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Optimising Performance

The following guide lists some common things to check when you are experiencing performance issues in vMix.

Graphics Card


The graphics card is used for all input and output video processing in vMix.

A modern mid range graphics card such as the Nvidia GT650 is recommended for vMix. 
The faster the graphics card, the more inputs you can add and the higher the resolution that can be used for streaming and recording.

Check the Render Time reading at the bottom of the main vMix window. If this is consistently above 20ms, the graphics card is likely at its limit.

CPU

The CPU is primarily used for audio/video compression and is used by the Recording and Streaming features in vMix.

Highly compressed video formats such as MP4 (H264) require a fast CPU such as a Intel Core i7.
In contrast MPEG-2 / AVI generally require a lower amount of CPU usage but the files they create are larger for equivalent quality.

You can see if CPU is the bottleneck by keeping an eye on the Recording Information window while Recording.
This window can be found by clicking the [i] button next to the Recording Setup and Start buttons at the bottom of the main vMix window.
This will show the number of dropped frames and the likely cause.

Optimal Settings


The following settings should be checked to ensure vMix can provide the best performance possible.

Settings - Display
Master Frame Rate and Output Size should be set to match the cameras used as closely as possible.

Settings - Performance - Output Format
This should be set to UYVY or YUY2

Settings - Performance - Low Latency Capture
This adds additional load on to the Graphics Card and should be unticked unless low latency is preferred.

Settings - External Output
When streaming, the Frame Rate and Output Size here should match the size and frame rate selected in the Streaming window
For example if you are streaming at 1280x720 at 30fps, select those sizes and frame rates here as well.

Settings - Audio
Master Sample Rate and Master Bit Rate should be set to 48000 and 16 Bit PCM respectively.
When streaming, you can achieve a slightly higher audio quality by selecting 44100 here, but in most circumstances
48000 is preferred.












Last Updated: Saturday, 15 March 2014 8:09:53 PM

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