Low Frame Rate (?) playback

naysayer

I have one video that looks a little flashy (as if it's playing at a very low frame rate) whenever I play it back in ME 1.6. It's encoded the same way as all my other videos which all play quite well so I'm a little confused. The actual frame rate I usually get when I play it hovers around 40 fps while the video was encoded at 25 fps. Here are the specs. ME 1.6 Scratch live 1.9.2 h.264 1280 by 688 4500 kbps keyframe every 12 frames multipass ME set to 100 percent output on a 1280 by 720 secondary display v-sync or whatever the thing that stops tearing is called is ON but there's no difference when it's off. This video DOES include a lot of motion so it could be a keyframe thing? 12 is a lot though. Thanks in advance :)

naysayer

oh whoops duh. MBP 2010 2.8 ghz i7 8gb ram nvidia geforce 330m normal hd (not solid state but video is on internal hard drive) Also my buffer is at 1 gig.

naysayer

oh and I posted this in the wrong forum. I really goofed this haha :(

Nick

"1280 by 688" <- that's probably the problem right there.... MixEmergency can play back multiple HD videos, but I don't generally recommend it unless you have one of the newer 2011 MacBook Pros (ideally you don't want your CPU maxed out). Are your other videos HD also?

naysayer

Pretty much all my videos are 1280 by 720 and are playing fine... Should I check my processor use while I'm doing this and get back to you? I seem to remember it normally being around 40 percent and going up to 60 percent when playing both videos but ill have to check that. I do have access to a 2011 mbp but it's the baseline model I think. Would this be better? It's mainly this one video that looks bogus.

naysayer

Okay jsut checked actually. Ran two 1280 by 720 videos at the same time with the crossfader in the middle for about 4-5 minutes. Both with same export settings as above. Cpu usage stayed around 20-30 percent (including the system usage). Mix emergency was using up 40-50 percent of this. Is that adequate? Do i need to test this over an hour with multiple videos?

Nick

Does the CPU increase or decrease when you do the same test but with the problem video?

naysayer

The cpu usage doesn't show any noticable difference with the problem video. I'm thinking maybe this could be something happening to all my videos but I'm only noticing it in this video that has so much MOTION in it? I tried outputting 720p videos to a 480p screen (with my secondary display SET to 480p) and it looked slightly better but I was getting a lower frame rate (around 30fps).

naysayer

Phwoar Here's the bizarre thing. It makes an improvement if I output at 60hz (even though I'm outputting a video of 25fps??) My TV is Australian sony hdtv so I assume it can refresh at either rate. Still weird huh. In fact when I output at like 60hz with a big buffer of 2gb it runs smoothly and is acceptable. Not as good as my other videos but definitely acceptable. I'm going to try re-encoding the video with a lot of key frames and see if this helps. How do you do minimum and maximum keyframes when exporting from FCP using quicktime conversion? Also hard drive space is not an issue at the moment so considering that is there any advantage in using codecs that compress less or put less strain on the processor? Thanks for putting up with me. :)

Nick

If you're output is set to 60 Hz now, what was it set to before? I'm not sure specifically about export from FCP, but in QuickTime compression panel there should be a "Key Frames:" section that you can select "Every" and then enter a number of frames to use. A value around 25 should be fine for most videos. Regarding codecs: this is dependant on the computer I guess. Most people use high quality settings for H.264 (which compresses very well) with videos at 640 x 480.

naysayer

It was at 50hz before. This was based (naively?) on the assumption that my videos are all at 25 fps and that is pal and so is 50hz so i could reduce the possibility of screen tearing etc.

Nick

The screen won't tear because of the refresh rate. MixEmergency syncs the screen refreshes to the refresh rate of the monitor.... though there is an advanced option "Sync Output to Screen Refresh" that you can use to disable this syncing.

naysayer

Okay so is the choice between 60 and 50 hz arbitrary then?

Nick

In most cases it's best to set it to 50 Hz if you have that option, as 60 Hz is the same refresh rate as the internal screen of your MacBook Pro and can cause stuttering waveforms in Scratch Live. But if it's working better for you at 60 Hz, then you can leave it there.