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The file-name extension .webm is used for media files using the WebM multimedia format, which consists of the WebM container (a subset of the Matroska container) and audio and video streams with independet enconding and quality settings.

Description of the issue:

For files in the WebM format, the program file says that files are raw data, instead of determining and displaying the real file-format, which is WebM. Besides, Nautilus doesn't display the technical metadata of files in this format.

Why is the file program not displaying the file format for WebM files?

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closed as not a real question by Jorge Castro, Christopher Kyle Horton, Takkat, Amith KK, Anwar Shah Sep 19 '12 at 17:36

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

Welcome to askubuntu! Please reformulate your post such that there is a clear question that can be answered by the community. Otherwise, you might find filing a bug report more useful. – January Sep 17 '12 at 12:25
I have edited my post. But if you want it in a question(s) format, it would be like this: "why the 'file' program is not displaying the file format for WebM files? Is that correct? Is that a bug? Is that something that nobody cares about? Is someone going to do something about it? Is it already known by linux developers?,...." – Pili Sep 17 '12 at 17:35
No I don't want a question; this is askubuntu, a site for specific questions and problems. Everything else is off topic, and there is a multitude of sites where you can express your opinion about what and how should be corrected, starting with the Ubuntu bug report system. – January Sep 17 '12 at 17:54
+1 @January .... – Geppettvs D'Constanzo Sep 17 '12 at 18:16
Thank you. First I will try to see if it is a bug or what, and that is exactly what I am doing here. – Pili Sep 17 '12 at 18:30

The short answer is: yes, it is supported. At least on Ubuntu 12.04, when I download a WebM video, I get

user@machine:~$ wget
(...output truncated...)
Saving to: `gizmo.webm'
(...output truncated...)
user@machine:~$ file gizmo.webm 
gizmo.webm: WebM

It might be that your files are not correctly encoded and do not contain the magic numbers at the beginning of the file that allow to determine the file type. Maybe you could give us links to files that are not correctly identified by the file utility, or otherwise state how you created them.

EDIT: The Ubuntu version of the OP is 11.04 and apparently does not contain an up to date magic file recognizing WebM as a valid file format, possibly due to the fact that at time of 11.04 release the WebM was barely a year old. The magic file from 12.04 correctly recognizes the format.

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OK. In my case, I am using several WebM files, which are correctly decoded and the video and audio are correctly displayed, with no error comments, by all my multimedia programs. I created the WebM files with youtube-dl command which has that format as the default output format. – Pili Sep 17 '12 at 18:01
I have just downloaded, with wget, the gizmo file you give in your example and the file command continues displaying "data" as the real file type. – Pili Sep 17 '12 at 18:10
Cool. So we know that there is a problem with your system. Which Ubuntu version are you using? (Type lsb_release -a to find that out) Which libmagic1 version are you using? (type apt-cache show libmagic1). – January Sep 17 '12 at 18:21
$ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 11.04 Release: 11.04 Codename: natty. What do you want me to run apt-cache...... for?. Yes, I have that library installed – Pili Sep 17 '12 at 18:36
Ok. That makes sense, and that is what I was thinking the cause might be, the moment you posted an example that didn't work for me. And I don't see why the update should not apply to Natty; but no, it is not an LTS. The LTS is 10.04 Lucid Lynx. So what should be done? P.S. Don't worry I argue much, much more about "windoze" and apple, in all senses, it is just a matter of style, to spurr people. – Pili Sep 17 '12 at 19:00

Just for your consideration: Parts of this answer comes from: Is there an application that will render the popular web video formats? which links to: Reduce avi size without losing too much quality

The webpage related to "Video Formats" provides an extensive and really comprehensive list of video formats, its available software which can be used to play each one and the "popularity".

You may also wish to take a look to the "Digital Container format" and the table of "Comparison of container formats".

Based on that information, we find that:

[The Webm file format is a] Compressed video file created using the WebM format, an open, high-quality video standard; stores video compressed using VP8 technology and audio compressed using Ogg Vorbis compression; commonly used for delivering online videos using the HTML5 tag.

