[Ffmpeg-devel] [PATCH] seeking in GXF
Reimar Döffinger
Reimar.Doeffinger
Sun Jul 30 16:45:06 CEST 2006
Hello,
attached patch add seeking for gxf files (both with and without index).
It probably still contains some bad/ugly code, but I can't think clearly
anymore today. So if someone can have a look or test it, please do so.
Btw. is there some kind of flag to for libavformat not to use the index
in a file and resolve to generic seeking instead?
Greetings,
Reimar D?ffinger
-------------- next part --------------
Index: libavformat/gxf.c
===================================================================
--- libavformat/gxf.c (revision 5865)
+++ libavformat/gxf.c (working copy)
@@ -26,6 +26,32 @@
PKT_UMF = 0xfd
} pkt_type_t;
+typedef enum {
+ MAT_NAME = 0x40,
+ MAT_FIRST_FIELD = 0x41,
+ MAT_LAST_FIELD = 0x42,
+ MAT_MARK_IN = 0x43,
+ MAT_MARK_OUT = 0x44,
+ MAT_SIZE = 0x45
+} mat_tag_t;
+
+typedef enum {
+ TRACK_NAME = 0x4c,
+ TRACK_AUX = 0x4d,
+ TRACK_VER = 0x4e,
+ TRACK_MPG_AUX = 0x4f,
+ TRACK_FPS = 0x50,
+ TRACK_LINES = 0x51,
+ TRACK_FPF = 0x52
+} track_tag_t;
+
+typedef struct {
+ int32_t first_field;
+ int32_t last_field;
+ AVRational frames_per_second;
+ int32_t fields_per_frame;
+} st_info_t;
+
/**
* \brief parses a packet header, extracting type and length
* \param pb ByteIOContext to read header from
@@ -147,9 +173,120 @@
return s->nb_streams - 1;
}
+/**
+ * \brief filters out interesting tags from material information.
+ * \param len lenght of tag section, will be adjusted to contain remaining bytes
+ * \param si struct to store collected information into
+ */
+static void gxf_material_tags(ByteIOContext *pb, int *len, st_info_t *si) {
+ while (*len >= 2) {
+ mat_tag_t tag = get_byte(pb);
+ int tlen = get_byte(pb);
+ *len -= 2;
+ if (tlen > *len)
+ return;
+ *len -= tlen;
+ switch (tag) {
+ case MAT_FIRST_FIELD:
+ if (tlen != 4)
+ break;
+ si->first_field = get_be32(pb);
+ tlen = 0;
+ break;
+ case MAT_LAST_FIELD:
+ if (tlen != 4)
+ break;
+ si->last_field = get_be32(pb);
+ tlen = 0;
+ break;
+ }
+ url_fskip(pb, tlen);
+ }
+}
+
+/**
+ * \brief convert fps tag value to AVRational fps
+ * \param fps fps value from tag
+ * \return fps as AVRational, or 0 / 0 if unknown
+ */
+static AVRational fps_tag2avr(int32_t fps) {
+ AVRational res = {0, 0};
+ switch (fps) {
+ case 1:
+ res.num = 60;
+ res.den = 1;
+ break;
+ case 2:
+ res.num = 60000;
+ res.den = 1001;
+ break;
+ case 3:
+ res.num = 50;
+ res.den = 1;
+ break;
+ case 4:
+ res.num = 30;
+ res.den = 1;
+ break;
+ case 5:
+ res.num = 30000;
+ res.den = 1001;
+ break;
+ case 6:
+ res.num = 25;
+ res.den = 1;
+ break;
+ case 7:
+ res.num = 24;
+ res.den = 1;
+ break;
+ case 8:
+ res.num = 24000;
+ res.den = 1001;
+ break;
+ }
+ return res;
+}
+
+/**
+ * \brief filters out interesting tags from track information.
