decklinksrc pipeline optimization

[John P Poet]

When using decklinksrc to capture to a transport stream file, it typically
drops a couple of frames per second:

5:08:39.613148080 30644 0x7fc74404c070 WARN        decklinkvideosrc
gstdecklinkvideosrc.cpp:868:gst_decklink_video_src_got_frame:<decklinkvideosrc0>
Dropped 1 old frames from 5:08:38.003250892 to 5:08:38.003250892
5:08:39.846702910 30644 0x7fc74404c070 WARN        decklinkvideosrc
gstdecklinkvideosrc.cpp:868:gst_decklink_video_src_got_frame:<decklinkvideosrc0>
Dropped 1 old frames from 5:08:38.236822745 to 5:08:38.236822745
5:08:40.213862509 30644 0x7fc74404c070 WARN        decklinkvideosrc
gstdecklinkvideosrc.cpp:868:gst_decklink_video_src_got_frame:<decklinkvideosrc0>
Dropped 1 old frames from 5:08:38.603868288 to 5:08:38.603868288
5:08:41.014465627 30644 0x7fc74404c070 WARN        decklinkvideosrc
gstdecklinkvideosrc.cpp:868:gst_decklink_video_src_got_frame:<decklinkvideosrc0>
Dropped 1 old frames from 5:08:39.404694929 to 5:08:39.404694929
5:08:41.615139285 30644 0x7fc74404c070 WARN        decklinkvideosrc
gstdecklinkvideosrc.cpp:868:gst_decklink_video_src_got_frame:<decklinkvideosrc0>
Dropped 1 old frames from 5:08:40.005314910 to 5:08:40.005314910
5:08:42.349376088 30644 0x7fc74404c070 WARN        decklinkvideosrc
gstdecklinkvideosrc.cpp:868:gst_decklink_video_src_got_frame:<decklinkvideosrc0>
Dropped 1 old frames from 5:08:40.739405998 to 5:08:40.739405998
5:08:42.883078722 30644 0x7fc74404c070 WARN        decklinkvideosrc
gstdecklinkvideosrc.cpp:868:gst_decklink_video_src_got_frame:<decklinkvideosrc0>
Dropped 1 old frames from 5:08:41.273290426 to 5:08:41.273290426

I have played around with queue to try to eliminate those drops, but all I
have achieved is to delay them.  Once they start up, they never stop.  My
most recent attempt is:

gst-launch-1.0 -v decklinkvideosrc device-number=${DEVICE} mode=12
do-timestamp=true output-cc=true video-format=2 duplex-mode=0 ! queue
max-size-buffers=4096 max-size-bytes=0 max-size-time=0 ! autovideoconvert !
queue max-size-buffers=4096 max-size-bytes=0 max-size-time=0 ! nvh264enc !
h264parse ! queue max-size-buffers=4096 max-size-bytes=0 max-size-time=0 !
mpegtsmux name=mux ! queue max-size-buffers=4096 max-size-bytes=0
max-size-time=0 ! filesink location=/storage1/SDI/video-nv.ts
decklinkaudiosrc device-number=${DEVICE} ! queue max-size-buffers=4096
max-size-bytes=0 max-size-time=0 ! audioconvert ! queue
max-size-buffers=4096 max-size-bytes=0 max-size-time=0 ! avenc_ac3
bitrate=480000 ! ac3parse ! queue max-size-buffers=4096 max-size-bytes=0
max-size-time=0 ! mux.

I feel like I must be handing this wrong.  Can someone give me some advise
on how to optimize this pipeline?  Note: my eventual goal, is to include
captions.

Thank you,

John
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