3 * Copyright (c) 2001 Fabrice Bellard.
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 #include "liba52/a52.h"
24 static const char* liba52name = "liba52.so.0";
28 * liba52 - Copyright (C) Aaron Holtzman
29 * released under the GPL license.
31 typedef struct AC3DecodeState {
32 UINT8 inbuf[4096]; /* input buffer */
41 * virtual method table
43 * using this function table so the liba52 doesn't
44 * have to be really linked together with ffmpeg
45 * and might be linked in runtime - this allows binary
46 * distribution of ffmpeg library which doens't depend
47 * on liba52 library - but if user has it installed
48 * it will be used - user might install such library
52 a52_state_t* (*a52_init)(uint32_t mm_accel);
53 sample_t* (*a52_samples)(a52_state_t * state);
54 int (*a52_syncinfo)(uint8_t * buf, int * flags,
55 int * sample_rate, int * bit_rate);
56 int (*a52_frame)(a52_state_t * state, uint8_t * buf, int * flags,
57 sample_t * level, sample_t bias);
58 void (*a52_dynrng)(a52_state_t * state,
59 sample_t (* call) (sample_t, void *), void * data);
60 int (*a52_block)(a52_state_t * state);
61 void (*a52_free)(a52_state_t * state);
66 static void* dlsymm(void* handle, const char* symbol)
68 void* f = dlsym(handle, symbol);
70 fprintf(stderr, "A52 Decoder - function '%s' can't be resolved\n", symbol);
75 static int a52_decode_init(AVCodecContext *avctx)
77 AC3DecodeState *s = avctx->priv_data;
80 s->handle = dlopen(liba52name, RTLD_LAZY);
83 fprintf(stderr, "A52 library %s could not be opened! \n%s\n", liba52name, dlerror());
86 s->a52_init = (a52_state_t* (*)(uint32_t)) dlsymm(s->handle, "a52_init");
87 s->a52_samples = (sample_t* (*)(a52_state_t*)) dlsymm(s->handle, "a52_samples");
88 s->a52_syncinfo = (int (*)(uint8_t*, int*, int*, int*)) dlsymm(s->handle, "a52_syncinfo");
89 s->a52_frame = (int (*)(a52_state_t*, uint8_t*, int*, sample_t*, sample_t)) dlsymm(s->handle, "a52_frame");
90 s->a52_block = (int (*)(a52_state_t*)) dlsymm(s->handle, "a52_block");
91 s->a52_free = (void (*)(a52_state_t*)) dlsymm(s->handle, "a52_free");
92 if (!s->a52_init || !s->a52_samples || !s->a52_syncinfo
93 || !s->a52_frame || !s->a52_block || !s->a52_free)
99 /* static linked version */
101 s->a52_init = ff_a52_init;
102 s->a52_samples = ff_a52_samples;
103 s->a52_syncinfo = ff_a52_syncinfo;
104 s->a52_frame = ff_a52_frame;
105 s->a52_block = ff_a52_block;
106 s->a52_free = ff_a52_free;
108 s->state = s->a52_init(0); /* later use CPU flags */
109 s->samples = s->a52_samples(s->state);
110 s->inbuf_ptr = s->inbuf;
116 /**** the following two functions comes from a52dec */
117 static inline int blah (int32_t i)
121 else if (i < 0x43bf8000)
123 return i - 0x43c00000;
126 static inline void float_to_int (float * _f, INT16 * s16, int nchannels)
129 int32_t * f = (int32_t *) _f; // XXX assumes IEEE float format
133 for (i = 0; i < 256; i++) {
134 for (c = 0; c < nchannels; c += 256)
135 s16[j++] = blah (f[i + c]);
141 #define HEADER_SIZE 7
143 static int a52_decode_frame(AVCodecContext *avctx,
144 void *data, int *data_size,
145 UINT8 *buf, int buf_size)
147 AC3DecodeState *s = avctx->priv_data;
150 int sample_rate, bit_rate;
151 short *out_samples = data;
153 static const int ac3_channels[8] = {
154 2, 1, 2, 3, 3, 4, 4, 5
159 while (buf_size > 0) {
160 len = s->inbuf_ptr - s->inbuf;
161 if (s->frame_size == 0) {
162 /* no header seen : find one. We need at least 7 bytes to parse it */
163 len = HEADER_SIZE - len;
166 memcpy(s->inbuf_ptr, buf_ptr, len);
170 if ((s->inbuf_ptr - s->inbuf) == HEADER_SIZE) {
171 len = s->a52_syncinfo(s->inbuf, &s->flags, &sample_rate, &bit_rate);
173 /* no sync found : move by one byte (inefficient, but simple!) */
174 memcpy(s->inbuf, s->inbuf + 1, HEADER_SIZE - 1);
178 /* update codec info */
179 avctx->sample_rate = sample_rate;
180 s->channels = ac3_channels[s->flags & 7];
181 if (s->flags & A52_LFE)
183 if (avctx->channels == 0)
184 /* No specific number of channel requested */
185 avctx->channels = s->channels;
186 else if (s->channels < avctx->channels) {
187 fprintf(stderr, "ac3dec: AC3 Source channels are less than specified: output to %d channels.. (frmsize: %d)\n", s->channels, len);
188 avctx->channels = s->channels;
190 avctx->bit_rate = bit_rate;
193 } else if (len < s->frame_size) {
194 len = s->frame_size - len;
198 memcpy(s->inbuf_ptr, buf_ptr, len);
204 if (avctx->channels == 1)
206 else if (avctx->channels == 2)
209 flags |= A52_ADJUST_LEVEL;
211 if (s->a52_frame(s->state, s->inbuf, &flags, &level, 384)) {
213 s->inbuf_ptr = s->inbuf;
217 for (i = 0; i < 6; i++) {
218 if (s->a52_block(s->state))
220 float_to_int(s->samples, out_samples + i * 256 * avctx->channels, avctx->channels);
222 s->inbuf_ptr = s->inbuf;
224 *data_size = 6 * avctx->channels * 256 * sizeof(INT16);
228 return buf_ptr - buf;
231 static int a52_decode_end(AVCodecContext *avctx)
233 AC3DecodeState *s = avctx->priv_data;
234 s->a52_free(s->state);
241 AVCodec ac3_decoder = {
245 sizeof(AC3DecodeState),