[FFmpeg-trac] #10211(avfilter:closed): Concat filter with `-re` (realtime) inputs does not keep realtimeness

[FFmpeg]

#10211: Concat filter with `-re` (realtime) inputs does not keep realtimeness
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             Reporter:  Brad Isbell  |                    Owner:  (none)
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:  avfilter
              Version:  git-master   |               Resolution:  invalid
             Keywords:  concat       |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Changes (by Gyan):

 * status:  new => closed
 * resolution:   => invalid

Comment:

 It's working as expected. Each file reader (demuxer) runs in its own
 thread, and populates that input's packet queue asynchronously at 1x in
 this command. However, the concat filter only consumes each input when its
 turn comes for appendage. Since both inputs are of the same duration and
 readrate limited to the same speed, the 2nd input has been fully ingested
 into memory when concat gets to it.

 Use the realtime filter after concat instead to limit output speed.
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Ticket URL: <https://trac.ffmpeg.org/ticket/10211#comment:1>
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