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* Copyright (c) 2006 Reimar Doeffinger.
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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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MAT_FIRST_FIELD = 0x41,
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MAT_LAST_FIELD = 0x42,
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AVRational frames_per_second;
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int32_t fields_per_frame;
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* \brief parses a packet header, extracting type and length
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* \param pb ByteIOContext to read header from
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* \param type detected packet type is stored here
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* \param length detected packet length, excluding header is stored here
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* \return 0 if header not found or contains invalid data, 1 otherwise
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static int parse_packet_header(ByteIOContext *pb, pkt_type_t *type, int *length) {
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if (get_byte(pb) != 1)
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*length = get_be32(pb);
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if ((*length >> 24) || *length < 16)
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if (get_byte(pb) != 0xe1)
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if (get_byte(pb) != 0xe2)
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* \brief check if file starts with a PKT_MAP header
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static int gxf_probe(AVProbeData *p) {
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static const uint8_t startcode[] = {0, 0, 0, 0, 1, 0xbc}; // start with map packet
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static const uint8_t endcode[] = {0, 0, 0, 0, 0xe1, 0xe2};
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if (!memcmp(p->buf, startcode, sizeof(startcode)) &&
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!memcmp(&p->buf[16 - sizeof(endcode)], endcode, sizeof(endcode)))
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return AVPROBE_SCORE_MAX;
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* \brief gets the stream index for the track with the specified id, creates new
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* stream if not found
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* \param stream id of stream to find / add
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* \param format stream format identifier
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static int get_sindex(AVFormatContext *s, int id, int format) {
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for (i = 0; i < s->nb_streams; i++) {
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if (s->streams[i]->id == id)
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st = av_new_stream(s, id);
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st->codec->codec_type = CODEC_TYPE_VIDEO;
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st->codec->codec_id = CODEC_ID_MJPEG;
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st->codec->codec_type = CODEC_TYPE_VIDEO;
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st->codec->codec_id = CODEC_ID_DVVIDEO;
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st->codec->codec_type = CODEC_TYPE_VIDEO;
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st->codec->codec_id = CODEC_ID_DVVIDEO;
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st->codec->codec_type = CODEC_TYPE_VIDEO;
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st->codec->codec_id = CODEC_ID_MPEG2VIDEO;
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st->need_parsing = 2; // get keyframe flag etc.
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st->codec->codec_type = CODEC_TYPE_VIDEO;
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st->codec->codec_id = CODEC_ID_MPEG1VIDEO;
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st->need_parsing = 2; // get keyframe flag etc.
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st->codec->codec_type = CODEC_TYPE_AUDIO;
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st->codec->codec_id = CODEC_ID_PCM_S24LE;
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st->codec->channels = 1;
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st->codec->sample_rate = 48000;
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st->codec->bit_rate = 3 * 1 * 48000 * 8;
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st->codec->block_align = 3 * 1;
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st->codec->bits_per_sample = 24;
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st->codec->codec_type = CODEC_TYPE_AUDIO;
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st->codec->codec_id = CODEC_ID_PCM_S16LE;
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st->codec->channels = 1;
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st->codec->sample_rate = 48000;
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st->codec->bit_rate = 2 * 1 * 48000 * 8;
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st->codec->block_align = 2 * 1;
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st->codec->bits_per_sample = 16;
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st->codec->codec_type = CODEC_TYPE_AUDIO;
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st->codec->codec_id = CODEC_ID_AC3;
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st->codec->channels = 2;
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st->codec->sample_rate = 48000;
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st->codec->codec_type = CODEC_TYPE_DATA;
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st->codec->codec_id = CODEC_ID_NONE;
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st->codec->codec_type = CODEC_TYPE_UNKNOWN;
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st->codec->codec_id = CODEC_ID_NONE;
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return s->nb_streams - 1;
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* \brief filters out interesting tags from material information.
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* \param len lenght of tag section, will be adjusted to contain remaining bytes
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* \param si struct to store collected information into
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static void gxf_material_tags(ByteIOContext *pb, int *len, st_info_t *si) {
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si->first_field = AV_NOPTS_VALUE;
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si->last_field = AV_NOPTS_VALUE;
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mat_tag_t tag = get_byte(pb);
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int tlen = get_byte(pb);
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uint32_t value = get_be32(pb);
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if (tag == MAT_FIRST_FIELD)
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si->first_field = value;
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else if (tag == MAT_LAST_FIELD)
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si->last_field = value;
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* \brief convert fps tag value to AVRational fps
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* \param fps fps value from tag
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* \return fps as AVRational, or 0 / 0 if unknown
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static AVRational fps_tag2avr(int32_t fps) {
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extern const AVRational ff_frame_rate_tab[];
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if (fps < 1 || fps > 9) fps = 9;
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return ff_frame_rate_tab[9 - fps]; // values have opposite order
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* \brief convert UMF attributes flags to AVRational fps
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* \param fps fps value from flags
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* \return fps as AVRational, or 0 / 0 if unknown
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static AVRational fps_umf2avr(uint32_t flags) {
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static const AVRational map[] = {{50, 1}, {60000, 1001}, {24, 1},
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{25, 1}, {30000, 1001}};
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int idx = av_log2((flags & 0x7c0) >> 6);
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* \brief filters out interesting tags from track information.
