apps/codecs/a52.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2005 Dave Chapman
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21
  22 #include "codeclib.h"
  23 #include <inttypes.h>  /* Needed by a52.h */
  24 #include <codecs/liba52/config-a52.h>
  25 #include <codecs/liba52/a52.h>
  26
  27 CODEC_HEADER
  28
  29 #define BUFFER_SIZE 4096
  30
  31 #define A52_SAMPLESPERFRAME (6*256)
  32
  33 static a52_state_t *state;
  34 static unsigned long samplesdone;
  35 static unsigned long frequency;
  36
  37 /* used outside liba52 */
  38 static uint8_t buf[3840] IBSS_ATTR;
  39
  40 static inline void output_audio(sample_t *samples)
  41 {
  42     ci->yield();
  43     ci->pcmbuf_insert(&samples[0], &samples[256], 256);
  44 }
  45
  46 static void a52_decode_data(uint8_t *start, uint8_t *end)
  47 {
  48     static uint8_t *bufptr = buf;
  49     static uint8_t *bufpos = buf + 7;
  50     /*
  51      * sample_rate and flags are static because this routine could
  52      * exit between the a52_syncinfo() and the ao_setup(), and we want
  53      * to have the same values when we get back !
  54      */
  55     static int sample_rate;
  56     static int flags;
  57     int bit_rate;
  58     int len;
  59
  60     while (1) {
  61         len = end - start;
  62         if (!len)
  63             break;
  64         if (len > bufpos - bufptr)
  65             len = bufpos - bufptr;
  66         memcpy(bufptr, start, len);
  67         bufptr += len;
  68         start += len;
  69         if (bufptr == bufpos) {
  70             if (bufpos == buf + 7) {
  71                 int length;
  72
  73                 length = a52_syncinfo(buf, &flags, &sample_rate, &bit_rate);
  74                 if (!length) {
  75                     //DEBUGF("skip\n");
  76                     for (bufptr = buf; bufptr < buf + 6; bufptr++)
  77                         bufptr[0] = bufptr[1];
  78                     continue;
  79                 }
  80                 bufpos = buf + length;
  81             } else {
  82                 /* Unity gain is 1 << 26, and we want to end up on 28 bits
  83                    of precision instead of the default 30.
  84                  */
  85                 level_t level = 1 << 24;
  86                 sample_t bias = 0;
  87                 int i;
  88
  89                 /* This is the configuration for the downmixing: */
  90                 flags = A52_STEREO | A52_ADJUST_LEVEL;
  91
  92                 if (a52_frame(state, buf, &flags, &level, bias))
  93                     goto error;
  94                 a52_dynrng(state, NULL, NULL);
  95                 frequency = sample_rate;
  96
  97                 /* An A52 frame consists of 6 blocks of 256 samples
  98                    So we decode and output them one block at a time */
  99                 for (i = 0; i < 6; i++) {
 100                     if (a52_block(state))
 101                         goto error;
 102                     output_audio(a52_samples(state));
 103                     samplesdone += 256;
 104                 }
 105                 ci->set_elapsed(samplesdone/(frequency/1000));
 106                 bufptr = buf;
 107                 bufpos = buf + 7;
 108                 continue;
 109             error:
 110                 //logf("Error decoding A52 stream\n");
 111                 bufptr = buf;
 112                 bufpos = buf + 7;
 113             }
 114         }
 115     }
 116 }
 117
 118 /* this is the codec entry point */
 119 enum codec_status codec_main(void)
 120 {
 121     size_t n;
 122     unsigned char *filebuf;
 123     int sample_loc;
 124     int retval;
 125
 126     /* Generic codec initialisation */
 127     ci->configure(DSP_SET_STEREO_MODE, STEREO_NONINTERLEAVED);
 128     ci->configure(DSP_SET_SAMPLE_DEPTH, 28);
 129
 130 next_track:
 131     if (codec_init()) {
 132         retval = CODEC_ERROR;
 133         goto exit;
 134     }
 135
 136     while (!ci->taginfo_ready)
 137         ci->yield();
 138
 139     ci->configure(DSP_SWITCH_FREQUENCY, ci->id3->frequency);
 140     codec_set_replaygain(ci->id3);
 141
 142     /* Intialise the A52 decoder and check for success */
 143     state = a52_init(0);
 144
 145     /* The main decoding loop */
 146     if (ci->id3->offset) {
 147         if (ci->seek_buffer(ci->id3->offset)) {
 148             samplesdone = (ci->id3->offset / ci->id3->bytesperframe) *
 149                 A52_SAMPLESPERFRAME;
 150             ci->set_elapsed(samplesdone/(ci->id3->frequency / 1000));
 151         }
 152     }
 153     else {
 154         samplesdone = 0;
 155     }
 156
 157     while (1) {
 158         if (ci->stop_codec || ci->new_track)
 159             break;
 160
 161         if (ci->seek_time) {
 162             sample_loc = (ci->seek_time - 1)/1000 * ci->id3->frequency;
 163
 164             if (ci->seek_buffer((sample_loc/A52_SAMPLESPERFRAME)*ci->id3->bytesperframe)) {
 165                 samplesdone = sample_loc;
 166                 ci->set_elapsed(samplesdone/(ci->id3->frequency/1000));
 167             }
 168             ci->seek_complete();
 169         }
 170
 171         filebuf = ci->request_buffer(&n, BUFFER_SIZE);
 172
 173         if (n == 0) /* End of Stream */
 174             break;
 175
 176         a52_decode_data(filebuf, filebuf + n);
 177         ci->advance_buffer(n);
 178     }
 179     retval = CODEC_OK;
 180
 181     if (ci->request_next_track())
 182         goto next_track;
 183
 184 exit:
 185     a52_free(state);
 186     return retval;
 187 }