libavcodec/liba52.c

   1 /*
   2  * A52 decoder using liba52
   3  * Copyright (c) 2001 Fabrice Bellard.
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file a52dec.c
  24  * A52 decoder using liba52
  25  */
  26
  27 #include "avcodec.h"
  28 #include <a52dec/a52.h>
  29
  30 #ifdef CONFIG_LIBA52BIN
  31 #include <dlfcn.h>
  32 static const char* liba52name = "liba52.so.0";
  33 #endif
  34
  35 /**
  36  * liba52 - Copyright (C) Aaron Holtzman
  37  * released under the GPL license.
  38  */
  39 typedef struct AC3DecodeState {
  40     int flags;
  41     int channels;
  42     a52_state_t* state;
  43     sample_t* samples;
  44
  45     /*
  46      * virtual method table
  47      *
  48      * using this function table so the liba52 doesn't
  49      * have to be really linked together with ffmpeg
  50      * and might be linked in runtime - this allows binary
  51      * distribution of ffmpeg library which doens't depend
  52      * on liba52 library - but if user has it installed
  53      * it will be used - user might install such library
  54      * separately
  55      */
  56     void* handle;
  57     a52_state_t* (*a52_init)(uint32_t mm_accel);
  58     sample_t* (*a52_samples)(a52_state_t * state);
  59     int (*a52_syncinfo)(uint8_t * buf, int * flags,
  60                           int * sample_rate, int * bit_rate);
  61     int (*a52_frame)(a52_state_t * state, uint8_t * buf, int * flags,
  62                        sample_t * level, sample_t bias);
  63     void (*a52_dynrng)(a52_state_t * state,
  64                          sample_t (* call) (sample_t, void *), void * data);
  65     int (*a52_block)(a52_state_t * state);
  66     void (*a52_free)(a52_state_t * state);
  67
  68 } AC3DecodeState;
  69
  70 #ifdef CONFIG_LIBA52BIN
  71 static void* dlsymm(void* handle, const char* symbol)
  72 {
  73     void* f = dlsym(handle, symbol);
  74     if (!f)
  75         av_log( NULL, AV_LOG_ERROR, "A52 Decoder - function '%s' can't be resolved\n", symbol);
  76     return f;
  77 }
  78 #endif
  79
  80 static av_cold int a52_decode_init(AVCodecContext *avctx)
  81 {
  82     AC3DecodeState *s = avctx->priv_data;
  83
  84 #ifdef CONFIG_LIBA52BIN
  85     s->handle = dlopen(liba52name, RTLD_LAZY);
  86     if (!s->handle)
  87     {
  88         av_log( avctx, AV_LOG_ERROR, "A52 library %s could not be opened! \n%s\n", liba52name, dlerror());
  89         return -1;
  90     }
  91     s->a52_init = (a52_state_t* (*)(uint32_t)) dlsymm(s->handle, "a52_init");
  92     s->a52_samples = (sample_t* (*)(a52_state_t*)) dlsymm(s->handle, "a52_samples");
  93     s->a52_syncinfo = (int (*)(uint8_t*, int*, int*, int*)) dlsymm(s->handle, "a52_syncinfo");
  94     s->a52_frame = (int (*)(a52_state_t*, uint8_t*, int*, sample_t*, sample_t)) dlsymm(s->handle, "a52_frame");
  95     s->a52_block = (int (*)(a52_state_t*)) dlsymm(s->handle, "a52_block");
  96     s->a52_free = (void (*)(a52_state_t*)) dlsymm(s->handle, "a52_free");
  97     if (!s->a52_init || !s->a52_samples || !s->a52_syncinfo
  98         || !s->a52_frame || !s->a52_block || !s->a52_free)
  99     {
 100         dlclose(s->handle);
 101         return -1;
 102     }
 103 #else
 104     s->handle = 0;
 105     s->a52_init = a52_init;
 106     s->a52_samples = a52_samples;
 107     s->a52_syncinfo = a52_syncinfo;
 108     s->a52_frame = a52_frame;
 109     s->a52_block = a52_block;
 110     s->a52_free = a52_free;
 111 #endif
 112     s->state = s->a52_init(0); /* later use CPU flags */
 113     s->samples = s->a52_samples(s->state);
 114
 115     /* allow downmixing to stereo or mono */
