mirror of https://git.ffmpeg.org/ffmpeg.git
Support for seeking, both with and without index and correct timestamps
Originally committed as revision 5880 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Reimar Döffinger
parent
0e15b7b0dd
commit
907a051009
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@ -17,6 +17,7 @@
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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 "avformat.h"
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#include "common.h"
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typedef enum {
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PKT_MAP = 0xbc,
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@ -26,6 +27,32 @@ typedef enum {
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PKT_UMF = 0xfd
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} pkt_type_t;
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typedef enum {
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MAT_NAME = 0x40,
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MAT_FIRST_FIELD = 0x41,
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MAT_LAST_FIELD = 0x42,
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MAT_MARK_IN = 0x43,
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MAT_MARK_OUT = 0x44,
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MAT_SIZE = 0x45
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} mat_tag_t;
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typedef enum {
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TRACK_NAME = 0x4c,
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TRACK_AUX = 0x4d,
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TRACK_VER = 0x4e,
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TRACK_MPG_AUX = 0x4f,
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TRACK_FPS = 0x50,
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TRACK_LINES = 0x51,
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TRACK_FPF = 0x52
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} track_tag_t;
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typedef struct {
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int64_t first_field;
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int64_t last_field;
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AVRational frames_per_second;
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int32_t fields_per_frame;
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} st_info_t;
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/**
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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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@ -147,11 +174,116 @@ static int get_sindex(AVFormatContext *s, int id, int format) {
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return s->nb_streams - 1;
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}
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/**
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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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*/
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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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while (*len >= 2) {
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mat_tag_t tag = get_byte(pb);
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int tlen = get_byte(pb);
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*len -= 2;
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if (tlen > *len)
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return;
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*len -= tlen;
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if (tlen == 4) {
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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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} else
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url_fskip(pb, tlen);
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}
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}
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/**
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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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*/
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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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}
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/**
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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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*/
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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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return map[idx];
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}
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/**
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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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*/
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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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while (*len >= 2) {
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track_tag_t tag = get_byte(pb);
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int tlen = get_byte(pb);
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*len -= 2;
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if (tlen > *len)
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return;
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*len -= tlen;
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if (tlen == 4) {
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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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} else
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url_fskip(pb, tlen);
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}
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}
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/**
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* \brief read index from FLT packet into stream 0 av_index
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*/
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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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int i;
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pkt_len -= 8;
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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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map_cnt = 1000;
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}
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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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return;
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}
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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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}
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static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
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ByteIOContext *pb = &s->pb;
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pkt_type_t pkt_type;
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int map_len;
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int len;
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AVRational main_timebase = {0, 0};
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st_info_t si;
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int i;
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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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return 0;
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@ -168,6 +300,7 @@ static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
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return 0;
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}
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map_len -= len;
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gxf_material_tags(pb, &len, &si);
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url_fskip(pb, len);
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map_len -= 2;
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len = get_be16(pb); // length of track description
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@ -178,11 +311,14 @@ static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
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map_len -= len;
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while (len > 0) {
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int track_type, track_id, track_len;
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AVStream *st;
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int idx;
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len -= 4;
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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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len -= track_len;
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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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@ -194,26 +330,125 @@ static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
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continue;
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}
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track_id &= 0x3f;
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get_sindex(s, track_id, track_type);
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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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}
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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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}
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if (len < 0)
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av_log(s, AV_LOG_ERROR, "GXF: invalid track description length specified\n");
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if (map_len)
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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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return -1;
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}
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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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return -1;
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}
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}
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if (pkt_type == PKT_UMF) {
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if (len >= 9) {
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AVRational fps;
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len -= 9;
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url_fskip(pb, 5);
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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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}
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} else
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av_log(s, AV_LOG_INFO, "GXF: UMF packet too short\n");
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} else
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av_log(s, AV_LOG_INFO, "GXF: UMF packet missing\n");
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url_fskip(pb, len);
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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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if (main_timebase.num && main_timebase.den)
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st->time_base = main_timebase;
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else {
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st->start_time = st->duration = AV_NOPTS_VALUE;
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}
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}
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return 0;
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}
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#define READ_ONE() \
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{ \
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if (!max_interval-- || url_feof(pb)) \
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goto out; \
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tmp = tmp << 8 | get_byte(pb); \
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}
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/**
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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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*/
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static int64_t gxf_resync_media(AVFormatContext *s, uint64_t max_interval, int track, int timestamp) {
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uint32_t tmp;
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uint64_t last_pos;
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uint64_t last_found_pos = 0;
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int cur_track;
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int64_t cur_timestamp = AV_NOPTS_VALUE;
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int len;
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ByteIOContext *pb = &s->pb;
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pkt_type_t type;
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tmp = 0xff;
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start:
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while (tmp)
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READ_ONE();
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READ_ONE();
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if (tmp != 1)
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goto start;
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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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goto start;
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}
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get_byte(pb);
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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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goto start;
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}
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out:
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if (last_found_pos)
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url_fseek(pb, last_found_pos, SEEK_SET);
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return cur_timestamp;
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}
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static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {
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ByteIOContext *pb = &s->pb;
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pkt_type_t pkt_type;
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int pkt_len;
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while (!url_feof(pb)) {
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int track_type, track_id, ret;
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int field_nr;
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if (!parse_packet_header(pb, &pkt_type, &pkt_len)) {
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if (!url_feof(pb))
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av_log(s, AV_LOG_ERROR, "GXF: sync lost\n");
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return -1;
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}
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if (pkt_type == PKT_FLT) {
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gxf_read_index(s, pkt_len);
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continue;
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}
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if (pkt_type != PKT_MEDIA) {
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url_fskip(pb, pkt_len);
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continue;
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@ -225,7 +460,7 @@ static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {
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pkt_len -= 16;
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track_type = get_byte(pb);
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track_id = get_byte(pb);
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get_be32(pb); // field number
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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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@ -235,11 +470,45 @@ static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {
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// as well.
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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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pkt->pts = field_nr;
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return ret;
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}
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return AVERROR_IO;
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}
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static int gxf_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) {
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uint64_t pos;
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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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int64_t found;
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int idx;
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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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if (idx < 0)
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return -1;
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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 (ABS(found - timestamp) > 4)
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return -1;
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return 0;
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}
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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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int64_t res;
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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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return res;
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}
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AVInputFormat gxf_demuxer = {
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"gxf",
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"GXF format",
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@ -248,5 +517,6 @@ AVInputFormat gxf_demuxer = {
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gxf_header,
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gxf_packet,
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NULL,
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NULL,
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gxf_seek,
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gxf_read_timestamp,
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};
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