There are many factors that influence Isadora’s video processing speed, including the speed and type of your processor, amount of RAM installed on your computer, hard disk speed, the format in which the video files are stored, and several other factors. This section details several tips to help you get the very fastest frame rates from Isadora.

Tip 1: The Three Most Important Factors: CPU, Graphics Card (GPU) and the Hard Drive.

CPU: Simply put, you want the fastest CPU you can get your hands on. At this point, on macOS that means Apple silicon (ARM/M1) and it means Intel i9 processors on Windows.

GPU: Your computer's graphics card (GPU) is also important. macOS doesn't offer many options when it comes to GPUs; you get what you get when you purchase the computer, and (except for the ultra expensive Mac Pro) you can't upgrade it. On Windows, you can make a wider range of choices. While you can spend a lot of money to get the fastest gaming GPU out there you may not see massive improvements in performance as a result. That's because video processing doesn't have the same performance needs as gaming. Usually, finding something in the middle will give the best cost/performance ratio when working with Isadora.

HARD DRIVE: At this point, SSD hard drives are the norm – you should not be using older, physical drives with spinning platters for professional video work. If your computer's internal drive is one of those older models, consider purchasing an external SSD drive and playing your video files from there.

MINIMUM REQUIREMENTS: Make sure to review the Isadora 3 System Requirements to ensure you're working with a machine that meets our minimum system requirements.

Tip 2: Add as much RAM (Random Access Memory) to your computer as you can afford.

Modern operating systems rely on a feature called “virtual memory.” When the computer senses that some data that resides in your computers RAM (i.e. the extremely fast internal memory linked to your main processor) has not been used for a while, it will write it out to disk to make more RAM available to other applications. This is called “page swapping” and can adversely affect performance.

The best way to solve this problem is to add more RAM to your computer. As a general rule, 2 Gigabytes is a good base line. 4 Gigabytes is even better. Page swapping will often take place on machines with less memory than 2 Gigabytes of memory.

Tip 3: Don’t run other applications at the same time as Isadora.

Every running application consumes system resources. So, especially when using Isadora for a live performance, don’t run any other applications at the same time. Even if they aren’t “doing anything” they get some of the processor’s time, and thus slow down Isadora.

Tip 4: Keep your video resolution as low as you can.

The biggest burden any real-time video software faces is the size of the image it has to process. This data has to be brought in from the hard drive or from a live camera input, moved through any effects, and sent to the graphics card for output. It’s a simple relationship: as resolution increases, the speed at which those frames can be processed decreases.

BONUS TIP: If you are outputting to video projector with HD resolution (e.g., 1920×1080) there is no reason to play a full res 4K HD video because half the pixels won't be seen if you do. You should limit the resolution of the clips in your show to the resolution of the video output device you're using.

Tip 5: Keep all video resolution consistent

When Isadora has to combine two video streams of different resolutions (e.g., with the Video Mixer actor), it has to scale one stream to match the resolution of the other. (Which one gets scaled is determined by the “Video Image Processing” section of the Video tab in the Preferences.) Even on a fast graphics card (GPU), scaling takes extra time so you want to avoid it as much as possible. If all of the video streams you are processing are the same resolution, you will get the best possible performance.

Tip 6: In addition to changing the resolution of your files, choosing the correct codec is crucial

High Definition (HD) - HAP (macOS and Windows)

The fastest codec in terms of performance is HAP created by VidVox. HAP is especially fast because it does not need to be decoded by the CPU; instead the frames are loaded directly into your graphics card (GPU) – in other words, there is no decompression step.

Furthermore, because each frame is encoded individually, HAP files will play both forwards and backwards equally well, and can quickly seek to any frame in the file. (For more detail on these points, see "H264 should not always be your first choice" below.)

Another advantage is that you can play HAP movies on both macOS and Windows; if you need to move your show from on platform to another, HAP should definitely be your choice.

