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Parse index chunk so that seeking in modern .rm files becomes a lot faster.

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Has been tested against streamed / non-seekable input and passes make
seektest. See "[PATCH] rmdec.c: parse INDX chunk" thread on mailinglist.

Originally committed as revision 18013 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Ronald S. Bultje 2009-03-16 13:03:23 +00:00
parent aa0bd99295
commit 2d6f301470
1 changed files with 54 additions and 2 deletions
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56
libavformat/rmdec.c
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@ -292,6 +292,49 @@ skip:
return 0;
}
/** this function assumes that the demuxer has already seeked to the start
* of the INDX chunk, and will bail out if not. */
static int rm_read_index(AVFormatContext *s)
{
ByteIOContext *pb = s->pb;
unsigned int size, n_pkts, str_id, next_off, n, pos, pts;
AVStream *st;
do {
if (get_le32(pb) != MKTAG('I','N','D','X'))
return -1;
size = get_be32(pb);
if (size < 20)
return -1;
url_fskip(pb, 2);
n_pkts = get_be32(pb);
str_id = get_be16(pb);
next_off = get_be32(pb);
for (n = 0; n < s->nb_streams; n++)
if (s->streams[n]->id == str_id) {
st = s->streams[n];
break;
}
if (n == s->nb_streams)
goto skip;
for (n = 0; n < n_pkts; n++) {
url_fskip(pb, 2);
pts = get_be32(pb);
pos = get_be32(pb);
url_fskip(pb, 4); /* packet no. */
av_add_index_entry(st, pos, pts, 0, 0, AVINDEX_KEYFRAME);
}
skip:
if (next_off && url_ftell(pb) != next_off &&
url_fseek(pb, next_off, SEEK_SET) < 0)
return -1;
} while (next_off);
return 0;
}
static int rm_read_header_old(AVFormatContext *s, AVFormatParameters *ap)
{
@ -314,6 +357,7 @@ static int rm_read_header(AVFormatContext *s, AVFormatParameters *ap)
unsigned int tag;
int tag_size;
unsigned int start_time, duration;
unsigned int data_off = 0, indx_off = 0;
char buf[128];
int flags = 0;
@ -357,8 +401,8 @@ static int rm_read_header(AVFormatContext *s, AVFormatParameters *ap)
get_be32(pb); /* nb packets */
get_be32(pb); /* duration */
get_be32(pb); /* preroll */
get_be32(pb); /* index offset */
get_be32(pb); /* data offset */
indx_off = get_be32(pb); /* index offset */
data_off = get_be32(pb); /* data offset */
get_be16(pb); /* nb streams */
flags = get_be16(pb); /* flags */
break;
@ -400,6 +444,14 @@ static int rm_read_header(AVFormatContext *s, AVFormatParameters *ap)
if (!rm->nb_packets && (flags & 4))
rm->nb_packets = 3600 * 25;
get_be32(pb); /* next data header */
if (!data_off)
data_off = url_ftell(pb) - 18;
if (indx_off && url_fseek(pb, indx_off, SEEK_SET) >= 0) {
rm_read_index(s);
url_fseek(pb, data_off + 18, SEEK_SET);
}
return 0;
}