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Author Topic: Stuttering videos on iMac i5 2.5GHz mid 2011 El Capitan  (Read 5669 times)

akira54

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Stuttering videos on iMac i5 2.5GHz mid 2011 El Capitan
« on: November 13, 2016, 02:10:56 pm »

I noticed quite a bit of "stuttering" when the camera is panning. Is there anything I can do about this in the settings? When I switch to W7 in bootcamp on the same machine I do not have this problem, but I would prefer to remain in "native" mode. Suggestions would be appreciated. The only thing I have tried so far is to enable hardware acceleration, but it made no difference.
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akira54

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Re: Stuttering videos on iMac i5 2.5GHz mid 2011 El Capitan
« Reply #1 on: November 14, 2016, 12:31:57 pm »

I investigated a little further and looked at the same video in Windows bootcamp and is was smooth as silk there. Nothing else was running on OSX (El Capitan), no backups or internet access and I only re-installed El Capitan, like MC21, from scratch a few days ago. To show the problem I have uploaded a short video filmed with my phone. You can download it here: https://ln.sync.com/dl/c0c21b510#bydayh3w-2pka9vms-823uwvzb-e5pjawyu

PS. The 1.17 Mb upload limit here is silly.
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Hendrik

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Re: Stuttering videos on iMac i5 2.5GHz mid 2011 El Capitan
« Reply #2 on: November 15, 2016, 03:34:55 am »

A 2011 iMac isn't the most powerful machine one might imagine - what kind of videos are you playing? Did you try any lower resolution videos to check if its just a performance issue?
Unfortunately we don't support Hardware Accelerated decoding on a Mac yet.
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akira54

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Re: Stuttering videos on iMac i5 2.5GHz mid 2011 El Capitan
« Reply #3 on: November 15, 2016, 04:05:13 am »

Playing videos should not require "the most powerful machine imaginable"  ;) and all I was trying to play was a scaled down TV documentary. Moreover, it played flawlessly under Windows 7 on the same machine (bootcamp).
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Hendrik

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Re: Stuttering videos on iMac i5 2.5GHz mid 2011 El Capitan
« Reply #4 on: November 15, 2016, 05:11:01 am »

Without having access to a particular machine I cannot help you, as every system is different, especially if performance could be a factor, so please try to answer the questions.

- What kind of video are you playing? Width/height/codec? Is it interlaced?
You can get detailed information with MediaInfo (https://mediaarea.net/nn/MediaInfo/Download/Mac_OS)

- Does the same problem happen with different videos? All of them? Just some?

- Can you check CPU usage while playing to check for performance constraints?

- Which OSX are you using? 64-bit?

Video playback is entirely different on Windows, so comparing to that is not very conclusive.
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akira54

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Re: Stuttering videos on iMac i5 2.5GHz mid 2011 El Capitan
« Reply #5 on: November 15, 2016, 05:12:33 am »

Thanks Hendrik. I am at work now but I will check the details for you tonight and let you know. Thanks for taking this up.
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akira54

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Re: Stuttering videos on iMac i5 2.5GHz mid 2011 El Capitan
« Reply #6 on: November 15, 2016, 01:34:52 pm »

Video 1.72Gb
1280x720
Constant framerate
MPEG4
Progressive scan
Framerate 25 FPS

MacMini
OSX 10.11.6 (El Capitan)
i5 2.5 Ghz 2 core
AMD Radeon HD 6630M 256 Mb
8Gb memory
CPU running at some 24% peaking at 30-33%. Makes no difference what video I run, TV recording or full resolution Bluray rip with all the audio bells and whistles.

