Premiere Pro has a comprehensive suite of Video Effects in the box – blurs, warps, chroma-keying and outstanding colour correction. Here we’ll look at the results for both primary and secondary colour correction when we hardware-accelerate the Mercury playback engine that drives Premiere’s real-time effects.
Our workstation boasts NVIDIA’s Maximus technology, which uses the company’s CUDA platform to combine a Quadro workstation-class graphics card with a Tesla companion card, delivering extreme performance. CUDA can tap a Quadro card alone, but by including the Tesla card, we enjoy real-time playback with both the Fast Color Corrector, fixing issues with the contrast, and the Three-Way Color Corrector, bringing out the flesh tones.
Once the colour correction task is offloaded onto the NVIDIA GPU, you can add multiple secondary correctors to any clip. This guide uses the same project as our previous look at how Maximus can accelerate Premiere Pro’s Chroma Key effect.
Premiere Pro features a setting called ‘fractional playback’. Click on the output icon (three intersecting coloured circles) in the Source or Program panel. The Playback Resolution and Paused Resolution settings dictate what level of playback or still-frame quality you wish to achieve.
Lowering the resolution will facilitate smooth playback without dropped frames under heavy system load. You should experiment to
find the best setting for your system.
This screenshot shows a complex nested sequence. There are many layers of video of different formats, with a variety of colour corrections, motion effects and mattes applied. The system has been set to ‘Mercury Playback Engine Software Only’.
The timeline has a red bar at the top, and it has been necessary to drop Playback resolution to ¼. The system activity monitor shows that the CPU load is high; frames are being dropped.
Here, using exactly the same timeline, we have set the project to ‘Mercury Play-back Engine GPU Acceleration’. The timeline now has a yellow bar, and plays in real time at Full playback resolution. The CPU load has been substantially de-creased as the NVIDIA GPU takes on the video-effects processing load.
Open the Effects panel. The suite of effects is fully searchable in the top dialog box. You can click on the ‘Accelerated Effects’ icon at the top left, in yellow, to filter the list to show only CUDA-optimised effects. If you don’t have a CUDA card in your system, these icons will be greyed out.
The shot that has been loaded in the Program window has a ‘flat’ look, and will benefit both from increased contrast and from a highlight being added to the flesh tones.
Typing the word ‘fast’ into the Search field will reveal the Fast Color Corrector. This is a GPU effect, as shown by the accelerated effect icon. Drag the Fast Color Corrector to the clip you wish to grade.
This shows us all of the available controls for the Fast Color Corrector. In this case we are going to play with the Input Levels slider.
We have lifted the shadows (blacks) to around 30, and dropped the highlights (whites) to around 225. Note the improved contrast as compared to Step 5. The clips play in real time with the effect offloaded to the GPU, whatever the source video format.
Next we are going to look at bringing out the flesh tone of the male character in the image. Search within the Effects panel for the Three-Way Color Corrector. Drag and add this to the clip in the timeline, as a second effect in addition to ‘Fast Color Corrector’.
At the bottom of the Three-Way panel are the controls that are relevant specifically to secondary colour correction.
Next to the word ‘Center’ is the principal hue swatch that the colour corrector will use to create the matte selection.
In the effect’s Output dropdown menu, select the Mask option. This will show the matte selection that is active. It’s worth noting that this matte is created live, and you can play back the video to see how the matte works through the duration of the clip.
Select the first eyedropper tool as shown to the right of the hue display swatch in Step 10, and click on area of the subject’s skin in the program monitor corresponding to the tone that you wish to focus on. Premiere Pro will begin to create a matte based on areas that are close to this hue.
Now click on the second eyedropper tool, the one with a ‘+’ sign next to it, and then click on a darker shade of the subject’s skin. Keep clicking on the ‘+’ eyedropper and back onto various shades of the skin until you begin to build up a more solid matte. Repeat until a fairly full representation of the face is visible.
Put the Output dropdown back to ‘Composite’. While the Three-Way Color Corrector allows you independent control over highlights, midtones and shadows, for simplicity we are going to change the ‘Tonal Range’ dropdown to ‘Master’. This will give us a single hue wheel, and allow us to modify the all of the shades we identified in one operation.
Here we have modified the Master Saturation to almost double its original level. Also shift the central control cursor within the hue wheel so that it sits out towards the orange part of the spectrum, giving a more natural and pronounced skin hue.
It only takes a single step to configure Premiere Pro to take advantage of the power of Quadro and Tesla cards. Open Premiere Pro and select Project > Project Settings and then the General tab. Ensure you select ‘Mercury Playback Engine GPU Acceleration’.
With a Maximus workstation, you can edit and encode video faster, better and more accurately than ever before. Offering a combination of GPU-based acceleration from both NVIDIA’s Quadro graphics cards and Tesla companion boards, a Maximus workstation delivers real-time performance that’s just not possible in software alone.
Edit in real time with more layers, and combine complex effects without having to settle for low-resolution previews – with Maximus you can see your work exactly as it will appear when output. And when it’s time to produce your completed project, you’ll see almost six times the performance of a similarly priced rendering/encoding station. Maximus enables you to spend more time being creative, and less watching crawling progress bars or guessing how an effect will be rendered. All this allows you to produce better work and hit tight deadlines with room to breathe.
To learn more about how Maximus can help take your workstation to the next level, visit www.nvidia.co.uk/maximus
Premiere Pro CS5.5 is part of the Creative Suite 5.5 Production Premium and Master Collection, as well as being available separately. The video editing application is underpinned by the Mercury playback engine.
This is the name given to describe the performance gains achieved now that the application is natively 64-bit and multithreaded. In many cases you can achieve realtime playback with native camera files, often even while mixing a range of formats and effects in a single timeline.
Further improvements to the workflow result when using a qualified NVIDIA CUDA-based graphics card, which allows many video effects to run natively on the GPU, freeing up resources and increasing overall system power.
For more details visit www.adobe.com/products/premiere