libavformat/aacdec.c

   1 /*
   2  * raw ADTS AAC demuxer
   3  * Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
   4  * Copyright (c) 2009 Robert Swain ( rob opendot cl )
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include "libavutil/avassert.h"
  24 #include "libavutil/intreadwrite.h"
  25 #include "avformat.h"
  26 #include "avio_internal.h"
  27 #include "internal.h"
  28 #include "id3v1.h"
  29 #include "id3v2.h"
  30 #include "apetag.h"
  31
  32 #define ADTS_HEADER_SIZE 7
  33
  34 static int adts_aac_probe(const AVProbeData *p)
  35 {
  36     int max_frames = 0, first_frames = 0;
  37     int fsize, frames;
  38     const uint8_t *buf0 = p->buf;
  39     const uint8_t *buf2;
  40     const uint8_t *buf;
  41     const uint8_t *end = buf0 + p->buf_size - 7;
  42
  43     buf = buf0;
  44
  45     for (; buf < end; buf = buf2 + 1) {
  46         buf2 = buf;
  47
  48         for (frames = 0; buf2 < end; frames++) {
  49             uint32_t header = AV_RB16(buf2);
  50             if ((header & 0xFFF6) != 0xFFF0) {
  51                 if (buf != buf0) {
  52                     // Found something that isn't an ADTS header, starting
  53                     // from a position other than the start of the buffer.
  54                     // Discard the count we've accumulated so far since it
  55                     // probably was a false positive.
  56                     frames = 0;
  57                 }
  58                 break;
  59             }
  60             fsize = (AV_RB32(buf2 + 3) >> 13) & 0x1FFF;
  61             if (fsize < 7)
  62                 break;
  63             fsize = FFMIN(fsize, end - buf2);
  64             buf2 += fsize;
  65         }
  66         max_frames = FFMAX(max_frames, frames);
  67         if (buf == buf0)
  68             first_frames = frames;
  69     }
  70
  71     if (first_frames >= 3)
  72         return AVPROBE_SCORE_EXTENSION + 1;
  73     else if (max_frames > 100)
  74         return AVPROBE_SCORE_EXTENSION;
  75     else if (max_frames >= 3)
  76         return AVPROBE_SCORE_EXTENSION / 2;
  77     else if (first_frames >= 1)
  78         return 1;
  79     else
  80         return 0;
  81 }
  82
  83 static int adts_aac_resync(AVFormatContext *s)
  84 {
  85     uint16_t state;
  86
  87     // skip data until an ADTS frame is found
  88     state = avio_r8(s->pb);
  89     while (!avio_feof(s->pb) && avio_tell(s->pb) < s->probesize) {
  90         state = (state << 8) | avio_r8(s->pb);
  91         if ((state >> 4) != 0xFFF)
  92             continue;
  93         avio_seek(s->pb, -2, SEEK_CUR);
  94         break;
  95     }
  96     if (s->pb->eof_reached)
  97         return AVERROR_EOF;
  98     if ((state >> 4) != 0xFFF)
  99         return AVERROR_INVALIDDATA;
 100
 101     return 0;
 102 }
 103
 104 static int adts_aac_read_header(AVFormatContext *s)
 105 {
 106     AVStream *st;
 107     int ret;
 108
 109     st = avformat_new_stream(s, NULL);
 110     if (!st)
 111         return AVERROR(ENOMEM);
 112
 113     st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
 114     st->codecpar->codec_id   = s->iformat->raw_codec_id;
 115     st->need_parsing         = AVSTREAM_PARSE_FULL_RAW;
 116
 117     ff_id3v1_read(s);
