aac_afh.c

   1 /*
   2  * Copyright (C) 2006-2007 Andre Noll <maan@systemlinux.org>
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     This program is distributed in the hope that it will be useful,
  10  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *     GNU General Public License for more details.
  13  *
  14  *     You should have received a copy of the GNU General Public License
  15  *     along with this program; if not, write to the Free Software
  16  *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  17  */
  18 /*
  19  * based in parts on libfaad, Copyright (C) 2003-2005 M. Bakker,
  20  * Ahead Software AG
  21  */
  22
  23 /** \file aac_afh.c para_server's aac audio format handler */
  24
  25 #include "server.h"
  26 #include "error.h"
  27 #include "string.h"
  28 #include "aac.h"
  29
  30 static int aac_find_stsz(unsigned char *buf, size_t buflen, off_t *skip)
  31 {
  32         int i;
  33
  34         for (i = 0; i + 16 < buflen; i++) {
  35                 unsigned char *p = buf + i;
  36                 unsigned sample_count, sample_size;
  37
  38                 if (p[0] != 's' || p[1] != 't' || p[2] != 's' || p[3] != 'z')
  39                         continue;
  40                 PARA_INFO_LOG("found stsz@%d\n", i);
  41                 i += 8;
  42                 sample_size = aac_read_int32(buf + i);
  43                 PARA_INFO_LOG("sample size: %d\n", sample_size);
  44                 i += 4;
  45                 sample_count = aac_read_int32(buf + i);
  46                 i += 4;
  47                 PARA_INFO_LOG("sample count: %d\n", sample_count);
  48                 *skip = i;
  49                 return sample_count;
  50         }
  51         return -E_STSZ;
  52 }
  53
  54 static ssize_t aac_compute_chunk_table(struct audio_format_info *afi,
  55                 unsigned char *map, size_t numbytes)
  56 {
  57         int ret, i;
  58         size_t sum = 0;
  59         off_t skip;
  60
  61         ret = aac_find_stsz(map, numbytes, &skip);
  62         if (ret < 0)
  63                 return ret;
  64         afi->chunks_total = ret;
  65         PARA_INFO_LOG("sz table has %lu entries\n", afi->chunks_total);
  66         afi->chunk_table = para_malloc((afi->chunks_total + 1) * sizeof(size_t));
  67         for (i = 1; i <= afi->chunks_total; i++) {
  68                 if (skip + 4 > numbytes)
  69                         break;
  70                 sum += aac_read_int32(map + skip);
  71                 afi->chunk_table[i] = sum;
  72                 skip += 4;
  73 //              if (i < 10 || i + 10 > afi->chunks_total)
  74 //                      PARA_DEBUG_LOG("offset #%d: %zu\n", i, afi->chunk_table[i]);
  75         }
  76         return skip;
  77 }
  78
  79 static int aac_set_chunk_tv(struct audio_format_info *afi,
  80                 mp4AudioSpecificConfig *mp4ASC, long unsigned *seconds)
  81 {
  82         float tmp = mp4ASC->sbr_present_flag == 1? 2047 : 1023;
  83         struct timeval total;
  84         long unsigned ms = 1000.0 * afi->chunks_total * tmp
  85                 / mp4ASC->samplingFrequency;
  86
  87         if (!mp4ASC->samplingFrequency)
  88                 return -E_MP4ASC;
  89         ms = 1000.0 * afi->chunks_total * tmp / mp4ASC->samplingFrequency;
  90         ms2tv(ms, &total);
  91         tv_divide(afi->chunks_total, &total, &afi->chunk_tv);
  92         PARA_INFO_LOG("%luHz, %lus (%lu x %lums)\n",
  93                 mp4ASC->samplingFrequency, ms / 1000,
  94                 afi->chunks_total, tv2ms(&afi->chunk_tv));
  95         if (ms < 1000)
  96                 return -E_MP4ASC;
  97         *seconds = ms / 1000;
  98         return 1;
  99 }
 100
 101 /*
 102  * Init m4a file and write some tech data to given pointers.
 103  */
 104 static int aac_get_file_info(char *map, size_t numbytes,
 105                 struct audio_format_info *afi)
 106 {
 107         int i;
 108         size_t skip;
 109         ssize_t ret;
 110         unsigned long rate = 0, decoder_len;
 111         unsigned char channels = 0;
 112         mp4AudioSpecificConfig mp4ASC;
 113         NeAACDecHandle handle;
 114         unsigned char *umap = (unsigned char *) map;
 115
 116         ret = aac_find_esds(umap, numbytes, &skip);
 117         if (ret < 0)
 118                 goto out;
 119         decoder_len = ret;
 120         handle = aac_open();
 121         ret = -E_AACDEC_INIT;
 122         if (NeAACDecInit(handle, umap + skip, decoder_len, &rate, &channels))
 123                 goto out;
 124         if (!channels)
 125                 goto out;
 126         PARA_INFO_LOG("rate: %lu, channels: %d\n", rate, channels);
 127         ret = -E_MP4ASC;
 128         if (NeAACDecAudioSpecificConfig(umap + skip, numbytes - skip, &mp4ASC))
 129                 goto out;
 130         if (!mp4ASC.samplingFrequency)
 131                 goto out;
 132         ret = aac_compute_chunk_table(afi, umap, numbytes);
 133         if (ret < 0)
 134                 goto out;
 135         skip = ret;
 136         ret = aac_set_chunk_tv(afi, &mp4ASC, &afi->seconds_total);
 137         if (ret < 0)
 138                 goto out;
 139         ret = aac_find_entry_point(umap + skip, numbytes - skip, &skip);
 140         if (ret < 0)
 141                 goto out;
 142         afi->chunk_table[0] = ret;
 143         for (i = 1; i<= afi->chunks_total; i++)
 144                 afi->chunk_table[i] += ret;
 145         afi->channels = channels;
 146         afi->frequency = rate;
 147         ret = (afi->chunk_table[afi->chunks_total] - afi->chunk_table[0]) * 8; /* bits */
 148         ret += (channels * afi->seconds_total * 500); /* avoid rounding error */
 149         afi->bitrate = ret / (channels * afi->seconds_total * 1000);
 150         sprintf(afi->info_string, "audio_file_info1:%lu x %lums, "
 151                 "%uHz, %d channel%s, %ukb/s\n"
 152                 "audio_file_info2:\n"
 153                 "audio_file_info3:\n",
 154                 afi->chunks_total, tv2ms(&afi->chunk_tv),
 155                 afi->frequency, channels, channels == 1? "" : "s", afi->bitrate
 156         );
 157         tv_scale(20, &afi->chunk_tv, &afi->eof_tv);
 158         ret = 1;
 159 out:
 160         return ret;
 161 }
 162
 163 static const char* aac_suffixes[] = {"m4a", "mp4", NULL};
 164 /**
 165  * the init function of the aac audio format handler
 166  *
 167  * \param afh pointer to the struct to initialize
 168  */
 169 void aac_afh_init(struct audio_format_handler *afh)
 170 {
 171         afh->get_file_info = aac_get_file_info,
 172         afh->suffixes = aac_suffixes;
 173 }