double secs = pos < 0 ? 0. : pos / rate;
AVRational time_base = st->time_base;
int64_t tstmp = time_base.num > 0 ? secs * time_base.den/time_base.num : 0;
- if( nudge != AV_NOPTS_VALUE ) tstmp += nudge;
+ if( !tstmp ) {
+ if( st->nb_index_entries > 0 ) tstmp = st->index_entries[0].timestamp;
+ else if( st->start_time != AV_NOPTS_VALUE ) tstmp = st->start_time;
+ else if( st->first_dts != AV_NOPTS_VALUE ) tstmp = st->first_dts;
+ else tstmp = INT64_MIN+1;
+ }
+ else if( nudge != AV_NOPTS_VALUE ) tstmp += nudge;
int idx = st->index;
#if 0
// seek all streams using the default timebase.
}
int ret = avformat_seek_file(fmt_ctx, st->index, -INT64_MAX, seek, INT64_MAX, flags);
#else
- int ret = av_seek_frame(fmt_ctx, idx, tstmp, AVSEEK_FLAG_ANY);
+// finds the first index frame below the target time
+ int flags = AVSEEK_FLAG_BACKWARD | AVSEEK_FLAG_ANY;
+ int ret = av_seek_frame(fmt_ctx, idx, tstmp, flags);
#endif
int retry = MAX_RETRY;
while( ret >= 0 ) {