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b5fc215e2d
Assuming there is no padding between the last packet and the index, this prevents the index from being parsed as a normal packet, with non- sensical data.
138 lines
3.7 KiB
C
138 lines
3.7 KiB
C
/*
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* MODS demuxer
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* Copyright (c) 2015-2016 Florian Nouwt
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* Copyright (c) 2017 Adib Surani
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* Copyright (c) 2020 Paul B Mahol
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* Copyright (c) 2026 Link Mauve
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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 "libavutil/intreadwrite.h"
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#include "avformat.h"
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#include "demux.h"
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#include "internal.h"
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typedef struct MODSDemuxContext {
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uint32_t index_pos;
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} MODSDemuxContext;
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static int mods_probe(const AVProbeData *p)
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{
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if (memcmp(p->buf, "MODSN3\x0a\x00", 8))
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return 0;
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if (AV_RB32(p->buf + 8) == 0)
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return 0;
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if (AV_RB32(p->buf + 12) == 0)
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return 0;
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if (AV_RB32(p->buf + 16) == 0)
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return 0;
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return AVPROBE_SCORE_MAX;
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}
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static int mods_read_header(AVFormatContext *s)
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{
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AVIOContext *pb = s->pb;
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MODSDemuxContext *ctx = s->priv_data;
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AVRational fps;
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int64_t pos;
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int64_t timestamp;
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int num_keyframes;
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const AVIndexEntry *e;
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AVStream *st = avformat_new_stream(s, NULL);
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if (!st)
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return AVERROR(ENOMEM);
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avio_skip(pb, 8);
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st->nb_frames = avio_rl32(pb);
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st->duration = st->nb_frames;
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st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
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st->codecpar->codec_id = AV_CODEC_ID_MOBICLIP;
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st->codecpar->width = avio_rl32(pb);
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st->codecpar->height = avio_rl32(pb);
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fps.num = avio_rl32(pb);
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fps.den = 0x1000000;
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avpriv_set_pts_info(st, 64, fps.den, fps.num);
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avio_skip(pb, 16);
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pos = avio_rl32(pb);
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num_keyframes = avio_rl32(pb);
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avio_seek(pb, pos, SEEK_SET);
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ctx->index_pos = pos;
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for (int i = 0; i < num_keyframes; ++i) {
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timestamp = avio_rl32(pb);
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pos = avio_rl32(pb);
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if (avio_feof(pb))
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return AVERROR_INVALIDDATA;
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av_add_index_entry(st, pos, timestamp, 0, 0, AVINDEX_KEYFRAME);
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}
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e = avformat_index_get_entry(st, 0);
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if (!e)
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return AVERROR_INVALIDDATA;
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avio_seek(pb, e->pos, SEEK_SET);
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return 0;
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}
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static int mods_read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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AVIOContext *pb = s->pb;
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MODSDemuxContext *ctx = s->priv_data;
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unsigned size;
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int64_t pos;
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int ret;
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const AVIndexEntry *e;
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if (avio_feof(pb))
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return AVERROR_EOF;
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/* This assumes the keyframes index directly follows the last packet. */
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pos = avio_tell(pb);
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if (pos == ctx->index_pos)
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return AVERROR_EOF;
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size = avio_rl32(pb) >> 14;
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ret = av_get_packet(pb, pkt, size);
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pkt->pos = pos;
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pkt->stream_index = 0;
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e = avformat_index_get_entry_from_timestamp(s->streams[0], pos, 0);
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if (e)
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pkt->flags |= AV_PKT_FLAG_KEY;
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return ret;
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}
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const FFInputFormat ff_mods_demuxer = {
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.p.name = "mods",
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.p.long_name = NULL_IF_CONFIG_SMALL("MobiClip MODS"),
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.p.extensions = "mods",
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.p.flags = AVFMT_GENERIC_INDEX,
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.priv_data_size = sizeof(MODSDemuxContext),
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.read_probe = mods_probe,
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.read_header = mods_read_header,
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.read_packet = mods_read_packet,
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};
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