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I often run across various videos on the internet, on various sites (for example, You Tube and many other sites). Sometimes, I go back to view the videos again, and they are gone. I assume that the person who posted them has removed them. Or maybe the site itself has removed them, for whatever reason. Who knows? Anyways, it often upsets me. So, here is my question. When I run across a video on the internet, is there some way that I can save it onto my computer or my hard drive or wherever? So that I can prevent the possibility that I return in the future and the video is gone? Thanks. Joseph A. Spadaro ( talk) 05:39, 5 April 2016 (UTC)
It's also probably not the best option if you need to download lots of files in one go. And with the way Youtube works now, if you want certain qualities (particularly 1080P) you may need to download the video and audio seperately so either need a video player that can handle that or need to mux them with a seperate program. I don't know if Youtube-dl has a built in muxer, but it can't be that hard to integrate one (whether you use the command line directly or a GUI with support for that built in). The number of sites supported by Keepvid is likely smaller then Youtube-dl
The big advantage of course with Keepvid is that you don't need anything other than your browser and something to play the video provided Javascript is enabled (and the security settings don't otherwise prevent it running) and the site doesn't need Java forn downloads. (If it does then you need Java in addition and security settings to allow it.)
Nil Einne ( talk) 07:14, 6 April 2016 (UTC)
Thanks, all. Joseph A. Spadaro ( talk) 17:55, 7 April 2016 (UTC)
I was asked, given an array A[1...n] of positive integers, to create an array S[1...n] where S[i] is the maximum of all k such that all elements at places A[i-k...i] are not bigger than A[i].The creation of S should be at O(n). The hint says that we may use a stack.
For example,
index | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
A | 2 | 7 | 18 | 5 | 14 | 3 | 9 | 11 | 13 | 15 |
S | 1 | 2 | 3 | 1 | 2 | 1 | 2 | 3 | 4 | 7 |
I thought about a trivial algorithm that works at O(n^2) and scans all numbers from A[i] backwards until it finds j such that A[j]>A[i]. Another algorithm I thought on, that doesn't use a stack, works in the following way: if A[i]<A[i-1], S[i]=1. Otherwise, S[i] should be at least S[i-1]+1. So go backwards from A[i-1] at "jumps" of S[i-1] until a number bigger than S[i] is found (in the example above, when we are at index=10, 15>13 and S[9]=4 therefore we jump 4 places backwards and arrive at index=5; 15>14 and S[5]=2 so we jump 2 places backwards an arrive at index=3. now 15<18 therefore S[10] would be the sum of the distances we traveled plus one: 4+2+1=7. The latter algorithm is clearly more efficient than the naive one, but I don't know how to assess its complexity.
I'd appreciate it if someone could help me with a way to asses the complexity of the algorithm or, preferably, give an hint regarding the solution that uses a stack.
Thanks! — Preceding unsigned comment added by 212.179.21.194 ( talk) 08:21, 5 April 2016 (UTC)
Pretty simple, I have a video file I recorded and edited (currently saved as a .avi) and for some reason, my video editor software doesn't have options to change the volume. Usually I use Avidemux for editing, but searching online brings up a bunch of forum threads where people have asked this question, been given simple instructions and responded to say they don't work. I have also followed the same instructions and found that they don't work, hence the simple conclusion that Avidemux cannot change the volume of this file type.
So, looks like I'll have to find alternative software, the internet is full of free to download video editing programs, half of which are viruses and half are massive things that have far more options and settings than I need. Any suggestions of software I can get just to carry out this one simple task?
Thank you,
86.24.139.55 ( talk) 16:14, 5 April 2016 (UTC)
In terms of increasing the volume, I think the bigger issue is whether you can decompress and recompress it as I assume it's compressed. Most common unencrypted audio file formats can be decompressed by something (or otherwise converted to simple uncompressed PCM that most audio software can understand). And worst case scenario if you can play it back somehow on your PC, you can probably use the analog hole. I don't think this is likely to be a problem though since AFAIK even Dolby TrueHD and DTS-HD can be decoded [1] in some way although I'm not certain if they can decode all channels and losslessly, although most video aren't intended to have these formats exclusively anyway.
