diff options
Diffstat (limited to 'ffmpeg/libavformat/mp3dec.c')
| -rw-r--r-- | ffmpeg/libavformat/mp3dec.c | 329 |
1 files changed, 329 insertions, 0 deletions
diff --git a/ffmpeg/libavformat/mp3dec.c b/ffmpeg/libavformat/mp3dec.c new file mode 100644 index 0000000..57e4ba3 --- /dev/null +++ b/ffmpeg/libavformat/mp3dec.c @@ -0,0 +1,329 @@ +/* + * 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 "internal.h" +#include "id3v2.h" +#include "id3v1.h" +#include "libavcodec/mpegaudiodecheader.h" + +#define XING_FLAG_FRAMES 0x01 +#define XING_FLAG_SIZE 0x02 +#define XING_FLAG_TOC 0x04 + +#define XING_TOC_COUNT 100 + +typedef struct { + int64_t filesize; + int xing_toc; + int start_pad; + int end_pad; +} MP3Context; + +/* mp3 read */ + +static int mp3_read_probe(AVProbeData *p) +{ + int max_frames, first_frames = 0; + int fsize, frames, sample_rate; + uint32_t header; + const 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 = avpriv_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>200)return AVPROBE_SCORE_MAX/2; + else if(max_frames>=4) return AVPROBE_SCORE_MAX/4; + else if(ff_id3v2_match(buf0, ID3v2_DEFAULT_MAGIC) && 2*ff_id3v2_tag_len(buf0) >= p->buf_size) + return AVPROBE_SCORE_MAX/8; + else if(max_frames>=1) return 1; + else return 0; +//mpegps_mp3_unrecognized_format.mpg has max_frames=3 +} + +static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration) +{ + int i; + MP3Context *mp3 = s->priv_data; + + if (!filesize && + !(filesize = avio_size(s->pb))) { + av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n"); + return; + } + + for (i = 0; i < XING_TOC_COUNT; i++) { + uint8_t b = avio_r8(s->pb); + + av_add_index_entry(s->streams[0], + av_rescale(b, filesize, 256), + av_rescale(i, duration, XING_TOC_COUNT), + 0, 0, AVINDEX_KEYFRAME); + } + mp3->xing_toc = 1; +} + +/** + * 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) +{ + MP3Context *mp3 = s->priv_data; + 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; + int is_cbr; + + v = avio_rb32(s->pb); + if(ff_mpa_check_header(v) < 0) + return -1; + + if (avpriv_mpegaudio_decode_header(&c, v) == 0) + vbrtag_size = c.frame_size; + if(c.layer != 3) + return -1; + + spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */ + + /* Check for Xing / Info tag */ + avio_skip(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1]); + v = avio_rb32(s->pb); + is_cbr = v == MKBETAG('I', 'n', 'f', 'o'); + if (v == MKBETAG('X', 'i', 'n', 'g') || is_cbr) { + v = avio_rb32(s->pb); + if(v & XING_FLAG_FRAMES) + frames = avio_rb32(s->pb); + if(v & XING_FLAG_SIZE) + size = avio_rb32(s->pb); + if (v & XING_FLAG_TOC && frames) + read_xing_toc(s, size, av_rescale_q(frames, (AVRational){spf, c.sample_rate}, + st->time_base)); + if(v & 8) + avio_skip(s->pb, 4); + + v = avio_rb32(s->pb); + if(v == MKBETAG('L', 'A', 'M', 'E') || v == MKBETAG('L', 'a', 'v', 'f')) { + avio_skip(s->pb, 21-4); + v= avio_rb24(s->pb); + mp3->start_pad = v>>12; + mp3-> end_pad = v&4095; + st->skip_samples = mp3->start_pad + 528 + 1; + av_log(s, AV_LOG_DEBUG, "pad %d %d\n", mp3->start_pad, mp3-> end_pad); + } + } + + /* 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); + + if(frames) + st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate}, + st->time_base); + if (size && frames && !is_cbr) + st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf); + + return 0; +} + +static int mp3_read_header(AVFormatContext *s) +{ + MP3Context *mp3 = s->priv_data; + AVStream *st; + int64_t off; + + st = avformat_new_stream(s, NULL); + if (!st) + return AVERROR(ENOMEM); + + st->codec->codec_type = AVMEDIA_TYPE_AUDIO; + st->codec->codec_id = AV_CODEC_ID_MP3; + st->need_parsing = AVSTREAM_PARSE_FULL_RAW; + st->start_time = 0; + + // lcm of all mp3 sample rates + avpriv_set_pts_info(st, 64, 1, 14112000); + + s->pb->maxsize = -1; + off = avio_tell(s->pb); + + if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX)) + ff_id3v1_read(s); + + if(s->pb->seekable) + mp3->filesize = avio_size(s->pb); + + 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) +{ + MP3Context *mp3 = s->priv_data; + int ret, size; + int64_t pos; + + size= MP3_PACKET_SIZE; + pos = avio_tell(s->pb); + if(mp3->filesize > ID3v1_TAG_SIZE && pos < mp3->filesize) + size= FFMIN(size, mp3->filesize - pos); + + ret= av_get_packet(s->pb, pkt, size); + if (ret <= 0) { + if(ret<0) + return ret; + return AVERROR_EOF; + } + + pkt->flags &= ~AV_PKT_FLAG_CORRUPT; + pkt->stream_index = 0; + + 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; +} + +static int check(AVFormatContext *s, int64_t pos) +{ + int64_t ret = avio_seek(s->pb, pos, SEEK_SET); + unsigned header; + MPADecodeHeader sd; + if (ret < 0) + return ret; + header = avio_rb32(s->pb); + if (ff_mpa_check_header(header) < 0) + return -1; + if (avpriv_mpegaudio_decode_header(&sd, header) == 1) + return -1; + return sd.frame_size; +} + +static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp, + int flags) +{ + MP3Context *mp3 = s->priv_data; + AVIndexEntry *ie; + AVStream *st = s->streams[0]; + int64_t ret = av_index_search_timestamp(st, timestamp, flags); + int i, j; + + if (!mp3->xing_toc) { + st->skip_samples = timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0; + + return -1; + } + + if (ret < 0) + return ret; + + ie = &st->index_entries[ret]; + ret = avio_seek(s->pb, ie->pos, SEEK_SET); + if (ret < 0) + return ret; + +#define MIN_VALID 3 + for(i=0; i<4096; i++) { + int64_t pos = ie->pos + i; + for(j=0; j<MIN_VALID; j++) { + ret = check(s, pos); + if(ret < 0) + break; + pos += ret; + } + if(j==MIN_VALID) + break; + } + if(j!=MIN_VALID) + i=0; + + ret = avio_seek(s->pb, ie->pos + i, SEEK_SET); + if (ret < 0) + return ret; + ff_update_cur_dts(s, st, ie->timestamp); + st->skip_samples = ie->timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0; + return 0; +} + +AVInputFormat ff_mp3_demuxer = { + .name = "mp3", + .long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"), + .priv_data_size = sizeof(MP3Context), + .read_probe = mp3_read_probe, + .read_header = mp3_read_header, + .read_packet = mp3_read_packet, + .read_seek = mp3_seek, + .flags = AVFMT_GENERIC_INDEX, + .extensions = "mp2,mp3,m2a", /* XXX: use probe */ +}; |