Wikipedia:Reference desk/Archives/Computing/2020 December 28

= December 28 =

Video editing problems on Linux
I have an MP4 video file on my Fedora 32 Linux system that I'd like to edit by cutting out parts of it. I tried to import the file to OpenShot but that caused OpenShot to just hang. It's been several hours and OpenShot has not reacted at all. I searched for other Linux video editors and found VidCutter, which is able to import and edit the file just fine. However, VidCutter splits the video into several "chapters", and what is annoying, sometimes leaves pauses of a couple of seconds between these "chapters".

OpenShot is able to import pretty much all other MP4 files all OK, just not this one. I tried to run ffmpeg on the file first but that doesn't help. Also, while ffmpeg runs all OK on the original file, it crashes on the file edited by VidCutter.

How can I find out what is wrong with this file and why is OpenShot unable to import it? J I P &#124; Talk 01:38, 28 December 2020 (UTC)


 * No idea about openshot but clipping out parts of a video with ffmpeg is not terribly hard if you don't mind grovelling through the man pages to find the right options. The ffmpeg wiki (trac.ffmpeg.org/wiki) has some ok help pages for doing stuff like that too. 2601:648:8202:96B0:0:0:0:313A (talk) 01:46, 28 December 2020 (UTC)


 * I use ffmpeg for all video-editing such purposes, however, I STRONGLY recommend AGAINST using the man pages to try to figure out how to do something like this. The way that I usually look up how to do some specific complex/advanced editing procedure with ffmpeg is to just google/duckduckgo 'how to do such-and-such with ffmpeg' or something of the like; usually find the answer very quickly that way. Firejuggler86 (talk) 17:46, 4 January 2021 (UTC)
 * I've used kdenlive, which is in the Fedora repo, without any trouble. As with any video editor, you'll need to run through a tutorial to get an understanding of how it works, but it is easy to load a video, use dhe slicer to create cuts in the video, delete the sections you don't want, and slide over the sections you do want to fill in the gaps. Normally, it loads video and audio in separate editable tracks, but you can lock them together so cutting one also cuts the other. 97.82.165.112 (talk) 12:55, 28 December 2020 (UTC)
 * I tried to install kdenlive but it failed. It looks like dnf is able to find the package but unable to download it. Here is the result when I typed :  J I P  &#124; Talk 00:59, 29 December 2020 (UTC)

Last metadata expiration check: 1:26:59 ago on Tue 29 Dec 2020 01:30:01 AM EET. Dependencies resolved.

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=================================================================== Package                 Arch   Version                       Repository  Size

