aac_afh.c

   1 /*
   2  * Copyright (C) 2006-2007 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6 /*
   7  * based in parts on libfaad, Copyright (C) 2003-2005 M. Bakker,
   8  * Ahead Software AG
   9  */
  10
  11 /** \file aac_afh.c para_server's aac audio format handler */
  12
  13 #include "para.h"
  14 #include "afh.h"
  15 #include "server.h"
  16 #include "error.h"
  17 #include "string.h"
  18 #include "aac.h"
  19
  20 static int aac_find_stsz(unsigned char *buf, size_t buflen, off_t *skip)
  21 {
  22         int i;
  23
  24         for (i = 0; i + 16 < buflen; i++) {
  25                 unsigned char *p = buf + i;
  26                 unsigned sample_count, sample_size;
  27
  28                 if (p[0] != 's' || p[1] != 't' || p[2] != 's' || p[3] != 'z')
  29                         continue;
  30                 PARA_DEBUG_LOG("found stsz@%d\n", i);
  31                 i += 8;
  32                 sample_size = aac_read_int32(buf + i);
  33                 PARA_DEBUG_LOG("sample size: %d\n", sample_size);
  34                 i += 4;
  35                 sample_count = aac_read_int32(buf + i);
  36                 i += 4;
  37                 PARA_DEBUG_LOG("sample count: %d\n", sample_count);
  38                 *skip = i;
  39                 return sample_count;
  40         }
  41         return -E_STSZ;
  42 }
  43
  44 static ssize_t aac_compute_chunk_table(struct audio_format_info *afi,
  45                 unsigned char *map, size_t numbytes)
  46 {
  47         int ret, i;
  48         size_t sum = 0;
  49         off_t skip;
  50
  51         ret = aac_find_stsz(map, numbytes, &skip);
  52         if (ret < 0)
  53                 return ret;
  54         afi->chunks_total = ret;
  55         PARA_DEBUG_LOG("sz table has %lu entries\n", afi->chunks_total);
  56         afi->chunk_table = para_malloc((afi->chunks_total + 1) * sizeof(size_t));
  57         for (i = 1; i <= afi->chunks_total; i++) {
  58                 if (skip + 4 > numbytes)
  59                         break;
  60                 sum += aac_read_int32(map + skip);
  61                 afi->chunk_table[i] = sum;
  62                 skip += 4;
  63 //              if (i < 10 || i + 10 > afi->chunks_total)
  64 //                      PARA_DEBUG_LOG("offset #%d: %zu\n", i, afi->chunk_table[i]);
  65         }
  66         return skip;
  67 }
  68
  69 static int aac_set_chunk_tv(struct audio_format_info *afi,
  70                 mp4AudioSpecificConfig *mp4ASC, long unsigned *seconds)
  71 {
  72         float tmp = mp4ASC->sbr_present_flag == 1? 2047 : 1023;
  73         struct timeval total;
  74         long unsigned ms = 1000.0 * afi->chunks_total * tmp
  75                 / mp4ASC->samplingFrequency;
  76
  77         if (!mp4ASC->samplingFrequency)
  78                 return -E_MP4ASC;
  79         ms = 1000.0 * afi->chunks_total * tmp / mp4ASC->samplingFrequency;
  80         ms2tv(ms, &total);
  81         tv_divide(afi->chunks_total, &total, &afi->chunk_tv);
  82         PARA_INFO_LOG("%luHz, %lus (%lu x %lums)\n",
  83                 mp4ASC->samplingFrequency, ms / 1000,
  84                 afi->chunks_total, tv2ms(&afi->chunk_tv));
  85         if (ms < 1000)
  86                 return -E_MP4ASC;
  87         *seconds = ms / 1000;
  88         return 1;
  89 }
  90
  91 /*
  92  * Init m4a file and write some tech data to given pointers.
  93  */
  94 static int aac_get_file_info(char *map, size_t numbytes,
  95                 struct audio_format_info *afi)
  96 {
  97         int i;
  98         size_t skip;
  99         ssize_t ret;
 100         unsigned long rate = 0, decoder_len;
 101         unsigned char channels = 0;
 102         mp4AudioSpecificConfig mp4ASC;
 103         NeAACDecHandle handle = NULL;
 104         unsigned char *umap = (unsigned char *) map;
 105
 106         ret = aac_find_esds(umap, numbytes, &skip, &decoder_len);
 107         if (ret < 0)
 108                 goto out;
 109         handle = aac_open();
 110         ret = -E_AAC_AFH_INIT;
 111         if (NeAACDecInit(handle, umap + skip, decoder_len, &rate, &channels))
 112                 goto out;
 113         if (!channels)
 114                 goto out;
 115         PARA_DEBUG_LOG("rate: %lu, channels: %d\n", rate, channels);
 116         ret = -E_MP4ASC;
 117         if (NeAACDecAudioSpecificConfig(umap + skip, numbytes - skip, &mp4ASC))
 118                 goto out;
 119         if (!mp4ASC.samplingFrequency)
 120                 goto out;
 121         ret = aac_compute_chunk_table(afi, umap, numbytes);
 122         if (ret < 0)
 123                 goto out;
 124         skip = ret;
 125         ret = aac_set_chunk_tv(afi, &mp4ASC, &afi->seconds_total);
 126         if (ret < 0)
 127                 goto out;
 128         ret = aac_find_entry_point(umap + skip, numbytes - skip, &skip);
 129         if (ret < 0)
 130                 goto out;
 131         afi->chunk_table[0] = ret;
 132         for (i = 1; i<= afi->chunks_total; i++)
 133                 afi->chunk_table[i] += ret;
 134         afi->channels = channels;
 135         afi->frequency = rate;
 136         ret = (afi->chunk_table[afi->chunks_total] - afi->chunk_table[0]) * 8; /* bits */
 137         ret += (channels * afi->seconds_total * 500); /* avoid rounding error */
 138         afi->bitrate = ret / (channels * afi->seconds_total * 1000);
 139         sprintf(afi->info_string, "audio_file_info1:%lu x %lums, "
 140                 "%uHz, %d channel%s, %ukb/s\n"
 141                 "audio_file_info2:\n"
 142                 "audio_file_info3:\n",
 143                 afi->chunks_total, tv2ms(&afi->chunk_tv),
 144                 afi->frequency, channels, channels == 1? "" : "s", afi->bitrate
 145         );
 146         tv_scale(20, &afi->chunk_tv, &afi->eof_tv);
 147         ret = 1;
 148 out:
 149         if (handle)
 150                 NeAACDecClose(handle);
 151         return ret;
 152 }
 153
 154 static const char* aac_suffixes[] = {"m4a", "mp4", NULL};
 155 /**
 156  * the init function of the aac audio format handler
 157  *
 158  * \param afh pointer to the struct to initialize
 159  */
 160 void aac_afh_init(struct audio_format_handler *afh)
 161 {
 162         afh->get_file_info = aac_get_file_info,
 163         afh->suffixes = aac_suffixes;
 164 }