The WEBM container format is based on the Matroska container, which stores Matroska video in .MKV files. Most major Web browsers will support WebM as part of HTML5 video delivery. WebM is an alternative to the patented h.264 and MPEG4 standards, and is suitable for commercial and non-commercial applications.

NOTE: Google acquired ON2, the original developer of VP8 technology. VP8 is now an open and free technology.

Nevertheless, the information that seems to be lacking in such file format may be related to the metadata/tags, which is well known that the file format doesn't give any support for such elements, thus the information won't appear. See the table of "Comparison of container formats" for information related to "metadata/tags" in the proper column.

So, we can say that Ubuntu isn't giving such "deteriorating" image for a per-file-format related issue. Maybe the file format itself is giving a less complex set of information on its own, which isn't Ubuntu blame (nor any other OS).

Good luck!

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I didn't say, nor mean, that "Ubuntu is giving a deteriorating image for a per-file-format related issue." What I mean is that thousands of issues (like this one, for example) are deteriorating Linux's image. Which is completely different. – Pili Sep 17 '12 at 18:21
Just for your information: This is a place related to Ubuntu which is also Linux. Maybe you want to take your question to a different forum, let's say: Debian and say that your question and words refers to "Linux in general" and not only Debian, in both cases, if the question isn't related to Ubuntu nor Debian you may consider that there are support forums for almost any Linux distribution and you can choose the proper forum whose distro is causing your issues, if so... Good luck! – Geppettvs D'Constanzo Sep 17 '12 at 18:29
Why don't you let me try here, finish with the issue and then decide if I have to go somewhere else to understand what happens? Why? For you info we are trying to see what is the matter, down here, in the same page. – Pili Sep 17 '12 at 18:45
I didn't say that. Of course you can and feel welcome, always. But even here they have certain "rules" (which I don't also like indeed) that we should observe in order to obtain the proper support. As from me it is ok. But you dropped a comment which I felt like answering. Sorry if I offended you but it wasn't my intentions. I apologize if I was rude. And I hope you find the answer to your questions soon. Good luck and have a nice day :) – Geppettvs D'Constanzo Sep 17 '12 at 18:48
Ok, thank you very much – Pili Sep 17 '12 at 18:53

If you want to extract info from multimedia formats like WebM, Matroska and others you have a variety of tools to choose from.


MediaInfo is a project dedicated to providing a tool that displays the most relevant technical and tag meta data for video and audio files in a unified way for the plethora of formats out there. It is in the repositories as of 12.04 and can be installed via the mediainfo package.

Example output looks like this:

$ mediainfo big-buck-bunny_trailer.webm 
Unique ID                                : 94077224337973666327274415816295077565 (0x46C69D45A185A9294D3D0A2F750056BD)
Complete name                            : big-buck-bunny_trailer.webm
Format                                   : WebM
Format version                           : Version 1
File size                                : 2.06 MiB
Duration                                 : 32s 480ms
Overall bit rate mode                    : Variable
Overall bit rate                         : 533 Kbps
Encoded date                             : UTC 2010-05-20 08:21:12
Writing application                      : Sorenson Squeeze
Writing library                          :

ID                                       : 1
Format                                   : VP8
Codec ID                                 : V_VP8
Duration                                 : 32s 480ms
Bit rate                                 : 439 Kbps
Width                                    : 640 pixels
Height                                   : 360 pixels
Display aspect ratio                     : 16:9
Frame rate                               : 25.000 fps
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 0.076
Stream size                              : 1.70 MiB (82%)
Language                                 : English
Default                                  : Yes
Forced                                   : No

ID                                       : 2
Format                                   : Vorbis
Format settings, Floor                   : 1
Codec ID                                 : A_VORBIS
Duration                                 : 32s 480ms
Bit rate mode                            : Variable
Bit rate                                 : 64.0 Kbps
Channel(s)                               : 1 channel
Sampling rate                            : 44.1 KHz
Compression mode                         : Lossy
Stream size                              : 254 KiB (12%)
Writing library                          : libVorbis (Everywhere) (20100325 (Everywhere))
Language                                 : English
Default                                  : Yes
Forced                                   : No


Exiftool from the libimage-exiftool-perl package knows a lot of formats, too. Additionally it can write meta data and provides a lot of information about the file similar to mediainfo. For more information see the exiftool manpage.

