2 * copyright (c) 2001 Fabrice Bellard
4 * This file is part of FFmpeg.
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 * mpeg audio declarations for both encoder and decoder.
30 #include "bitstream.h"
33 /* max frame size, in samples */
34 #define MPA_FRAME_SIZE 1152
36 /* max compressed frame size */
37 #define MPA_MAX_CODED_FRAME_SIZE 1792
39 #define MPA_MAX_CHANNELS 2
41 #define SBLIMIT 32 /* number of subbands */
48 /* header + layer + bitrate + freq + lsf/mpeg25 */
49 #define SAME_HEADER_MASK \
50 (0xffe00000 | (3 << 17) | (0xf << 12) | (3 << 10) | (3 << 19))
52 #define MP3_MASK 0xFFFE0CCF
54 /* define USE_HIGHPRECISION to have a bit exact (but slower) mpeg
57 #ifdef USE_HIGHPRECISION
58 #define FRAC_BITS 23 /* fractional bits for sb_samples and dct */
59 #define WFRAC_BITS 16 /* fractional bits for window */
61 #define FRAC_BITS 15 /* fractional bits for sb_samples and dct */
62 #define WFRAC_BITS 14 /* fractional bits for window */
65 #if defined(USE_HIGHPRECISION) && defined(CONFIG_AUDIO_NONSHORT)
66 typedef int32_t OUT_INT;
67 #define OUT_MAX INT32_MAX
68 #define OUT_MIN INT32_MIN
69 #define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 31)
71 typedef int16_t OUT_INT;
72 #define OUT_MAX INT16_MAX
73 #define OUT_MIN INT16_MIN
74 #define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 15)
78 typedef int16_t MPA_INT;
80 typedef int32_t MPA_INT;
83 #define BACKSTEP_SIZE 512
88 typedef struct MPADecodeContext {
89 DECLARE_ALIGNED_8(uint8_t, last_buf[2*BACKSTEP_SIZE + EXTRABYTES]);
92 /* next header (used in free format parsing) */
93 uint32_t free_format_next_header;
97 int sample_rate_index; /* between 0 and 8 */
105 DECLARE_ALIGNED_16(MPA_INT, synth_buf[MPA_MAX_CHANNELS][512 * 2]);
106 int synth_buf_offset[MPA_MAX_CHANNELS];
107 DECLARE_ALIGNED_16(int32_t, sb_samples[MPA_MAX_CHANNELS][36][SBLIMIT]);
108 int32_t mdct_buf[MPA_MAX_CHANNELS][SBLIMIT * 18]; /* previous samples, for layer 3 MDCT */
112 void (*compute_antialias)(struct MPADecodeContext *s, struct GranuleDef *g);
113 int adu_mode; ///< 0 for standard mp3, 1 for adu formatted mp3
115 int error_resilience;
116 AVCodecContext* avctx;
119 int ff_mpa_l2_select_table(int bitrate, int nb_channels, int freq, int lsf);
120 int ff_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate);
121 void ff_mpa_synth_init(MPA_INT *window);
122 void ff_mpa_synth_filter(MPA_INT *synth_buf_ptr, int *synth_buf_offset,
123 MPA_INT *window, int *dither_state,
124 OUT_INT *samples, int incr,
125 int32_t sb_samples[SBLIMIT]);
127 /* fast header check for resync */
128 static inline int ff_mpa_check_header(uint32_t header){
130 if ((header & 0xffe00000) != 0xffe00000)
133 if ((header & (3<<17)) == 0)
136 if ((header & (0xf<<12)) == 0xf<<12)
139 if ((header & (3<<10)) == 3<<10)
144 #endif /* MPEGAUDIO_H */