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=================================================================== Installing: kdenlive                x86_64 20.12.0-7.fc32                unitedrpms  12 M Installing dependencies: accounts-qml-module     x86_64 0.7-1.fc32                    fedora      87 k breeze-icon-theme        noarch 5.75.0-1.fc32                 updates    3.7 M dbusmenu-qt5             x86_64 0.9.3-0.22.20160218.fc32      fedora      85 k docbook-dtds             noarch 1.0-75.fc32                   fedora     280 k docbook-style-xsl        noarch 1.79.2-11.fc32                fedora     1.2 M dvdauthor                x86_64 0.7.2-11.fc32                 fedora     237 k dvgrab                   x86_64 3.5-25.20160616gite46042.fc32 fedora     173 k ebook-tools-libs         x86_64 0.2.2-16.fc32                 fedora      31 k kaccounts-integration    x86_64 20.04.1-1.fc32                updates    117 k kde-filesystem           x86_64 4-63.fc32                     fedora      43 k kde-settings             noarch 32.0-3.fc32                   fedora      32 k kf5-attica               x86_64 5.75.0-1.fc32                 updates    182 k kf5-filesystem           x86_64 5.75.0-1.fc32                 updates     11 k kf5-karchive             x86_64 5.75.0-1.fc32                 updates    109 k kf5-kauth                x86_64 5.75.0-1.fc32                 updates    125 k kf5-kbookmarks           x86_64 5.75.0-1.fc32                 updates    162 k kf5-kcodecs              x86_64 5.75.0-1.fc32                 updates    178 k kf5-kcompletion          x86_64 5.75.0-1.fc32                 updates    136 k kf5-kconfig-core         x86_64 5.75.0-1.fc32                 updates    330 k kf5-kconfig-gui          x86_64 5.75.0-1.fc32                 updates     50 k kf5-kconfigwidgets       x86_64 5.75.0-1.fc32                 updates    400 k kf5-kcoreaddons          x86_64 5.75.0-1.fc32                 updates    450 k kf5-kcrash               x86_64 5.75.0-1.fc32                 updates     33 k kf5-kdbusaddons          x86_64 5.75.0-1.fc32                 updates     75 k kf5-kdeclarative         x86_64 5.75.0-1.fc32                 updates    320 k kf5-kdoctools            x86_64 5.75.0-1.fc32                 updates    613 k kf5-kfilemetadata        x86_64 5.75.0-1.fc32                 updates    221 k kf5-kglobalaccel         x86_64 5.75.0-2.fc32                 updates     62 k kf5-kglobalaccel-libs    x86_64 5.75.0-2.fc32                 updates     99 k kf5-kguiaddons           x86_64 5.75.0-1.fc32                 updates     80 k kf5-ki18n                x86_64 5.75.0-1.fc32                 updates    1.3 M kf5-kiconthemes          x86_64 5.75.0-1.fc32                 updates    179 k kf5-kinit                x86_64 5.75.0-1.fc32                 updates    182 k kf5-kio-core             x86_64 5.75.0-2.fc32                 updates    616 k kf5-kio-core-libs        x86_64 5.75.0-2.fc32                 updates    481 k kf5-kio-doc              noarch 5.75.0-2.fc32                 updates    2.6 M kf5-kio-file-widgets     x86_64 5.75.0-2.fc32                 updates    308 k kf5-kio-gui              x86_64 5.75.0-2.fc32                 updates     84 k kf5-kio-ntlm             x86_64 5.75.0-2.fc32                 updates     21 k kf5-kio-widgets          x86_64 5.75.0-2.fc32                 updates    248 k kf5-kio-widgets-libs     x86_64 5.75.0-2.fc32                 updates    411 k kf5-kitemviews           x86_64 5.75.0-1.fc32                 updates    130 k kf5-kjobwidgets          x86_64 5.75.0-1.fc32                 updates    114 k kf5-knewstuff            x86_64 5.75.0-1.fc32                 updates    844 k kf5-knotifications       x86_64 5.75.0-1.fc32                 updates    156 k kf5-knotifyconfig        x86_64 5.75.0-1.fc32                 updates    108 k kf5-kpackage             x86_64 5.75.0-1.fc32                 updates    221 k kf5-kservice             x86_64 5.75.0-1.fc32                 updates    358 k kf5-ktextwidgets         x86_64 5.75.0-1.fc32                 updates    322 k kf5-kwallet              x86_64 5.75.0-1.fc32                 updates    343 k kf5-kwallet-libs         x86_64 5.75.0-1.fc32                 updates    103 k kf5-kwidgetsaddons       x86_64 5.75.0-1.fc32                 updates    1.6 M kf5-kwindowsystem        x86_64 5.75.0-1.fc32                 updates    192 k kf5-kxmlgui              x86_64 5.75.0-1.fc32                 updates    688 k kf5-purpose              x86_64 5.75.0-1.fc32                 updates    416 k kf5-solid                x86_64 5.75.0-1.fc32                 updates    399 k kf5-sonnet-core          x86_64 5.75.0-1.fc32                 updates    164 k kf5-sonnet-ui            x86_64 5.75.0-1.fc32                 updates    162 k libaccounts-glib         x86_64 1.25-1.fc32                   updates     87 k libaccounts-qt5          x86_64 1.16-1.fc32                   fedora      61 k libebur128               x86_64 1.2.4-3.fc32                  fedora      23 k libid3tag                x86_64 0.15.1b-32.fc32               fedora      51 k librttr                  x86_64 0.9.6-1.fc32                  unitedrpms 727 k libzip                   x86_64 1.6.1-1.fc32                  fedora      60 k mlt                      x86_64 1:6.22.1-8.fc32               unitedrpms 841 k mlt-freeworld            x86_64 1:6.22.1-8.fc32               unitedrpms  64 k movit                    x86_64 1.6.2-5.fc32                  fedora     222 k movit-data               noarch 1.6.2-5.fc32                  fedora      26 k opusfile                 x86_64 0.12-1.fc32                   updates     53 k phonon-qt5               x86_64 4.11.1-3.fc32                 fedora     309 k polkit-qt5-1             x86_64 0.113.0-2.fc32                fedora      81 k poppler-qt5              x86_64 0.84.0-2.fc32                 fedora     202 k qt5-qtgraphicaleffects   x86_64 5.14.2-1.fc32                 updates    111 k qt5-qtquickcontrols2     x86_64 5.14.2-1.fc32                 updates    1.5 M qt5-qtspeech             x86_64 5.14.2-1.fc32                 updates     44 k sgml-common              noarch 0.6.3-54.fc32                 fedora      55 k signon                   x86_64 8.60-5.fc32                   fedora     356 k signon-plugin-oauth2     x86_64 0.22-12.fc32                  fedora      89 k sox                      x86_64 14.4.2.0-28.fc32              fedora     426 k Installing weak dependencies: catdoc                  x86_64 0.95-8.fc32                   fedora     110 k phonon-qt5-backend-gstreamer x86_64 2:4.10.0-1.fc32              fedora     175 k qt5-qtspeech-speechd     x86_64 5.14.2-1.fc32                 updates     24 k