+ * \param len lenght of tag section, will be adjusted to contain remaining bytes
+ * \param si struct to store collected information into
+ */
+static void gxf_track_tags(ByteIOContext *pb, int *len, st_info_t *si) {
+ while (*len >= 2) {
+ track_tag_t tag = get_byte(pb);
+ int tlen = get_byte(pb);
+ *len -= 2;
+ if (tlen > *len)
+ return;
+ *len -= tlen;
+ switch (tag) {
+ case TRACK_FPS:
+ if (tlen != 4)
+ break;
+ si->frames_per_second = fps_tag2avr(get_be32(pb));
+ tlen = 0;
+ break;
+ case TRACK_FPF:
+ if (tlen != 4)
+ break;
+ si->fields_per_frame = get_be32(pb);
+ if (si->fields_per_frame != 1 && si->fields_per_frame != 2)
+ si->fields_per_frame = 1;
+ tlen = 0;
+ break;
+ }
+ url_fskip(pb, tlen);
+ }
+}
+
static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
+ AVRational main_timebase = {0, 0};
+ AVStream *st;
ByteIOContext *pb = &s->pb;
pkt_type_t pkt_type;
+ st_info_t si = {-1 , -1, {0, 0}, 1};
int map_len;
int len;
if (!parse_packet_header(pb, &pkt_type, &map_len) || pkt_type != PKT_MAP) {
@@ -168,6 +305,7 @@
return 0;
}
map_len -= len;
+ gxf_material_tags(pb, &len, &si);
url_fskip(pb, len);
map_len -= 2;
len = get_be16(pb); // length of track description
@@ -178,11 +316,13 @@
map_len -= len;
while (len > 0) {
int track_type, track_id, track_len;
+ int idx;
len -= 4;
track_type = get_byte(pb);
track_id = get_byte(pb);
track_len = get_be16(pb);
len -= track_len;
+ gxf_track_tags(pb, &track_len, &si);
url_fskip(pb, track_len);
if (!(track_type & 0x80)) {
av_log(s, AV_LOG_ERROR, "GXF: invalid track type %x\n", track_type);
@@ -194,26 +334,125 @@
continue;
}
track_id &= 0x3f;
- get_sindex(s, track_id, track_type);
+ idx = get_sindex(s, track_id, track_type);
+ if (idx < 0) continue;
+ st = s->streams[idx];
+ st->time_base.num = si.frames_per_second.den;
+ st->time_base.den = si.frames_per_second.num * si.fields_per_frame;
+ if (!main_timebase.den || !main_timebase.num)
+ main_timebase = st->time_base;
+ if (si.first_field >= 0) {
+ st->start_time = si.first_field;
+ if (si.last_field >= 0)
+ st->duration = si.last_field - si.first_field;
+ }
}
if (len < 0)
av_log(s, AV_LOG_ERROR, "GXF: invalid track description length specified\n");
if (map_len)
url_fskip(pb, map_len);
+ if (main_timebase.num && main_timebase.den) {
+ int i;
+ for (i = 0; i < s->nb_streams; i++) {
+ st = s->streams[i];
+ if (!st->time_base.num || !st->time_base.den)
+ st->time_base = main_timebase;
+ }
+ }
return 0;
}
+/**
+ * \brief read index from FLT packet into stream 0 av_index
+ */
+static void gxf_read_index(AVFormatContext *s, ByteIOContext *pb, int pkt_len) {
+ AVStream *st = s->streams[0];
+ uint32_t fields_per_map = get_le32(pb);
+ uint32_t map_cnt = get_le32(pb);
+ int i;
+ pkt_len -= 8;
+ if (map_cnt > 1000) {
+ av_log(s, AV_LOG_ERROR, "GXF: too many index entries %u (%x)\n", map_cnt, map_cnt);
+ map_cnt = 1000;
+ }
+ if (pkt_len < 4 * map_cnt) {
+ av_log(s, AV_LOG_ERROR, "GXF: invalid index length\n");
+ url_fskip(pb, pkt_len);
+ return;
+ }
+ pkt_len -= 4 * map_cnt;
+ av_add_index_entry(st, 0, 0, 0, 0, 0);
+ for (i = 0; i < map_cnt; i++)
+ av_add_index_entry(st, get_le32(pb) * 1024, i * fields_per_map + 1, 0, 0, 0);
+ url_fskip(pb, pkt_len);
+}
+
+#define READ_ONE() \
+ { \
+ if (!max_interval-- || url_feof(pb)) \
+ goto out; \
+ tmp = tmp << 8 | get_byte(pb); \
+ }
+
+/**
