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ffmpeg / libavformat / mp3.c @ 80242f9b

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/*
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 * MP3 muxer and demuxer
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 * Copyright (c) 2003 Fabrice Bellard
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 *
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 * This file is part of FFmpeg.
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 *
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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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 *
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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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 *
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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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 */
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#include <strings.h>
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#include "libavutil/avstring.h"
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#include "libavutil/intreadwrite.h"
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#include "avformat.h"
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#include "id3v2.h"
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#include "id3v1.h"
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#if CONFIG_MP3_DEMUXER
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#include "libavcodec/mpegaudio.h"
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#include "libavcodec/mpegaudiodecheader.h"
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/* mp3 read */
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static int mp3_read_probe(AVProbeData *p)
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{
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    int max_frames, first_frames = 0;
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    int fsize, frames, sample_rate;
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    uint32_t header;
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    uint8_t *buf, *buf0, *buf2, *end;
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    AVCodecContext avctx;
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    buf0 = p->buf;
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    if(ff_id3v2_match(buf0)) {
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        buf0 += ff_id3v2_tag_len(buf0);
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    }
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    max_frames = 0;
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    buf = buf0;
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    end = p->buf + p->buf_size - sizeof(uint32_t);
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    for(; buf < end; buf= buf2+1) {
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        buf2 = buf;
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        for(frames = 0; buf2 < end; frames++) {
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            header = AV_RB32(buf2);
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            fsize = ff_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
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            if(fsize < 0)
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                break;
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            buf2 += fsize;
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        }
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        max_frames = FFMAX(max_frames, frames);
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        if(buf == buf0)
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            first_frames= frames;
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    }
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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_MAX/2+1;
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    else if(max_frames>500)return AVPROBE_SCORE_MAX/2;
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    else if(max_frames>=4) return AVPROBE_SCORE_MAX/4;
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    else if(buf0!=p->buf)  return AVPROBE_SCORE_MAX/4-1;
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    else if(max_frames>=1) return 1;
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    else                   return 0;
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//mpegps_mp3_unrecognized_format.mpg has max_frames=3
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}
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/**
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 * Try to find Xing/Info/VBRI tags and compute duration from info therein
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 */
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static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
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{
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    uint32_t v, spf;
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    int frames = -1; /* Total number of frames in file */
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    const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
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    MPADecodeHeader c;
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    int vbrtag_size = 0;
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    v = get_be32(s->pb);
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    if(ff_mpa_check_header(v) < 0)
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      return -1;
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    if (ff_mpegaudio_decode_header(&c, v) == 0)
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        vbrtag_size = c.frame_size;
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    if(c.layer != 3)
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        return -1;
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    /* Check for Xing / Info tag */
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    url_fseek(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1], SEEK_CUR);
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    v = get_be32(s->pb);
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    if(v == MKBETAG('X', 'i', 'n', 'g') || v == MKBETAG('I', 'n', 'f', 'o')) {
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        v = get_be32(s->pb);
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        if(v & 0x1)
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            frames = get_be32(s->pb);
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    }
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    /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
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    url_fseek(s->pb, base + 4 + 32, SEEK_SET);
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    v = get_be32(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(get_be16(s->pb) == 1) {
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            /* skip delay, quality and total bytes */
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            url_fseek(s->pb, 8, SEEK_CUR);
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            frames = get_be32(s->pb);
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        }
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    }
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    if(frames < 0)
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        return -1;
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    /* Skip the vbr tag frame */
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    url_fseek(s->pb, base + vbrtag_size, SEEK_SET);
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    spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
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    st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate},
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                                st->time_base);
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    return 0;
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}
