Wikipedia:Reference desk/Archives/Miscellaneous/2016 July 9

Welcome to the Wikipedia Miscellaneous 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.

July 9

Why are there many subtitle files for one movie

If I download a "wrong" subs file, the subtitles will begin to get an incrementing offset to the movie. My question is why, if the movie is exactly the same length, no matter its source. For example, a 720p BR version of the movie needs a differenct subs file than a 1080p version. But the movie in both cases is expected to be the same length. Gil_mo (talk) 17:16, 9 July 2016 (UTC)

The number of frames per second, and hence total number of frames for the movie, may be more at the lower resolution. StuRat (talk) 17:40, 9 July 2016 (UTC)

Does that mean that the same movie runs in a slightly "slow motion" than another version of it? Gil_mo (talk) 20:29, 9 July 2016 (UTC)

There are several different frame rate standards. Movies (on film) are usually 24 fps. Television in the United States (NTSC) is 29.97 fps (often incorrectly referred to as 30 fps). Television in some other countries that use PAL is 25 fps. There are some other less widely used standards. However video encoders often allow you to encode at any arbitrary frame rate, so depending on where the video originated it may have some other frame rate. Ideally the playback device (presumably your computer if you're using subtitle files) will play at the frame rate in which the movie was encoded, so the movie won't play fast or slow even if it's encoded at an unusual frame rate. Most subtitle formats specify the point where each subtitle should appear as a time (in seconds/milliseconds), so if the movie is being played at the correct frame rate, the subtitles should appear at the correct time. But there are a lot of reasons why something can go wrong in this process. Some encoders may misreport their frame rate (eg. encode at 29.97 but report the frame rate at 30). Or the Presentation timestamp values encoded in the video may not be correct. The rate at which the subtitles are drifting from the correct point may give a clue as to what's going on. CodeTalker (talk) 22:07, 9 July 2016 (UTC)

By my math, the difference between 29.97 and 30 fps would mean the subtitles would drift off by 3.6 seconds after an hour, or 7.2 seconds after 2 hours. So, that should be enough to be noticeable, especially in long movies. StuRat (talk) 22:44, 9 July 2016 (UTC)

[the camera pans very slowly over all of Old Rose's photos and maybe gets to her body] Suddenly: [Caption]: Ah! Sagittarian Milky Way (talk) 01:45, 10 July 2016 (UTC)

A 720P file would not need a different file from a 1080P file unless you're talking about subpicture type subtitles formats where the subtitles are actually images but in the download world there are fairly rare except for files which come (or are embedded into) Bluray rips. If you have these type of subtitles, they will generally be multiple MB even compressed. (The common format has two files, a small sub and a larger idx although compressed idx are supported.) In fact, even then you don't really need different subtitles, it's fairly unlikely the files for the 720P or whatever version are anything other than automatically downscaled variants of the original subtitles probably at 1080P and any decent player should be able to handle this without any problems or difference in quality from what the release does. (An exception may be fansubs, but I'm not aware many fansubs are in subpicture format. Then again, I rarely deal with them.) Still if you're distributing a 720P variant (let alone a SD aka BR-Rip), it makes sense to distribute already downscaled 720P subtitles with it.

For non subpicture formats (i.e. the common standalone srt/sub files that are few tens of k), there's basically no reason to have different subtitles for 720P and 1080P, if it's the same source (but with the same frame rate). However to aide automatic recognition, the subtitles may be renamed to be the same as the video file name, and these may then be uploaded separately to sites providing subtitles. If you actually compare the files, you'll probably find there are no differences other than the possibility someone added their name or whatever.

However for different sources (regardless of resolution), you will often need different subtitles for proper synchronisation. Either the ripper or the source may make slightly different cuts. Notably, for something from TV, ads are often need to be removed, or maybe there's something slightly longer or shorter at the beginning. WebDL and Bluray or DVD releases don't require ad removal, still they may be a bit different. Sometimes you even get something more complicated like different intro sequences or missing "previously on" sequences.

Additionally, there can be different versions of subtitles perhaps coming from different sources. E.g. the Bluray or DVD will have their own subpicture subtitles which will generally be OCRed. You can get hearing impaired versions i.e. with descriptions of non speaking sounds (some DVDs or Blurays will have both). For TV releases the subtitles may come from the broadcast, or fans, or other services. Dedicated fans or whoever may correct errors in subtitles. Some subtitles have colour. These different sources of subtitles may be synchronised to other releasers by fans. (As hinted above, I'm not thinking of fansubs which add another layer of complexity.)

As mentioned above, for TV releases you can also get problems due to differences between framerate. I don't think 30 vs 29.97 is likely to be much of a problem unless you're talking about a completely incompetent releaser. But DVD/Blurays and web-DL (and particularly web-rips) from Europe or many places outside the Americas may be 25 FPS. This can include of US TV, and sometimes the only Blurays available may be from outside the US. In the US and other parts of the Americas, TV releases may be 29.97 FPS. WebDL and BluRay or modern DVDs will often be 24FPS or probably 23.976 FPS. However whether the release is 29.97 or 23.976 it normally shouldn't cause sync issues ignoring the other problems (differences between releases) since these aren't speed up but simply have frames added or removed, it's only 25FPS where these are normally sped up or slowed down.

