/* * 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/opt.h" #include "libavutil/avstring.h" #include "libavutil/intreadwrite.h" #include "libavutil/crc.h" #include "libavutil/dict.h" #include "libavutil/mathematics.h" #include "avformat.h" #include "internal.h" #include "avio_internal.h" #include "id3v2.h" #include "id3v1.h" #include "replaygain.h" #include "libavcodec/avcodec.h" #include "libavcodec/mpegaudiodecheader.h" #define XING_FLAG_FRAMES 0x01 #define XING_FLAG_SIZE 0x02 #define XING_FLAG_TOC 0x04 #define XING_FLAC_QSCALE 0x08 #define XING_TOC_COUNT 100 #define SAME_HEADER_MASK \ (0xffe00000 | (3 << 17) | (3 << 10) | (3 << 19)) typedef struct { AVClass *class; int64_t filesize; int xing_toc; int start_pad; int end_pad; int usetoc; unsigned frames; /* Total number of frames in file */ unsigned header_filesize; /* Total number of bytes in the stream */ int is_cbr; } MP3DecContext; enum CheckRet { CHECK_WRONG_HEADER = -1, CHECK_SEEK_FAILED = -2, }; static int check(AVIOContext *pb, int64_t pos, uint32_t *header); /* mp3 read */ static int mp3_read_probe(AVProbeData *p) { int max_frames, first_frames = 0; int whole_used = 0; int frames, ret; int framesizes, max_framesizes; uint32_t header; const uint8_t *buf, *buf0, *buf2, *end; buf0 = p->buf; end = p->buf + p->buf_size - sizeof(uint32_t); while(buf0 < end && !*buf0) buf0++; max_frames = 0; max_framesizes = 0; buf = buf0; for(; buf < end; buf= buf2+1) { buf2 = buf; for(framesizes = frames = 0; buf2 < end; frames++) { MPADecodeHeader h; header = AV_RB32(buf2); ret = avpriv_mpegaudio_decode_header(&h, header); if (ret != 0) break; buf2 += h.frame_size; framesizes += h.frame_size; } max_frames = FFMAX(max_frames, frames); max_framesizes = FFMAX(max_framesizes, framesizes); if(buf == buf0) { first_frames= frames; if (buf2 == end + sizeof(uint32_t)) whole_used = 1; } } // keep this in sync with ac3 probe, both need to avoid // issues with MPEG-files! if (first_frames>=7) return AVPROBE_SCORE_EXTENSION + 1; else if(max_frames>200 && p->buf_size < 2*max_framesizes)return AVPROBE_SCORE_EXTENSION; else if(max_frames>=4 && p->buf_size < 2*max_framesizes) return AVPROBE_SCORE_EXTENSION / 2; else if(ff_id3v2_match(buf0, ID3v2_DEFAULT_MAGIC) && 2*ff_id3v2_tag_len(buf0) >= p->buf_size) return p->buf_size < PROBE_BUF_MAX ? AVPROBE_SCORE_EXTENSION / 4 : AVPROBE_SCORE_EXTENSION - 2; else if(first_frames > 1 && whole_used) return 5; else if(max_frames>=1 && p->buf_size < 10*max_framesizes) 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; MP3DecContext *mp3 = s->priv_data; int fast_seek = s->flags & AVFMT_FLAG_FAST_SEEK; int fill_index = (mp3->usetoc || fast_seek) && duration > 0; if (!filesize && !(filesize = avio_size(s->pb))) { av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n"); fill_index = 0; } for (i = 0; i < XING_TOC_COUNT; i++) { uint8_t b = avio_r8(s->pb); if (fill_index) av_add_index_entry(s->streams[0], av_rescale(b, filesize, 256), av_rescale(i, duration, XING_TOC_COUNT), 0, 0, AVINDEX_KEYFRAME); } if (fill_index) mp3->xing_toc = 1; } static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st, MPADecodeHeader *c, uint32_t spf) { #define LAST_BITS(k, n) ((k) & ((1 << (n)) - 1)) #define MIDDLE_BITS(k, m, n) LAST_BITS((k) >> (m), ((n) - (m) + 1)) uint16_t crc; uint32_t v; char version[10]; uint32_t peak = 0; int32_t r_gain = INT32_MIN, a_gain = INT32_MIN; MP3DecContext *mp3 = s->priv_data; static const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}}; uint64_t fsize = avio_size(s->pb); fsize = fsize >= avio_tell(s->pb) ? fsize - avio_tell(s->pb) : 0; /* Check for Xing / Info tag */ avio_skip(s->pb, xing_offtbl[c->lsf == 1][c->nb_channels == 1]); v = avio_rb32(s->pb); mp3->is_cbr = v == MKBETAG('I', 'n', 'f', 'o'); if (v != MKBETAG('X', 'i', 'n', 'g') && !mp3->is_cbr) return; v = avio_rb32(s->pb); if (v & XING_FLAG_FRAMES) mp3->frames = avio_rb32(s->pb); if (v & XING_FLAG_SIZE) mp3->header_filesize = avio_rb32(s->pb); if (fsize && mp3->header_filesize) { uint64_t min, delta; min = FFMIN(fsize, mp3->header_filesize); delta = FFMAX(fsize, mp3->header_filesize) - min; if (fsize > mp3->header_filesize && delta > min >> 4) { mp3->frames = 0; av_log(s, AV_LOG_WARNING, "invalid concatenated file detected - using bitrate for duration\n"); } else if (delta > min >> 4) { av_log(s, AV_LOG_WARNING, "filesize and duration do not match (growing file?)\n"); } } if (v & XING_FLAG_TOC) read_xing_toc(s, mp3->header_filesize, av_rescale_q(mp3->frames, (AVRational){spf, c->sample_rate}, st->time_base)); /* VBR quality */ if (v & XING_FLAC_QSCALE) avio_rb32(s->pb); /* Encoder short version string */ memset(version, 0, sizeof(version)); avio_read(s->pb, version, 9); /* Info Tag revision + VBR method */ avio_r8(s->pb); /* Lowpass filter value */ avio_r8(s->pb); /* ReplayGain peak */ v = avio_rb32(s->pb); peak = av_rescale(v, 100000, 1 << 23); /* Radio ReplayGain */ v = avio_rb16(s->pb); if (MIDDLE_BITS(v, 13, 15) == 1) { r_gain = MIDDLE_BITS(v, 0, 8) * 10000; if (v & (1 << 9)) r_gain *= -1; } /* Audiophile ReplayGain */ v = avio_rb16(s->pb); if (MIDDLE_BITS(v, 13, 15) == 2) { a_gain = MIDDLE_BITS(v, 0, 8) * 10000; if (v & (1 << 9)) a_gain *= -1; } /* Encoding flags + ATH Type */ avio_r8(s->pb); /* if ABR {specified bitrate} else {minimal bitrate} */ avio_r8(s->pb); /* Encoder delays */ v= avio_rb24(s->pb); if(AV_RB32(version) == MKBETAG('L', 'A', 'M', 'E') || AV_RB32(version) == MKBETAG('L', 'a', 'v', 'f') || AV_RB32(version) == MKBETAG('L', 'a', 'v', 'c') ) { mp3->start_pad = v>>12; mp3-> end_pad = v&4095; st->start_skip_samples = mp3->start_pad + 528 + 1; if (mp3->frames) { st->first_discard_sample = -mp3->end_pad + 528 + 1 + mp3->frames * (int64_t)spf; st->last_discard_sample = mp3->frames * (int64_t)spf; } if (!st->start_time) st->start_time = av_rescale_q(st->start_skip_samples, (AVRational){1, c->sample_rate}, st->time_base); av_log(s, AV_LOG_DEBUG, "pad %d %d\n", mp3->start_pad, mp3-> end_pad); } /* Misc */ avio_r8(s->pb); /* MP3 gain */ avio_r8(s->pb); /* Preset and surround info */ avio_rb16(s->pb); /* Music length */ avio_rb32(s->pb); /* Music CRC */ avio_rb16(s->pb); /* Info Tag CRC */ crc = ffio_get_checksum(s->pb); v = avio_rb16(s->pb); if (v == crc) { ff_replaygain_export_raw(st, r_gain, peak, a_gain, 0); av_dict_set(&st->metadata, "encoder", version, 0); } } static void mp3_parse_vbri_tag(AVFormatContext *s, AVStream *st, int64_t base) { uint32_t v; MP3DecContext *mp3 = s->priv_data; /* 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); mp3->header_filesize = avio_rb32(s->pb); mp3->frames = avio_rb32(s->pb); } } } /** * 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; MPADecodeHeader c; int vbrtag_size = 0; MP3DecContext *mp3 = s->priv_data; int