It looks as if all videos have this problem. I checked some TV shows, bluray rips, dvd rips and they all did it. In all cases the rips are NAS based (LAN). I'll try it later tonight with a SSD attached to the Mini to rule out a LAN bandwidth problem because in my experience on other machines W7 has a faster LAN connection with the server than my Macs have.
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akira54

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Re: Stuttering videos on iMac i5 2.5GHz mid 2011 El Capitan
« Reply #7 on: December 02, 2016, 12:50:41 pm »

Finally got around to testing the LAN throughput and can state categorically that it has nothing to do with that either (I quadrupled the throughput by switching to AFP). So is it the video processor? The mac has 8Gb memory, surely that should be enough? Since it was suggested it wasn't very powerful I checked the processor and it turns out to score slightly higher than the i5s in the 2014 Mac Mini, so that cannot be it either, can it? Could it be a MC problem?
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blgentry

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Re: Stuttering videos on iMac i5 2.5GHz mid 2011 El Capitan
« Reply #8 on: December 02, 2016, 05:19:06 pm »

I have an 2011 Macbook Pro with a 2.0 GHz quad core i7.  A reasonable machine even though it's "old" now.  For quite some time I've been watching lots of video with MC21 and MC22 for Mac.

Most of the time it's normal.  But some fraction of the time, I see "juddering" that's very similar to the video that was posted.  Stop, start, stop, start, all in rapid succession.  In some cases, I think the source video might be the problem.  In others I'm not so sure.

A month or so ago, I tried to do some concrete experiments with 24 fps video as this frame rate is known to have weird issues with 30 fps (and 60 fps) devices.  Pretty much all modern LCD monitors are 60 fps so...  I used a well known movie, The Fifth Element, and saw some of this juddering behavior.  But I couldn't totally nail it down.  So I just moved on with my life and kept watching videos with MC.  It wasn't perfect but...

A few weeks ago, my MBP was repaired and when it returned it was running a fresh installation of the latest OSX, 11.12 Sierra.

I've just done some more testing with this machine and the same movie.  I can't seem to induce the juddering at all.  Well.. maybe just a teeny tiny bit here and there.  But nothing like it was before.  It's nearly perfect now.

A few things are different on this machine.  I'm not sure which is the most important, but I have guesses.  Here they are:

1.  Previously my internal hard drive was about 85% full.  This time I've kept it rather empty by moving large files to an external hard drive.  It's less than 30% full now.  Previously I've noticed MC seemingly behaving worse and worse the more full the internal (OS) hard drive became.
2.  OSX 11.12 appears to have much better memory management than the previous OSX I was using, which was 10.9.5 (Mavericks).  It seems to use less RAM overall and does on the fly memory compression.
3.  My hardware was repaired, including a new motherboard.

I think 1 or 2 is probably the big factor.  If I had to guess I'd probably say 1 is the biggest factor, but I'm really not sure.  All I know is that my video juddering is substantially reduced now.  Though I need to do more testing.

Brian.
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akira54

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Re: Stuttering videos on iMac i5 2.5GHz mid 2011 El Capitan
« Reply #9 on: December 24, 2016, 12:30:18 pm »

Brian thanks for the response. I have been wrecking my brain over this issue now for several months and have reached a few tentative conclusions and I would love some feedback from those who are in the know about such things. First the good news. It wasn't MC at least not directly, but this is also where things become complicated. here are the facts:

(1) MC never used to have this problem until recently.

(2) Our home theater has both a projector (Sony VPL-HW50ES) and a monitor installed. I only ever use the monitor if I want to listen to some music without being bothered by projector noise. However, when I did test it with videos that showed a lot of judder I discovered that on the monitor the judder was gone.

(3) I then realised that a few months ago I sold my relatively new Denon AV receiver (AVRX3000) and replaced it with my much older one (Denon AVR-4308) which has far superior sound quality. To rule out the receiver (which otherwise does not give me any grief with the BR player, Sat receiver and PS3) I bypassed it for video and plugged the HDMI cable from my Mac Mini (W7 Bootcamp) straight into the projector. The resulting picture was smooth as a baby's bottom.

Since the setup in 3 causes some problems with switching sources I would still like to resolve it, but have a hard time reaching any conclusions based on the facts. Since my other sources (BR player etc) do not cause the problems I am having with the Mac Mini could it be that the output HDMI video signal is not correctly processed by the receiver? If so, is there anything I can do? If that plays a part, why does everything look fine on the TV monitor?

Any ideas on how I might proceed with this (what to test) would be appreciated.
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