| /* |
| * MP3 demuxer |
| * Copyright (c) 2003 Fabrice Bellard |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #include "libavutil/avstring.h" |
| #include "libavutil/intreadwrite.h" |
| #include "libavutil/dict.h" |
| #include "libavutil/mathematics.h" |
| #include "avformat.h" |
| #include "id3v2.h" |
| #include "id3v1.h" |
| #include "libavcodec/mpegaudiodecheader.h" |
| |
| /* mp3 read */ |
| |
| static int mp3_read_probe(AVProbeData *p) |
| { |
| int max_frames, first_frames = 0; |
| int fsize, frames, sample_rate; |
| uint32_t header; |
| uint8_t *buf, *buf0, *buf2, *end; |
| AVCodecContext avctx; |
| |
| buf0 = p->buf; |
| end = p->buf + p->buf_size - sizeof(uint32_t); |
| while(buf0 < end && !*buf0) |
| buf0++; |
| |
| max_frames = 0; |
| buf = buf0; |
| |
| for(; buf < end; buf= buf2+1) { |
| buf2 = buf; |
| |
| for(frames = 0; buf2 < end; frames++) { |
| header = AV_RB32(buf2); |
| fsize = ff_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate); |
| if(fsize < 0) |
| break; |
| buf2 += fsize; |
| } |
| max_frames = FFMAX(max_frames, frames); |
| if(buf == buf0) |
| first_frames= frames; |
| } |
| // keep this in sync with ac3 probe, both need to avoid |
| // issues with MPEG-files! |
| if (first_frames>=4) return AVPROBE_SCORE_MAX/2+1; |
| else if(max_frames>500)return AVPROBE_SCORE_MAX/2; |
| else if(max_frames>=4) return AVPROBE_SCORE_MAX/4; |
| else if(max_frames>=1) return 1; |
| else return 0; |
| //mpegps_mp3_unrecognized_format.mpg has max_frames=3 |
| } |
| |
| /** |
| * Try to find Xing/Info/VBRI tags and compute duration from info therein |
| */ |
| static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base) |
| { |
| uint32_t v, spf; |
| unsigned frames = 0; /* Total number of frames in file */ |
| unsigned size = 0; /* Total number of bytes in the stream */ |
| const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}}; |
| MPADecodeHeader c; |
| int vbrtag_size = 0; |
| |
| v = avio_rb32(s->pb); |
| if(ff_mpa_check_header(v) < 0) |
| return -1; |
| |
| if (ff_mpegaudio_decode_header(&c, v) == 0) |
| vbrtag_size = c.frame_size; |
| if(c.layer != 3) |
| return -1; |
| |
| /* Check for Xing / Info tag */ |
| avio_skip(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1]); |
| v = avio_rb32(s->pb); |
| if(v == MKBETAG('X', 'i', 'n', 'g') || v == MKBETAG('I', 'n', 'f', 'o')) { |
| v = avio_rb32(s->pb); |
| if(v & 0x1) |
| frames = avio_rb32(s->pb); |
| if(v & 0x2) |
| size = avio_rb32(s->pb); |
| } |
| |
| /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */ |
| avio_seek(s->pb, base + 4 + 32, SEEK_SET); |
| v = avio_rb32(s->pb); |
| if(v == MKBETAG('V', 'B', 'R', 'I')) { |
| /* Check tag version */ |
| if(avio_rb16(s->pb) == 1) { |
| /* skip delay and quality */ |
| avio_skip(s->pb, 4); |
| size = avio_rb32(s->pb); |
| frames = avio_rb32(s->pb); |
| } |
| } |
| |
| if(!frames && !size) |
| return -1; |
| |
| /* Skip the vbr tag frame */ |
| avio_seek(s->pb, base + vbrtag_size, SEEK_SET); |
| |
| spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */ |
| if(frames) |
| st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate}, |
| st->time_base); |
| if(size && frames) |
| st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf); |
| |
| return 0; |
| } |
| |
| static int mp3_read_header(AVFormatContext *s, |
| AVFormatParameters *ap) |
| { |
| AVStream *st; |
| int64_t off; |
| |
| st = av_new_stream(s, 0); |
| if (!st) |
| return AVERROR(ENOMEM); |
| |
| st->codec->codec_type = AVMEDIA_TYPE_AUDIO; |
| st->codec->codec_id = CODEC_ID_MP3; |
| st->need_parsing = AVSTREAM_PARSE_FULL; |
| st->start_time = 0; |
| |
| // lcm of all mp3 sample rates |
| av_set_pts_info(st, 64, 1, 14112000); |
| |
| off = avio_tell(s->pb); |
| |
| if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX)) |
| ff_id3v1_read(s); |
| |
| if (mp3_parse_vbr_tags(s, st, off) < 0) |
| avio_seek(s->pb, off, SEEK_SET); |
| |
| /* the parameters will be extracted from the compressed bitstream */ |
| return 0; |
| } |
| |
| #define MP3_PACKET_SIZE 1024 |
| |
| static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt) |
| { |
| int ret, size; |
| // AVStream *st = s->streams[0]; |
| |
| size= MP3_PACKET_SIZE; |
| |
| ret= av_get_packet(s->pb, pkt, size); |
| |
| pkt->stream_index = 0; |
| if (ret <= 0) { |
| if(ret<0) |
| return ret; |
| return AVERROR_EOF; |
| } |
| |
| if (ret > ID3v1_TAG_SIZE && |
| memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0) |
| ret -= ID3v1_TAG_SIZE; |
| |
| /* note: we need to modify the packet size here to handle the last |
| packet */ |
| pkt->size = ret; |
| return ret; |
| } |
| |
| AVInputFormat ff_mp3_demuxer = { |
| .name = "mp3", |
| .long_name = NULL_IF_CONFIG_SMALL("MPEG audio layer 2/3"), |
| .read_probe = mp3_read_probe, |
| .read_header = mp3_read_header, |
| .read_packet = mp3_read_packet, |
| .flags= AVFMT_GENERIC_INDEX, |
| .extensions = "mp2,mp3,m2a", /* XXX: use probe */ |
| }; |