ret; ffio_init_checksum(s->pb, ff_crcA001_update, 0); v = avio_rb32(s->pb); ret = avpriv_mpegaudio_decode_header(&c, v); if (ret < 0) return ret; else if (ret == 0) vbrtag_size = c.frame_size; if(c.layer != 3) return -1; spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */ mp3->frames = 0; mp3->header_filesize = 0; mp3_parse_info_tag(s, st, &c, spf); mp3_parse_vbri_tag(s, st, base); if (!mp3->frames && !mp3->header_filesize) return -1; /* Skip the vbr tag frame */ avio_seek(s->pb, base + vbrtag_size, SEEK_SET); if (mp3->frames) st->duration = av_rescale_q(mp3->frames, (AVRational){spf, c.sample_rate}, st->time_base); if (mp3->header_filesize && mp3->frames && !mp3->is_cbr) st->codecpar->bit_rate = av_rescale(mp3->header_filesize, 8 * c.sample_rate, mp3->frames * (int64_t)spf); return 0; } static int mp3_read_header(AVFormatContext *s) { MP3DecContext *mp3 = s->priv_data; AVStream *st; int64_t off; int ret; int i; s->metadata = s->internal->id3v2_meta; s->internal->id3v2_meta = NULL; st = avformat_new_stream(s, NULL); if (!st) return AVERROR(ENOMEM); st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO; st->codecpar->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 & AVIO_SEEKABLE_NORMAL) mp3->filesize = avio_size(s->pb); if (mp3_parse_vbr_tags(s, st, off) < 0) avio_seek(s->pb, off, SEEK_SET); ret = ff_replaygain_export(st, s->metadata); if (ret < 0) return ret; off = avio_tell(s->pb); for (i = 0; i < 64 * 1024; i++) { uint32_t header, header2; int frame_size; if (!(i&1023)) ffio_ensure_seekback(s->pb, i + 1024 + 4); frame_size = check(s->pb, off + i, &header); if (frame_size > 0) { ret = avio_seek(s->pb, off, SEEK_SET); if (ret < 0) return ret; ffio_ensure_seekback(s->pb, i + 1024 + frame_size + 4); ret = check(s->pb, off + i + frame_size, &header2); if (ret >= 0 && (header & SAME_HEADER_MASK) == (header2 & SAME_HEADER_MASK)) { av_log(s, i > 0 ? AV_LOG_INFO : AV_LOG_VERBOSE, "Skipping %d bytes of junk at %"PRId64".\n", i, off); ret = avio_seek(s->pb, off + i, SEEK_SET); if (ret < 0) return ret; break; } else if (ret == CHECK_SEEK_FAILED) { av_log(s, AV_LOG_ERROR, "Invalid frame size (%d): Could not seek to %"PRId64".\n", frame_size, off + i + frame_size); return AVERROR(EINVAL); } } else if (frame_size == CHECK_SEEK_FAILED) { av_log(s, AV_LOG_ERROR, "Failed to read frame size: Could not seek to %"PRId64".\n", (int64_t) (i + 1024 + frame_size + 4)); return AVERROR(EINVAL); } ret = avio_seek(s->pb, off, SEEK_SET); if (ret < 0) return ret; } // the seek index is relative to the end of the xing vbr headers for (i = 0; i < st->nb_index_entries; i++) st->index_entries[i].pos += avio_tell(s->pb); /* 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) { MP3DecContext *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; return ret; } #define SEEK_WINDOW 4096 static int check(AVIOContext *pb, int64_t pos, uint32_t *ret_header) { int64_t ret = avio_seek(pb, pos, SEEK_SET); uint8_t header_buf[4]; unsigned header; MPADecodeHeader sd; if (ret < 0) return CHECK_SEEK_FAILED; ret = avio_read(pb, &header_buf[0], 4); /* We should always find four bytes for a valid mpa header. */ if (ret < 4) return CHECK_SEEK_FAILED; header = AV_RB32(&header_buf[0]); if (ff_mpa_check_header(header) < 0) return CHECK_WRONG_HEADER; if (avpriv_mpegaudio_decode_header(&sd, header) == 1) return CHECK_WRONG_HEADER; if (ret_header) *ret_header = header; return sd.frame_size; } static int64_t mp3_sync(AVFormatContext *s, int64_t target_pos, int flags) { int dir = (flags&AVSEEK_FLAG_BACKWARD) ? -1 : 1; int64_t best_pos; int best_score, i, j; int64_t ret; avio_seek(s->pb, FFMAX(target_pos - SEEK_WINDOW, 0), SEEK_SET); ret = avio_seek(s->pb, target_pos, SEEK_SET); if (ret < 0) return ret; #define MIN_VALID 3 best_pos = target_pos; best_score = 999; for(i=0; i<SEEK_WINDOW; i++) { int64_t pos = target_pos + (dir > 0 ? i - SEEK_WINDOW/4 : -i); int64_t candidate = -1; int score = 999; if (pos < 0) continue; for(j=0; j<MIN_VALID; j++) { ret = check(s->pb, pos, NULL); if(ret < 0) { if (ret == CHECK_WRONG_HEADER) { break; } else if (ret == CHECK_SEEK_FAILED) { av_log(s, AV_LOG_ERROR, "Could not seek to %"PRId64".\n", pos); return AVERROR(EINVAL); } } if ((target_pos - pos)*dir <= 0 && FFABS(MIN_VALID/2-j) < score) { candidate = pos; score = FFABS(MIN_VALID/2-j); } pos += ret; } if (best_score > score && j == MIN_VALID) { best_pos = candidate; best_score = score; if(score == 0) break; } } return avio_seek(s->pb, best_pos, SEEK_SET); } static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) { MP3DecContext *mp3 = s->priv_data; AVIndexEntry *ie, ie1; AVStream *st = s->streams[0]; int64_t best_pos; int fast_seek = s->flags & AVFMT_FLAG_FAST_SEEK; int64_t filesize = mp3->header_filesize; if (filesize <= 0) { int64_t size = avio_size(s->pb); if (size > 0 && size > s->internal->data_offset) filesize = size - s->internal->data_offset; } if (mp3->xing_toc && (mp3->usetoc || (fast_seek && !mp3->is_cbr))) { int64_t ret = av_index_search_timestamp(st, timestamp, flags); // NOTE: The MP3 TOC is not a precise lookup table. Accuracy is worse // for bigger files. av_log(s, AV_LOG_WARNING, "Using MP3 TOC to seek; may be imprecise.\n"); if (ret < 0) return ret; ie = &st->index_entries[ret]; } else if (fast_seek && st->duration > 0 && filesize > 0) { if (!mp3->is_cbr) av_log(s, AV_LOG_WARNING, "Using scaling to seek VBR MP3; may be imprecise.\n"); ie = &ie1; timestamp = av_clip64(timestamp, 0, st->duration); ie->timestamp = timestamp; ie->pos = av_rescale(timestamp, filesize, st->duration) + s->internal->data_offset; } else { return -1; // generic index code } best_pos = mp3_sync(s, ie->pos, flags); if (best_pos < 0) return best_pos; if (mp3->is_cbr && ie == &ie1 && mp3->frames) { int frame_duration = av_rescale(st->duration, 1, mp3->frames); ie1.timestamp = frame_duration * av_rescale(best_pos - s->internal->data_offset, mp3->frames, mp3->header_filesize); } ff_update_cur_dts(s, st, ie->timestamp); return 0; } static const AVOption options[] = { { "usetoc", "use table of contents", offsetof(MP3DecContext, usetoc), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, AV_OPT_FLAG_DECODING_PARAM}, { NULL }, }; static const AVClass demuxer_class = { .class_name = "mp3", .item_name = av_default_item_name, .option = options, .version = LIBAVUTIL_VERSION_INT, .category = AV_CLASS_CATEGORY_DEMUXER, }; AVInputFormat ff_mp3_demuxer = { .name = "mp3", .long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"), .read_probe = mp3_read_probe, .read_header = mp3_read_header, .read_packet = mp3_read_packet, .read_seek = mp3_seek, .priv_data_size = sizeof(MP3DecContext), .flags = AVFMT_GENERIC_INDEX, .extensions = "mp2,mp3,m2a,mpa", /* XXX: use probe */ .priv_class = &demuxer_class, };