Get Started Part 2: Deferred Capture and Subcapture

Learn more about capturing streams with deferred capture. Explore how to create small streams from bigger streams with subcapture.

Hello. I'm Justin Hardin. I'm one of the engineers on the Graphics Performance Analyzers team. This is episode two of our GPA Framework Quick Tips series. Last time, Pamela showed some capture and playback options for this quick tip. I'd like to show you our deferred and subcapture features. Deferred capture is very easy to use. Simply add the capture layer as usual, but also add a layer argument called deferred and set equal to true. Also set the HUD layer to get a visual indication of what's going on.

When the application starts, you'll notice a message on the HUD that says stream capture off. This means that we are not currently capturing any API calls. To begin capturing, press the L key and you'll see that the HUD layer now says stream capture on. When you are finished recording, just press the L again and close the application. Now let's play back our new stream.

When GPA player is launched with the deferred capture stream, it will start playback on the frame that the L key was pressed. This can be very useful for cutting out long menu sequences in your application and getting straight into the important gameplay. Now let's explore the subcapture feature. Our deferred capture stream is already short, but maybe we were only interested in the small part of that stream.

We can trim it down with GPA subcapture recorder. Let's say we only want to keep five frames starting from frame ten, so we'll add -s option with our frames in range notation. Finally, we add our deferred capture stream and launch. You'll see the stream start to play back, and once we've played over our range of interest, then playback will end.

Then we'll have a small five frame stream that we can play back and use with any of our other command line tools. Another added bonus is that subcapture streams will also be compressed and use less space than other streams. Smaller streams will make doing comparisons and regression testing easier.

Try out these features and tune in next time when Jay will show you how GPA Metrics Collector can help you gather precise metrics.

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