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fpsdisplaysink

What it is

fpsdisplaysink is a video sink wrapper used for quick performance checks. It receives video buffers, sends them to a real video sink, and measures:

  • current FPS
  • average FPS
  • dropped-frame rate
  • rendered-frame count
  • dropped-frame count

By default it draws the FPS text on top of the video. It can also print or emit the measurements without drawing text.

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gst-launch-1.0 videotestsrc ! fpsdisplaysink

Use another sink as backend

fpsdisplaysink is not usually the final renderer by itself. It owns an internal video-sink property, and that property can be set to another sink.

Use xvimagesink:

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gst-launch-1.0 videotestsrc ! fpsdisplaysink video-sink=xvimagesink

Use autovideosink:

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gst-launch-1.0 videotestsrc ! fpsdisplaysink video-sink=autovideosink

Use fakesink when you want to benchmark the pipeline without displaying video:

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gst-launch-1.0 videotestsrc ! fpsdisplaysink video-sink=fakesink text-overlay=false

Use a more complex backend by quoting the sink bin:

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gst-launch-1.0 videotestsrc ! fpsdisplaysink \
    video-sink="glimagesink sync=false"

Set video-sink before the pipeline starts. In application code, configure it while the pipeline is still in NULL state.

Useful properties

Property Use
video-sink Select the real backend sink used to render or consume video.
text-overlay Show FPS text on the video. Set false for headless logging or benchmarking.
fps-update-interval Measurement update period in milliseconds. Default is 500.
sync Sync rendering to the pipeline clock. Set false to measure how fast the pipeline can run.
silent Disable status message output.
signal-fps-measurements Emit the fps-measurements signal for application code.

Example: measure max throughput without display sync:

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gst-launch-1.0 videotestsrc num-buffers=300 ! fpsdisplaysink \
    video-sink=fakesink \
    text-overlay=false \
    sync=false

Example: update the FPS display once per second:

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gst-launch-1.0 videotestsrc ! fpsdisplaysink fps-update-interval=1000

Runtime measurements

The element exposes read-only counters:

  • frames-rendered: number of frames rendered by the backend sink
  • frames-dropped: number of frames dropped by the backend sink
  • min-fps: minimum measured FPS
  • max-fps: maximum measured FPS
  • last-message: current status text

For applications, enable signal-fps-measurements=true and connect to the fps-measurements signal. The callback receives:

  • fps: current measured FPS
  • droprate: current dropped-frame rate
  • avgfps: average FPS

Common patterns

Display video and overlay FPS:

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gst-launch-1.0 v4l2src ! videoconvert ! fpsdisplaysink

Measure a decode pipeline without drawing overlay text:

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gst-launch-1.0 filesrc location=input.mp4 ! decodebin ! videoconvert ! \
    fpsdisplaysink text-overlay=false video-sink=autovideosink

Benchmark a pipeline without a real display:

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gst-launch-1.0 filesrc location=input.mp4 ! decodebin ! videoconvert ! \
    fpsdisplaysink text-overlay=false video-sink=fakesink sync=false

Reference