gstreamer/subprojects/gst-devtools/validate/tests/launcher_tests/multipipe.validatetest

set-globals,
  appsrc_props="handle-segment-change=true \
                automatic-eos=false \
                min-latency=0 \
                max-latency=-1 \
                format=time \
                is-live=true \
                max-buffers=0 \
                max-bytes=0 \
                max-time=5000000000 \
                leaky-type=downstream"

meta,
    args = {
      "appsrc name=src $(appsrc_props) ! videoconvert ! $(videosink) name=sink",
    },
    handles-states=true

# Start a new pipeline with an `appsink`
create-sub-pipeline,
  name=subpipeline,
  desc="videotestsrc ! timeoverlay ! appsink name=appsink sync=true max-buffers=10 drop=true",
  scenario={
      [meta, ignore-eos=true],
    }

# Pull sample from the sub pipeline and push it into the main pipeline appsrc
# as soon as the pipeline will start
appsrc-push, target-element-name=src, from-appsink="subpipeline/appsink"
# And preroll the pipeline
play

# Seek on the sub pipeline
run-on-sub-pipeline,
  pipeline-name=subpipeline,
  action=[seek, flags=accurate+flush, start=5.0, stop=15.0]

# Then forward 10 buffers from sub pipeline to main pipeline
foreach,
  i=[0, 10],
  actions = {
    [
      appsrc-push, target-element-name=src, from-appsink="subpipeline/appsink",
    ],
  }

# And seek the sub pipeline again
run-on-sub-pipeline,
  pipeline-name=subpipeline,
  action=[seek, flags=accurate+flush, start=1.0, stop=5.0]

# And forward 10 more buffers from sub pipeline to main pipeline
foreach,
  i=[0, 10],
  actions = {
    [
      appsrc-push, target-element-name=src, from-appsink="subpipeline/appsink",
    ],
  }

# Stop the sub pipeline
run-on-sub-pipeline,
  pipeline-name=subpipeline,
  action=[stop]

# And finish everything by marking main pipeline as EOS
appsrc-eos, target-element-name=src