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* \param len length of tag section, will be adjusted to contain remaining bytes
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* \param si struct to store collected information into
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static void gxf_track_tags(ByteIOContext *pb, int *len, st_info_t *si) {
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si->frames_per_second = (AVRational){0, 0};
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si->fields_per_frame = 0;
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track_tag_t tag = get_byte(pb);
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int tlen = get_byte(pb);
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uint32_t value = get_be32(pb);
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if (tag == TRACK_FPS)
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si->frames_per_second = fps_tag2avr(value);
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else if (tag == TRACK_FPF && (value == 1 || value == 2))
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si->fields_per_frame = value;
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* \brief read index from FLT packet into stream 0 av_index
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static void gxf_read_index(AVFormatContext *s, int pkt_len) {
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ByteIOContext *pb = &s->pb;
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AVStream *st = s->streams[0];
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uint32_t fields_per_map = get_le32(pb);
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uint32_t map_cnt = get_le32(pb);
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if (map_cnt > 1000) {
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av_log(s, AV_LOG_ERROR, "GXF: too many index entries %u (%x)\n", map_cnt, map_cnt);
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if (pkt_len < 4 * map_cnt) {
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av_log(s, AV_LOG_ERROR, "GXF: invalid index length\n");
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url_fskip(pb, pkt_len);
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pkt_len -= 4 * map_cnt;
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av_add_index_entry(st, 0, 0, 0, 0, 0);
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for (i = 0; i < map_cnt; i++)
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av_add_index_entry(st, (uint64_t)get_le32(pb) * 1024,
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i * (uint64_t)fields_per_map + 1, 0, 0, 0);
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url_fskip(pb, pkt_len);
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static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
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ByteIOContext *pb = &s->pb;
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AVRational main_timebase = {0, 0};
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if (!parse_packet_header(pb, &pkt_type, &map_len) || pkt_type != PKT_MAP) {
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av_log(s, AV_LOG_ERROR, "GXF: map packet not found\n");
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if (get_byte(pb) != 0x0e0 || get_byte(pb) != 0xff) {
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av_log(s, AV_LOG_ERROR, "GXF: unknown version or invalid map preamble\n");
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len = get_be16(pb); // length of material data section
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av_log(s, AV_LOG_ERROR, "GXF: material data longer than map data\n");
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gxf_material_tags(pb, &len, &si);
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len = get_be16(pb); // length of track description
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av_log(s, AV_LOG_ERROR, "GXF: track description longer than map data\n");
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int track_type, track_id, track_len;
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track_type = get_byte(pb);
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track_id = get_byte(pb);
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track_len = get_be16(pb);
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gxf_track_tags(pb, &track_len, &si);
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url_fskip(pb, track_len);
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if (!(track_type & 0x80)) {
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av_log(s, AV_LOG_ERROR, "GXF: invalid track type %x\n", track_type);
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if ((track_id & 0xc0) != 0xc0) {
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av_log(s, AV_LOG_ERROR, "GXF: invalid track id %x\n", track_id);
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idx = get_sindex(s, track_id, track_type);
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if (idx < 0) continue;
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st = s->streams[idx];
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if (!main_timebase.num || !main_timebase.den) {
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main_timebase.num = si.frames_per_second.den;
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main_timebase.den = si.frames_per_second.num * si.fields_per_frame;
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st->start_time = si.first_field;
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if (si.first_field != AV_NOPTS_VALUE && si.last_field != AV_NOPTS_VALUE)
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st->duration = si.last_field - si.first_field;
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av_log(s, AV_LOG_ERROR, "GXF: invalid track description length specified\n");
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url_fskip(pb, map_len);
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if (!parse_packet_header(pb, &pkt_type, &len)) {
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av_log(s, AV_LOG_ERROR, "GXF: sync lost in header\n");
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if (pkt_type == PKT_FLT) {
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gxf_read_index(s, len);
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if (!parse_packet_header(pb, &pkt_type, &len)) {
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av_log(s, AV_LOG_ERROR, "GXF: sync lost in header\n");
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if (pkt_type == PKT_UMF) {
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url_fskip(pb, 5); // preamble
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url_fskip(pb, 0x30); // payload description
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fps = fps_umf2avr(get_le32(pb));
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if (!main_timebase.num || !main_timebase.den) {
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// this may not always be correct, but simply the best we can get
