[FFmpeg-trac] #6650(ffmpeg:new): Re: previous post [feature request]

[FFmpeg]

#6650: Re: previous post [feature request]
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             Reporter:               |                     Type:
  thomas_johnson                     |  enhancement
               Status:  new          |                 Priority:  important
            Component:  ffmpeg       |                  Version:
             Keywords:               |  unspecified
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
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 This is just a reply to my previous post, but because I promised I'll file
 a new request if you don't see a comment I posted on my previous request
 and therefore I'm filing new post here.

 My previous post: https://trac.ffmpeg.org/ticket/6645

 In my previous post I requested a feature: enable saving files to
 different extensions. Some people from your team responded saying that
 "Ffmpeg doesn't even determine format by extension, it determines format
 by file content". So, apparently you've missed my point. Ffmpeg may (and
 probably does) determine input format by file content. But, how in the
 world Ffmpeg can determine output file format by its content? What are you
 talking about?

 Please read the previous post (if you didn't already), and more important:
 read my last comment on that post, because I don't want to repeat
 everything I've said in that comment. I will just remind you that in that
 comment I've said that I had postead a question about this on stack
 overflow, and ffmpeg experts responded that what I'm trying to do is not
 easy at all and that I probably need to file a feature request here.

 And when I filed my first feature request, you said that it is invalid
 because ffmpeg determines format by file content and not by extension. I
 really have no idea what you were talking about. Ffmpeg cannot detect
 output file format by its content. Which content? Output file is not saved
 yet, about which content are you talking about.

 You probably didn't even read my previous feature request carefuly. My
 feature request makes sense and if you didn't udnerstand what I had was
 talking about, then I can explain it more clearly if you want.

 Simply, what members of your team said (in comments on my previous
 request, before it got invalidated) is outright false. How can ffmpeg
 detect output format by its content? Output file is not saved yet, it has
 no content. So, clearly ffmpeg detects output format by its extension.

 Here is an example:

 If I want to encode a png file into mp4 file, then I can do the following:

 ffmpeg -hide_banner -i 1.png 1.mp4

 But, what if I want my output file to be encoded as mp4 file, but to have
 file name "2.png"? For this particular case, it is possible by providing
 "-f mp4" commabnd line argument.

 However, I asked on stack overflow: given extensions (lets say "mkv") and
 given output file name (for example "2.mp4"), which command line arguments
 one need to pass in order to encode file as mkv file, but file needs to be
 named "2.mp4"? It turned out (and ffmpeg experts explained it) that it is
 not easy. It is not easy at all, because each different extension require
 different arguments to be passed. As I explained in previous post, for
 example video files require "-f ext" where ext is target extension, and
 image files require "-f image2 -c:v ext". But, definitelly, it is not for
 all extensions and all video and image files.

 I'm looking for a way to create a program which will for given file name
 and target extension (different from real extension) output command line
 arguemnts for ffmpeg required to encode file to that extension (like we
 passed original extension in file name). In my previous post in comment,
 members of your developer team explained that what I'm looking for is easy
 and that there is no need for feature request and that ffmpeg already
 detects format by file content and that extension is only fallback.

 But, I've just explained here that no matter what you say, ffmpeg will
 never be able to detect output format by file content, because output file
 is not saved yet. There are two possibilities: 1) you've completelly
 misunderstood my previous post or 2) you didn't even read my previous post
 entirely.

 Probably you underestimated (or didn't understand) what I was talking
 about. To explain it again, I'm not ffmpeg expert, but people on stack
 overflow know what they are talkign about. If it is still unclear what I'm
 requestion, then ask me what is unclear to you and I'll explain it again,
 as brief as I can.

 IMPORTANT: Please don't post any comment here before you 1) Read my
 previous post, 2) Read my last comment on my previous post and 3) Read
 this whole post. I hope we will avoid further misunderstanding. Thanks.

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Ticket URL: <https://trac.ffmpeg.org/ticket/6650>
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