However I don't believe there's any open source or freely available software capable of encoding to a number of audio formats like DTS-HD or Dobly TrueHD. So depending on what your source audio format is, you may need to change it to something else. Although I'm surprised anyone would store any such format in AVI, perhaps the more likely problem is if it's some weird audio format which is not supported by any modern software. Particularly in the later, there doesn't seem to be a good reason to keep the older format anyway so just encode it to Advanced Audio Coding or Opus (audio format) (or perhaps MP3 if you have real ancient devices.)
BTW certain audio formats have some sort of gain or other such volume setting standard, which you can try to use to adjust the audio without recompressing, but playback software don't always implement proper support for these settings so they can be a bit hit and miss. (I also wonder if it's theoretically possible to increase volume directly on the compressed format somehow. Not exactly lossless but not exactly recompressing then decompressing. But even if this is possible I don't think it's particularly common and I also wonder how it will deal with clipping and dynamic range compression issues anyway.)
I don't know how relevant this is but note if you have a decent video player, you should be able to play the files in perfect sync without muxing them, although you will need the modified audio and video. You could potentially use a frame server to edit the video if it fulfills you're need presuming your computer is able to handle any processing real time. Probably similar for the audio. Alternatively just play back both files at nearly the same time if you don't care about perfect synchronisation. If you aren't editing the video, I imagine most audio processing can be handled real time on any modern computer provided the software allows it.
I have an annoying problem with my iPad and iPod. When browsing the Internet and scrolling up and down pages, it sometimes highlights the word my finger is over, giving me a black box with options to copy, define, or share, covering the text above. I need to tap the screen multiple times to get rid of the box. Is there any way to do it permanently? KägeTorä - (影虎) ( もしもし!) 17:37, 5 April 2016 (UTC)
Computing desk | ||
---|---|---|
< April 4 | << Mar | April | May >> | April 6 > |
Welcome to the Wikipedia Computing Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
I often run across various videos on the internet, on various sites (for example, You Tube and many other sites). Sometimes, I go back to view the videos again, and they are gone. I assume that the person who posted them has removed them. Or maybe the site itself has removed them, for whatever reason. Who knows? Anyways, it often upsets me. So, here is my question. When I run across a video on the internet, is there some way that I can save it onto my computer or my hard drive or wherever? So that I can prevent the possibility that I return in the future and the video is gone? Thanks. Joseph A. Spadaro ( talk) 05:39, 5 April 2016 (UTC)
It's also probably not the best option if you need to download lots of files in one go. And with the way Youtube works now, if you want certain qualities (particularly 1080P) you may need to download the video and audio seperately so either need a video player that can handle that or need to mux them with a seperate program. I don't know if Youtube-dl has a built in muxer, but it can't be that hard to integrate one (whether you use the command line directly or a GUI with support for that built in). The number of sites supported by Keepvid is likely smaller then Youtube-dl
The big advantage of course with Keepvid is that you don't need anything other than your browser and something to play the video provided Javascript is enabled (and the security settings don't otherwise prevent it running) and the site doesn't need Java forn downloads. (If it does then you need Java in addition and security settings to allow it.)
Nil Einne ( talk) 07:14, 6 April 2016 (UTC)
Thanks, all. Joseph A. Spadaro ( talk) 17:55, 7 April 2016 (UTC)
I was asked, given an array A[1...n] of positive integers, to create an array S[1...n] where S[i] is the maximum of all k such that all elements at places A[i-k...i] are not bigger than A[i].The creation of S should be at O(n). The hint says that we may use a stack.