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static int mp3_read_header(AVFormatContext *s,
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                           AVFormatParameters *ap)
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{
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    AVStream *st;
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    int64_t off;
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    st = av_new_stream(s, 0);
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    if (!st)
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        return AVERROR(ENOMEM);
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    st->codec->codec_type = CODEC_TYPE_AUDIO;
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    st->codec->codec_id = CODEC_ID_MP3;
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    st->need_parsing = AVSTREAM_PARSE_FULL;
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    st->start_time = 0;
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    // lcm of all mp3 sample rates
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    av_set_pts_info(st, 64, 1, 14112000);
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    ff_id3v2_read(s);
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    off = url_ftell(s->pb);
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    if (!av_metadata_get(s->metadata, "", NULL, AV_METADATA_IGNORE_SUFFIX))
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        ff_id3v1_read(s);
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    if (mp3_parse_vbr_tags(s, st, off) < 0)
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        url_fseek(s->pb, off, SEEK_SET);
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    /* the parameters will be extracted from the compressed bitstream */
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    return 0;
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}
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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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{
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    int ret, size;
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    //    AVStream *st = s->streams[0];
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    size= MP3_PACKET_SIZE;
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    ret= av_get_packet(s->pb, pkt, size);
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    pkt->stream_index = 0;
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    if (ret <= 0) {
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        return AVERROR(EIO);
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    }
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    /* note: we need to modify the packet size here to handle the last
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       packet */
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    pkt->size = ret;
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    return ret;
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}
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AVInputFormat mp3_demuxer = {
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    "mp3",
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    NULL_IF_CONFIG_SMALL("MPEG audio layer 2/3"),
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    0,
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    mp3_read_probe,
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    mp3_read_header,
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    mp3_read_packet,
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    .flags= AVFMT_GENERIC_INDEX,
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    .extensions = "mp2,mp3,m2a", /* XXX: use probe */
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    .metadata_conv = ff_id3v2_metadata_conv,
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};
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#endif
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#if CONFIG_MP2_MUXER || CONFIG_MP3_MUXER
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static int id3v1_set_string(AVFormatContext *s, const char *key,
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                            uint8_t *buf, int buf_size)
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{
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    AVMetadataTag *tag;
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    if ((tag = av_metadata_get(s->metadata, key, NULL, 0)))
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        strncpy(buf, tag->value, buf_size);
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    return !!tag;
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}
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static int id3v1_create_tag(AVFormatContext *s, uint8_t *buf)
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{
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    AVMetadataTag *tag;
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    int i, count = 0;
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    memset(buf, 0, ID3v1_TAG_SIZE); /* fail safe */
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    buf[0] = 'T';
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    buf[1] = 'A';
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    buf[2] = 'G';
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    count += id3v1_set_string(s, "title",   buf +  3, 30);
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    count += id3v1_set_string(s, "author",  buf + 33, 30);
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    count += id3v1_set_string(s, "album",   buf + 63, 30);
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    count += id3v1_set_string(s, "date",    buf + 93,  4);
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    count += id3v1_set_string(s, "comment", buf + 97, 30);
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    if ((tag = av_metadata_get(s->metadata, "track", NULL, 0))) {
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        buf[125] = 0;
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        buf[126] = atoi(tag->value);
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        count++;
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    }
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    buf[127] = 0xFF; /* default to unknown genre */
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    if ((tag = av_metadata_get(s->metadata, "genre", NULL, 0))) {
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        for(i = 0; i <= ID3v1_GENRE_MAX; i++) {
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            if (!strcasecmp(tag->value, ff_id3v1_genre_str[i])) {
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                buf[127] = i;
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                count++;
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                break;
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            }
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        }
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    }
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    return count;
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}
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/* simple formats */
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static void id3v2_put_size(AVFormatContext *s, int size)
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{
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    put_byte(s->pb, size >> 21 & 0x7f);
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    put_byte(s->pb, size >> 14 & 0x7f);
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    put_byte(s->pb, size >> 7  & 0x7f);
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    put_byte(s->pb, size       & 0x7f);
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}
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static void id3v2_put_ttag(AVFormatContext *s, const char *buf, int len,
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                           uint32_t tag)
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{
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    put_be32(s->pb, tag);
