Wikipedia:Reference desk/Archives/Computing/2010 May 29

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May 29

H.264 video and frame dropping

I have significant problems with frame dropping when playing hi-definition video in MKV / H.264 format. I have tried to rationalize this away by blaming Win Vista or poor software/codecs. The other possibility, hardware performance, would surprise me: is a quad core Q6600 with an Nvidia GTX 260 video card not powerful enough to play hi-def video to perfection? The frame dropping tends to occur during complicated motion scenes, but can also occur in other video in the most mundane places. The degree of it is definitely dependent on the video, making me think that the way it was encoded is a factor as well. I am looking for suggestions on codecs/software that might help, or thoughts on whether the specified system doesn't cut it. Do codecs vary enough in quality that a person needs to purchase one? Any codec recommendations? (In SMPlayer, the option to "skip loop filter" does significantly reduce frame dropping, but the quality difference can be noticeable.) Thanks, Riggr Mortis (talk) 01:55, 29 May 2010 (UTC)

I would highly recommend VLC Player --- try it and see what the playblack performance is like. Doubt its hardware performance, but if VLC still gives you issues, I'd say (1) Upgrade your video drivers and (2) run a video-card burn-in test. Keep us posted. --rocketrye12 ^{talk/contribs} 15:07, 29 May 2010 (UTC)

VLC player was actually my first software choice, so naturally I blamed it and tried other software. At first Mplayer seemed better, then the benefit disappeared. I am using the latest Nvidia drivers... VLC has a lot of advanced video options that might help, but they are really technical options, too advanced for me to mess with. Riggr Mortis (talk) 22:03, 29 May 2010 (UTC)

I see. Is there any rhyme or reason to the dropped frames?--rocketrye12 ^{talk/contribs} 00:59, 30 May 2010 (UTC)

Note that it may be dropping frames completely at random, and they may just be more noticeable during motion shots. The problem with the quad core is that it's probably only using a single core for your video, so you're really only using 25% of the CPU. What's worse, there may also be other stuff running on that same core. Try rebooting to clear up any crap, then use the Task Manager to kill all non-vital applications. See if that doesn't solve the issue, and let us know the results. StuRat (talk) 02:08, 30 May 2010 (UTC)

On Windows I tend to use something like CCCP and Media Player Classic-HC and it hasn't failed me yet. Try installing CCCP with MPC-HC and enabling hardware accelerated decoding (although it worked fine for me without it, on a Q6600 at 3Ghz and an ATI4850), that should give you smooth playback with barely any load on the CPU. --antilived^{T | C | G} 02:24, 30 May 2010 (UTC)

Thanks for the help all. Antilived, I uninstalled SMPlayer (the only program that would have included more codecs than a plain Win installation has, as I had to reinstall Vista recently) -- and installed CCCP, which includes MPC-HC. I tested the worst-offending video in the worst-offending scene, and no sign of frame dropping! I will try the tip on offloading to the video card as well (I thought this "just happened", but I guess not) -- but it is already a vast improvement. We'll see if it stays this way. For now I'm confused but delighted (getting too old to care about "reasons" in computing any more...) StuRat, your comment reminded me that one can force a process to a particular core in the Task Manager, which may/might have been worth looking at too, but there was something stranger going on than pure CPU stuff. Riggr Mortis (talk) 03:45, 31 May 2010 (UTC)

Great to hear.--rocketrye12 ^{talk/contribs} 14:35, 31 May 2010 (UTC)

Regarding Keyboards

I recently purchased a cheap keyboard and for general purpose, it works really great. However, I do like to game occasionally and I have noticed that certain key combinations will result in certain ignored keys (namely when I press Q, W, and Spacebar at the same time, the result is the Spacebar refuses to respond until I relinquish my hold on one of the other keys).

