WMA compatible decoder. More...

#include "avcodec.h"
#include "internal.h"
#include "wma.h"
#include <assert.h>

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 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.
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.
static void	decode_exp_lsp (WMACodecContext *s, int ch)
	decode exponents coded with LSP coefficients (same idea as Vorbis)
static int	decode_exp_vlc (WMACodecContext *s, int ch)
	decode exponents coded with VLC codes
static void	wma_window (WMACodecContext s, float out)
	Apply MDCT window and add into output.
static int	wma_decode_block (WMACodecContext *s)
static int	wma_decode_frame (WMACodecContext s, int16_t samples)
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
AVCodec	ff_wmav1_decoder
AVCodec	ff_wmav2_decoder

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

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

Definition at line 44 of file wmadec.c.

Referenced by decode_exp_vlc().

#define EXPVLCBITS 8

Definition at line 43 of file wmadec.c.

Referenced by decode_exp_vlc(), and wma_decode_init().

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

Definition at line 47 of file wmadec.c.

Referenced by wma_decode_block().

#define HGAINVLCBITS 9

Definition at line 46 of file wmadec.c.

Referenced by wma_decode_block(), and wma_decode_init().

Function Documentation

static void decode_exp_lsp	(	WMACodecContext *	s,
		int	ch
	)

static

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

Definition at line 227 of file wmadec.c.

Referenced by wma_decode_block().

static int decode_exp_vlc	(	WMACodecContext *	s,
		int	ch
	)

static

decode exponents coded with VLC codes

Definition at line 329 of file wmadec.c.

Referenced by wma_decode_block().

static av_cold void flush ( AVCodecContext * avctx )

static

Definition at line 937 of file wmadec.c.

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 146 of file wmadec.c.

Referenced by wma_lsp_to_curve().

static int wma_decode_block ( WMACodecContext * s )

static

Returns: 0 if OK. 1 if last block of frame. return -1 if unrecorrable error.

Definition at line 445 of file wmadec.c.

Referenced by wma_decode_frame().

static int wma_decode_frame	(	WMACodecContext *	s,
		int16_t *	samples
	)

static

Definition at line 773 of file wmadec.c.

Referenced by wma_decode_superframe().

static int wma_decode_init ( AVCodecContext * avctx )

static

Definition at line 83 of file wmadec.c.

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

static

Definition at line 810 of file wmadec.c.

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 197 of file wmadec.c.

Referenced by decode_exp_lsp().

static void wma_lsp_to_curve_init	(	WMACodecContext *	s,
		int	frame_len
	)

static

Definition at line 165 of file wmadec.c.

Referenced by wma_decode_init().

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 393 of file wmadec.c.

Referenced by wma_decode_block().

Variable Documentation

AVCodec ff_wmav1_decoder

Initial value:

 {
    .name           = "wmav1",
    .type           = AVMEDIA_TYPE_AUDIO,
    .id             = CODEC_ID_WMAV1,
    .priv_data_size = sizeof(WMACodecContext),
    .init           = wma_decode_init,
    .close          = ff_wma_end,
    .decode         = wma_decode_superframe,
    .flush          = flush,
    .capabilities   = CODEC_CAP_DR1,
    .long_name      = NULL_IF_CONFIG_SMALL("Windows Media Audio 1"),
}

Definition at line 945 of file wmadec.c.

AVCodec ff_wmav2_decoder

Initial value:

 {
    .name           = "wmav2",
    .type           = AVMEDIA_TYPE_AUDIO,
    .id             = CODEC_ID_WMAV2,
    .priv_data_size = sizeof(WMACodecContext),
    .init           = wma_decode_init,
    .close          = ff_wma_end,
    .decode         = wma_decode_superframe,
    .flush          = flush,
    .capabilities   = CODEC_CAP_DR1,
    .long_name      = NULL_IF_CONFIG_SMALL("Windows Media Audio 2"),
}

Definition at line 958 of file wmadec.c.

const float pow_tab[]

static

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

Definition at line 245 of file wmadec.c.

Macros

Functions

Variables

Detailed Description

Macro Definition Documentation

Function Documentation

Variable Documentation