libmpdemux/demux_aac.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4
   5 #include "config.h"
   6 #include "mp_msg.h"
   7 #include "help_mp.h"
   8
   9 #include "stream.h"
  10 #include "demuxer.h"
  11 #include "parse_es.h"
  12 #include "stheader.h"
  13
  14 #include "ms_hdr.h"
  15
  16 typedef struct {
  17         uint8_t *buf;
  18         uint64_t size;  /// amount of time of data packets pushed to demuxer->audio (in bytes)
  19         float time;     /// amount of time elapsed based upon samples_per_frame/sample_rate (in milliseconds)
  20         float last_pts; /// last pts seen
  21         int bitrate;    /// bitrate computed as size/time
  22 } aac_priv_t;
  23
  24 /// \param srate (out) sample rate
  25 /// \param num (out) number of audio frames in this ADTS frame
  26 /// \return size of the ADTS frame in bytes
  27 /// aac_parse_frames needs a buffer at least 8 bytes long
  28 int aac_parse_frame(uint8_t *buf, int *srate, int *num)
  29 {
  30         int i = 0, sr, fl = 0, id;
  31         static int srates[] = {96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050, 16000, 12000, 11025, 8000, 0, 0, 0};
  32
  33         if((buf[i] != 0xFF) || ((buf[i+1] & 0xF6) != 0xF0))
  34                 return 0;
  35
  36         id = (buf[i+1] >> 3) & 0x01;    //id=1 mpeg2, 0: mpeg4
  37         sr = (buf[i+2] >> 2)  & 0x0F;
  38         if(sr > 11)
  39                 return 0;
  40         *srate = srates[sr];
  41
  42         fl = ((buf[i+3] & 0x03) << 11) | (buf[i+4] << 3) | ((buf[i+5] >> 5) & 0x07);
  43         *num = (buf[i+6] & 0x02) + 1;
  44
  45         return fl;
  46 }
  47
  48 static int demux_aac_init(demuxer_t *demuxer)
  49 {
  50         aac_priv_t *priv;
  51
  52         priv = calloc(1, sizeof(aac_priv_t));
  53         if(!priv)
  54                 return 0;
  55
  56         priv->buf = (uint8_t*) malloc(8);
  57         if(!priv->buf)
  58         {
  59                 free(priv);
  60                 return 0;
  61         }
  62
  63         demuxer->priv = priv;
  64         return 1;
  65 }
  66
  67 static void demux_close_aac(demuxer_t *demuxer)
  68 {
  69         aac_priv_t *priv = (aac_priv_t *) demuxer->priv;
  70
  71         if(!priv)
  72                 return;
  73
  74         if(priv->buf)
  75                 free(priv->buf);
  76
  77         free(demuxer->priv);
  78
  79         return;
  80 }
  81
  82 /// returns DEMUXER_TYPE_AAC if it finds 8 ADTS frames in 32768 bytes, 0 otherwise
  83 static int demux_aac_probe(demuxer_t *demuxer)
  84 {
  85         int cnt = 0, c, len, srate, num;
  86         off_t init, probed;
  87         aac_priv_t *priv;
  88
  89         if(! demux_aac_init(demuxer))
  90         {
  91                 mp_msg(MSGT_DEMUX, MSGL_ERR, "COULDN'T INIT aac_demux, exit\n");
  92                 return 0;
  93         }
  94
  95         priv = (aac_priv_t *) demuxer->priv;
  96
  97         init = probed = stream_tell(demuxer->stream);
  98         while(probed-init <= 32768 && cnt < 8)
  99         {
 100                 c = 0;
 101                 while(c != 0xFF)
 102                 {
 103                         c = stream_read_char(demuxer->stream);
 104                         if(c < 0)
 105                                 goto fail;
 106                 }
 107                 priv->buf[0] = 0xFF;
 108                 if(stream_read(demuxer->stream, &(priv->buf[1]), 7) < 7)
 109                         goto fail;
 110
 111                 len = aac_parse_frame(priv->buf, &srate, &num);
 112                 if(len > 0)
 113                 {
 114                         cnt++;
 115                         stream_skip(demuxer->stream, len - 8);
 116                 }
 117                 probed = stream_tell(demuxer->stream);
 118         }
 119
 120         stream_seek(demuxer->stream, init);
 121         if(cnt < 8)
 122                 goto fail;
 123
 124         mp_msg(MSGT_DEMUX, MSGL_V, "demux_aac_probe, INIT: %"PRIu64", PROBED: %"PRIu64", cnt: %d\n", init, probed, cnt);
 125         return DEMUXER_TYPE_AAC;
 126
 127 fail:
 128         mp_msg(MSGT_DEMUX, MSGL_V, "demux_aac_probe, failed to detect an AAC stream\n");
 129         return 0;
 130 }
 131
 132 static demuxer_t* demux_aac_open(demuxer_t *demuxer)
 133 {
 134         sh_audio_t *sh;
 135
 136         sh = new_sh_audio(demuxer, 0);
 137         sh->ds = demuxer->audio;
 138         sh->format = mmioFOURCC('M', 'P', '4', 'A');
 139         demuxer->audio->sh = sh;
 140
 141         demuxer->filepos = stream_tell(demuxer->stream);
 142
