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