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main_timebase.num = fps.den;
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main_timebase.den = fps.num;
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av_log(s, AV_LOG_INFO, "GXF: UMF packet too short\n");
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av_log(s, AV_LOG_INFO, "GXF: UMF packet missing\n");
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if (!main_timebase.num || !main_timebase.den)
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main_timebase = (AVRational){1, 50}; // set some arbitrary fallback
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for (i = 0; i < s->nb_streams; i++) {
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AVStream *st = s->streams[i];
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av_set_pts_info(st, 32, main_timebase.num, main_timebase.den);
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if (!max_interval-- || url_feof(pb)) \
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tmp = tmp << 8 | get_byte(pb); \
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* \brief resync the stream on the next media packet with specified properties
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* \param max_interval how many bytes to search for matching packet at most
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* \param track track id the media packet must belong to, -1 for any
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* \param timestamp minimum timestamp (== field number) the packet must have, -1 for any
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* \return timestamp of packet found
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static int64_t gxf_resync_media(AVFormatContext *s, uint64_t max_interval, int track, int timestamp) {
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uint64_t last_found_pos = 0;
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int64_t cur_timestamp = AV_NOPTS_VALUE;
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ByteIOContext *pb = &s->pb;
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last_pos = url_ftell(pb);
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url_fseek(pb, -5, SEEK_CUR);
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if (!parse_packet_header(pb, &type, &len) || type != PKT_MEDIA) {
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url_fseek(pb, last_pos, SEEK_SET);
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cur_track = get_byte(pb);
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cur_timestamp = get_be32(pb);
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last_found_pos = url_ftell(pb) - 16 - 6;
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if ((track >= 0 && track != cur_track) || (timestamp >= 0 && timestamp > cur_timestamp)) {
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url_fseek(pb, last_pos, SEEK_SET);
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url_fseek(pb, last_found_pos, SEEK_SET);
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return cur_timestamp;
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static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {
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ByteIOContext *pb = &s->pb;
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while (!url_feof(pb)) {
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int track_type, track_id, ret;
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if (!parse_packet_header(pb, &pkt_type, &pkt_len)) {
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av_log(s, AV_LOG_ERROR, "GXF: sync lost\n");
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if (pkt_type == PKT_FLT) {
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gxf_read_index(s, pkt_len);
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if (pkt_type != PKT_MEDIA) {
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url_fskip(pb, pkt_len);
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av_log(s, AV_LOG_ERROR, "GXF: invalid media packet length\n");
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track_type = get_byte(pb);
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track_id = get_byte(pb);
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field_nr = get_be32(pb);
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get_be32(pb); // field information
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get_be32(pb); // "timeline" field number
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get_byte(pb); // flags
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get_byte(pb); // reserved
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// NOTE: there is also data length information in the
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// field information, it might be better to take this into account
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ret = av_get_packet(pb, pkt, pkt_len);
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pkt->stream_index = get_sindex(s, track_id, track_type);
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static int gxf_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) {
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uint64_t maxlen = 100 * 1024 * 1024;
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AVStream *st = s->streams[0];
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int64_t start_time = s->streams[stream_index]->start_time;
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if (timestamp < start_time) timestamp = start_time;
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idx = av_index_search_timestamp(st, timestamp - start_time,
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AVSEEK_FLAG_ANY | AVSEEK_FLAG_BACKWARD);
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pos = st->index_entries[idx].pos;
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if (idx < st->nb_index_entries - 2)
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maxlen = st->index_entries[idx + 2].pos - pos;
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maxlen = FFMAX(maxlen, 200 * 1024);
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url_fseek(&s->pb, pos, SEEK_SET);
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found = gxf_resync_media(s, maxlen, -1, timestamp);
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if (FFABS(found - timestamp) > 4)
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static int64_t gxf_read_timestamp(AVFormatContext *s, int stream_index,
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int64_t *pos, int64_t pos_limit) {
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ByteIOContext *pb = &s->pb;
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url_fseek(pb, *pos, SEEK_SET);
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res = gxf_resync_media(s, pos_limit - *pos, -1, -1);
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*pos = url_ftell(pb);
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AVInputFormat gxf_demuxer = {