We have the following question on Stack Overflow:

Convert a video to MP4 (H.264/AAC) with ffmpeg

If I don't make a mistake, Safari currently need MP4 (H.264/AAC) video encoded for the HTML5 <video> element.

So I tried to convert a video to this format with ffmpeg. However when I enter the shell command ffmpeg -i video.flv video.mp4, the returned error is: [...]

Error message and further details follow.

Somebody posted the following answer:

ffmpeg is an excellent application on video conversion. It supports most of the file formats.

AVI to 3GP:

ffmpeg -i video_clip.avi-s qcif -vcodec h263 -acodec mp3 -ac 1 -ar 8000 -r 25 -ab 32 -y clip.3gp

ffmpeg -i inputfile.avi -s qcif -vcodec h263 -acodec aac -ac 1 -ar 8000 -r 25 -ab 32 -y outputfile.3gp

3GP to AVI:

ffmpeg -i clip.3gp -f avi -vcodec xvid -acodec mp3 -ar 22050 file.avi

Convert videos Ubuntu

I flagged this answer with the following custom message:

This answer is noise. The OP has problems converting flv to mp4, while this answer displays command for avi to 3gp and 3gp to avi conversion.

and I got the following response:

declined - flags should not be used to indicate technical inaccuracies, or an altogether wrong answer

I don't care about a single declined flag (after all, they don't count for badges any more), but I'd still like to understand where I went wrong. After all, the text for flagging as not an answer reads:

This was posted as an answer, but it does not answer the question. It should possibly be an edit, a comment, another question, or deleted altogether.

In my opinion, this answer does not answer the question. I don't know if it's right or wrong, but it addresses a completely different problem.

  • 9
    I see where you're coming from. However, in my experience "Not an answer" is usually reserved for things which are truly not answers. (i.e. comments, questions, etc.) Downvoting in this case would be a more appropriate approach, perhaps leaving a comment. Deferring the decision of whether or not something is a good/true answer to a moderator does often result in the response you've gotten. – Bart May 21 '12 at 15:30
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    @Bart: OK, but where is the line? Clearly, if I posted a very detailed tutorial on how to export bookmarks from Chrome to Firefox, it would have been deleted. Except from the coincidental fact that both question and answer involve the command ffmpeg, I see no difference. – Dennis May 21 '12 at 15:35
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    @Bart I wish I could flag your comment as "not a comment" since it's really an answer. – Some Helpful Commenter May 21 '12 at 15:38
  • In such an extreme case I would just add a custom message explaining the situation. I.e. reduce the amount of work needed for a mod to take the decision. If you're clear and it's clear, it might just work. @SomeHelpfulCommenter I thought about it, but thought it better for an actual mod to answer this more authoritatively. – Bart May 21 '12 at 15:40

Moderators, by and large, simply don't have time to critically review answers to see if they're appropriate. Nor are moderators expert enough on every topic to weigh answers for accuracy.

"Not an answer" refers to "answers" like:

  • I have the same problem. Any luck?
  • You're awesome.
  • That worked for me. Thanks?
  • I have another question on a related subject...
  • I like cheese.

...and other drek that's not even attempting to answer the question.

If the answer looks like a genuine answer to the question, no matter how far afield it may in fact be, a Moderator is going to leave it.

That's what downvotes and comments are for, after all.

(And, presumably, someone with a whole host of downvotes on their answer and a bunch of "that isn't answering the question" comments will delete their "answer" and make the Internet a better place. Or not, but future readers will be able to see at a glance that the answer isn't helpful.)

  • 5
    But you are awesome and I do like cheese.... – Bart May 21 '12 at 15:46
  • 2
    OK, that makes sense. I guess I just got hung up on the it does not answer the question part... – Dennis May 21 '12 at 15:46
  • 1
    @Dennis That part has caused confusion before. What you need to remember is that moderators can't be expected to know if the answer answers the question, we have 12 mods and a megabazillion of answers. The mods combined expertise is impressive but it's unreasonable to ask them to judge the technical accuracy of potentially every answer on SO. The NAN flag should be used when it's obvious that the "answer" doesn't even come close to an honest effort to answer the question, everything else (incl. technical inaccuracies) should be dealt with by the community through voting. – yannis May 21 '12 at 15:56
  • The system works. The answer is now grayed out, which is almost as good as deletion. – Dennis May 21 '12 at 16:10
  • 1
    @Dennis as an aside there is a faq on What is an acceptable answer – Some Helpful Commenter May 21 '12 at 16:50
  • @SomeHelpfulCommenter: OK, if we go by Robert Harvey's answer, my flag should have been marked as helpful. – Dennis May 21 '12 at 16:53
  • 2
    @Dennis and if Robert Harvey's answer was the accepted answer by the community it would have a score of 47 instead of 8. – Some Helpful Commenter May 21 '12 at 17:20
  • @Dennis: deleted. – user7116 May 21 '12 at 21:36
  • @six: Why was the answer deleted? – ale May 23 '12 at 17:42
  • @AlEverett: a question from 2009 (which belongs on SuperUser) didn't need a -5 tangentially related answer from 2011. – user7116 May 23 '12 at 20:35
  • @six: Did the community step in and delete the answer, or did a Moderator step in and remove it? If it's the latter, then the OP has a legitimate gripe about his flag being rejected. – ale May 24 '12 at 13:06
  • 1
    @AlEverett: just realized you're not 10k on SO, my apologies. Three community members took care of it (myself included). – user7116 May 24 '12 at 21:53

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