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moving nearly identical binary search code from nut/mpeg/asf to utils.c

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Originally committed as revision 3003 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer
2004-04-12 16:50:03 +00:00
parent ee77723580
commit 8d14a25c3e
5 changed files with 198 additions and 413 deletions
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120
libavformat/asf.c
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@@ -422,6 +422,8 @@ static int asf_get_packet(AVFormatContext *s)
int rsize = 9;
int c;
if((url_ftell(&s->pb) - s->data_offset) % asf->packet_size)
return -1;
assert((url_ftell(&s->pb) - s->data_offset) % asf->packet_size == 0);
c = get_byte(pb);
@@ -705,7 +707,7 @@ static void asf_reset_header(AVFormatContext *s)
asf->asf_st= NULL;
}
static int64_t asf_read_pts(AVFormatContext *s, int64_t *ppos, int stream_index)
static int64_t asf_read_pts(AVFormatContext *s, int stream_index, int64_t *ppos, int64_t pos_limit)
{
ASFContext *asf = s->priv_data;
AVPacket pkt1, *pkt = &pkt1;
@@ -718,15 +720,19 @@ static int64_t asf_read_pts(AVFormatContext *s, int64_t *ppos, int stream_index)
for(i=0; i<s->nb_streams; i++){
start_pos[i]= pos;
}
pos= (pos+asf->packet_size-1-s->data_offset)/asf->packet_size*asf->packet_size+ s->data_offset;
*ppos= pos;
url_fseek(&s->pb, pos, SEEK_SET);
//printf("asf_read_pts\n");
url_fseek(&s->pb, pos*asf->packet_size + s->data_offset, SEEK_SET);
asf_reset_header(s);
for(;;){
if (av_read_frame(s, pkt) < 0){
av_log(s, AV_LOG_INFO, "seek failed\n");
return AV_NOPTS_VALUE;
}
pts= pkt->pts;
av_free_packet(pkt);
@@ -736,10 +742,10 @@ static int64_t asf_read_pts(AVFormatContext *s, int64_t *ppos, int stream_index)
asf_st= s->streams[i]->priv_data;
assert((asf_st->packet_pos - s->data_offset) % asf->packet_size == 0);
pos= (asf_st->packet_pos - s->data_offset) / asf->packet_size;
pos= asf_st->packet_pos;
av_add_index_entry(s->streams[i], pos, pts, pos - start_pos[i] + 1, AVINDEX_KEYFRAME);
start_pos[i]= pos + 1;
start_pos[i]= asf_st->packet_pos + 1;
if(pkt->stream_index == stream_index)
break;
@@ -755,112 +761,13 @@ static int64_t asf_read_pts(AVFormatContext *s, int64_t *ppos, int stream_index)
static int asf_read_seek(AVFormatContext *s, int stream_index, int64_t pts)
{
ASFContext *asf = s->priv_data;
AVStream *st;
int64_t pos;
int64_t pos_min, pos_max, pts_min, pts_max, cur_pts, pos_limit;
int no_change;
if (stream_index == -1)
stream_index= av_find_default_stream_index(s);
if (asf->packet_size <= 0)
return -1;
pts_max=
pts_min= AV_NOPTS_VALUE;
pos_max= pos_limit= -1; // gcc thinks its uninitalized
if(av_seek_frame_binary(s, stream_index, pts)<0)
return -1;
st= s->streams[stream_index];
if(st->index_entries){
AVIndexEntry *e;
int index;
index= av_index_search_timestamp(st, pts);
e= &st->index_entries[index];
if(e->timestamp <= pts){
pos_min= e->pos;
pts_min= e->timestamp;
#ifdef DEBUG_SEEK
printf("unsing cached pos_min=0x%llx dts_min=%0.3f\n",
pos_min,pts_min / 90000.0);
#endif
}else{
assert(index==0);
}
index++;
if(index < st->nb_index_entries){
e= &st->index_entries[index];
assert(e->timestamp >= pts);
pos_max= e->pos;
pts_max= e->timestamp;
pos_limit= pos_max - e->min_distance;
#ifdef DEBUG_SEEK
printf("unsing cached pos_max=0x%llx dts_max=%0.3f\n",
pos_max,pts_max / 90000.0);
#endif
}
}
if(pts_min == AV_NOPTS_VALUE){
pos_min = 0;
pts_min = asf_read_pts(s, &pos_min, stream_index);
if (pts_min == AV_NOPTS_VALUE) return -1;
}
if(pts_max == AV_NOPTS_VALUE){
pos_max = (url_filesize(url_fileno(&s->pb)) - 1 - s->data_offset) / asf->packet_size; //FIXME wrong
pts_max = s->duration; //FIXME wrong
pos_limit= pos_max;
}
no_change=0;
while (pos_min < pos_limit) {
int64_t start_pos;
assert(pos_limit <= pos_max);
if(no_change==0){
int64_t approximate_keyframe_distance= pos_max - pos_limit;
// interpolate position (better than dichotomy)
pos = (int64_t)((double)(pos_max - pos_min) *
(double)(pts - pts_min) /
(double)(pts_max - pts_min)) + pos_min - approximate_keyframe_distance;
}else if(no_change==1){
// bisection, if interpolation failed to change min or max pos last time
pos = (pos_min + pos_limit)>>1;
}else{
// linear search if bisection failed, can only happen if there are very few or no keyframes between min/max
pos=pos_min;
}
if(pos <= pos_min)
pos= pos_min + 1;
else if(pos > pos_limit)
pos= pos_limit;
start_pos= pos;
// read the next timestamp
cur_pts = asf_read_pts(s, &pos, stream_index);
if(pos == pos_max)
no_change++;
else
no_change=0;
#ifdef DEBUG_SEEK
printf("%Ld %Ld %Ld / %Ld %Ld %Ld target:%Ld limit:%Ld start:%Ld\n", pos_min, pos, pos_max, pts_min, cur_pts, pts_max, pts, pos_limit, start_pos);
#endif
assert (cur_pts != AV_NOPTS_VALUE);
if (pts < cur_pts) {
pos_limit = start_pos - 1;
pos_max = pos;
pts_max = cur_pts;
} else {
pos_min = pos;
pts_min = cur_pts;
/* check if we are lucky */
if (pts == cur_pts)
break;
}
}
pos = pos_min;
url_fseek(&s->pb, pos*asf->packet_size + s->data_offset, SEEK_SET);
asf_reset_header(s);
return 0;
}
@@ -874,6 +781,7 @@ static AVInputFormat asf_iformat = {
asf_read_packet,
asf_read_close,
asf_read_seek,
asf_read_pts,
};
#ifdef CONFIG_ENCODERS