Mplayer "strobo" jerkiness despite RTC=1024

[toni]

Hello!

I know this is not a gentoo thing, but it might have something to do with gentoo's special kernel patches and upgrades...

Maybe it's just my pro's eye. Maybe I have been in advertising and TV for too long, but maybe the mplayer has a problem...
It seemed jerky at first, so I fixed the RTC timer to 1024 and voila... the movies are playing smoother even for non-root user, but still NOT as smooth as they should be...

The jerkiness goes unnoticed by most observers, but there is a slight "stroboscopic" effect, much like a 25 fps vs 50 f/2ps.... (yes, there is a difference in smoothness). It seems like the frames were not motion blurred enough. On slow sliding scenes (ie Starwars intro) there is slight speed-ups and slow-downs - about 2-3 per second. It seems like every 7-8 fast frames there are 3-4 slow ones. The jerkiness is not abrupt, it's quite smooth, so most people never notice it.

It's quite annoying though, especially because I have seen this movie in a windows player. It's smooth and rock solid.

Anyone knows a sollution?
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[toni]

Hello!

I love this. A problem noone else has or has experienced. I also love solving this problem all by myself (take a look at https://forums.gentoo.org/viewtopic.php?t=17022). Everyone is invited to hide their own acorns in this thread.

I rounded up the problem to be either the scheduler in kernel or the way mplayer acualy decodes video streams. Ok I needn't be a rocket scientist for this one. Actually This descovery doesn't solve anything. Bugger.

Our Gentoo patched kernel 2.4.19-r10 is feature-packed. It's like a walking army of patches. I didn't even bother to read through /usr/src/linux/patches.txt. Ijust looked at the first few nasty ones:

The O(1) scheduler (new preemptive scheduler)
XX_defconfig (sane value configuration file)
XX_futexes-2.0.2* (new threading)
XX_gcc3-compile-opts (athlon optimisations)

Any of these coud cause this, as well as -march=athlon-4 or -mcpu=athlon-4, whichever I used on this piece of software. While it's rather temting to spend several nights in a row fixing a simple problem I shouldn't have in the first place, I have yet to deciede what path to take...

Some other OS, no mentioned (a non option, really).
Some other player (perhaps)
Some other kernel (oh please, not more of this crap)
Some other eyes (see option 1)
Some other monitor (no, this one is crappy enough and this error shows still)
Some other brain (got that one)

THE JOY!
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[The Jaff]

Ive noticed this too.. Very slight jerky playback of most formats in mplayer. I run gentoo-sources 2.4.20-r5 on a P4 1.7 Ghz with 512 Mb RDRAM. Cpu utilization never goes above 40% when playing for example the 640xsomething new trailer for matrix reloaded so it shouldnt be unsufficient hardware. Oh, my graphics card is a GeForce3 64mb.
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There are 11 kinds of people - those who know binary, and those who can't count.

[Tuna]

try adding the following to your /etc/mplayer.conf and see if it helps

[The Jaff]

mc=0.001 did nothing for me but using oss (-ao=oss) for audio output did the trick (i think sdl was used by default on my system). Playback is much smoother now.

Further info:

MPlayer 0.90-3.2.2 (C) 2000-2003 Arpad Gereoffy (see DOCS)

CPU: Intel Pentium 4 Xeon Foster (Family: 8, Stepping: 2)
Detected cache-line size is 64 bytes
CPUflags: MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
Compiled for x86 CPU with extensions: MMX MMX2 SSE SSE2
...
VO: [xv] 640x346 => 640x346 Packed YUY2
...
AO: [oss] 44100Hz 2ch Signed 16-bit (Little-Endian) (2 bps)

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There are 11 kinds of people - those who know binary, and those who can't count.

[paranode]

Ah this worked well for me also, thanks for the tip. It was using the arts server in KDE for me before. Switching to OSS helped smoothness as well as synchronization.

Also, if you like Mplayer and want to use your KDE theme (if you use KDE), check out kmplayer. It uses mplayer as the video engine but has a KDE-native GUI instead of the one that gmplayer uses.
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Meh.

[crunchtime]

Could be the codec, or perhaps the way the movie was encoded.

I'm more of sound than a visual guy, but my father used to do video encoding for a living so you pickup some things, but I still may be wrong.

I see a lot of movies these days encoded with 23.97 fps,
off the top of my head isn't the ntsc standard nearly 30fps.
And pal is 25 fps.

If you're used to broadcast quality video you're bound to notice the difference.

I remember there used to be an option in the windows version of Divx, where there was an option to enable smooth playback and a slider to decide playback quality vs cpu. They made a difference.

To be honest though, I've noticed a lot of Mpeg4 stuff (divx,xvid, etc) has problems with fast moving scenes if not encoded correctly, even on hardware encoders.

However since it works fine on windows, I believe that the stroboscopic effect you are having could well be the refresh rate of your monitor/tv If you are watching on a monitor, try setting the refresh higher.
Perhaps on windows the video playback is synced to the refresh of the monitor??? (just a guess) If you are watching on a TV there are even more variables, check that your tv output matches the pal or ntsc standard, check in your tv manual perhaps.

Hope thats of some help, a really bad strobo effect bugs me, but if its really slight I tend to get used to it. However thats not easy if your used to near perfect video.

I know the feeling, listening to music on Tannoy Reveals, if I go somewhere else and hear speakers distorting, or rattling it bugs the hell out of me.

[paranode]