+ * \brief resync the stream on the next media packet with specified properties
+ * \param max_interval how many bytes to search for matching packet at most
+ * \param track track id the media packet must belong to, -1 for any
+ * \param timestamp minimum timestamp (== field number) the packet must have, -1 for any
+ * \return timestamp of packet found
+ */
+static int64_t gxf_resync_media(AVFormatContext *s, uint64_t max_interval, int track, int timestamp) {
+ uint32_t tmp;
+ uint64_t last_pos;
+ uint64_t last_found_pos = 0;
+ int cur_track;
+ int64_t cur_timestamp = AV_NOPTS_VALUE;
+ int len;
+ ByteIOContext *pb = &s->pb;
+ pkt_type_t type;
+ tmp = 0xff;
+start:
+ while (tmp)
+ READ_ONE();
+ READ_ONE();
+ if (tmp != 1)
+ goto start;
+ last_pos = url_ftell(pb);
+ url_fseek(pb, -5, SEEK_CUR);
+ if (!parse_packet_header(pb, &type, &len) || type != PKT_MEDIA) {
+ url_fseek(pb, last_pos, SEEK_SET);
+ goto start;
+ }
+ get_byte(pb);
+ cur_track = get_byte(pb);
+ cur_timestamp = get_be32(pb);
+ last_found_pos = url_ftell(pb) - 16 - 6;
+ if ((track >= 0 && track != cur_track) || (timestamp >= 0 && timestamp > cur_timestamp)) {
+ url_fseek(pb, last_pos, SEEK_SET);
+ goto start;
+ }
+out:
+ if (last_found_pos)
+ url_fseek(pb, last_found_pos, SEEK_SET);
+ return cur_timestamp;
+}
+
static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {
ByteIOContext *pb = &s->pb;
pkt_type_t pkt_type;
int pkt_len;
while (!url_feof(pb)) {
int track_type, track_id, ret;
+ int field_nr;
if (!parse_packet_header(pb, &pkt_type, &pkt_len)) {
if (!url_feof(pb))
av_log(s, AV_LOG_ERROR, "GXF: sync lost\n");
return -1;
}
+ if (pkt_type == PKT_FLT) {
+ gxf_read_index(s, pb, pkt_len);
+ continue;
+ }
if (pkt_type != PKT_MEDIA) {
url_fskip(pb, pkt_len);
continue;
@@ -225,7 +464,7 @@
pkt_len -= 16;
track_type = get_byte(pb);
track_id = get_byte(pb);
- get_be32(pb); // field number
+ field_nr = get_be32(pb);
get_be32(pb); // field information
get_be32(pb); // "timeline" field number
get_byte(pb); // flags
@@ -235,11 +474,42 @@
// as well.
ret = av_get_packet(pb, pkt, pkt_len);
pkt->stream_index = get_sindex(s, track_id, track_type);
+ pkt->pts = field_nr;
return ret;
}
return AVERROR_IO;
}
+static int gxf_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) {
+ uint64_t pos;
+ uint64_t maxlen = 100 * 1024 * 1024;
+ AVStream *st = s->streams[0];
+ int64_t start_time = s->streams[stream_index]->start_time;
+ int idx;
+ if (timestamp < start_time) timestamp = start_time;
+ idx = av_index_search_timestamp(st, timestamp - start_time,
+ AVSEEK_FLAG_ANY | AVSEEK_FLAG_BACKWARD);
+ if (idx < 0)
+ return -1;
+ pos = st->index_entries[idx].pos;
+ if (idx < st->nb_index_entries - 2)
+ maxlen = st->index_entries[idx + 2].pos - pos;
+ if (maxlen < 200 * 1024) maxlen = 200 * 1024;
+ url_fseek(&s->pb, pos, SEEK_SET);
+ gxf_resync_media(s, maxlen, -1, timestamp);
+ return 0;
+}
+
+static int64_t gxf_read_timestamp(AVFormatContext *s, int stream_index,
+ int64_t *pos, int64_t pos_limit) {
+ ByteIOContext *pb = &s->pb;
+ int64_t res;
+ url_fseek(pb, *pos, SEEK_SET);
+ res = gxf_resync_media(s, pos_limit - *pos, -1, -1);
+ *pos = url_ftell(pb);
+ return res;
+}
+
AVInputFormat gxf_demuxer = {
"gxf",
"GXF format",
@@ -248,5 +518,6 @@
gxf_header,
gxf_packet,
NULL,
- NULL,
+ gxf_seek,
+ gxf_read_timestamp,
};
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