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Support for seeking, both with and without index and correct timestamps

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Originally committed as revision 5880 to svn://svn.ffmpeg.org/ffmpeg/trunk
pull/126/head
Reimar Döffinger 19 years ago
parent 0e15b7b0dd
commit 907a051009
1 changed files with 273 additions and 3 deletions
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  1. 276
      libavformat/gxf.c

276
libavformat/gxf.c
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@ -17,6 +17,7 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avformat.h"
#include "common.h"
typedef enum {
PKT_MAP = 0xbc,
@ -26,6 +27,32 @@ typedef enum {
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 {
int64_t first_field;
int64_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
@ -147,11 +174,116 @@ static int get_sindex(AVFormatContext *s, int id, int format) {
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) {
si->first_field = AV_NOPTS_VALUE;
si->last_field = AV_NOPTS_VALUE;
while (*len >= 2) {
mat_tag_t tag = get_byte(pb);
int tlen = get_byte(pb);
*len -= 2;
if (tlen > *len)
return;
*len -= tlen;
if (tlen == 4) {
uint32_t value = get_be32(pb);
if (tag == MAT_FIRST_FIELD)
si->first_field = value;
else if (tag == MAT_LAST_FIELD)
si->last_field = value;
} else
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) {
extern const AVRational ff_frame_rate_tab[];
if (fps < 1 || fps > 9) fps = 9;
return ff_frame_rate_tab[9 - fps]; // values have opposite order
}
/**
* \brief convert UMF attributes flags to AVRational fps
* \param fps fps value from flags
* \return fps as AVRational, or 0 / 0 if unknown
*/
static AVRational fps_umf2avr(uint32_t flags) {
static const AVRational map[] = {{50, 1}, {60000, 1001}, {24, 1},
{25, 1}, {30000, 1001}};
int idx = av_log2((flags & 0x7c0) >> 6);
return map[idx];
}
/**
* \brief filters out interesting tags from track information.
* \param len length 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) {
si->frames_per_second = (AVRational){0, 0};
si->fields_per_frame = 0;
while (*len >= 2) {
track_tag_t tag = get_byte(pb);
int tlen = get_byte(pb);
*len -= 2;
if (tlen > *len)
return;
*len -= tlen;
if (tlen == 4) {
uint32_t value = get_be32(pb);
if (tag == TRACK_FPS)
si->frames_per_second = fps_tag2avr(value);
else if (tag == TRACK_FPF && (value == 1 || value == 2))
si->fields_per_frame = value;
} else
url_fskip(pb, tlen);
}
}
/**
* \brief read index from FLT packet into stream 0 av_index
*/
static void gxf_read_index(AVFormatContext *s, int pkt_len) {
ByteIOContext *pb = &s->pb;
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, (uint64_t)get_le32(pb) * 1024,
i * (uint64_t)fields_per_map + 1, 0, 0, 0);
url_fskip(pb, pkt_len);
}
static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
ByteIOContext *pb = &s->pb;
pkt_type_t pkt_type;
int map_len;
int len;
AVRational main_timebase = {0, 0};
st_info_t si;
int i;
if (!parse_packet_header(pb, &pkt_type, &map_len) || pkt_type != PKT_MAP) {
av_log(s, AV_LOG_ERROR, "GXF: map packet not found\n");
return 0;
@ -168,6 +300,7 @@ static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
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 +311,14 @@ static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
map_len -= len;
while (len > 0) {
int track_type, track_id, track_len;
AVStream *st;
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 +330,125 @@ static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
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];
if (!main_timebase.num || !main_timebase.den) {
main_timebase.num = si.frames_per_second.den;
main_timebase.den = si.frames_per_second.num * si.fields_per_frame;
}
st->start_time = si.first_field;
if (si.first_field != AV_NOPTS_VALUE && si.last_field != AV_NOPTS_VALUE)
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 (!parse_packet_header(pb, &pkt_type, &len)) {
av_log(s, AV_LOG_ERROR, "GXF: sync lost in header\n");
return -1;
}
if (pkt_type == PKT_FLT) {
gxf_read_index(s, len);
if (!parse_packet_header(pb, &pkt_type, &len)) {
av_log(s, AV_LOG_ERROR, "GXF: sync lost in header\n");
return -1;
}
}
if (pkt_type == PKT_UMF) {
if (len >= 9) {
AVRational fps;
len -= 9;
url_fskip(pb, 5);
fps = fps_umf2avr(get_le32(pb));
if (!main_timebase.num || !main_timebase.den) {
// this may not always be correct, but simply the best we can get
main_timebase.num = fps.den;
main_timebase.den = fps.num;
}
} else
av_log(s, AV_LOG_INFO, "GXF: UMF packet too short\n");
} else
av_log(s, AV_LOG_INFO, "GXF: UMF packet missing\n");
url_fskip(pb, len);
for (i = 0; i < s->nb_streams; i++) {
AVStream *st = s->streams[i];
if (main_timebase.num && main_timebase.den)
st->time_base = main_timebase;
else {
st->start_time = st->duration = AV_NOPTS_VALUE;
}
}
return 0;
}
#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, pkt_len);
continue;
}
if (pkt_type != PKT_MEDIA) {
url_fskip(pb, pkt_len);
continue;
@ -225,7 +460,7 @@ static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {
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 +470,45 @@ static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {
// 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;
int64_t found;
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;
maxlen = FFMAX(maxlen, 200 * 1024);
url_fseek(&s->pb, pos, SEEK_SET);
found = gxf_resync_media(s, maxlen, -1, timestamp);
if (ABS(found - timestamp) > 4)
return -1;
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 +517,6 @@ AVInputFormat gxf_demuxer = {
gxf_header,
gxf_packet,
NULL,
NULL,
gxf_seek,
gxf_read_timestamp,
};

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