Transaction Summary

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=================================================================== Install 83 Packages

Total download size: 40 M Installed size: 202 M Is this ok [y/N]: y Downloading Packages: [MIRROR] librttr-0.9.6-1.fc32.x86_64.rpm: Status code: 404 for https://osdn.net/projects/unitedrpms/storage/32/x86_64/librttr-0.9.6-1.fc32.x86_64.rpm (IP: 202.221.179.17) [MIRROR] mlt-6.22.1-8.fc32.x86_64.rpm: Status code: 404 for https://osdn.net/projects/unitedrpms/storage/32/x86_64/mlt-6.22.1-8.fc32.x86_64.rpm (IP: 202.221.179.17) [MIRROR] kdenlive-20.12.0-7.fc32.x86_64.rpm: Status code: 404 for https://osdn.net/projects/unitedrpms/storage/32/x86_64/kdenlive-20.12.0-7.fc32.x86_64.rpm (IP: 202.221.179.17) [MIRROR] mlt-6.22.1-8.fc32.x86_64.rpm: Status code: 404 for https://sourceforge.net/projects/unitedrpms/files/32/x86_64/mlt-6.22.1-8.fc32.x86_64.rpm (IP: 216.105.38.13) [MIRROR] mlt-6.22.1-8.fc32.x86_64.rpm: Status code: 404 for https://sourceforge.net/projects/unitedrpms/files/32/x86_64/mlt-6.22.1-8.fc32.x86_64.rpm (IP: 216.105.38.13) [MIRROR] mlt-6.22.1-8.fc32.x86_64.rpm: Status code: 404 for https://sourceforge.net/projects/unitedrpms/files/32/x86_64/mlt-6.22.1-8.fc32.x86_64.rpm (IP: 216.105.38.13) [FAILED] mlt-6.22.1-8.fc32.x86_64.rpm: No more mirrors to try - All mirrors were already tried without success (2-3/83): kdenlive-2 2% [                    ] 328 kB/s | 873 kB     02:03 ETA The downloaded packages were saved in cache until the next successful transaction. You can remove cached packages by executing 'dnf clean packages'. Error: Error downloading packages: Cannot download mlt-6.22.1-8.fc32.x86_64.rpm: All mirrors were tried


 * Never mind, now it worked. I have installed kdenlive but not tried it out yet. It's way past my bedtime here. J I P  &#124; Talk 01:16, 29 December 2020 (UTC)

New Laptop ?
I have about $500 in gift money, and what I want is a new laptop computer running Windows. I have an old laptop, but it is frustratingly slow, primarily for launching applications. What I want to do with it is to view web sites and edit Word documents and use Zoom and get reasonable launch time and response time. The problem with the current one is that it takes too long to launch applications and to switch between applications. It gives good response when in Word. It appears to have 4 Gb of RAM and a rated speed of 1.6 Ghz. I get much better, much better response time on a desktop computer with 12 Gb of RAM and a rated speed of 2.4 Ghz. The CPU speed stated by the Task Manager keeps varying, which only reminds me that when I was involved in mainframe capacity analysis, it was said that MIPS stood for Meaningless Indicator of Processor Speed. So is there anything in particular that I should be looking for to keep performance adequate while keeping price moderate? I don't want or need anything neat like animation, but I know that some web sites like to do animation that you haven't requested. I don't care if little toons dance in the corner, but I do care if dancing toons slow down my replying to my email. By the way, yes, I do want to use and edit Wikipedia from the laptop, but Wikipedia is normally a web site that isn't difficult or demanding.

