720p strange motion problems (ATV 1 and possibly 2?)

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Level 1

127 points

720p strange motion problems (ATV 1 and possibly 2?)

I posted the following on avforums.com in response to a post where another person is experiencing motion problems with their Apple TV. In an effort to 'compare notes', I thought I'd share it here too:

Here's an odd thing I noticed:

I have a first-gen Apple TV, which thankfully will output at 1080p. Why thankfully? Well, if it's set to 720p, I get a very odd motion issue where every few seconds, it looks like the video 'catches up' with itself - not dropped frames as such, but variations in frame rate.

This is particularly noticeable on HD content from the iTunes store (24fps and 25fps content).

Experimenting with the settings on my TV revealed a strange issue here. When this motion weirdness was happening, if I went into the TV menu and stepped through each of the motion plus settings Off>Low>Medium>High and then back to 'off' the problem went away.

There seems to be a 'mis-timing' on the 720p outputs of the ATV that confuses the TV, but with the Gen 1 version, setting the ATV to output 1080p stops it. Obviously, I won't be able to do this with ATV mk 2 as it only outputs max 720p so I'm not buying one just yet.

Also, on these forums, I think I saw someone say that if your TV has an auto-lipsync setting that turning it off could also have an impact.

Does all this sound familiar to other ATV users? Particularly those of you with Samsung TVs?

I hate HDMI.

iMac 27" 3.06 C2D, iMac 24" 2.8 GHz, Mac OS X (10.6.5), Time Capsule 1TB; AppleTV 160GB; iPod Touch 2nd Gen 32GB; iMac G5; iMac G3 DV

Posted on Apr 5, 2011 8:57 AM

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Answer 1

Apr 5, 2011 5:42 PM in response to Easybourne

I've noticed that some TV's are better than others when it comes to scaling and playing non native frame rates.

Is your TV a full HD TV, if so then when you output from the Apple Tv at 1080p the TV doesn't do any scaling and may possibly play that content better.

Out of 6 TV's in our house we have one that has similar issues to yours, the others do not. I've found that by switching to 60Hz for 24 and 30 fps video and 50 Hz for 25 fps, the issue is removed.

The problem then is that the Apple TV 2 doesn't currently offer you the option of switching between 50 & 60 Hz.

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Answer 2

Easybourne Author

Level 1

127 points

Apr 6, 2011 12:15 AM in response to Winston Churchill

Winston,

In my case, this happens whether the ATV 1 is set to output 50hz or 60hz. It even happens when the frame rate and output are precisely matched: eg. British HD content (25fps) played with ATV set to 50hz.

Doesn't happen quite so much with SD.

I'm think perhaps if I get an ATV2 and run it through an AV receiver that can upscale to 1080p, that this may get around the problem as the TV will be fed the 1080p it prefers. (I need a new receiver at some point anyway!)

Oh, and can I just ask if the one troublesome TV you have is a Samsung by any chance?

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Answer 3

Apr 6, 2011 2:41 AM in response to Easybourne

If your issue persists whether you use 50/60Hz, there may be another issue. Video generally has a variable bit rate, this allows scenes with lots of detail to use more data at the expense of less detailed scenes at another point in the video. High motion or panning require higher bit rates and sometimes if the datarate is too high this can cause juddering. It's possible, but I'm only theorising that a similar issue might occur on the TV while it's scaling high motion scenes, which of course it won't need to do when the Apple TV is outputting at 1080p.

The TV I have issues with is a Sharp.

Incidentally do you get a 1080p/50 Hz option from your Apple TV, all my TV's only seem to support 1080P/60 Hz (Which is simply written as 1080p in the Apple TV menu. I've always wondered whether Apple TV doesn't have the 1080/50 option or whether it's just a coincidence that none of my TV's do

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Answer 4

Easybourne Author

Level 1

127 points

Apr 6, 2011 3:06 AM in response to Winston Churchill

The issue usually occurs with HD video that is output at 720p, so this would fit with the data-rate theory except that the motion anomaly occurs at regular intervals and also during 'undemanding' scenes of little movement. I still favour the poor scaling/mis-timing theory as it seems to fit the facts better. Weirdly though, if I set my Blu-Ray player to output 720p, it will do so with no complaints from the TV whether it is outputting 50Hz of 60Hz material.

As for the 1080p setting on the ATV 1, yes, there is but one option available (60hz only, but not labelled as such). Though my TV will support 1080p @ 50Hz because my Blu-Ray player upscales PAL DVDs to 1080p and the TV reports these as being 50Hz.

I hate HDMI.

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Answer 5

Apr 6, 2011 5:11 AM in response to Easybourne

Easybourne wrote:
The issue usually occurs with HD video that is output at 720p, so this would fit with the data-rate theory except that the motion anomaly occurs at regular intervals and also during 'undemanding' scenes of little movement.

This issue has been bugging me since I bought the ATV2.

I own a SONY kdl32ex703 1080p TV - the "stuttering" only occurs with HD Video at 24fps, 25fps play flawlessly.
I did eventually find a fix - the TV has two settings that control the smoothness of the picture, one is called "Motionflow" and has no effect on the "stuttering" issue, the other is something called "Film Mode" which "+provides smoother picture movement+" turning off this setting resolves the problem.

I also own the iPad2 which, interestingly, suffers from the same problem when plugged directly into the TV via HDMI even though it outputs at 1080p. Again, setting "Film Mode" to off resolves the issue.

Could this problem be specific to H.264 video?, my Lacie "LaCinema" has no such issues and plays mkv files at 24fps at full 1080p

Regards

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Answer 6

Dec 20, 2011 9:49 PM in response to Josef Kowalewski

Thanks a bunch, "turning Film Mode Off" tip solved the issue I've been trying to address for weeks...

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