Looking through the keyboard article here on Wikipedia seems to indicate that the control processor might be at fault here. But there also seems to be some indication that it could be on the software/driver end of things too. Does anyone have any insights as to what the root cause may be? Thanks! -Amordea (talk) 03:26, 29 May 2010 (UTC)

Poor keyboard design. See Keyboard_technology#Keyboard_switch_matrix and Rollover (key). Basically in order to avoid having to wire each key into the keyboard's circuitry they're arranged in a sort of grid so that they can share connections. Depending on how this is done it can make certain key combination impossible. Or worse, certain key combination may 'fool' the keyboard into think you've pressed some other, seemingly unrelated key. APL (talk) 04:02, 29 May 2010 (UTC)

Alas, I figured this to be the case. Was just hoping there was something I was missing. Thanks for clearing up the specifics! -Amordea (talk) 04:16, 29 May 2010 (UTC)

Note that many games allow you to redefine which keys you use, so you could hopefully find a combo that works on your k/b. StuRat (talk) 02:00, 30 May 2010 (UTC)

Video screenshots

I am editing video-files (under Linux with Avidemux) and would like to make an overview with screenshots. I tried this with Gimp and Krita, but with both, when I save it, I get a very small file with some coloured blocks, but no photograph. What I do is open the edited video with Mplayer, press PrintScreen, open a new file with Gimp or Krita, press Ctrl-V (which has confusing results, but that is a different matter) and then save the file. But then when I go to the file in the file browser it turns out to be very small and when I open it I see aforementioned blocks in stead of the screenshot. Am I doing something wrong, or better, is there a more handy program to do this? DirkvdM (talk) 14:45, 29 May 2010 (UTC)

Without seeing what you are getting as a result, it is hard to tell, but it sounds like you are having the video piped out through a hardware accelerator which makes it inaccessible to your standard screenshot programs. Your easy options are either to temporarily disable hardware acceleration (no clue how to do that in Linux), or to use the built-in screenshot command in VLC. MPlayer probably has one as well. Usually the built-in screenshot command is "smart" enough to avoid problems with video acceleration. (Video acceleration sends the video directly to the card and bypasses the regular CPU memory or something along those lines. So when you do a screenshot of accelerated video, you just get a blank spot that is the placeholder for where the video card will directly pipe the video.) --Mr.98 (talk) 19:08, 29 May 2010 (UTC)

Oh, forgot to mention, with the VLC snapshot feature I also get just a 'blank' (green, actually). Strangely, though, sometimes it does work, but most of the time not, and I haven't figured out what I do differently. And it also works just fine with photographs. I can't figure out whether I have hardware acceleration and according to this site, with Xorg one can't find out for certain anyway.

However, I have found a workaround. Since I only need thumbs to recognise the scenes, nothing fancy, I decided to just take photographs of the screen. :) Simple, and it works. DirkvdM (talk) 07:50, 30 May 2010 (UTC)

Excerpts from DVDs

For a University project I want to put together a short collection of excerpts from a number of DVDs. I don't really mind if what I end up with is a .mov file (or similar) or a physical DVD. Quality isn't a big issue, either. My first thought was just to plug a DVD player into a DVD recorder, but I've heard that may be "nobbled" in some way to avoid piracy. I've tried using screen capture software while running the DVD on a media player but that doesn't work.

What's the simplest way to achieve what I'm aiming for, here? AndyJones (talk) 14:54, 29 May 2010 (UTC)

So for the simplest/cost-free way to pull a couple of clips together, screen capture is your best bet. What screen capture software did you try that did not work? Try CamStudio, and see if you still have the issue. I am fairly certain that what you are trying to achieve here falls under academic/scholarly provisions in Fair Use and therefore you are probably in the clear of copyright woes. As for another solution, you could convert the DVD to a .avi/.mov file using a ripping program, then bring that finished file into an editing program, cut it and repeat for the multiple DVDs. --rocketrye12 ^{talk/contribs} 15:15, 29 May 2010 (UTC)

I do this fairly often for courses; I've found the easiest way to be HandBrake+QuickTime#QuickTime_Pro. The $30 you spend on QT Pro is worth it; it makes it so that you can basically just copy and paste video in a very intuitive way in Quicktime, and then save the whole thing as a MOV file. I find this method to be a million times easier than free video editors, converting between a plethora of formats, etc. This is simple and anyone can do it with a minimal amount of experience editing video, unlike just about every other method I have seen. I know you're probably thinking, "oh, $30 is quite a lot for something I might only use a few times", but remember that 1. Time is money! If you value your time at all, then $30 is not that bad, compared to spending hours and hours fiddling with other programs that half-way do the job in a way you understand, and 2. Once you learn how to do this once, you'll probably find yourself with more opportunities to use it. I do little video edits all the time

now, just because it's easy to do—it takes no time at all in QT Pro to dice up a large file into small files, or clip the ends off files, or extract small parts of larger files and combine them into one big file. OK, soapbox rant ended! --Mr.98 (talk) 21:16, 29 May 2010 (UTC)