Are there any particular questions that I should ask the sales person, or any particular questions that you (the readers of the Reference Desk) want to ask me to clarify what I need? Robert McClenon (talk) 05:19, 28 December 2020 (UTC)


 * Most important is an SSD drive, either SATA or preferably M.2 NVMe (the NVMe article doesn't show an M.2).  Second, at least 8GB of RAM.  The reason the task manager shows different speeds of the CPU at different times is because of Turbo Boost, where it actually runs at different speeds. Bubba73 You talkin' to me? 06:12, 28 December 2020 (UTC)
 * I agree with an SSD but I'm skeptical there is any reason to prefer M.2 NVMe over SATA for a $500 laptop except if it makes no difference to the cost or specs or with highly specific requirements/use cases. At $500 an ultrabook type laptop is likely out. So the size advantage for M.2 over a 2.5" SATA is likely to be of limited advantage. And the performance advantage is going to be theoretical for most purposes except synthetic benchmarks. To be fair, M.2. isn't necessarily going to be more expensive nowadays but the point is, M.2 over SATA is generally a very low priority feature at that price range so it's not something to concentrate on. I.E. For most people, you'll gain more by giving other feature differences higher priority. BTW, while I admit I know little about how Task Manager works, I strongly suspect it can show a varying frequency even if the CPU has no Turbo Boost, since basically all x86 CPUs for about 15 years have used Dynamic frequency scaling as part of their power saving system and this should definitely be enabled in a laptop. I assume that Task Manager can show the frequency below the based under very light loads. (Definitely other monitoring apps do.) Although to be fair, it's also almost unheard of to lack turbo boost for a long time now, especially for a laptop chip. But Intel did a lot of weird things especially with their low end chips. Nil Einne (talk) 08:18, 28 December 2020 (UTC)


 * OK, I looked up some tests for loading Windows and games. The M.2 is only a tiny bit faster than a SATA SSD at that (not nearly enough to notice).  The M.2 should be a lot better with some intensive database work of if you have to swap memory to the drive.  Bubba73 You talkin' to me? 06:48, 29 December 2020 (UTC)
 * Thank you, User:Bubba73. The advantages of the solid state drive are clear, including as to reliability.  I didn't mention that I might want to use the laptop on trains after the travel weather returns to normal, and the SSD has better vibration resistance.  The performance problems that I am currently having may be due to inadequate RAM.  Are there any other issues?  Robert McClenon (talk) 09:44, 30 December 2020 (UTC)
 * Those are the main things. Also, an SSD doesn't use up the battery as much as a hard drive.  Bubba73 You talkin' to me? 16:44, 30 December 2020 (UTC)
 * Thank you again, User:Bubba73. I realize now that I forgot to identify one more criterion, which is three USB ports.  I have never been able to use a touchpad or whatever it is called, and have always relied on a mouse, and that requires a USB port, unless you have some other oddball way of connecting the device.  One port is needed for a flash drive, and one more port is a good idea for whatever.  You mention that the SSD doesn't use the battery as much as a conventional hard drive.  That is obvious after you think about it, because energy is used to spin the disk.  And any dancing toons in the corner also use energy, even if you didn't tell them to dance.  Robert McClenon (talk) 01:58, 31 December 2020 (UTC)
 * , there are lots of Bluetooth mice (and keyboards) floating around now. I have some, and they work great. Elizium23 (talk) 02:03, 31 December 2020 (UTC)
 * You can connect multiple devices with a USB hub, which is cheap. Laptops increasingly have touchscreens now, though you might be a little below the price point for that. Personally I wouldn't bother with sales people; their job is to get you to spend money you don't need to. Just look through some online rankings and pick what you like in your price point. And if you buy used you can strech your money more. I bought my laptop used and got a great bargain. Only "issue" was a meaningless cosmetic blemish on a corner. --47.152.93.24 (talk) 02:45, 31 December 2020 (UTC)
 * { What they said about bluetooth and USB hubs is correct. I have a bluetooth keyboard for when I use such a device.  Bubba73 You talkin' to me? 05:26, 31 December 2020 (UTC)

How can I print a cheque using my computer and standard printer?
Is there any free software available that will enable me to fill out all the required details onscreen and then print it to a paper cheque from my chequebook?

