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