Again, ignoring the other problems, it's obviously not that difficult to automatically correct sync for frame rate difference but many players don't even have semi-automatic (semi as the file probably doesn't have the framerate) correction built in. And in fact the .sub format (which uses frames rather than time) shouldn't even have problems but .srt predominates.

Nil Einne (talk) 05:36, 10 July 2016 (UTC)

Police killing BLACK people

Americans,

These days we have very good TV / Computer coverage so we can see what happens in your police. Attacks of black peoples.

Questions.

Before computers and social medias, did these killings also happen like this commonly, did TV and computer users not find out because they did not happen (1950's, 60's, 70s) so this was common? I asked? We only hear now because of phone movie cameras, facebook? Sad. — Preceding unsigned comment added by 93.85.60.246 (talk) 17:45, 9 July 2016 (UTC)

Yes, that certainly is the logical conclusion. If anything, you would expect fewer unjustified killings by police now that they have to fear somebody with a cell phone camera. (Many police also have dashboard cameras and wear body cameras, but they have an amazing ability to "lose" the footage from those whenever they show anything incriminating, or to ensure that anything incriminating isn't in front of those cameras.) StuRat (talk) 17:52, 9 July 2016 (UTC)

Sometimes the camera malfunctions in advance so there's no video to lose. —Tamfang (talk) 21:24, 9 July 2016 (UTC)

Man, this is embarassing. This isn't the f**g seventies. Not all Eastern Europeans are this ignorant. Sorry, could not resist. Asmrulz (talk) 20:57, 9 July 2016 (UTC)

This was incorrectly closed as "not a forum". This question seems legit and not too polemic. EvergreenFir (talk) Please {{re}} 21:06, 9 July 2016 (UTC)

This is not a request for references, it is an "address" to Americans and an invitation, at best to debate. "Not too polemical" is not found in the guidelines at the top of the page. μηδείς (talk) 21:43, 9 July 2016 (UTC)

This is a question that needs to be asked. We're not all savages, surely. Why do cops hate black people so much?--WaltCip (talk) 23:36, 9 July 2016 (UTC)

Have you stopped beating your roommate yet? ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:55, 9 July 2016 (UTC)

The OP's question is a reasonable request for information that is probably researchable. The fact that some editors here may react strongly to the question is no justification for hiding the thread as a means of censorship. Those editors will have to deal with their feelings. Akld guy (talk) 23:42, 9 July 2016 (UTC)

Ironically, the OP's question qualifies as a drive-by shooting. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:55, 9 July 2016 (UTC)

I've seen the phrase "It's not the shootings that are new, it's the cameras" used to capture this sentiment, an era that entered the popular consciousness in the wake of the Rodney King beating, trial, and subsequent riots. Police brutality in the United States (and the linked articles therein) is probably the most apropos article to provide. Matt Deres (talk) 13:00, 10 July 2016 (UTC)

The treatment of protestors at Selma in the 1960s was filmed and shown on national TV, which also was an eye-opening event. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:40, 11 July 2016 (UTC)

Yes, and TV was also important in ending the Vietnam war, but no doubt many events of the day went unreported, because TV cameras couldn't be everywhere. StuRat (talk)

No small number of crimes are prosecuted from videos the perpetrators themselves made. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:55, 11 July 2016 (UTC)

BTW, if you want a specific example of where camera footage would have been valuable in the previous decades, the death of Fred Hampton, a leader of the Black Panthers, seems to have been a preplanned assassination. As it was the evidence was ignored and the police, et al, believed (although they were forced to accept a settlement in a civil case), but camera footage might have been enough to convict the police and accomplices of murder. StuRat (talk) 01:57, 11 July 2016 (UTC)

I remember that case. Given it was the Chicago police, and if they'd had body cams, the cameras probably would have been "not working". ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:20, 11 July 2016 (UTC)

Yep, and if anyone inside had cell phone cameras then the police would have destroyed them, but live streaming would have been harder to stop. One law change we need is that any attempt by police to stop filming or destroy video should absolutely be viewed as destruction of evidence and require immediate firing. If the Chief of Police doesn't immediately fire cops for that, then he should be fired. This is a case where "zero tolerance" is actually needed. Also, police have been shown to be willing to lie under oath to protect their own, so any testimony by police should be treated with a high degree of skepticism. StuRat (talk) 02:25, 11 July 2016 (UTC)

There are some states where there has been discussion of banning videotaping of cops doing their job. Nothing suspicious about that, eh? ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:08, 11 July 2016 (UTC)

The argument there presumably is that film of cops causes riots, but it's obviously the cops doing things they shouldn't that is the root cause, and film, along with prosecutions, is the only way to end that. The same arguments were made against pics of prisoner abuses in Iraq, for example. StuRat (talk) 03:12, 11 July 2016 (UTC)

One thing we know about politicians is that they are very much in favor of "transparency" - by the other side. Not by their own side, necessarily - except when it serves their purposes. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:04, 13 July 2016 (UTC)

Ironically politicians' attempts to keep things secret, which they claim are in the public interest, but are really to cover up their own bad behavior, are often highly transparent. StuRat (talk) 19:02, 13 July 2016 (UTC)

• To the best of my knowledge, the effect of technology on bringing police shootings to public attention has not been addressed by academic literature yet. There has been analysis on police shootings based on race and weapons though (see [1]). I know of a repository of articles about race and policing if someone is looking for something in particular. EvergreenFir (talk) Please {{re}} 03:46, 11 July 2016 (UTC)