I don't want to generate my own cheques, to make it clear. Just be able to put an existing blank paper cheque in my printer and do it that way instead of filling it out with pen and ink. Obviously, I'll still need to sign it by hand.

A Google search is utterly useless for this. Full of spammers and people talking about commercial cheque printing. --Iloveparrots (talk) 11:24, 28 December 2020 (UTC)


 * What search terms did you use? A Google search for "cheque template" brings up plenty of free templates that you can use. But you can just create your own, which is what I would be inclined do for something so straightforward. It should only take you three or four trial-and-error attempts (onto blank paper) to get the fields in the correct location to print a cheque.--Shantavira|feed me 12:25, 28 December 2020 (UTC)


 * Many word processing applications allow one to create a text in about any format and layout, and send it to a printer in size 6″ × 23/4″ or whatever size is desired. I regularly use this for address labels, just using whatever I happen to have as software. The paper feed of your printer must be able to feed pieces of paper the size of a cheque. --Lambiam 13:29, 28 December 2020 (UTC)
 * The majority of banks and credit unions will produce and mail a paper check if necessary when you use their "bill pay" service. Of course you'll have to check (hah) with yours. --47.152.93.24 (talk) 02:50, 31 December 2020 (UTC)

question about distributed source code management systems
I know that one of the advantages of a distributed source code management (SCM) system such as git is that it's free'n'easy to make commits to my local copy of the repo. I know that I'm not polluting anyone else's copy of the repo unless/until they choose to pull my changes.

My question concerns identifying the changes someone else might want to pull. Suppose I've made these five commits, in this order:
 * 1) preliminary implementation of required new feature A
 * 2) implementation of required new feature B
 * 3) cosmetic change to clean up existing whitespace and comments (unrelated to any new features)
 * 4) implementation of experimental feature C
 * 5) completed implementation of required new feature A

So I might want someone else to pull changes 1 and 5 together as a unit. Or I might want them to pull change 2. I probably won't ask anyone to pull change 3 until I have several more changes in that category. And I may never ask anyone to pull change 4 at all, if I decide that feature C isn't useful after all, or something. But the point is that I'll never be asking someone else to just "sync to my branch".

I know that git makes branching exceptionally easy and lightweight, and that if I could manage to work on features A, B, C, and cosmetic changes on four separate branches, I'd have no problem distinguishing the changes and distributing them separately. But I don't tend to work that way; I tend to have one working copy with several unrelated sets of changes going on at once.

Are there SCM's that assist with this sort of situation, or am I doomed to clean up my messes manually? 71.174.177.111 (talk) 18:49, 28 December 2020 (UTC)


 * You can use "git cherry-pick" to pull individual diffs into a new branch, but it's also good to get used to putting new feature development into new branches. Then use git rebase to squash together groups of related commits in order to not spam the main repo with noise.  As for other vcs, darcs has a theory of commuting patches that might help with that.  I never got good at using it though.  It had a successor camp in development that seems abandoned now, but there is something new called pijul that I think takes up some of the same ideas.  I haven't looked at it yet but have heard it mentioned here and there.  The basic idea of commuting patches is that you can apply them in a different order than they were originally made in, for purposes like what you describe.  It takes some machinery (implemented in the vcs) to keep track of when that is doable. 2601:648:8202:96B0:0:0:0:313A (talk) 21:57, 28 December 2020 (UTC)


 * Thank you! It looks like "commuting patches" describe just the issue I'm talking about. I found this page which is presumably the theory you were talking about, and this page describing various "patch management" tools which might be run on top of git or another SCM. (And finally this page full of cynical commentary about why such management is impossible, or shouldn't be necessary If Only people managed their development differently.) 71.174.177.111 (talk) 00:01, 29 December 2020 (UTC)