[FFmpeg-user] Dropping frames on simple split and recombine.

[Scott Chamberlain]

I am working with filters for the first time. As a simple experiment I take
a video, split into two streams, one stream I leave unchanged, the other I
segment in to 3 more streams using "select". I then take the 3 segments,
rebase them to 0 time, then combine them back together with "cocat". I then
combine the original stream and the concated stream using "vstack".

split[original],select='1+gt(t,5)+gt(t,10)':n=3[v1][v2][v3];[v1]setpts=PTS-STARTPTS[v1o];[v2]setpts=PTS-STARTPTS[v2o];[v3]setpts=PTS-STARTPTS[v3o];[v1o][v2o][v3o]concat=n=3[modified];[original][modified]vstack

I during the processing I get the warnings:

[Parsed_vstack_6 @ 0000000000d5ee60] [framesync @ 0000000000c77cc8] Buffer
queue overflow, dropping.
    Last message repeated 234 times
[output stream 0:0 @ 0000000000d592c0] 100 buffers queued in output stream
0:0, something may be wrong.

And in my output video the top stream (which I should be the original
unmodified stream) freezes at around the 7.03 mark.

What is going wrong that is causing this to happen? I have attached the
original source video, the modified output, and the log file generated by
using the "-report" argument.

Scott Chamberlain

P.S. I had to zip up the log, otherwise my email is over the 250 KB size
limit and the unziped version was rejected by the moderator.
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