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DavidPatrick

Image Sequence Playback

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I've been playing around with image sequence playback in WO 6 (Just upgraded to 6.1.6), and can't seem to get smooth playback. 

 

My test file is 8228 x 1200, which is admittedly pretty large. But if I make a HAP 6-chunk encode, it plays beautifully. 

 

However, I've tried a TIFF uncompressed, PNG uncompressed, and JPG sequences, and all of them drop frames significantly. 

 

Specs:

Intel i7 3.6GHz

16 GB RAM

1TB m.2 NVMe SSD connected via PCIe 3.0. (Read speeds are consistently over 2.0 GB/s)

nVidia P4000 card

 

I'm sending it out across three outputs from one machine.

 

Am I pushing beyond the limits of what Watchout can currently do? Or am I experiencing a bottleneck from somewhere? Has anyone else consistently gotten smooth playback of an image sequence in the 8k+ range? In theory since each image file, even in the TIFF version, is under 30mb, I should be under 900 mb / s @ 30fps. Which is less than half the read speeds I'm getting when I test the drive. Is my math wrong on that?

 

Obviously HAP is the solution for now, but we're very interested in the possibilities image sequence playback offers. 

 

Thanks!

dp

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With one big video like that, you overload one of the threads while not utilizing other threads at all.

 

You will get better results with the image sequences

if you break that one big file in to 1080p sized chunks and
spread the decode load over more of the threads in the cpu.

That is essentially what the HAP chunks provide without having to break up the while video.

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Are you absolutely certain that the tiff files are uncompressed? If they are, their size should be equal down to the byte. Although compression would help with the disk load, it adds some (or a lot) of work to the CPU. 

 

How did you measure the read speed of the disk? Some test applications use buffers that are too small when testing, meaning that most or all of the transfer speed measured is due to caching somewhere in the system, which is always faster than reading from the disk. 

 

You could give targa (.tga) image sequences a try. It is fully supported in Watchout, and is the fastest way to play an uncompressed image sequence, since the internal pixel byte ordering is correct. Tiff files usually need some byte-flipping, which adds a slight delay.

 

/Erik 

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