 116     if (avctx->channels > 0 && avctx->request_channels > 0 &&
 117             avctx->request_channels < avctx->channels &&
 118             avctx->request_channels <= 2) {
 119         avctx->channels = avctx->request_channels;
 120     }
 121
 122     return 0;
 123 }
 124
 125 /**** the following function comes from a52dec */
 126 static inline void float_to_int (float * _f, int16_t * s16, int nchannels)
 127 {
 128     int i, j, c;
 129     int32_t * f = (int32_t *) _f;       // XXX assumes IEEE float format
 130
 131     j = 0;
 132     nchannels *= 256;
 133     for (i = 0; i < 256; i++) {
 134         for (c = 0; c < nchannels; c += 256)
 135             s16[j++] = av_clip_int16(f[i + c] - 0x43c00000);
 136     }
 137 }
 138
 139 /**** end */
 140
 141 #define HEADER_SIZE 7
 142
 143 static int a52_decode_frame(AVCodecContext *avctx,
 144                             void *data, int *data_size,
 145                             uint8_t *buf, int buf_size)
 146 {
 147     AC3DecodeState *s = avctx->priv_data;
 148     int flags, i, len;
 149     int sample_rate, bit_rate;
 150     short *out_samples = data;
 151     float level;
 152     static const int ac3_channels[8] = {
 153         2, 1, 2, 3, 3, 4, 4, 5
 154     };
 155
 156     *data_size= 0;
 157
 158     if (buf_size < HEADER_SIZE) {
 159         av_log(avctx, AV_LOG_ERROR, "Error decoding frame, not enough bytes for header\n");
 160         return -1;
 161     }
 162     len = s->a52_syncinfo(buf, &s->flags, &sample_rate, &bit_rate);
 163     if (len == 0) {
 164         av_log(avctx, AV_LOG_ERROR, "Error decoding frame, no sync byte at begin\n");
 165         return -1;
 166     }
 167     if (buf_size < len) {
 168         av_log(avctx, AV_LOG_ERROR, "Error decoding frame, not enough bytes\n");
 169         return -1;
 170     }
 171     /* update codec info */
 172     avctx->sample_rate = sample_rate;
 173     s->channels = ac3_channels[s->flags & 7];
 174     if (s->flags & A52_LFE)
 175             s->channels++;
 176     if (avctx->request_channels > 0 &&
 177         avctx->request_channels <= 2 &&
 178         avctx->request_channels < s->channels) {
 179         avctx->channels = avctx->request_channels;
 180     } else {
 181         avctx->channels = s->channels;
 182     }
 183     avctx->bit_rate = bit_rate;
 184     flags = s->flags;
 185     if (avctx->channels == 1)
 186         flags = A52_MONO;
 187     else if (avctx->channels == 2)
 188         flags = A52_STEREO;
 189     else
 190         flags |= A52_ADJUST_LEVEL;
 191     level = 1;
 192     if (s->a52_frame(s->state, buf, &flags, &level, 384)) {
 193     fail:
 194         av_log(avctx, AV_LOG_ERROR, "Error decoding frame\n");
 195         return -1;
 196     }
 197     for (i = 0; i < 6; i++) {
 198         if (s->a52_block(s->state))
 199             goto fail;
 200         float_to_int(s->samples, out_samples + i * 256 * avctx->channels, avctx->channels);
 201     }
 202     *data_size = 6 * avctx->channels * 256 * sizeof(int16_t);
 203     return len;
 204 }
 205
 206 static av_cold int a52_decode_end(AVCodecContext *avctx)
 207 {
 208     AC3DecodeState *s = avctx->priv_data;
 209     s->a52_free(s->state);
 210 #ifdef CONFIG_LIBA52BIN
 211     dlclose(s->handle);
 212 #endif
 213     return 0;
 214 }
 215
 216 AVCodec liba52_decoder = {
 217     "liba52",
 218     CODEC_TYPE_AUDIO,
 219     CODEC_ID_AC3,
 220     sizeof(AC3DecodeState),
 221     a52_decode_init,
 222     NULL,
 223     a52_decode_end,
 224     a52_decode_frame,
 225     .long_name = NULL_IF_CONFIG_SMALL("liba52 ATSC A/52 / AC-3"),
 226 };