Subtitle rendering causes stuttering on slow-cpu machines.
#1
Hello,

this may have been discussed earlier but I couldn't find any signs of progress anywhere.

The rendering of subtitles seems to be done in the same thread as the video renderer.
When playing hd content on an atom/ion machine, the rendering of subtitles causes stutters/frameskips very often because it "freezes the picture" until the subtitle rendering has finished. This problem is especially apparent with chinese subtitles (due to the more advanced font sets I assume), which makes hd content pretty much unwatchable on this kind of htpc. Without subtitles, it runs smooth.

Is anyone working on this?

I found a ticket regarding this issue: http://trac.xbmc.org/ticket/10258

Edit: http://forum.xbmc.org/showthread.php?tid=91230

As I said, this is not only happening with chinese subtitles, but with normal english ones aswell, but to a smaller extent.

Let's just call this thread a highlight of the issue. This really needs to be fixed.
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#2
Any updates on this or tweaks that fix this issue?

Installed OpenELEC on my Revo R3700 this morning and noriced this issue still remains...

/Niklas

deppan Wrote:Hello,

this may have been discussed earlier but I couldn't find any signs of progress anywhere.

The rendering of subtitles seems to be done in the same thread as the video renderer.
When playing hd content on an atom/ion machine, the rendering of subtitles causes stutters/frameskips very often because it "freezes the picture" until the subtitle rendering has finished. This problem is especially apparent with chinese subtitles (due to the more advanced font sets I assume), which makes hd content pretty much unwatchable on this kind of htpc. Without subtitles, it runs smooth.

Is anyone working on this?

I found a ticket regarding this issue: http://trac.xbmc.org/ticket/10258

Edit: http://forum.xbmc.org/showthread.php?tid=91230

As I said, this is not only happening with chinese subtitles, but with normal english ones aswell, but to a smaller extent.

Let's just call this thread a highlight of the issue. This really needs to be fixed.
Reply
#3
same issue from korean subtitle

I have using Xt-ultra (openelec installed)
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#4
Yeah, latest XBMC Eden still having same issue.
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#5
I have this problem too. Any news on this issue?
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#6
Found a particularly bad case using just english subtitles. From Tsukimi's Acchi Kocchi episode 02 (8 bit): starting at 19:53 there is a section that produces excessive CPU usage, resulting in massive frame drops. What parts of this script are likely to be the cause of the CPU? I'm guessing a combination of the blur and fade.

Relevant section of subtitles: http://pastebin.com/LmSegrwB
Debug log (trimmed to only show the relevant section) at: http://pastebin.com/PMnt3sjn
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#7
Same problem here both on ATV 1 Crystalbuntu with Broadcom x15 card and on my XBMCbuntu with 1 core cpu + NV 8400 GT.

The first 4-5 subtitles causing hiccups. After that it's OK if there are subtitles rendered continuously. But for example with forced subtitles in Avatar where you get subtitles only in every 20 min or so it will cause some dropped frames even in the middle of the movie.

I can confirm that with XBMC Live 9.11 this wasn't a problem. I installed it on my htpc just do check this specific issue.

It must be something since Dharma what is causing this. Maybe some eyecandy feature.

Is this something that can be fixed ?

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#8
I just wanted to add the info that the cpu usage never even reaches 40-50% while playing a video (mostly about 30%) so those first 4-5 subtitles that are causing the tiny hiccups are maybe not even related to the cpu power.

Anyone has an idea why are there minor hiccups while rendering the first few subtitles ? What is the bottleneck here ?
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