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
26 #include "liba52/a52.h"
30 static const char* liba52name = "liba52.so.0";
34 * liba52 - Copyright (C) Aaron Holtzman
35 * released under the GPL license.
37 typedef struct AC3DecodeState {
38 uint8_t inbuf[4096]; /* input buffer */
47 * virtual method table
49 * using this function table so the liba52 doesn't
50 * have to be really linked together with ffmpeg
51 * and might be linked in runtime - this allows binary
52 * distribution of ffmpeg library which doens't depend
53 * on liba52 library - but if user has it installed
54 * it will be used - user might install such library
58 a52_state_t* (*a52_init)(uint32_t mm_accel);
59 sample_t* (*a52_samples)(a52_state_t * state);
60 int (*a52_syncinfo)(uint8_t * buf, int * flags,
61 int * sample_rate, int * bit_rate);
62 int (*a52_frame)(a52_state_t * state, uint8_t * buf, int * flags,
63 sample_t * level, sample_t bias);
64 void (*a52_dynrng)(a52_state_t * state,
65 sample_t (* call) (sample_t, void *), void * data);
66 int (*a52_block)(a52_state_t * state);
67 void (*a52_free)(a52_state_t * state);
72 static void* dlsymm(void* handle, const char* symbol)
74 void* f = dlsym(handle, symbol);
76 fprintf(stderr, "A52 Decoder - function '%s' can't be resolved\n", symbol);
81 static int a52_decode_init(AVCodecContext *avctx)
83 AC3DecodeState *s = avctx->priv_data;
86 s->handle = dlopen(liba52name, RTLD_LAZY);
89 fprintf(stderr, "A52 library %s could not be opened! \n%s\n", liba52name, dlerror());
92 s->a52_init = (a52_state_t* (*)(uint32_t)) dlsymm(s->handle, "a52_init");
93 s->a52_samples = (sample_t* (*)(a52_state_t*)) dlsymm(s->handle, "a52_samples");
94 s->a52_syncinfo = (int (*)(uint8_t*, int*, int*, int*)) dlsymm(s->handle, "a52_syncinfo");
95 s->a52_frame = (int (*)(a52_state_t*, uint8_t*, int*, sample_t*, sample_t)) dlsymm(s->handle, "a52_frame");
96 s->a52_block = (int (*)(a52_state_t*)) dlsymm(s->handle, "a52_block");
97 s->a52_free = (void (*)(a52_state_t*)) dlsymm(s->handle, "a52_free");
98 if (!s->a52_init || !s->a52_samples || !s->a52_syncinfo
99 || !s->a52_frame || !s->a52_block || !s->a52_free)
105 /* static linked version */
107 s->a52_init = a52_init;
108 s->a52_samples = a52_samples;
109 s->a52_syncinfo = a52_syncinfo;
110 s->a52_frame = a52_frame;
111 s->a52_block = a52_block;
112 s->a52_free = a52_free;
114 s->state = s->a52_init(0); /* later use CPU flags */
115 s->samples = s->a52_samples(s->state);
116 s->inbuf_ptr = s->inbuf;
122 /**** the following two functions comes from a52dec */
123 static inline int blah (int32_t i)
127 else if (i < 0x43bf8000)
129 return i - 0x43c00000;
132 static inline void float_to_int (float * _f, int16_t * s16, int nchannels)
135 int32_t * f = (int32_t *) _f; // XXX assumes IEEE float format
139 for (i = 0; i < 256; i++) {
140 for (c = 0; c < nchannels; c += 256)
141 s16[j++] = blah (f[i + c]);
147 #define HEADER_SIZE 7
149 static int a52_decode_frame(AVCodecContext *avctx,
150 void *data, int *data_size,
151 uint8_t *buf, int buf_size)
153 AC3DecodeState *s = avctx->priv_data;
156 int sample_rate, bit_rate;
157 short *out_samples = data;
159 static const int ac3_channels[8] = {
160 2, 1, 2, 3, 3, 4, 4, 5
164 while (buf_size > 0) {
165 len = s->inbuf_ptr - s->inbuf;
166 if (s->frame_size == 0) {
167 /* no header seen : find one. We need at least 7 bytes to parse it */
168 len = HEADER_SIZE - len;
171 memcpy(s->inbuf_ptr, buf_ptr, len);
175 if ((s->inbuf_ptr - s->inbuf) == HEADER_SIZE) {
176 len = s->a52_syncinfo(s->inbuf, &s->flags, &sample_rate, &bit_rate);
178 /* no sync found : move by one byte (inefficient, but simple!) */
179 memcpy(s->inbuf, s->inbuf + 1, HEADER_SIZE - 1);
183 /* update codec info */
184 avctx->sample_rate = sample_rate;
185 s->channels = ac3_channels[s->flags & 7];
186 if (s->flags & A52_LFE)
188 if (avctx->channels == 0)
189 /* No specific number of channel requested */
190 avctx->channels = s->channels;
191 else if (s->channels < avctx->channels) {
192 av_log(avctx, AV_LOG_ERROR, "ac3dec: AC3 Source channels are less than specified: output to %d channels.. (frmsize: %d)\n", s->channels, len);
193 avctx->channels = s->channels;
195 avctx->bit_rate = bit_rate;
198 } else if (len < s->frame_size) {
199 len = s->frame_size - len;
203 memcpy(s->inbuf_ptr, buf_ptr, len);
209 if (avctx->channels == 1)
211 else if (avctx->channels == 2)
214 flags |= A52_ADJUST_LEVEL;
216 if (s->a52_frame(s->state, s->inbuf, &flags, &level, 384)) {
218 s->inbuf_ptr = s->inbuf;
222 for (i = 0; i < 6; i++) {
223 if (s->a52_block(s->state))
225 float_to_int(s->samples, out_samples + i * 256 * avctx->channels, avctx->channels);
227 s->inbuf_ptr = s->inbuf;
229 *data_size = 6 * avctx->channels * 256 * sizeof(int16_t);
233 return buf_ptr - buf;
236 static int a52_decode_end(AVCodecContext *avctx)
238 AC3DecodeState *s = avctx->priv_data;
239 s->a52_free(s->state);
246 AVCodec ac3_decoder = {
250 sizeof(AC3DecodeState),