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    id3v2_put_size(s, len + 1);
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    put_be16(s->pb, 0);
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    put_byte(s->pb, 3); /* UTF-8 */
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    put_buffer(s->pb, buf, len);
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}
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static int mp3_write_packet(struct AVFormatContext *s, AVPacket *pkt)
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{
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    put_buffer(s->pb, pkt->data, pkt->size);
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    put_flush_packet(s->pb);
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    return 0;
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}
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static int mp3_write_trailer(struct AVFormatContext *s)
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{
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    uint8_t buf[ID3v1_TAG_SIZE];
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    /* write the id3v1 tag */
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    if (id3v1_create_tag(s, buf) > 0) {
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        put_buffer(s->pb, buf, ID3v1_TAG_SIZE);
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        put_flush_packet(s->pb);
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    }
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    return 0;
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}
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#endif /* CONFIG_MP2_MUXER || CONFIG_MP3_MUXER */
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#if CONFIG_MP2_MUXER
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AVOutputFormat mp2_muxer = {
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    "mp2",
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    NULL_IF_CONFIG_SMALL("MPEG audio layer 2"),
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    "audio/x-mpeg",
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    "mp2,m2a",
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    0,
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    CODEC_ID_MP2,
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    CODEC_ID_NONE,
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    NULL,
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    mp3_write_packet,
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    mp3_write_trailer,
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};
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#endif
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#if CONFIG_MP3_MUXER
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/**
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 * Write an ID3v2.4 header at beginning of stream
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 */
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static int mp3_write_header(struct AVFormatContext *s)
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{
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    AVMetadataTag *t = NULL;
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    int totlen = 0;
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    int64_t size_pos, cur_pos;
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    put_be32(s->pb, MKBETAG('I', 'D', '3', 0x04)); /* ID3v2.4 */
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    put_byte(s->pb, 0);
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    put_byte(s->pb, 0); /* flags */
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    /* reserve space for size */
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    size_pos = url_ftell(s->pb);
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    put_be32(s->pb, 0);
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    while ((t = av_metadata_get(s->metadata, "", t, AV_METADATA_IGNORE_SUFFIX))) {
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        uint32_t tag = 0;
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        if (t->key[0] == 'T' && strcmp(t->key, "TSSE")) {
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            int i;
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            for (i = 0; *ff_id3v2_tags[i]; i++)
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                if (AV_RB32(t->key) == AV_RB32(ff_id3v2_tags[i])) {
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                    int len = strlen(t->value);
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                    tag = AV_RB32(t->key);
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                    totlen += len + ID3v2_HEADER_SIZE + 2;
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                    id3v2_put_ttag(s, t->value, len + 1, tag);
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                    break;
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                }
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        }
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        if (!tag) { /* unknown tag, write as TXXX frame */
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            int   len = strlen(t->key), len1 = strlen(t->value);
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            char *buf = av_malloc(len + len1 + 2);
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            if (!buf)
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                return AVERROR(ENOMEM);
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            tag = MKBETAG('T', 'X', 'X', 'X');
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            strcpy(buf,           t->key);
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            strcpy(buf + len + 1, t->value);
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            id3v2_put_ttag(s, buf, len + len1 + 2, tag);
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            totlen += len + len1 + ID3v2_HEADER_SIZE + 3;
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            av_free(buf);
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        }
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    }
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    if(!(s->streams[0]->codec->flags & CODEC_FLAG_BITEXACT)) {
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        totlen += strlen(LIBAVFORMAT_IDENT) + ID3v2_HEADER_SIZE + 2;
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        id3v2_put_ttag(s, LIBAVFORMAT_IDENT, strlen(LIBAVFORMAT_IDENT) + 1,
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                       MKBETAG('T', 'S', 'S', 'E'));
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    }
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    cur_pos = url_ftell(s->pb);
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    url_fseek(s->pb, size_pos, SEEK_SET);
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    id3v2_put_size(s, totlen);
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    url_fseek(s->pb, cur_pos, SEEK_SET);
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    return 0;
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}
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AVOutputFormat mp3_muxer = {
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    "mp3",
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    NULL_IF_CONFIG_SMALL("MPEG audio layer 3"),
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    "audio/x-mpeg",
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    "mp3",
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    0,
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    CODEC_ID_MP3,
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    CODEC_ID_NONE,
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    mp3_write_header,
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    mp3_write_packet,
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    mp3_write_trailer,
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    .metadata_conv = ff_id3v2_metadata_conv,
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};
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#endif