extern/ffmpeg/libavcodec/a52dec.c

   1 /*
   2  * A52 decoder
   3  * Copyright (c) 2001 Fabrice Bellard.
   4  *
   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.
   9  *
  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.
  14  *
  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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20 /**
  21  * @file a52dec.c
  22  * A52 decoder.
  23  */
  24
  25 #include "avcodec.h"
  26 #include "liba52/a52.h"
  27
  28 #ifdef CONFIG_A52BIN
  29 #include <dlfcn.h>
  30 static const char* liba52name = "liba52.so.0";
  31 #endif
  32
  33 /**
  34  * liba52 - Copyright (C) Aaron Holtzman
  35  * released under the GPL license.
  36  */
  37 typedef struct AC3DecodeState {
  38     uint8_t inbuf[4096]; /* input buffer */
  39     uint8_t *inbuf_ptr;
  40     int frame_size;
  41     int flags;
  42     int channels;
  43     a52_state_t* state;
  44     sample_t* samples;
  45
  46     /*
  47      * virtual method table
  48      *
  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
  55      * separately
  56      */
  57     void* handle;
  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);
  68
  69 } AC3DecodeState;
  70
  71 #ifdef CONFIG_A52BIN
  72 static void* dlsymm(void* handle, const char* symbol)
  73 {
  74     void* f = dlsym(handle, symbol);
  75     if (!f)
  76         av_log( NULL, AV_LOG_ERROR, "A52 Decoder - function '%s' can't be resolved\n", symbol);
  77     return f;
  78 }
  79 #endif
  80
  81 static int a52_decode_init(AVCodecContext *avctx)
  82 {
  83     AC3DecodeState *s = avctx->priv_data;
  84
  85 #ifdef CONFIG_A52BIN
  86     s->handle = dlopen(liba52name, RTLD_LAZY);
  87     if (!s->handle)
  88     {
  89         av_log( avctx, AV_LOG_ERROR, "A52 library %s could not be opened! \n%s\n", liba52name, dlerror());
  90         return -1;
  91     }
  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)
 100     {
 101         dlclose(s->handle);
 102         return -1;
 103     }
 104 #else
 105     /* static linked version */
 106     s->handle = 0;
 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;
 113 #endif
 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;
 117     s->frame_size = 0;
 118
 119     return 0;
 120 }
 121
 122 /**** the following two functions comes from a52dec */
 123 static inline int blah (int32_t i)
 124 {
 125     if (i > 0x43c07fff)
 126         return 32767;
 127     else if (i < 0x43bf8000)
 128         return -32768;
 129     return i - 0x43c00000;
 130 }
 131
 132 static inline void float_to_int (float * _f, int16_t * s16, int nchannels)
 133 {
 134     int i, j, c;
 135     int32_t * f = (int32_t *) _f;       // XXX assumes IEEE float format
 136
 137     j = 0;
 138     nchannels *= 256;
 139     for (i = 0; i < 256; i++) {
 140         for (c = 0; c < nchannels; c += 256)
 141             s16[j++] = blah (f[i + c]);
 142     }
 143 }
 144
 145 /**** end */
 146
 147 #define HEADER_SIZE 7
 148
 149 static int a52_decode_frame(AVCodecContext *avctx,
 150                             void *data, int *data_size,
 151                             uint8_t *buf, int buf_size)
 152 {
 153     AC3DecodeState *s = avctx->priv_data;
 154     uint8_t *buf_ptr;
 155     int flags, i, len;
 156     int sample_rate, bit_rate;
 157     short *out_samples = data;
 158     float level;
 159     static const int ac3_channels[8] = {
 160         2, 1, 2, 3, 3, 4, 4, 5
 161     };
 162
 163     buf_ptr = buf;
 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;
 169             if (len > buf_size)
 170                 len = buf_size;
 171             memcpy(s->inbuf_ptr, buf_ptr, len);
 172             buf_ptr += len;
 173             s->inbuf_ptr += len;
 174             buf_size -= len;
 175             if ((s->inbuf_ptr - s->inbuf) == HEADER_SIZE) {
 176                 len = s->a52_syncinfo(s->inbuf, &s->flags, &sample_rate, &bit_rate);
 177                 if (len == 0) {
 178                     /* no sync found : move by one byte (inefficient, but simple!) */
 179                     memcpy(s->inbuf, s->inbuf + 1, HEADER_SIZE - 1);
 180                     s->inbuf_ptr--;
 181                 } else {
 182                     s->frame_size = len;
 183                     /* update codec info */
 184                     avctx->sample_rate = sample_rate;
 185                     s->channels = ac3_channels[s->flags & 7];
 186                     if (s->flags & A52_LFE)
 187                         s->channels++;
 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;
 194                     }
 195                     avctx->bit_rate = bit_rate;
 196                 }
 197             }
 198         } else if (len < s->frame_size) {
 199             len = s->frame_size - len;
 200             if (len > buf_size)
 201                 len = buf_size;
 202
 203             memcpy(s->inbuf_ptr, buf_ptr, len);
 204             buf_ptr += len;
 205             s->inbuf_ptr += len;
 206             buf_size -= len;
 207         } else {
 208             flags = s->flags;
 209             if (avctx->channels == 1)
 210                 flags = A52_MONO;
 211             else if (avctx->channels == 2)
 212                 flags = A52_STEREO;
 213             else
 214                 flags |= A52_ADJUST_LEVEL;
 215             level = 1;
 216             if (s->a52_frame(s->state, s->inbuf, &flags, &level, 384)) {
 217             fail:
 218                 s->inbuf_ptr = s->inbuf;
 219                 s->frame_size = 0;
 220                 continue;
 221             }
 222             for (i = 0; i < 6; i++) {
 223                 if (s->a52_block(s->state))
 224                     goto fail;
 225                 float_to_int(s->samples, out_samples + i * 256 * avctx->channels, avctx->channels);
 226             }
 227             s->inbuf_ptr = s->inbuf;
 228             s->frame_size = 0;
 229             *data_size = 6 * avctx->channels * 256 * sizeof(int16_t);
 230             break;
 231         }
 232     }
 233     return buf_ptr - buf;
 234 }
 235
 236 static int a52_decode_end(AVCodecContext *avctx)
 237 {
 238     AC3DecodeState *s = avctx->priv_data;
 239     s->a52_free(s->state);
 240 #ifdef CONFIG_A52BIN
 241     dlclose(s->handle);
 242 #endif
 243     return 0;
 244 }
 245
 246 AVCodec ac3_decoder = {
 247     "ac3",
 248     CODEC_TYPE_AUDIO,
 249     CODEC_ID_AC3,
 250     sizeof(AC3DecodeState),
 251     a52_decode_init,
 252     NULL,
 253     a52_decode_end,
 254     a52_decode_frame,
 255 };