The downside with HAP is that it is slow to compress and the file sizes will be much greater than H264/MP4 files.

For more info on encoding your files with HAP, see "Recompressing Your Files" below.

High Definition (HD) - Apple ProRes (macOS Only)

For the highest HD quality on macOS we recommend Apple ProRes. The color fidelity and image quality is excellent but it also requires produce significantly larger files than the H264/MP4 codecs.

Furthermore, because each frame is encoded individually, ApplePro Res files will play both forwards and backwards equally well, and can quickly seek to any frame in the file. (For more detail on these points, see "H264 should not always be your first choice" below.)

Photo JPEG (macOS and Windows)

While the Photo JPEG codec is ancient by now, and it is not recommended for full HD or 4K video, it is still has many advantages for smaller formats like 1280x720 or 640x360. The most important is that it requires less processor power to decompress the images when compared to many other codecs including H264/MP4 and Apple ProRes.

The downside of Photo JPEG that the image quality lower than with HAP, ApplePro Res or H264/MP4.

When compressing using Photo JPEG, we suggest using a quality setting of “high” (75%). Using a quality setting of “best” (100%) produces larger files that are not significantly better in image quality and are far slower to decompress.

H264 should not always be your first choice!

The H264 codec is extremely popular because it makes small files with good image quality. But it is not necessarily the best choice to use with Isadora (or any interactive video software) for several reasons.

First, the amount of CPU power required to decompress the image as it is read from your hard drive is significantly higher than for HAP, Apple ProPes or Photo JPEG. (HAP is the fastest in this regard.)

Second, H264 is only designed to play forward. If you always play your movies forward from start to finish, then this is not an issue. But, if you are a VJ or artist who is scrubbing video, or you often use the position input of the Movie Player actors, then H264 is most definitely not for you. If you play an H264 movie backward, or you scrub the video back and forth rapidly, you will see the CPU usage increase significantly. This is simply because the codec is not designed to deliver the images in reverse order.

Because the HAP, Apple Pro Res and Photo JPEG formats render each frame individually (i.e., the current image is not  related to the previous one), they play forwards and backwards equally well and are very fast when jumping to an arbitrary location within the clip.

Recompressing Your Files

You can use a number of software tools to output recompress your files to the formats listed above, e.g., Adobe Premiere (macOS and Windows) or Final Cut Pro (macOS only). For a free option on macOS, get the stable release of AVF Batch Converter from this GitHub page, as this can compress to nearly any macOS Compatible format. For Windows, take a look at our knowledge base article Create Windows Native HAP avi Video Files which lists both paid and free options.

Tip 7: The duration of a movie has little or no impact upon performance.

We often are asked: “Can Isadora play movies that are an hour long?” The answer is “yes,” because, in fact, the duration of a clip has little to do with playback performance.

The video playback software within the operating system only reads a small amount of the video file at a time, usually about a half-second in advance of where the current playback position. Thus, whether a clip is 1 or 1000 minutes long has little impact on performance. Far more important are the factors listed in the tips listed above.

Tip 8: Stick with one frame rate for all your videos.

Isadora will happily play videos of any frame rate within the same file. But for the smoothest playback performance, you should use the same frame rate for all your videos and set the Target Frame Rate in the General tab of the Isadora Preferences to the same rate.

Furthermore, you should set the Refresh rate of your monitor or video projector to a multiple of your chosen frame rate if at all possible. (Consult the manual for your monitor or projector to learn how to do this.)

For NTSC video rendered at 29.97fps:

  • Set the Target Frame Rate to 29.97 fps
  • Set the Monitor/Video Projector refresh rate to 60 Hz.

For PAL/SECAM video rendered at 25fps:

  • Set the Target Frame Rate to 25 fps
  • Set the Monitor/Video Projector refresh rate to 50 Hz.

For videos transferred from film at 24fps or 23.978 fps:

  • Set the Target Frame Rate to 24 fps or 23.978 as appropriate.
  • Set the Monitor/Video Projector refresh rate to 50 Hz.

