#define HGAINMAX   ((13 + HGAINVLCBITS - 1) / HGAINVLCBITS)

Definition at line 47 of file wmadec.c.

Referenced by wma_decode_block().

Function Documentation

wma_lsp_to_curve_init()

static av_cold void wma_lsp_to_curve_init ( WMACodecContext *  s, int  frame_len  )

static

Definition at line 155 of file wmadec.c.

Referenced by wma_decode_init().

wma_decode_init()

static av_cold int wma_decode_init ( AVCodecContext *  avctx )

static

Definition at line 70 of file wmadec.c.

Referenced by flush().

pow_m1_4()

static float pow_m1_4 ( WMACodecContext *  s, float  x  )

inlinestatic

compute x^-0.25 with an exponent and mantissa table.

We use linear interpolation to reduce the mantissa table size at a small speed expense (linear interpolation approximately doubles the number of bits of precision).

Definition at line 136 of file wmadec.c.

Referenced by wma_lsp_to_curve().

wma_lsp_to_curve()

static void wma_lsp_to_curve ( WMACodecContext *  s, float *  out, float *  val_max_ptr, int  n, float *  lsp  )

static

NOTE: We use the same code as Vorbis here.

Todo:

optimize it further with SSE/3Dnow

Definition at line 187 of file wmadec.c.

Referenced by decode_exp_lsp().

decode_exp_lsp()

static void decode_exp_lsp ( WMACodecContext *  s, int  ch  )

static

decode exponents coded with LSP coefficients (same idea as Vorbis)

Definition at line 216 of file wmadec.c.

Referenced by wma_decode_block().

decode_exp_vlc()

static int decode_exp_vlc ( WMACodecContext *  s, int  ch  )

static

decode exponents coded with VLC codes

Definition at line 318 of file wmadec.c.

Referenced by wma_decode_block().

wma_window()

static void wma_window ( WMACodecContext *  s, float *  out  )

static

Apply MDCT window and add into output.

We ensure that when the windows overlap their squared sum is always 1 (MDCT reconstruction rule).

Definition at line 381 of file wmadec.c.

Referenced by wma_decode_block().

wma_decode_block()

static int wma_decode_block ( WMACodecContext *  s )

static

Returns

0 if OK. 1 if last block of frame. return -1 if unrecoverable error.

Definition at line 431 of file wmadec.c.

Referenced by wma_decode_frame().

wma_decode_frame()

static int wma_decode_frame ( WMACodecContext *  s, float **  samples, int  samples_offset  )

static

Definition at line 769 of file wmadec.c.

Referenced by wma_decode_superframe().

wma_decode_superframe()

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

static

Definition at line 807 of file wmadec.c.

Referenced by flush().

flush()

static av_cold void flush ( AVCodecContext *  avctx )

static

Definition at line 962 of file wmadec.c.

Variable Documentation

pow_tab

const float pow_tab[]

static

pow(10, i / 16.0) for i in -60..95

Definition at line 234 of file wmadec.c.