Really? I mean, alright I won't say that it's silly to pay for software when there's obviously other free options out there, because I know that is debatable, but Quicktime?? I never understood why people allow the programs they use to dictate what file formats to use, which seems like an insane inconvenience, especially when it comes to video files where most of the files I use are NOT .mov .mp4. In fact, I avoid those formats because so many of the most accessible (though not industry standard) applications out there don't bother to support them! I think I'll stick to my open source tools. 210.165.30.169 (talk) 01:52, 2 June 2010 (UTC)

My need is slightly different from the OP, but it seems to fit within this category, so I'll ask here instead of starting a brand-new toplevel question:

I have some television programs copied to DVD, and I want to capture still frames of various people I see, so that I can post those JPEG images on my Web site to ask "who is this person seen here". I tried using screen-print of a paused DVD play on MS-Windows, which works fine with playing video from the network, but doesn't work when playing a local video. Screen-print of local DVD gives all-black JPEG and portal to live play (not single frame) in BMP format.

So the trick I discovered was to get a YouTube account, upload the entire video to that account, then play back from that YouTube vodeo, and viola screen-print got me single-video-frame JPEGs.

But after Google bought YouTube, it stopped working: I couldn't find my password to my YouTube account, so I tried password reset, and got the e-mail with the URL for resetting password, but it didn't work at all. Then I tried getting a brand-new YouTube account, and I got the e-mail with link to activate the account, but when I clicked the very first time on the activate-account link it said the account was (already) disabled. So it's no longer possible for me to upload DVD clip to YouTube then play it back to capture single frames. This is on a public computer lab where I'm not allowed to download any new software, so even if I could afford $40 for a special program to capture single video frames directly from DVD, I wouldn't be allowed to install it. Does anybody have any suggestions for solving my problem? 198.144.192.45 (talk) 17:49, 28 March 2011 (UTC) Twitter.Com/CalRobert (Robert Maas)

Windows Vista Audio

The audio output on my laptop has suddenly stopped working - there's a white cross on a red background on the speaker icon, with 'No Audio Output Device Installed' message. I've had no success with the troubleshooting in Vista, and searches on line for a solution don't provide clear answers. The laptop is a Compaq Presario A900 bought a couple of years ago. Any clues as to how to rectify this? Thanks in advance, Sophiepuss —Preceding unsigned comment added by Sophiepuss (talk • contribs) 18:19, 29 May 2010 (UTC)

Look in "device manager" (in the Control Panel); I think that somehow there is a problem with your audio driver, and if that's the case you'd expect to see an error against the built in audio device. If that's the case, the support section of Compaq/HP's website should provide you with a fresh one. -- Finlay McWalter • Talk 19:28, 29 May 2010 (UTC)

Computer won't sleep when Ethernet cable plugged in

Recently I plugged an Ethernet cable into my computer because lately the latency I have in WoW has gone from and average of 260ms to an average of 450ms. This question isn't about that though. I go and press the sleep button, or go through the start menu to do it, and have the computer go into sleep mode. However it will 'wake' right back up seconds later. I found out it was the Ethernet cable, because when I unplugged it, the computer would go to sleep and stay asleep until I jiggled the mouse, pressed enter, bumped the desk hard, etc. I know that the cable is plugged into the right port (on both ends), but I can't figure out why it won't go to sleep mode and stay that way. Does anyone know why this may occur? Shotgun5559 (Talk) (Contrib) 18:25, 29 May 2010 (UTC)

Oh I guess I should mention the fact that I use Vista as well. Shotgun5559 (Talk) (Contrib) 18:27, 29 May 2010 (UTC)

You may have "wake on LAN" set in the BIOS. Wake-on-LAN has details - you may have the BIOS set to the "wake on directed packet" or "wake on link" settings, which would mean other machines on the network sending to yours would wake it. Unless you're a server, turn wake-on-LAN off; if you do need to be a server, set the wake setting to wake-on-magic, and get a magic-packet-generator for your clients (which they send to wake the PC up before they send a print job or poke around in the network shares). -- Finlay McWalter • Talk 19:26, 29 May 2010 (UTC)

