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* Copyright (c) 2003 Fabrice Bellard
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* This file is part of FFmpeg.
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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#include "libavutil/opt.h"
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#include "libavutil/avstring.h"
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#include "libavutil/intreadwrite.h"
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#include "libavutil/crc.h"
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#include "libavutil/dict.h"
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#include "libavutil/mathematics.h"
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#include "avio_internal.h"
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#include "replaygain.h"
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#include "libavcodec/mpegaudiodecheader.h"
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#define XING_FLAG_FRAMES 0x01
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#define XING_FLAG_SIZE 0x02
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#define XING_FLAG_TOC 0x04
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#define XING_TOC_COUNT 100
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unsigned frames; /* Total number of frames in file */
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unsigned header_filesize; /* Total number of bytes in the stream */
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static int mp3_read_probe(AVProbeData *p)
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int max_frames, first_frames = 0;
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int fsize, frames, sample_rate;
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const uint8_t *buf, *buf0, *buf2, *end;
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end = p->buf + p->buf_size - sizeof(uint32_t);
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while(buf0 < end && !*buf0)
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for(; buf < end; buf= buf2+1) {
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if(ff_mpa_check_header(AV_RB32(buf2)))
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for(frames = 0; buf2 < end; frames++) {
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header = AV_RB32(buf2);
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fsize = avpriv_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
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max_frames = FFMAX(max_frames, frames);
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// keep this in sync with ac3 probe, both need to avoid
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// issues with MPEG-files!
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if (first_frames>=4) return AVPROBE_SCORE_EXTENSION + 1;
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else if(max_frames>200)return AVPROBE_SCORE_EXTENSION;
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else if(max_frames>=4 && max_frames >= p->buf_size/10000) return AVPROBE_SCORE_EXTENSION / 2;
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else if(ff_id3v2_match(buf0, ID3v2_DEFAULT_MAGIC) && 2*ff_id3v2_tag_len(buf0) >= p->buf_size)
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return p->buf_size < PROBE_BUF_MAX ? AVPROBE_SCORE_EXTENSION / 4 : AVPROBE_SCORE_EXTENSION - 2;
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else if(max_frames>=1 && max_frames >= p->buf_size/10000) return 1;
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//mpegps_mp3_unrecognized_format.mpg has max_frames=3
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static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration)
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MP3DecContext *mp3 = s->priv_data;
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int fill_index = mp3->usetoc && duration > 0;
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!(filesize = avio_size(s->pb))) {
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av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n");
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for (i = 0; i < XING_TOC_COUNT; i++) {
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uint8_t b = avio_r8(s->pb);
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av_add_index_entry(s->streams[0],
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av_rescale(b, filesize, 256),
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av_rescale(i, duration, XING_TOC_COUNT),
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0, 0, AVINDEX_KEYFRAME);
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static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
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MPADecodeHeader *c, uint32_t spf)
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#define LAST_BITS(k, n) ((k) & ((1 << (n)) - 1))
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#define MIDDLE_BITS(k, m, n) LAST_BITS((k) >> (m), ((n) - (m)))
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int32_t r_gain = INT32_MIN, a_gain = INT32_MIN;
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MP3DecContext *mp3 = s->priv_data;
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static const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
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uint64_t fsize = avio_size(s->pb);
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/* Check for Xing / Info tag */
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avio_skip(s->pb, xing_offtbl[c->lsf == 1][c->nb_channels == 1]);
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v = avio_rb32(s->pb);
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mp3->is_cbr = v == MKBETAG('I', 'n', 'f', 'o');
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if (v != MKBETAG('X', 'i', 'n', 'g') && !mp3->is_cbr)
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v = avio_rb32(s->pb);
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if (v & XING_FLAG_FRAMES)
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mp3->frames = avio_rb32(s->pb);
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if (v & XING_FLAG_SIZE)
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mp3->header_filesize = avio_rb32(s->pb);
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if (fsize && mp3->header_filesize) {
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min = FFMIN(fsize, mp3->header_filesize);
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delta = FFMAX(fsize, mp3->header_filesize) - min;
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if (fsize > mp3->header_filesize && delta > min >> 4) {
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} else if (delta > min >> 4) {
