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 "bswap.h"
  15 #include "ms_hdr.h"
  16
  17 typedef struct {
  18         uint8_t *buf;
  19         uint64_t size;  /// amount of time of data packets pushed to demuxer->audio (in bytes)
  20         float time;     /// amount of time elapsed based upon samples_per_frame/sample_rate (in milliseconds)
  21         float last_pts; /// last pts seen
  22         int bitrate;    /// bitrate computed as size/time
  23 } aac_priv_t;
  24
  25 /// \param srate (out) sample rate
  26 /// \param num (out) number of audio frames in this ADTS frame
  27 /// \return size of the ADTS frame in bytes
  28 /// aac_parse_frames needs a buffer at least 8 bytes long
  29 int aac_parse_frame(uint8_t *buf, int *srate, int *num)
  30 {
  31         int i = 0, sr, fl = 0, id;
  32         static int srates[] = {96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050, 16000, 12000, 11025, 8000, 0, 0, 0};
  33
  34         if((buf[i] != 0xFF) || ((buf[i+1] & 0xF6) != 0xF0))
  35                 return 0;
  36
  37         id = (buf[i+1] >> 3) & 0x01;    //id=1 mpeg2, 0: mpeg4
  38         sr = (buf[i+2] >> 2)  & 0x0F;
  39         if(sr > 11)
  40                 return 0;
  41         *srate = srates[sr];
  42
  43         fl = ((buf[i+3] & 0x03) << 11) | (buf[i+4] << 3) | ((buf[i+5] >> 5) & 0x07);
  44         *num = (buf[i+6] & 0x02) + 1;
  45
  46         return fl;
  47 }
  48
  49 static int demux_aac_init(demuxer_t *demuxer)
  50 {
  51         aac_priv_t *priv;
  52
  53         priv = calloc(1, sizeof(aac_priv_t));
  54         if(!priv)
  55                 return 0;
  56
  57         priv->buf = (uint8_t*) malloc(8);
  58         if(!priv->buf)
  59         {
  60                 free(priv);
  61                 return 0;
  62         }
  63
  64         demuxer->priv = priv;
  65         return 1;
  66 }
  67
  68 static void demux_close_aac(demuxer_t *demuxer)
  69 {
  70         aac_priv_t *priv = (aac_priv_t *) demuxer->priv;
  71
  72         if(!priv)
  73                 return;
  74
  75         if(priv->buf)
  76                 free(priv->buf);
  77
  78         free(demuxer->priv);
  79
  80         return;
  81 }
  82
  83 /// returns DEMUXER_TYPE_AAC if it finds 8 ADTS frames in 32768 bytes, 0 otherwise
  84 static int demux_aac_probe(demuxer_t *demuxer)
  85 {
  86         int cnt = 0, c, len, srate, num;
  87         off_t init, probed;
  88         aac_priv_t *priv;
  89
  90         if(! demux_aac_init(demuxer))
  91         {
  92                 mp_msg(MSGT_DEMUX, MSGL_ERR, "COULDN'T INIT aac_demux, exit\n");
  93                 return 0;
  94         }
  95
  96         priv = (aac_priv_t *) demuxer->priv;
  97
  98         init = probed = stream_tell(demuxer->stream);
  99         while(probed-init <= 32768 && cnt < 8)
 100         {
 101                 c = 0;
 102                 while(c != 0xFF)
 103                 {
 104                         c = stream_read_char(demuxer->stream);
 105                         if(c < 0)
 106                                 goto fail;
 107                 }
 108                 priv->buf[0] = 0xFF;
 109                 if(stream_read(demuxer->stream, &(priv->buf[1]), 7) < 7)
 110                         goto fail;
 111
 112                 len = aac_parse_frame(priv->buf, &srate, &num);
 113                 if(len > 0)
 114                 {
 115                         cnt++;
 116                         stream_skip(demuxer->stream, len - 8);
 117                 }
 118                 probed = stream_tell(demuxer->stream);
 119         }
 120
 121         stream_seek(demuxer->stream, init);
 122         if(cnt < 8)
 123                 goto fail;
 124
 125         mp_msg(MSGT_DEMUX, MSGL_V, "demux_aac_probe, INIT: %"PRIu64", PROBED: %"PRIu64", cnt: %d\n", init, probed, cnt);
 126         return DEMUXER_TYPE_AAC;
 127
 128 fail:
 129         mp_msg(MSGT_DEMUX, MSGL_V, "demux_aac_probe, failed to detect an AAC stream\n");
 130         return 0;
 131 }
 132
 133 static demuxer_t* demux_aac_open(demuxer_t *demuxer)
 134 {
 135         sh_audio_t *sh;
 136
 137         sh = new_sh_audio(demuxer, 0);
 138         sh->ds = demuxer->audio;
 139         sh->format = mmioFOURCC('M', 'P', '4', 'A');
 140         demuxer->audio->sh = sh;
 141
 142         demuxer->filepos = stream_tell(demuxer->stream);
 143
 144         return demuxer;
 145 }
 146
 147 static int demux_aac_fill_buffer(demuxer_t *demuxer, demux_stream_t *ds)
 148 {
 149         aac_priv_t *priv = (aac_priv_t *) demuxer->priv;