 143         return demuxer;
 144 }
 145
 146 static int demux_aac_fill_buffer(demuxer_t *demuxer, demux_stream_t *ds)
 147 {
 148         aac_priv_t *priv = (aac_priv_t *) demuxer->priv;
 149         demux_packet_t *dp;
 150         int c1, c2, len, srate, num;
 151         float tm = 0;
 152
 153         if(demuxer->stream->eof || (demuxer->movi_end && stream_tell(demuxer->stream) >= demuxer->movi_end))
 154                 return 0;
 155
 156         while(! demuxer->stream->eof)
 157         {
 158                 c1 = c2 = 0;
 159                 while(c1 != 0xFF)
 160                 {
 161                         c1 = stream_read_char(demuxer->stream);
 162                         if(c1 < 0)
 163                                 return 0;
 164                 }
 165                 c2 = stream_read_char(demuxer->stream);
 166                 if(c2 < 0)
 167                         return 0;
 168                 if((c2 & 0xF6) != 0xF0)
 169                         continue;
 170
 171                 priv->buf[0] = (unsigned char) c1;
 172                 priv->buf[1] = (unsigned char) c2;
 173                 if(stream_read(demuxer->stream, &(priv->buf[2]), 6) < 6)
 174                         return 0;
 175
 176                 len = aac_parse_frame(priv->buf, &srate, &num);
 177                 if(len > 0)
 178                 {
 179                         dp = new_demux_packet(len);
 180                         if(! dp)
 181                         {
 182                                 mp_msg(MSGT_DEMUX, MSGL_ERR, "fill_buffer, NEW_ADD_PACKET(%d)FAILED\n", len);
 183                                 return 0;
 184                         }
 185
 186
 187                         memcpy(dp->buffer, priv->buf, 8);
 188                         stream_read(demuxer->stream, &(dp->buffer[8]), len-8);
 189                         if(srate)
 190                                 tm = (float) (num * 1024.0/srate);
 191                         priv->last_pts += tm;
 192                         dp->pts = priv->last_pts;
 193                         //fprintf(stderr, "\nPTS: %.3f\n", dp->pts);
 194                         ds_add_packet(demuxer->audio, dp);
 195                         priv->size += len;
 196                         priv->time += tm;
 197
 198                         priv->bitrate = (int) (priv->size / priv->time);
 199                         demuxer->filepos = stream_tell(demuxer->stream);
 200
 201                         return len;
 202                 }
 203                 else
 204                         stream_skip(demuxer->stream, -6);
 205         }
 206
 207         return 0;
 208 }
 209
 210
 211 //This is an almost verbatim copy of high_res_mp3_seek(), from demux_audio.c
 212 static void demux_aac_seek(demuxer_t *demuxer, float rel_seek_secs, float audio_delay, int flags)
 213 {
 214         aac_priv_t *priv = (aac_priv_t *) demuxer->priv;
 215         demux_stream_t *d_audio=demuxer->audio;
 216         sh_audio_t *sh_audio=d_audio->sh;
 217         float time;
 218
 219         ds_free_packs(d_audio);
 220
 221         time = (flags & 1) ? rel_seek_secs - priv->last_pts : rel_seek_secs;
 222         if(time < 0)
 223         {
 224                 stream_seek(demuxer->stream, demuxer->movi_start);
 225                 time = priv->last_pts + time;
 226                 priv->last_pts = 0;
 227         }
 228
 229         if(time > 0)
 230         {
 231                 int len, nf, srate, num;
 232
 233                 nf = time * sh_audio->samplerate/1024;
 234
 235                 while(nf > 0)
 236                 {
 237                         if(stream_read(demuxer->stream,priv->buf, 8) < 8)
 238                                 break;
 239                         len = aac_parse_frame(priv->buf, &srate, &num);
 240                         if(len <= 0)
 241                         {
 242                                 stream_skip(demuxer->stream, -7);
 243                                 continue;
 244                         }
 245                         stream_skip(demuxer->stream, len - 8);
 246                         priv->last_pts += (float) (num*1024.0/srate);
 247                         nf -= num;
 248                 }
 249         }
 250 }
 251
 252
 253 demuxer_desc_t demuxer_desc_aac = {
 254   "AAC demuxer",
 255   "aac",
 256   "AAC",
 257   "Nico Sabbi",
 258   "Raw AAC files ",
 259   DEMUXER_TYPE_AAC,
 260   0, // unsafe autodetect
 261   demux_aac_probe,
 262   demux_aac_fill_buffer,
 263   demux_aac_open,
 264   demux_close_aac,
 265   demux_aac_seek,
 266   NULL
 267 };