Chrome tab crashes when loading a lot of images in Javascript

I have a Javascript image sequence object that uses one <canvas> tag in the DOM, calling clearRect and drawImage quickly to play the sequence. There are 3 different sequences consisting of 1,440 images each, only one sequence needs to be loaded at a time, but having them all queued up will make the experience faster and smoother.

The images are pretty big in dimension, 8680x1920 each, about 1.5mb each as JPG. I have buttons that load each set individually instead of all at once. Everything is fine loading in the first sequence set, but the second one crashes (Aw Snap page) in Chrome 51 in Windows 7 Business.

Dev is happening on my Mac Pro and works perfectly, letting me load all 3 sequences just fine. The specs of my Mac Pro are far lower than the PC. The PC is an i7 quad core, 32gb RAM, 2x M5000 Nvidia Quadro cards with a Sync card. My understanding is that Chrome isn't even utilizing most of those advanced pieces of hardware, but we need them for other parts.

I have tried setting the existing image objects to an empty source then setting them to null before loading in the next sequence, I have also tried removing the <canvas> tag from the DOM, but nothing seems to help. I also find that watching Chrome's Network tab shows the crashes to always happen just after 1.5gb has been transferred. Chrome's Task Manager has the tab hovering around 8gb of memory usage on both Windows and Mac with 1 sequence loaded.

This is an obscure, one-off installation that will be disconnected from the internet, so I'm not concerned so much about security concerns or best practices, just getting it to work through any means necessary.

UPDATED to reflect that I had recently changed the <img> tag to a <canvas> tag for performance reasons

Answers


You should not be loading the entire sequence at once. You're most likely running out of RAM. Load only a few frames ahead using Javascript in memory, then assign that image to your image tag. Be sure to clear that look ahead cache by overwriting the variables or using the delete operator.

Secondly, changing the src attribute will cause the entire DOM to redraw. This is because when the src attribute changes, the image is assumed to have possibly changed size, which will cause all elements after might have shifted and need redrawing.

It's a better idea to set the image as the background of a <div> and update the background-image styles. You can also write the image to a <canvas>. In both cases only element needs redrawing.

Finally, a <video> tag would probably be your best option since it's designed to handle frame sequences efficiently. In order to make it possible to scrub to individual frames without lag you can either encode with the keyframe every 1 frames setting, or simply encode the video in an uncompressed format that doesn't use keyframes. A keyframe is like snapshot at a particular interval in a video, all subsequent frames only redraw the parts that have changed since the last keyframe. So if keyframes are far apart, seeking to a particular frame requires the the keyframe be rendered, then all the subsequent frames in between be added to it to get the final image of the frame you're on. By putting a keyframe on every frame, it will make the video larger since it can't use the differential compression, but it will seek must faster.


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