 118     if ((s->pb->seekable & AVIO_SEEKABLE_NORMAL) &&
 119         !av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX)) {
 120         int64_t cur = avio_tell(s->pb);
 121         ff_ape_parse_tag(s);
 122         avio_seek(s->pb, cur, SEEK_SET);
 123     }
 124
 125     ret = adts_aac_resync(s);
 126     if (ret < 0)
 127         return ret;
 128
 129     // LCM of all possible ADTS sample rates
 130     avpriv_set_pts_info(st, 64, 1, 28224000);
 131
 132     return 0;
 133 }
 134
 135 static int handle_id3(AVFormatContext *s, AVPacket *pkt)
 136 {
 137     AVDictionary *metadata = NULL;
 138     AVIOContext ioctx;
 139     ID3v2ExtraMeta *id3v2_extra_meta = NULL;
 140     int ret;
 141
 142     ret = av_append_packet(s->pb, pkt, ff_id3v2_tag_len(pkt->data) - pkt->size);
 143     if (ret < 0) {
 144         return ret;
 145     }
 146
 147     ffio_init_context(&ioctx, pkt->data, pkt->size, 0, NULL, NULL, NULL, NULL);
 148     ff_id3v2_read_dict(&ioctx, &metadata, ID3v2_DEFAULT_MAGIC, &id3v2_extra_meta);
 149     if ((ret = ff_id3v2_parse_priv_dict(&metadata, id3v2_extra_meta)) < 0)
 150         goto error;
 151
 152     if (metadata) {
 153         if ((ret = av_dict_copy(&s->metadata, metadata, 0)) < 0)
 154             goto error;
 155         s->event_flags |= AVFMT_EVENT_FLAG_METADATA_UPDATED;
 156     }
 157
 158 error:
 159     av_packet_unref(pkt);
 160     ff_id3v2_free_extra_meta(&id3v2_extra_meta);
 161     av_dict_free(&metadata);
 162
 163     return ret;
 164 }
 165
 166 static int adts_aac_read_packet(AVFormatContext *s, AVPacket *pkt)
 167 {
 168     int ret, fsize;
 169
 170 retry:
 171     ret = av_get_packet(s->pb, pkt, ADTS_HEADER_SIZE);
 172     if (ret < 0)
 173         return ret;
 174
 175     if (ret < ADTS_HEADER_SIZE) {
 176         return AVERROR(EIO);
 177     }
 178
 179     if ((AV_RB16(pkt->data) >> 4) != 0xfff) {
 180         // Parse all the ID3 headers between frames
 181         int append = ID3v2_HEADER_SIZE - ADTS_HEADER_SIZE;
 182
 183         av_assert2(append > 0);
 184         ret = av_append_packet(s->pb, pkt, append);
 185         if (ret != append) {
 186             return AVERROR(EIO);
 187         }
 188         if (!ff_id3v2_match(pkt->data, ID3v2_DEFAULT_MAGIC)) {
 189             av_packet_unref(pkt);
 190             ret = adts_aac_resync(s);
 191         } else
 192             ret = handle_id3(s, pkt);
 193         if (ret < 0)
 194             return ret;
 195
 196         goto retry;
 197     }
 198
 199     fsize = (AV_RB32(pkt->data + 3) >> 13) & 0x1FFF;
 200     if (fsize < ADTS_HEADER_SIZE) {
 201         return AVERROR_INVALIDDATA;
 202     }
 203
 204     ret = av_append_packet(s->pb, pkt, fsize - pkt->size);
 205
 206     return ret;
 207 }
 208
 209 AVInputFormat ff_aac_demuxer = {
 210     .name         = "aac",
 211     .long_name    = NULL_IF_CONFIG_SMALL("raw ADTS AAC (Advanced Audio Coding)"),
 212     .read_probe   = adts_aac_probe,
 213     .read_header  = adts_aac_read_header,
 214     .read_packet  = adts_aac_read_packet,
 215     .flags        = AVFMT_GENERIC_INDEX,
 216     .extensions   = "aac",
 217     .mime_type    = "audio/aac,audio/aacp,audio/x-aac",
 218     .raw_codec_id = AV_CODEC_ID_AAC,
 219 };