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Both the title and question body of Stack Overflow question "How to download a video from an M3U8 file" ask how to download a M3U8 video based on a local file.

How to download a video from an M3U8 file

I have an M3U8 file saved locally.

I want to download video file from the above file. I have googled a lot and found M3U8 parser. But it did't help me.

I have attempted to download the video using the following code, but it always returns nil.

 NSString *str = [NSString stringWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"1" ofType:@"m3u8"] encoding:NSUTF8StringEncoding error:nil];
 M3U8SegmentInfoList *list=   [M3U8Parser m3u8SegmentInfoListFromPlanString:str baseURL:[NSURL URLWithString:@"http://hls.ted.com/talks/2238.m3u8?sponsor=Ripple"]];
    NSLog(@"%@",list);

How can I download this video?

From the question text and title, it doesn't look like there's any constraints on what type of solution is being sought. However, based on the question's tags (, ), it seems as though the asker is specifically attempting to download the video on an iOS mobile device using Objective-C. However, none of the answers work on an iOS mobile device, or use Objective-C.

What should be done with old questions like this with multiple upvoted answers that address the question actually asked, but which ignore the constraints suggested by the question tags?

Should the asker's apparent intent be thrown away and the tags removed, matching the question to the answers? Should the question be updated to make it clear it's looking for iOS/Objective-C answers, thus invalidating the answers? Should it be left as is, with an implication that the tags are more about the approach the user took, rather than a request for a certain type of answer?

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    This seems like a question that can/should only be answered on Meta Stack Overflow. Some SE sites allow answers to completely ignore the tags (eg Law’s jurisdiction tags). On other sites, a single tag can be the difference between a question being closed and open (RPG’s game system tags, though having the info in the question means the question will be edited and not closed).
    – Laurel
    Mar 10, 2021 at 3:34
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    In general, on SO you're not obliged to answer based on the tags. It's still preferrable. However, exceptions can be made, e.g., a question tagged Java about an algorithm might be answered with pseudocode. Or a language-agnostic question might be answered with Java code. Regex questions can often be answered without using regex using regular language features. A question about jQuery can be answered with vanilla JavaScript. And so on. So, "always stick to the tags" is not useful as a general policy.
    – VLAZ
    Mar 11, 2021 at 7:31

5 Answers 5

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The all important part of any question is its body so "any constraints on what type of solution is being sought" should be expressed there.

The title is intended to summarize the question body.

The tags are useful for potential answerers filtering questions down to those that they are most interested in seeing.

If either tags or titles reflect information not in the question body then I think the question body, title and/or tags should be edited so that they are in sync. The simplest edit may be to remove a tag that appears to not be relevant based on the body, but to ensure no important posted information is lost, and if a tag seems to have a legitimate purpose, it may be better to edit the body.

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    I agree, though I've seen a lot of Stack Overflow questions specifying the required implementation language in a tag, but not mentioning it in the question. If this were a new question, I'd update the question to match the tags. But it's an old question with multiple accepted answers by a user who's no longer active, so that's where I'm not sure the best course of action.
    – M. Justin
    Mar 10, 2021 at 1:07
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    Lots of SE sites use tags to provide information that is not always contained in the question. For example, Law.SE uses it for jurisdiction, and the tags are often the primary indication of that information. Removing jurisdiction tags that aren't mentioned in the body would be rather harmful.
    – Ryan M
    Mar 10, 2021 at 1:31
  • @RyanM I did not realize any sites did that but I’ve modified my last paragraph to try and address that concern.
    – PolyGeo
    Mar 10, 2021 at 2:57
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    But that said, answers on Law are not restricted to only the jurisdiction used in the tags, if the same question could be asked for a different jurisdiction (identical question that would have different answers if only the tags were changed).
    – Nij
    Mar 10, 2021 at 3:22
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Generally, Stack Overflow permits answers for related technologies. There are a few related questions about this on Meta Stack Overflow, with the general consensus being that if it's generally related, it might help someone who happens across the question (though it may attract downvotes). This approach is shared by other sites, including Law.SE, which permits answers for other jurisdictions (as long as they're labelled appropriately).