 150         demux_packet_t *dp;
 151         int c1, c2, len, srate, num;
 152         float tm = 0;
 153
 154         if(demuxer->stream->eof || (demuxer->movi_end && stream_tell(demuxer->stream) >= demuxer->movi_end))
 155                 return 0;
 156
 157         while(! demuxer->stream->eof)
 158         {
 159                 c1 = c2 = 0;
 160                 while(c1 != 0xFF)
 161                 {
 162                         c1 = stream_read_char(demuxer->stream);
 163                         if(c1 < 0)
 164                                 return 0;
 165                 }
 166                 c2 = stream_read_char(demuxer->stream);
 167                 if(c2 < 0)
 168                         return 0;
 169                 if((c2 & 0xF6) != 0xF0)
 170                         continue;
 171
 172                 priv->buf[0] = (unsigned char) c1;
 173                 priv->buf[1] = (unsigned char) c2;
 174                 if(stream_read(demuxer->stream, &(priv->buf[2]), 6) < 6)
 175                         return 0;
 176
 177                 len = aac_parse_frame(priv->buf, &srate, &num);
 178                 if(len > 0)
 179                 {
 180                         dp = new_demux_packet(len);
 181                         if(! dp)
 182                         {
 183                                 mp_msg(MSGT_DEMUX, MSGL_ERR, "fill_buffer, NEW_ADD_PACKET(%d)FAILED\n", len);
 184                                 return 0;
 185                         }
 186
 187
 188                         memcpy(dp->buffer, priv->buf, 8);
 189                         stream_read(demuxer->stream, &(dp->buffer[8]), len-8);
 190                         if(srate)
 191                                 tm = (float) (num * 1024.0/srate);
 192                         priv->last_pts += tm;
 193                         dp->pts = priv->last_pts;
 194                         //fprintf(stderr, "\nPTS: %.3f\n", dp->pts);
 195                         ds_add_packet(demuxer->audio, dp);
 196                         priv->size += len;
 197                         priv->time += tm;
 198
 199                         priv->bitrate = (int) (priv->size / priv->time);
 200                         demuxer->filepos = stream_tell(demuxer->stream);
 201
 202                         return len;
 203                 }
 204                 else
 205                         stream_skip(demuxer->stream, -6);
 206         }
 207
 208         return 0;
 209 }
 210
 211
 212 //This is an almost verbatim copy of high_res_mp3_seek(), from demux_audio.c
 213 static void demux_aac_seek(demuxer_t *demuxer, float rel_seek_secs, float audio_delay, int flags)
 214 {
 215         aac_priv_t *priv = (aac_priv_t *) demuxer->priv;
 216         demux_stream_t *d_audio=demuxer->audio;
 217         sh_audio_t *sh_audio=d_audio->sh;
 218         float time;
 219
 220         ds_free_packs(d_audio);
 221
 222         time = (flags & 1) ? rel_seek_secs - priv->last_pts : rel_seek_secs;
 223         if(time < 0)
 224         {
 225                 stream_seek(demuxer->stream, demuxer->movi_start);
 226                 time = priv->last_pts + time;
 227                 priv->last_pts = 0;
 228         }
 229
 230         if(time > 0)
 231         {
 232                 int len, nf, srate, num;
 233
 234                 nf = time * sh_audio->samplerate/1024;
 235
 236                 while(nf > 0)
 237                 {
 238                         if(stream_read(demuxer->stream,priv->buf, 8) < 8)
 239                                 break;
 240                         len = aac_parse_frame(priv->buf, &srate, &num);
 241                         if(len <= 0)
 242                         {
 243                                 stream_skip(demuxer->stream, -7);
 244                                 continue;
 245                         }
 246                         stream_skip(demuxer->stream, len - 8);
 247                         priv->last_pts += (float) (num*1024.0/srate);
 248                         nf -= num;
 249                 }
 250         }
 251         sh_audio->delay = priv->last_pts - (ds_tell_pts(demuxer->audio)-sh_audio->a_in_buffer_len)/(float)priv->bitrate;
 252 }
 253
 254
 255 demuxer_desc_t demuxer_desc_aac = {
 256   "AAC demuxer",
 257   "aac",
 258   "AAC",
 259   "Nico Sabbi",
 260   "Raw AAC files ",
 261   DEMUXER_TYPE_AAC,
 262   0, // unsafe autodetect
 263   demux_aac_probe,
 264   demux_aac_fill_buffer,
 265   demux_aac_open,
 266   demux_close_aac,
 267   demux_aac_seek,
 268   NULL
 269 };