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av_log(s, AV_LOG_WARNING,
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"filesize and duration do not match (growing file?)\n");
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if (v & XING_FLAG_TOC)
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read_xing_toc(s, mp3->header_filesize, av_rescale_q(mp3->frames,
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(AVRational){spf, c->sample_rate},
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/* Encoder short version string */
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memset(version, 0, sizeof(version));
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avio_read(s->pb, version, 9);
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/* Info Tag revision + VBR method */
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/* Lowpass filter value */
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/* ReplayGain peak */
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v = avio_rb32(s->pb);
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peak = av_rescale(v, 100000, 1 << 23);
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/* Radio ReplayGain */
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v = avio_rb16(s->pb);
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if (MIDDLE_BITS(v, 13, 15) == 1) {
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r_gain = MIDDLE_BITS(v, 0, 8) * 10000;
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/* Audiophile ReplayGain */
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v = avio_rb16(s->pb);
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if (MIDDLE_BITS(v, 13, 15) == 2) {
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a_gain = MIDDLE_BITS(v, 0, 8) * 10000;
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/* Encoding flags + ATH Type */
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/* if ABR {specified bitrate} else {minimal bitrate} */
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if(AV_RB32(version) == MKBETAG('L', 'A', 'M', 'E')
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|| AV_RB32(version) == MKBETAG('L', 'a', 'v', 'f')) {
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mp3->start_pad = v>>12;
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mp3-> end_pad = v&4095;
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st->skip_samples = mp3->start_pad + 528 + 1;
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st->start_time = av_rescale_q(st->skip_samples,
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(AVRational){1, c->sample_rate},
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av_log(s, AV_LOG_DEBUG, "pad %d %d\n", mp3->start_pad, mp3-> end_pad);
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/* Preset and surround info */
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crc = ffio_get_checksum(s->pb);
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v = avio_rb16(s->pb);
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ff_replaygain_export_raw(st, r_gain, peak, a_gain, 0);
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av_dict_set(&st->metadata, "encoder", version, 0);
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static void mp3_parse_vbri_tag(AVFormatContext *s, AVStream *st, int64_t base)
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MP3DecContext *mp3 = s->priv_data;
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/* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
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avio_seek(s->pb, base + 4 + 32, SEEK_SET);
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v = avio_rb32(s->pb);
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if (v == MKBETAG('V', 'B', 'R', 'I')) {
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/* Check tag version */
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if (avio_rb16(s->pb) == 1) {
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/* skip delay and quality */
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mp3->header_filesize = avio_rb32(s->pb);
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mp3->frames = avio_rb32(s->pb);
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* Try to find Xing/Info/VBRI tags and compute duration from info therein
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static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
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MP3DecContext *mp3 = s->priv_data;
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ffio_init_checksum(s->pb, ff_crcA001_update, 0);
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v = avio_rb32(s->pb);
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if(ff_mpa_check_header(v) < 0)
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if (avpriv_mpegaudio_decode_header(&c, v) == 0)
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vbrtag_size = c.frame_size;
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spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
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mp3->header_filesize = 0;
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mp3_parse_info_tag(s, st, &c, spf);
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mp3_parse_vbri_tag(s, st, base);
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if (!mp3->frames && !mp3->header_filesize)
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/* Skip the vbr tag frame */
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avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
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st->duration = av_rescale_q(mp3->frames, (AVRational){spf, c.sample_rate},
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if (mp3->header_filesize && mp3->frames && !mp3->is_cbr)
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st->codec->bit_rate = av_rescale(mp3->header_filesize, 8 * c.sample_rate, mp3->frames * (int64_t)spf);
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static int mp3_read_header(AVFormatContext *s)
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MP3DecContext *mp3 = s->priv_data;
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st = avformat_new_stream(s, NULL);
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return AVERROR(ENOMEM);
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st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
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st->codec->codec_id = AV_CODEC_ID_MP3;
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st->need_parsing = AVSTREAM_PARSE_FULL_RAW;
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// lcm of all mp3 sample rates
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avpriv_set_pts_info(st, 64, 1, 14112000);
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off = avio_tell(s->pb);
