I'm having trouble converting an unknown file type into MP3 so I can play it on VLC.

If I drag and drop it, it plays fine, but when I open it and attempt to choose VLC as its program, the "Always choose this program to open this kind of file" check box is grayed and I can't click it. I want to set VLC as the program for all of my music files that are like this.

I'm using Windows 7.

  • 13
    What is the extension of the file in question?
    – VL-80
    May 10, 2016 at 18:17
  • 14
    I am afraid in Windows you can not assign default applications for files without extension.
    – VL-80
    May 10, 2016 at 18:19
  • 6
    Try to add .mp3 to the end of the filename. This will give your OS a hint that this file could be opened with the VLC player. Keep in mind - it might happen that it's actual format is not MP3, but something else. With file extension set, you will be able to define default app for this file.
    – VL-80
    May 10, 2016 at 18:32
  • 24
    If you play the file by dragging and dropping, pause it, go to play-list, right-click on the file being played and click Information.... The Codec tab will tell you what kind of file it is, and you can rename to have an appropriate extension. Don't convert it! This will take time and degrade the quality. If you don't know what the appropriate extension should be, rename it to FileName.vlc and associate this extension with VLC.
    – AFH
    May 10, 2016 at 19:05
  • 12
    "Although it converts the file to an mp3 file..." No, it doesn't convert anything. You literally only changed the file name, which programs use as a hint about what's in the file. Do yourself a favor and disable the "Hide known extensions" setting. That will give you a clearer picture of what's going on. (I consider extension hiding to be one of the stupidest "features" ever, personally.)
    – jpmc26
    May 12, 2016 at 9:01

4 Answers 4


If you play the file by dragging and dropping, pause or stop it, then:

  • go to play-list,
  • right-click on the problem file, and
  • click Information...

The Codec tab will tell you what kind of file it is, and you can now exit and rename the file to add an appropriate extension.

Don't convert the file! This will take time and degrade the quality. If you don't know what the appropriate extension should be, rename it to FileName.vlc and associate this extension with VLC (any unused extension could be used, but this one is unlikely to be used by anything else).

  • 2
    Or just rename all the files to ".mp3" (if .mp3 is associated with VLC) assuming VLC can sort it out that is :)
    – rogerdpack
    May 10, 2016 at 22:51
  • 47
    This. Never convert a file just to get file association to work. Sheesh. Hiding file extensions is the absolute worst thing microsoft ever did. God forbid people understand how things work. May 11, 2016 at 7:11
  • 3
    @CandiedOrange I'm not sure it's the absolute worst thing... However, it should be pointed out that converting to MP3 is lossy, but surely VLC can convert to better formats if desired.
    – Auspex
    May 11, 2016 at 9:17
  • 7
    @Auspex - Most audio and all video formats in common use are lossy. If you convert to another lossy format, nothing will restore what has already been lost, and further degradation will inevitably occur.
    – AFH
    May 11, 2016 at 11:27
  • 2
    @corsiKa Why would you have to change the extension before opening it with your archiving tool of choice? May 13, 2016 at 7:12

To anyone who has exactly the same problem: don't let my answer misguide you. AFH's answer is right, it is better not to convert. Still, OP asked for it, OP got it.

Original answer:
If VLC can play this file it probably can convert it. There is convert/save entry in file menu (I have Polish locale set; actual entry may be slightly different in English). Add your file with add button, then pick convert from dropdown menu at the bottom. My VLC has MP3 profile out of the box.

  • 20
    Ignoring? You need a little patience. :) I rarely use Windows. My VLC is on Ubuntu but i believe it is similar to windows version. I have convert/save in file menu, then there is file tab with file list (originally empty) and add button. Is windows version much different? May 10, 2016 at 18:37
  • 4
    @Henry I have just installed brand new VLC on my old XP. It's all there. The shortcut is Ctrl+R. May 10, 2016 at 18:46
  • 15
    @KamilMaciorowski you are way too nice.
    – Moab
    May 10, 2016 at 20:14
  • 3
    @KamilMaciorowski Let me give you a honorary [sportsmanship] badge for your attitude.
    – totymedli
    May 10, 2016 at 21:00
  • 2
    Note that while conversion may lower the audio quality, there are good reasons to convert anyway - the main reason being that many portable players or smartphone music apps support few formats. MP3 is the "safe" choice in these cases.
    – sleske
    May 11, 2016 at 9:16

If you absolutely must convert the file to mp3, I would recommend ffmpeg.

You can convert your file on the command line:

ffmpeg -i random-audio-file -c:a libmp3lame -q:a 4 foobar.mp3

But as stated by others, if VLC can already play it, there's no need to convert it (and thus lose quality).

It's better to identify the filetype or codec, and rename the file to the appropriate extension which you can then bind in Windows to open with VLC by default.

To identify the filetype or audio format, you can use ffprobe (which is also part of ffmpeg). Or use various other tools such as MediaInfo which is perhaps more user friendly, especially for Windows users.


Blind, quick and dirty.

You stated that yours is an mp3 file without the extension (vlc played it).
You have not to convert it, you have simply to rename it adding the extension .mp3.
If you convert it you will loose something in term of quality.

Note that even if it was not an mp3 file probably each version of VLC will play it anyway even if you rename it with a wrong extension. The problem, if present, will remain but you will not be aware...

If you feel unconfortable reading the above answer maybe you want to read some lines more...
... A wiser way to proceed is to recognise which kind of file it is and which tools can help you...
but this is another quest(ion), many time asked, answered and closed before [q1],[q2] :-).

It is often possible because many standards require identification codes in specific parts of the file, usually in the beginning. That is the reason because vlc can play even a part of a file (not yet fully downloaded).

More you know about the file more ideas car arise after. So what are your options?

  • Vlc can do it, as suggested in another good answer [1].
  • If you have many files, it can be time consuming to repeat with a GUI that operation each time.
    Many tools, as for example TrID [2], can identify them for you and eventually automatically rename all the files.
  • Unfortunately, windows 7 by default do not include the gnu file command [3]. But fortunately you can download and install it. Then from a shell (execute the program cmd.exe), you can arrive to your file (cd yourpath) then write the command

    file MyUnknowFile

    and it will answer with something like

    Audio file with ID3 version 2.3.0, contains: MPEG ADTS, layer III, v1, 192 kbps, 44.1 kHz, Stereo

    I put in bold MPEG and layer III... so this is an mp3 file and this is the extension that your file has somehow lost. You have only to add it to your file. Do you remember "more you know ... more ideas"? I can read with ID3 and that gives me another idea (see below).

  • You can use an ID3 tag renamer [q3], yes you can change not only the extension but even the filename compliant with the information included in the ID3 tag !
  • You can use an online service to identify the song. Some of them are able to overcome the wrong extension too...

But the path of an heroic champion pass through the hard way. The way of the paladin is to see the binary (maybe the hexadecimal) code of your file in search of the magic numbers [w1] looking in a reference table [w2] to understand which file is... and eventually re-invent the wheel. :-).

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