ATV2 with subtitles enabled causes lag

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maruchan Offline
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Post: #1
I'm running Eden Beta 2 on 4.4.4 and if I have subtitles enabled (SRT/ASS) the video will begin to drop frames every time a new subtitle appears. This happens on 4.3 as well. I tried searching through old posts to no avail.

Is there a simple fix for this? Log file here.
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Ned Scott Offline
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Post: #2
Others have seen this too. Not sure what it is. Happened to me on my ATV2, but doesn't happen on my iPhone 4, which makes me think it might be a RAM issue. We do think that iOS 5.x (and ATV 4.4.4) takes more system resources, but what exactly, not sure, or what we can do about it. Interesting that you have this happen on ATV2 4.3, though. That could mean something else is happening here that needs to be looked at.
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zhango Offline
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Post: #3
I've seen this too with pgs subtitles. It appears as if the stuttering is worse when showing two lines of subtitles. When there is just one line there's just a quick stutter(skipping something like 2-3 frames). When two lines are displayed however the loss of frames are more drastic, I'd say a loss of maybe 15-20 frames.
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Memphiz Offline
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Post: #4
the one testfile with embedded ass subs from another thread let the framerate drop down to 7fps on one special scene.

This is reproducable with my atv2 on ios 4.4.4.

My second atv2 running ios 4.3 has no issues. So its a fact that 4.4.4 hits our performance hard - though there might be issues on xbmc as well of course.

AppleTV2/iPhone/iPod: HowTo find debug logs and everything else which the devs like so much: click here
HowTo setup NFS for XBMC: Wiki NFS
HowTo configure avahi (zeroconf): Wiki Avahi
READ THE IOS FAQ!: iOS FAQ
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basslover Offline
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Post: #5
I have this too. When a Subtitle line appears, it stutter for a frame or two, it is very annoying. It doesn't stutter if the subtitle switching within a second or two, but if it stopped for like more than 10 seconds, the next line of subtitle appears then the video stutters.

Edit:
My ATV2 is running old 4.1. Xbmc is Eden b1. No Add-on, Nothing else was installed.
(This post was last modified: 2012-01-22 15:53 by basslover.)
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maruchan Offline
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Post: #6
Hm, interesting that it even happens on 4.1. I remember this happening on 4.3 and I figured it was just a bug with XBMC that would be worked out when Eden hit. I know 4.4.4 uses more resources (and I might downgrade to 4.3 for that very reason), but if it is a RAM issue, how was XBMC able to handle subtitles on the old XBOX with only 64 megs of RAM?
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Memphiz Offline
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Post: #7
its not a ram issue imho

AppleTV2/iPhone/iPod: HowTo find debug logs and everything else which the devs like so much: click here
HowTo setup NFS for XBMC: Wiki NFS
HowTo configure avahi (zeroconf): Wiki Avahi
READ THE IOS FAQ!: iOS FAQ
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Haohmaru Offline
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Post: #8
I've opened a ticket because of this problem 7 months ago.
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maruchan Offline
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Post: #9
Glad to see there's a trac ticket open. I think most people run XBMC on modern multi-core machines, but since you reported seeing it on a single core + 8400GS, it's obviously an issue within XBMC itself that goes unnoticed by most users. I hope it gets fixed before Eden goes final. If any devs need more info, I'd be glad to post logs/samples, though it sounds like it's fairly consistent to reproduce on the ATV2.
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whitecom Offline
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Post: #10
I'm also seeing this problem on my ATV2. It's running 4.4.4 w/ Eden b2.

Here's a link to the log. https://pastee.org/qksv4

When subtitles are disabled, the audio and video playback smoothly.
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tarjan Offline
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Post: #11
You can watch the CPU utilization in top. I suggest using crunchyroll as a great source for subtitled material that is fairly low in resolution. Watch the utilization go from the 40% range to 95% (all in the AppleTV app) for simple subtitles then to 100% and stuttering for 2 lines or more of subtitling.

I think we need to get down to how does xbmc put the subtitles in there, I am sure it is a bit of cpu work but if it only takes 40% to get the video on screen, it certainly can't take another 60+% to show subtitles later in the same scene. Keep in mind, I'm not talking about turning subtitles on or off, just in the same video where subtitles are displayed then a few seconds later no speaking is going on so no subtitles and the video is smooth as glass.

BTW: if you go to the subtitles config and set a specific font/ignore ssa fonts it is "slightly" better. Still stutters and most things remain unwatchable.
(This post was last modified: 2012-01-27 18:48 by tarjan.)
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linusyang Offline
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Post: #12
Excuse me, does any developers try to solve this problem? It's still remained in the Eden beta 3 release with iOS 5.
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Ned Scott Offline
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Post: #13
linusyang Wrote:Excuse me, does any developers try to solve this problem? It's still remained in the Eden beta 3 release with iOS 5.

No, they all gave up and went home :P
</sarcasm>
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linusyang Offline
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Post: #14
Ned Scott Wrote:No, they all gave up and went home Tongue
</sarcasm>

Oh, it seems difficult to defeat this issue. Becuase of the CPU performance of A4, or not enough RAM to render subtitles? O_o
Anyway, thanks for great job!
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Ned Scott Offline
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Post: #15
linusyang Wrote:Oh, it seems difficult to defeat this issue. Becuase of the CPU performance of A4, or not enough RAM to render subtitles? O_o
Anyway, thanks for great job!

Something in iOS is eating up CPU resources. Probably one of those damn iClouds :)
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