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if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
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mp3->filesize = avio_size(s->pb);
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if (mp3_parse_vbr_tags(s, st, off) < 0)
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avio_seek(s->pb, off, SEEK_SET);
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ret = ff_replaygain_export(st, s->metadata);
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/* the parameters will be extracted from the compressed bitstream */
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#define MP3_PACKET_SIZE 1024
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static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
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MP3DecContext *mp3 = s->priv_data;
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size= MP3_PACKET_SIZE;
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pos = avio_tell(s->pb);
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if(mp3->filesize > ID3v1_TAG_SIZE && pos < mp3->filesize)
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size= FFMIN(size, mp3->filesize - pos);
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ret= av_get_packet(s->pb, pkt, size);
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pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
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pkt->stream_index = 0;
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if (ret >= ID3v1_TAG_SIZE &&
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memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0)
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ret -= ID3v1_TAG_SIZE;
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/* note: we need to modify the packet size here to handle the last
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static int check(AVFormatContext *s, int64_t pos)
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int64_t ret = avio_seek(s->pb, pos, SEEK_SET);
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header = avio_rb32(s->pb);
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if (ff_mpa_check_header(header) < 0)
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if (avpriv_mpegaudio_decode_header(&sd, header) == 1)
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return sd.frame_size;
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static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
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MP3DecContext *mp3 = s->priv_data;
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AVIndexEntry *ie, ie1;
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AVStream *st = s->streams[0];
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int64_t ret = av_index_search_timestamp(st, timestamp, flags);
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int dir = (flags&AVSEEK_FLAG_BACKWARD) ? -1 : 1;
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&& mp3->header_filesize > s->data_offset
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int64_t filesize = avio_size(s->pb);
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if (filesize <= s->data_offset)
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filesize = mp3->header_filesize;
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filesize -= s->data_offset;
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duration = av_rescale(st->duration, filesize, mp3->header_filesize - s->data_offset);
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timestamp = av_clip64(timestamp, 0, duration);
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ie->timestamp = timestamp;
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ie->pos = av_rescale(timestamp, filesize, duration) + s->data_offset;
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} else if (mp3->xing_toc) {
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ie = &st->index_entries[ret];
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st->skip_samples = timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0;
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avio_seek(s->pb, FFMAX(ie->pos - 4096, 0), SEEK_SET);
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ret = avio_seek(s->pb, ie->pos, SEEK_SET);
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for(i=0; i<4096; i++) {
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int64_t pos = ie->pos + (dir > 0 ? i - 1024 : -i);
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int64_t candidate = -1;
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for(j=0; j<MIN_VALID; j++) {
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if ((ie->pos - pos)*dir <= 0 && abs(MIN_VALID/2-j) < score) {
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score = abs(MIN_VALID/2-j);
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if (best_score > score && j == MIN_VALID) {
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best_pos = candidate;
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ret = avio_seek(s->pb, best_pos, SEEK_SET);
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ff_update_cur_dts(s, st, ie->timestamp);
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st->skip_samples = ie->timestamp <= 0 ? mp3->start_pad + 528 + 1 : 0;
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static const AVOption options[] = {
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{ "usetoc", "use table of contents", offsetof(MP3DecContext, usetoc), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 1, AV_OPT_FLAG_DECODING_PARAM},
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static const AVClass demuxer_class = {
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.item_name = av_default_item_name,
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.version = LIBAVUTIL_VERSION_INT,
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.category = AV_CLASS_CATEGORY_DEMUXER,
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AVInputFormat ff_mp3_demuxer = {
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.long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
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.read_probe = mp3_read_probe,
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.read_header = mp3_read_header,
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.read_packet = mp3_read_packet,
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.read_seek = mp3_seek,
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.priv_data_size = sizeof(MP3DecContext),
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.flags = AVFMT_GENERIC_INDEX,
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.extensions = "mp2,mp3,m2a,mpa", /* XXX: use probe */
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.priv_class = &demuxer_class,