x264 and ac3 sync issues

[Carpo]

this is a strange one - if i play a x264/ac3 in a mkv on my laptop 1.7 p4, i get sync issues be it if im jumping through seeking or just watching the film, yet if i watch the same mkv file on the same laptop under xp sp2 i get no issues, i have tried this under slackware and ubuntu and i get issues, avi/dvd/ogg/ogm etc play fine.

i would like to stick to linux but i have quite a few dvds backed as x264/ac3 in mkv

[nm]

Which player? Have you tried other players? What does top tell about CPU usage during playback?

[Carpo]

all players - seems vlc does best as you can hrdly tell there is any issue - cpu ranges from 50%-94% average is 60%+ under windows it plays fine, so i reckon its a codec/player issue on linux, because even some avis i made seem to have random lines pop up every now and again (looks to me like tearing - could be wrong tho)

edit: cpu even when ilding seems to be high 10%(max) and the laptop isnt even doing anything!!!

i think i may have to rethink using ubuntu and go back to slackware - as cpu wa never that high

[nm]

That is a bit strange since different players use very different A/V sync mechanisms. Does the problem persist when running MPlayer with -framedrop or alternatively -autosync 30?

[Carpo]

i have even tried other dirtros (using their own packages and compiling from source) and all the players seem to do the same on there, i have other mkvs that used to play without issue on linux - and now they are doing the same - mp3 ac3 or aac audio.

yes i tried what you said it helped, at first i tought it may have been my laptop, i have put winxp back on here and all the clips are playing fine - so im lost, and after replacing the hdd in here i dont really wanna keep formatting and re-installing

[nm]

yes i tried what you said it helped, at first i tought it may have been my laptop, i have put winxp back on here and all the clips are playing fine - so im lost, and after replacing the hdd in here i dont really wanna keep formatting and re-installing
If -framedrop helps, that means the laptop is simply too slow for playing back those files on Linux without dropping frames. Even though the CPU is not fully saturated, there may be CPU usage spikes that cause sync problems. The cause for performance problems compared to the XP installation could be due to display drivers or configuration and the H.264 decoder. Which graphics card does your laptop have and have you configured the players to use XVideo output (try mplayer -vo xv, to be sure)? Which decoders have you tried on Windows (VLC/libavcodec, ffdshow, CoreAVC, ...) and is the CPU usage as high on Windows as it is on Linux?

[Carpo]

atm it has xp on there - viideoo card is an M7 (7500 mobility) 32 meg, i have done another backup - chronicles of riddick and thats having issues and the cpu is hitting near 100% (98% to be precise) so yes im begining to think my laptop is showing its age.

so now i now that its just a case of what linux distro to use - norm i use slackware - but have tried ubuntu, not bad not a lover of gnome.

seeing as its a new drive in there (3 days old) i dont wanna keep formatting and re-installing to test each one, as i think thats what killed the other one off, i have moderate knowledge of linux and can get the things i need working on there, but which would you advise to use, im looking for ease of use, not a lot of work needing done to it to get it running smooth, general net and office use really, this i can do with slackware but there are a few things that need recompiling, and after the hdd dying a lot of progs need to be remade

slightly off topic but - if you had the option of using ac3 or aac (6ch) which would you use ? i only ask asi have done a test and the riddick back up doesnt seem to stutter as much if i use aac as the audio instead of the ac3

and last but not least - thanks for your help :)

[nm]

seeing as its a new drive in there (3 days old) i dont wanna keep formatting and re-installing to test each one, as i think thats what killed the other one off
Well, the drive doesn't like spinning up and down a lot, which it might do in a laptop with tight power-saving settings. Reading and writing (such as formatting) is not a problem nowadays and you can use quick format to just write the new filesystem on top of the old data.

i have moderate knowledge of linux and can get the things i need working on there, but which would you advise to use, im looking for ease of use, not a lot of work needing done to it to get it running smooth, general net and office use really, this i can do with slackware but there are a few things that need recompiling, and after the hdd dying a lot of progs need to be remade
I'd recommend Debian (Etch or Sid) or Ubuntu. Debian has a huge archive of packages, so you usually don't need to compile much yourself, but it may need some work and studying to get the desktop running at first (I haven't installed Debian recently, since my installations from 5-7 years ago run just fine and are up-to-date thanks to APT). It shouldn't be any harder than Slackware though.

Ubuntu is more desktop-oriented and user-friendly, but has less packages available in the repositories. If you don't like Gnome, just don't install it. Perhaps Xubuntu would be a good starting point with the minimal desktop. Then install whichever Window manager you want on top of it.


slightly off topic but - if you had the option of using ac3 or aac (6ch) which would you use ? i only ask asi have done a test and the riddick back up doesnt seem to stutter as much if i use aac as the audio instead of the ac3
I'd probably use the original audio track or re-encode to 2-channel Ogg Vorbis at q1 if I need to save bitrate. Strange that AC3 stutters more than AAC since AAC decoding is much harder. Are you using S/PDIF pass-through?

and last but not least - thanks for your help :)
No problem :)

[Carpo]

have tried ubuntu - its ok but i dont think its for me - seeing as its prob just the laptop being old i may go back to slackware :) - i know what im doing with that most of the time - tried debian before and it was a pain to setup on laptop, might give it another go :)

also after another test it seems like it may have been the size of the files - i have started to back them up without resizing them down, doing so also seems to help - 640x352 is easier for it to handle than 720x576 ;P

[nm]

Certainly, but 720x576 shouldn't be a problem for P4 1.7 GHz and libavcodec's decoder if bitrate is not allowed to jump too high (like over 5 Mbps, perhaps). That can be tuned with x264 parameters (--ratetol) while encoding. Or you can just allow the decoder/player to drop frames.

[Carpo]

when i have the kaptop set up again after i put slackware back on there - i will try the full size backup again - as with the 640 one the dropframe and autosync options did seem to help, even with them off the 640 one seemed to behhave better :) (the 256meg ram in there dont help tho ;) )

[danpos]

@Carpo

You can to try Zenwalk GNU/Linux (http://www.zenwalk.org) out since that it's based on Slackware but it's more up-to-date and optimized. It works great with old/low memory machines.

JFYI. :)

Regards,