Choppy 1080p video on 2.8GHz Core 2 Extreme iMac

[supabass18]

I am running VLC .86f on a new 2.8GHZ iMac with 4GB of RAM and the playback of some 1080p video files is choppy. I don't think it is a CPU speed issue because Activity Monitor shows only about 30%-40% usage. It plays fine in MPlayer, but the audio is messed up. Anyone have any tips to make VLC smoother?

[tabsaid]

I have the exact same issue, but with a mac pro. My CPU usage ranges from 20-25% but some 1080P stuff, mostly higher bitrate, is choppy and gives me slow machine, dropped frames errors. I only see 1 core working at a time in activity monitor, although it does switch cores constantly. VLC is multi threaded right? I have the same results with mplayer too. Video is great but audio is choppy. I know my machine can play this stuff back (quad 2.6 , 8800GT, 8GB ram). Any ideas to what the issue is would be great, Thanks

[tabsaid]

well I figured it out by doing some reading on the forum. VLC uses a decoder that only uses a single core. That is why you only use under 50% CPU and I only use 25% and we get bad playback. From what I read the FFmpeg team is working on a multi-threaded decoder. Can't express how much I look forward to this. Crappy to have all this headroom but not be able to playback stuff.

[madmax_2069]

i do know that allot of the slow playback issues in VLC for OS X doesnt take advantage of the video card in a Mac to help with the video playback like they are designed to (not to mention what was already said here about it not taking advantage of dual CPU/cores). on a windows machine even if you have a single core ( i have a P4 2.8ghz northwood ) and i can play HD content on it and it plays well, i can play 480p and 720p on my DA G4 using QT on Apples movie trailer site but in VLC you cant at all. all you see is the movie start to play anf the video freezes sometimes skipping into a green and multi colored corruption for video and the sound continues to play.

i think VLC for windows does take advantage of a video card to help with video playback and that takes loads off the CPU. on my P4 i have never seen my CPU usage go above 15% using VLC playing back video content. i havent tryed HD content in VLC on it i use the stock video players for that, but i would guess it would to allot better due to the fact it uses the video card to help video playback and it takes allot of burden off the CPU.

[snix]

Have you tried increasing the file cache value?

Open Preferences and go to:
Input / Codecs -> Access modules -> File

Increase the caching value in ms (I have mine set to 800ms).
Restart VLC, and try playing the file again.

Even MacBooks with 1.83Ghz C2D can play 1080p videos, so your processer should have no problem.

[Arite]

To improve performance try skipping the loop filter for H.264 as described here:
viewtopic.php?f=2&t=42328

You may also wish to try a nightly build of 0.9.0-git which has improved H.264 decoding:
http://nightlies.videolan.org/

Arite.