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timecodestamper: In live mode wait correctly for the latency to pass

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And also introduce 6 instead of 2 frames of latency compared to the LTC
audio input as that seems to be an upper bound for how much the LTC
library is lagging behind.
This commit is contained in:
Sebastian Dröge 2020-01-09 15:23:20 +02:00
parent 31d7862051
commit 0a499242e9
1 changed files with 12 additions and 5 deletions
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17
gst/timecode/gsttimecodestamper.c
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@ -878,13 +878,18 @@ gst_timecodestamper_query (GstBaseTransform * trans,
if (res && timecodestamper->vinfo.fps_n && timecodestamper->vinfo.fps_d) {
gst_query_parse_latency (query, &live, &min_latency, &max_latency);
if (live) {
latency =
/* Introduce additional 8 frames of latency for LTC processing as
* the LTC library seems to usually lag behind 1-6 frames with the
* values reported back to us. */
/* TODO: Figure out how to calculate this numbers */
latency = 8 *
gst_util_uint64_scale_int_ceil (GST_SECOND,
timecodestamper->vinfo.fps_d, timecodestamper->vinfo.fps_n);
min_latency += latency;
if (max_latency != GST_CLOCK_TIME_NONE)
max_latency += latency;
timecodestamper->latency = min_latency;
gst_query_set_latency (query, live, min_latency, max_latency);
} else {
timecodestamper->latency = 0;
}
@ -1179,9 +1184,11 @@ gst_timecodestamper_transform_ip (GstBaseTransform * vfilter,
timecodestamper->video_current_running_time = running_time;
/* Wait until the the audio is at least 2 frame durations ahead of the
* video to allow for some slack, or the video pad is flushing or the
* LTC pad is EOS. */
/* Wait to compensate for the latency we introduce and to allow the LTC
* audio to provide enough audio to extract timecodes, or until the video
* pad is flushing or the LTC pad is EOS.
* In non-live mode we introduce 4 frames of latency compared to the LTC
* audio, see LATENCY query handling for details. */
if (timecodestamper->video_live) {
GstClock *clock =
gst_element_get_clock (GST_ELEMENT_CAST (timecodestamper));
@ -1213,7 +1220,7 @@ gst_timecodestamper_transform_ip (GstBaseTransform * vfilter,
} else {
while ((timecodestamper->ltc_current_running_time == GST_CLOCK_TIME_NONE
|| timecodestamper->ltc_current_running_time <
running_time + 2 * frame_duration)
running_time + 8 * frame_duration)
&& !timecodestamper->video_flushing && !timecodestamper->ltc_eos) {
GST_TRACE_OBJECT (timecodestamper,
"Waiting for LTC audio to advance, EOS or flushing");