Uninstalling Ubuntu from Dual-Boot Vista/Ubuntu

I would like to uninstall Ubuntu 10.04 from this machine. I have it on dual-boot with Vista. After having installed it, I was told by the OS that there was not much disk space left on the partition, and this seemed to be causing problems with running programs and updating software etc. (the software update was bigger than the remaining available space). I am not interested in increasing the partition space, etc., and only want to remove Ubuntu and have the 25GB on the soon-to-be-redundant partition put back so it's usable from Vista. Can anyone tell me how to do this? Bear in mind, I would like to be able to do this from Vista, and not from Ubuntu, as some programs in Ubuntu are either not running correctly or not running at all. TIA! --KägeTorä - (影虎) (TALK) 20:12, 29 May 2010 (UTC)

(EDIT) I don't have the Vista CD, by the way. --KägeTorä - (影虎) (TALK) 20:17, 29 May 2010 (UTC)

Boot from an Ubuntu CD, delete the Ubuntu partition, resize the NTFS partition to fill the space, fix the master boot record with this method. As with all things involving low-level access to a disk (and indeed as with all things involving doing anything at all) make sure you have important files backed up (from Windows) onto an external disk before proceeding. -- Finlay McWalter • Talk 20:17, 29 May 2010 (UTC)

Sorry, "delete the ubuntu partition" really means "run gparted as administrator and carefully delete the Ubuntu partition (which will probably show as being an ext3 filesystem"). You might also have a linux swap partition to delete (which will be called "linux swap"), but make sure you don't delete any weird "unknown" partitions, as these might be Windows swap or OEM system restore partitions. -- Finlay McWalter • Talk 20:20, 29 May 2010 (UTC)

And getting to the recovery console on a cd-less OEM system might work like this. Or you can do it using the Linux boot CD like this. -- Finlay McWalter • Talk 20:24, 29 May 2010 (UTC)

Linux Mint upgrade question

I currently run LinuxMint 8. I downloaded the v.9 ISO. Will it be safe if I loop mount the v.9 ISO file, add it to my software repo, and do an upgrade via synaptic? Or will it completely screw my system?--117.196.130.43 (talk) 20:59, 29 May 2010 (UTC)

video

I want to encode a video, and I'd like the output video to be smaller than the original. How does one determine the correct width and height? So far what I've tried has caused weird aspect ratios. Thanks 82.44.55.254 (talk) 21:39, 29 May 2010 (UTC)

You need to deal in proportions, and therefore first determine the aspect ratio of the source video. Then, when scaling down, pick an arbitrary width or height and scale the opposite axis in accordance to the original ratio you derived from source. Here's an online calculator to simplify the proportion. If you can provide the actual pixel width/height, we can help size down if you are still stuck.--rocketrye12 ^{talk/contribs} 00:56, 30 May 2010 (UTC)

1. Divide width by height
2. Pick a new width
3. Divide it by the result. This is your new height.

Alternatively, instead of (2) and (3): pick a new height, multiply it by the result, and this is your new width. Also you can if you like swap width and height over in everything I said, if you do it consistently. 81.131.66.87 (talk) 01:50, 30 May 2010 (UTC)

CSS alphabetic characters

Is it possible to create a style in CSS, such as might be applied to a span element, which does something only to the alphabetic characters, and leaves numbers and symbols alone? 81.131.66.87 (talk) 23:35, 29 May 2010 (UTC)

No. You probably need to use Javascript if you want to something complicated like that. --Mr.98 (talk) 00:09, 30 May 2010 (UTC)

The set of CSS pseudo-elements is pretty small, and doesn't include anything like what you describe. The only thing I can think of is to generate the page that way: <span class='alpha'>asdf</span><span class='non-alpha'> 123 </span><span class='alpha'>asdf</span> If the page is automatically-generated already, it probably wouldn't be too hard to do, though it sure isn't very elegant. Paul (Stansifer) 00:22, 30 May 2010 (UTC)

Confirmed, not possible in CSS. Paul span alpha/non-alpha solution is the best I can think of without writing javascript to troll the page for alpha characters and do something to them.--rocketrye12 ^{talk/contribs} 00:58, 30 May 2010 (UTC)