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add support for generic seeking by reading timestamps in nuv

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This commit is contained in:
Joakim Plate 2011-09-12 19:33:31 +02:00
parent 46f415b553
commit 7768f6b1b9
1 changed files with 76 additions and 0 deletions
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76
libavformat/nuv.c
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@ -258,6 +258,81 @@ static int nuv_packet(AVFormatContext *s, AVPacket *pkt) {
return AVERROR(EIO);
}
/**
* \brief looks for the string RTjjjjjjjjjj in the stream too resync reading
* \return 1 if the syncword is found 0 otherwise.
*/
static int nuv_resync(AVFormatContext *s, int64_t pos_limit) {
AVIOContext *pb = s->pb;
uint32_t tag = 0;
while(!url_feof(pb) && avio_tell(pb) < pos_limit) {
tag = (tag << 8) | avio_r8(pb);
if (tag == MKBETAG('R','T','j','j') &&
(tag = avio_rb32(pb)) == MKBETAG('j','j','j','j') &&
(tag = avio_rb32(pb)) == MKBETAG('j','j','j','j'))
return 1;
}
return 0;
}
/**
* \brief attempts to read a timestamp from stream at the given stream position
* \return timestamp if successfull and AV_NOPTS_VALUE if failure
*/
static int64_t nuv_read_dts(AVFormatContext *s, int stream_index,
int64_t *ppos, int64_t pos_limit)
{
NUVContext *ctx = s->priv_data;
AVIOContext *pb = s->pb;
uint8_t hdr[HDRSIZE];
nuv_frametype frametype;
int size, key, idx;
int64_t pos, dts;
if (avio_seek(pb, *ppos, SEEK_SET) < 0)
return AV_NOPTS_VALUE;
if (!nuv_resync(s, pos_limit))
return AV_NOPTS_VALUE;
while (!url_feof(pb) && avio_tell(pb) < pos_limit) {
if (avio_read(pb, hdr, HDRSIZE) < HDRSIZE)
return AV_NOPTS_VALUE;
frametype = hdr[0];
size = PKTSIZE(AV_RL32(&hdr[8]));
switch (frametype) {
case NUV_SEEKP:
break;
case NUV_AUDIO:
case NUV_VIDEO:
if (frametype == NUV_VIDEO) {
idx = ctx->v_id;
key = hdr[2] == 0;
} else {
idx = ctx->a_id;
key = 1;
}
if (stream_index == idx) {
pos = avio_tell(s->pb) - HDRSIZE;
dts = AV_RL32(&hdr[4]);
// TODO - add general support in av_gen_search, so it adds positions after reading timestamps
av_add_index_entry(s->streams[stream_index], pos, dts, size + HDRSIZE, 0,
key ? AVINDEX_KEYFRAME : 0);
*ppos = pos;
return dts;
}
default:
avio_skip(pb, size);
break;
}
}
return AV_NOPTS_VALUE;
}
AVInputFormat ff_nuv_demuxer = {
.name = "nuv",
.long_name = NULL_IF_CONFIG_SMALL("NuppelVideo format"),
@ -265,5 +340,6 @@ AVInputFormat ff_nuv_demuxer = {
.read_probe = nuv_probe,
.read_header = nuv_header,
.read_packet = nuv_packet,
.read_timestamp = nuv_read_dts,
.flags = AVFMT_GENERIC_INDEX,
};