For example,
index | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
A | 2 | 7 | 18 | 5 | 14 | 3 | 9 | 11 | 13 | 15 |
S | 1 | 2 | 3 | 1 | 2 | 1 | 2 | 3 | 4 | 7 |
I thought about a trivial algorithm that works at O(n^2) and scans all numbers from A[i] backwards until it finds j such that A[j]>A[i]. Another algorithm I thought on, that doesn't use a stack, works in the following way: if A[i]<A[i-1], S[i]=1. Otherwise, S[i] should be at least S[i-1]+1. So go backwards from A[i-1] at "jumps" of S[i-1] until a number bigger than S[i] is found (in the example above, when we are at index=10, 15>13 and S[9]=4 therefore we jump 4 places backwards and arrive at index=5; 15>14 and S[5]=2 so we jump 2 places backwards an arrive at index=3. now 15<18 therefore S[10] would be the sum of the distances we traveled plus one: 4+2+1=7. The latter algorithm is clearly more efficient than the naive one, but I don't know how to assess its complexity.
I'd appreciate it if someone could help me with a way to asses the complexity of the algorithm or, preferably, give an hint regarding the solution that uses a stack.
Thanks! — Preceding unsigned comment added by 212.179.21.194 ( talk) 08:21, 5 April 2016 (UTC)
Pretty simple, I have a video file I recorded and edited (currently saved as a .avi) and for some reason, my video editor software doesn't have options to change the volume. Usually I use Avidemux for editing, but searching online brings up a bunch of forum threads where people have asked this question, been given simple instructions and responded to say they don't work. I have also followed the same instructions and found that they don't work, hence the simple conclusion that Avidemux cannot change the volume of this file type.
So, looks like I'll have to find alternative software, the internet is full of free to download video editing programs, half of which are viruses and half are massive things that have far more options and settings than I need. Any suggestions of software I can get just to carry out this one simple task?
Thank you,
86.24.139.55 ( talk) 16:14, 5 April 2016 (UTC)
In terms of increasing the volume, I think the bigger issue is whether you can decompress and recompress it as I assume it's compressed. Most common unencrypted audio file formats can be decompressed by something (or otherwise converted to simple uncompressed PCM that most audio software can understand). And worst case scenario if you can play it back somehow on your PC, you can probably use the analog hole. I don't think this is likely to be a problem though since AFAIK even Dolby TrueHD and DTS-HD can be decoded [1] in some way although I'm not certain if they can decode all channels and losslessly, although most video aren't intended to have these formats exclusively anyway.
However I don't believe there's any open source or freely available software capable of encoding to a number of audio formats like DTS-HD or Dobly TrueHD. So depending on what your source audio format is, you may need to change it to something else. Although I'm surprised anyone would store any such format in AVI, perhaps the more likely problem is if it's some weird audio format which is not supported by any modern software. Particularly in the later, there doesn't seem to be a good reason to keep the older format anyway so just encode it to Advanced Audio Coding or Opus (audio format) (or perhaps MP3 if you have real ancient devices.)
BTW certain audio formats have some sort of gain or other such volume setting standard, which you can try to use to adjust the audio without recompressing, but playback software don't always implement proper support for these settings so they can be a bit hit and miss. (I also wonder if it's theoretically possible to increase volume directly on the compressed format somehow. Not exactly lossless but not exactly recompressing then decompressing. But even if this is possible I don't think it's particularly common and I also wonder how it will deal with clipping and dynamic range compression issues anyway.)
I don't know how relevant this is but note if you have a decent video player, you should be able to play the files in perfect sync without muxing them, although you will need the modified audio and video. You could potentially use a frame server to edit the video if it fulfills you're need presuming your computer is able to handle any processing real time. Probably similar for the audio. Alternatively just play back both files at nearly the same time if you don't care about perfect synchronisation. If you aren't editing the video, I imagine most audio processing can be handled real time on any modern computer provided the software allows it.
I have an annoying problem with my iPad and iPod. When browsing the Internet and scrolling up and down pages, it sometimes highlights the word my finger is over, giving me a black box with options to copy, define, or share, covering the text above. I need to tap the screen multiple times to get rid of the box. Is there any way to do it permanently? KägeTorä - (影虎) ( もしもし!) 17:37, 5 April 2016 (UTC)