Video export speed affected by fps (frames per second)?

Aresby

Hey guys

As you know I've been concerned about the speed of exporting videos with release 4.58 and above (before then they seemed to generated more quickly).

I know NCH is aware that not all CPU power is being taken by the export (and will hopefully speed it up soon) but that aside Borate (or possibly one of the other tech specialists) mentioned that the export fps could affect the time if the video output was not the same fps as the source video(s).

So this week I generated my entire video with an fps of 20 (for both cameras) and exported with the same fps (usually I export at 25fps as per YouTube recommendations). It definitely seemed to export more quickly - quicker than real time which was my recent experience with VP. Can this be true? Incidentally the video quality at 20fps vs 25fps was (to my older eyes anyway) indistinguishable. So my 20 minute video finished in about 15 minutes this week, hurrah!

Just to muddy the water a little, this was the first video I generated with 16Gb installed (instead of 12Gb) but I didn't really see much more memory being used anyway so maybe this had no effect?

Anybody know about fps and export speed, either NCH or other users?

Video generated: .mp4 format, 8192 bps, 128 kHz audio, 20fps

c_major_2

Lower fps will definitely exports faster since you have less frames to be generated - the time to generate each frame is fixed regardless FPS.

[deleted]

Agree with @c_major.

It will have to encode less frames, so export time will be faster (in that particular case, you'd be looking at a minimum 20% speed increase) and it would also eliminate a frame-rate conversion process, so it would export even faster.

The extra ram might have helped, but only if other programs were also consuming a large amount of ram.

Aresby

So the decrease in rendering time was (mainly) due to to the reduction in frames actually being generated rather than a reduction in computation time in converting a 20fps source to 25fps. Oh well.

However, as I said, my video quality still looked good, there's little movement (so no blurring) in the video anyway (I do make the video sound boring but I'm hoping it's not!) so maybe I should stick to 20fps until NCH release a version of VP that consumes 101% of my CPU and can generate a 20 minute video in 5 minutes 😉 (I live in perpetual hope).

If you want to watch it, it's called "Watching paint dry, part 8". A real winner. 😃

c_major_2

@[deleted]

Yes, we are actively working on performance improvements.