Tip 9: Turn off the Video Capture when you’re not using it.

The Capture Control actor allows you to turn live video on and off from within an Isadora scene. If you are not using live video in a section of your piece, then use this actor to turn it on and off at the appropriate moment.

Tip 10: Bypass the Actors or turn off User Actors when not using them.

Many Actors have an input called ‘bypass’. When turned off (default), the effect functions normally. When turned on, the effect is disabled and the video input is passed directly to the video output. You can add a simillar functionality to your User Actor, but the video will not pass the User Actor when set to off. Double click the User Actor and a tab will open with the User Actors name. Inside the User Actor you can add a new actor called ‘User Actor On/Off’ to change the value from outside of the User Actor you have to add a ‘User Actor Input’ to it. The ‘User Actor On/Off’ activates or deactivates all of the actors within a User Actor.

Turning off User Actors or bypassing Actors is usefull when you want to save processor speed.

Tip 11: How to use Apple’s QuickTime Player 7 (Pro Edition) to recompress your movies.

Below are instructions on how to use the Apple’s QuickTime Player to store your movies in this format.

NOTE: While QuickTime and QuickTime Player are free, the Pro edition required to recompress movies costs $29.99 at the time of this writing. You must have the Pro Edition to recompress movies using QuickTime Player.

MAC OS X 10.6 and 10.7 Users: The instructions below are for QuickTime Player 7 which became an optional install since Mac OS X 10.6 (Snow Leopard). To install QuickTime Player 7 under Mac OS X 10.6 or later, follow these instructions.

Compressing Video with QuickTime Player 7 (Pro Edition)

  1. Open QuickTime Player by double clicking on its icon. Choose File > Open Movie to open the movie you want to recompress.
  2. Choose File > Export, or press Apple-E (Mac) or Control-E (Windows), to call up the export dialog.
  3. After the window appears, click the “Options” button to show the “Movie Settings” window.
  4. Then click the “Settings” button.
  5. Choose your desired compression format using the pop-up menu under the heading “Compressor”.
  6. Set the slider under “Quality” to the halfway point, which should be labeled “Medium.” You can use “High” if you like – you’re movies will be somewhat larger but the quality of the image may be somewhat better.
  7. In the text box to the right of “Frame Rate” type 30, if it is not already set to 30. (Use 25 if you are compressing PAL movies.) Uncheck the other two boxes that say Key Frame and Limit Data Rate.
  8. Press the “OK” button.
  9. You’re back at the “Movie Settings” window. Click on the “Size” button.
  10. Click the “Use Custom Size” radio button. Two text boxes marked “Width” and “Height” will appear.
  11. Type your desired sizes into the “Width” and “Height” text box.
  12. Press the “OK” button.
  13. You’re back at the “Movie Settings” window. Press the “OK” button.
  14. Choose a name for your movie (it should be different than the old name) and press the “Save” button.
  15. This process can take a while, depending on how long your movie is. A progress dialog (a window with a little blue “thermometer” type display) will appear to show how things are going.
  16. When the progress dialog disappears, your movie is done being compressed.
  17. Open the new movie and play it to see how it looks now.

To see the difference in size between the original movie and the newly compressed one, do the following:

  1. Bring the original movie to the front by clicking on its window.
  2. Choose Movie > Get Info to show a window that gives information about the movie.
  3. Choose “Movie” from the pop-up menu on the top left.
  4. Choose “General” from the pop-up menu on the top right.
  5. Look at the “Data Size” and “Data Rate” in that window. Take note of the values.
  6. Close the window by clicking on its close box in the top left or by choosing File > Close.
  7. Now bring the new movie to the front by clicking on its window.
  8. Follow the same procedure starting at Step 2 to show its Data Size and Data Rate.
  9. You’ll see how much smaller the movie is and how its data rate has been lowered through the resizing and compression process.