The problem with this question is that the answers ignored far more than the tags; they also ignored the body of the question (containing Objective-C code) and the topic of the website they're posting on (Stack Overflow, a site for questions about programming). Those answers are suggesting GUI apps that can be used to do the task, while the question clearly asks how to do so programmatically. If the asker had asked the question that they answered, it would have been off-topic on Stack Overflow.

Ideally, answers that are so clearly non-responsive should be removed quickly by curators/moderators. It becomes a trickier call once the error has gone uncorrected for long enough that the page has become a useful reference for a question other than the one asked, as has happened here.

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Some things to be noted about this specific case:

  • The question was asked in 2015, and has been viewed 47k times.
  • OP was last active in 2019.
  • The first(!) answer was posted in 2020.

I'm going to go out on a limb and say the OP probably no longer cares about this question. For that matter, what seems to be a fair number of people landing there from search probably don't care that it was supposed to be about iOS or Objective-C. So when the first answerer hijacked this question and posted an answer that's useful for your average user looking to download videos from M3U8 files, that turned out useful for a lot of people. And encouraged others to post alternative answers too, but further losing focus.

I suggest that we could edit the post to be more general and remove the mentions of iOS and Objective-C so that it reflects the existing answers when showing up in search, and put a historical lock on the post. And ask the OP to post it again if they still care.

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  • I'm not sure a lock would be beneficial. I don't see any reason why alternate or newly available approaches wouldn't be appropriate to add, and if it were locked there wouldn't be a place to do so without creating a duplicate of the question (which would then be closable as a duplicate). The rest of the suggestions seem reasonable to me, though.
    – M. Justin
    Mar 11, 2021 at 15:31
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    There doesn't have to be a place for those answers on Stack Overflow. Once the programming part is removed from the question, it becomes off-topic there, which is why I suggested the historical lock. It might be ontopic on Super User, but it's way too old to be migrated without help.
    – muru
    Mar 11, 2021 at 15:36
  • "I suggest that we could edit the post to be more general and remove the mentions of iOS and Objective-C so that it reflects the existing answers when showing up in search" Feels iffy to me. Seems like the opposite direction of a user posting a question, getting answers, then editing to invalidate them. We don't like that and I am not a fan of the inverse happening.
    – VLAZ
    Mar 12, 2021 at 7:28
  • @VLAZ I don't like it all that much but the other options are - delete all those answers, which feels like a waste, or keep the answers and the question in its current state, which is misleading in search, where the iOS/Objective C parts might show up in the preview. Ideally this should have been caught when the first answer was posted, but it's been allowed to run wild for a while now.
    – muru
    Mar 12, 2021 at 7:35
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    @muru I can't say I disagree. It seems no matter what happens to the question/answers is not going to be good in some direction. The absolute ideal situation would be to move the answers to a new question in SU, then leave the iOS one intact. Which is in Super User. But AFAIK, that's not possible. All options seem bad in one way or another. Mostly because people seem to have found value in the answers by ignoring the question. Yes, had this been caught earlier, it wouldn't have been much of a problem.
    – VLAZ
    Mar 12, 2021 at 7:39
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In this particular case, the option that was ultimately chosen was "alter the question to fit the answers, and close it as off-topic for the site".

Specifically, a diamond mod edited it to remove the Objective-C portions of the question (both the tag and the portion of the question that referred to Objective-C and/or used Objective-C code).

This used to have some code and technically be an Objective-C question, but none of the answers over the years paid any attention to that, so I'm making the executive decision to turn this into an effectively off-topic question and close it. Please re-ask any programming questions you may have.

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I mentioned in an earlier answer that question was altered to fit the answers and then closed (which I believe happened in June 2021).

However, since then the post was chosen to be deleted (I believe this occurred at the end of December, 2021).

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