FFmpeg
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WMA compatible decoder. More...
#include "libavutil/attributes.h"
#include "avcodec.h"
#include "internal.h"
#include "wma.h"
#include <assert.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. | |
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, 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 | |
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.
#define EXPVLCBITS 8 |
Definition at line 44 of file wmadec.c.
Referenced by decode_exp_vlc(), and wma_decode_init().
#define EXPMAX ((19+EXPVLCBITS-1)/EXPVLCBITS) |
Definition at line 45 of file wmadec.c.
Referenced by decode_exp_vlc().
#define HGAINVLCBITS 9 |
Definition at line 47 of file wmadec.c.
Referenced by wma_decode_block(), and wma_decode_init().
#define HGAINMAX ((13+HGAINVLCBITS-1)/HGAINVLCBITS) |
Definition at line 48 of file wmadec.c.
Referenced by wma_decode_block().
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Definition at line 154 of file wmadec.c.
Referenced by wma_decode_init().
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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 135 of file wmadec.c.
Referenced by wma_lsp_to_curve().
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NOTE: We use the same code as Vorbis here.
Definition at line 186 of file wmadec.c.
Referenced by decode_exp_lsp().
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decode exponents coded with LSP coefficients (same idea as Vorbis)
Definition at line 216 of file wmadec.c.
Referenced by wma_decode_block().
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decode exponents coded with VLC codes
Definition at line 318 of file wmadec.c.
Referenced by wma_decode_block().
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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 382 of file wmadec.c.
Referenced by wma_decode_block().
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Definition at line 434 of file wmadec.c.
Referenced by wma_decode_frame().
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Definition at line 767 of file wmadec.c.
Referenced by wma_decode_superframe().
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