Example output looks like this:

$ exiftool big-buck-bunny_trailer.webm 
ExifTool Version Number         : 8.60
File Name                       : big-buck-bunny_trailer.webm
Directory                       : .
File Size                       : 2.1 MB
File Modification Date/Time     : 2012:09:17 20:46:02+02:00
File Permissions                : rw-rw-r--
File Type                       : WEBM
MIME Type                       : video/webm
EBML Version                    : 1
EBML Read Version               : 1
Doc Type                        : webm
Doc Type Version                : 1
Doc Type Read Version           : 1
Timecode Scale                  : 1 ms
Duration                        : 0:00:32
Date/Time Original              : 2010:05:20 08:21:12Z
Muxing App                      :
Writing App                     : Sorenson Squeeze
Video Frame Rate                : 25
Video Codec ID                  : V_VP8
Video Codec Name                : VP8
Image Width                     : 640
Image Height                    : 360
Track Number                    : 2
Track Type                      : Audio
Track Timecode Scale            : 1
Audio Codec ID                  : A_VORBIS
Audio Codec Name                : Vorbis
Audio Sample Rate               : 44100
Image Size                      : 640x360


Specific to Matroska formats, like WebM, you can use mkvmerge -i or mkvinfo from the mkvtoolnix package or other tools for manipulating and creating Matroska files.

Example output looks like this:

$ mkvmerge -i big-buck-bunny_trailer.webm 
File 'big-buck-bunny_trailer.webm': container: Matroska
Track ID 0: video (V_VP8)
Track ID 1: audio (A_VORBIS)

$ mkvinfo big-buck-bunny_trailer.webm 
+ EBML head
|+ EBML version: 1
|+ EBML read version: 1
|+ EBML maximum ID length: 4
|+ EBML maximum size length: 8
|+ Doc type: webm
|+ (Unknown element: EBMLVoid; ID: 0xec size: 4)
|+ Doc type version: 1
|+ Doc type read version: 1
+ Segment, size 2165127
|+ Seek head (subentries will be skipped)
|+ Segment information
| + Segment UID: 0x46 0xc6 0x9d 0x45 0xa1 0x85 0xa9 0x29 0x4d 0x3d 0x0a 0x2f 0x75 0x00 0x56 0xbd
| + Timecode scale: 1000000
| + Duration: 32.480s (00:00:32.480)
| + Date: Thu May 20 08:21:12 2010 UTC
| + Muxing application:
| + Writing application: Sorenson Squeeze
|+ Segment tracks
| + A track
|  + Track number: 1 (track ID for mkvmerge & mkvextract: 0)
|  + Track UID: 3383112130
|  + Track type: video
|  + Default duration: 40.000ms (25.000 frames/fields per second for a video track)
|  + Timecode scale: 1
|  + Codec ID: V_VP8
|  + Codec name: VP8
|  + Video track
|   + Pixel width: 640
|   + Pixel height: 360
| + A track
|  + Track number: 2 (track ID for mkvmerge & mkvextract: 1)
|  + Track UID: 1552874170
|  + Track type: audio
|  + Timecode scale: 1
|  + Codec ID: A_VORBIS
|  + CodecPrivate, length 3097
|  + Codec name: Vorbis
|  + Audio track
|   + Sampling frequency: 44100
|+ Cues (subentries will be skipped)
|+ Cluster


At last there is avprobe from the libav-tools package, by the Libav project who forked FFmpeg.

Example output looks like this:

$ avprobe big-buck-bunny_trailer.webm 
avprobe version 0.8.3-4:0.8.3-0ubuntu0.12.04.1, Copyright (c) 2007-2012 the Libav developers
  built on Jun 12 2012 16:52:09 with gcc 4.6.3
[matroska,webm @ 0x19119a0] Estimating duration from bitrate, this may be inaccurate
Input #0, matroska,webm, from 'big-buck-bunny_trailer.webm':
  Duration: 00:00:32.48, start: 0.000000, bitrate: N/A
    Stream #0.0(eng): Video: vp8, yuv420p, 640x360, PAR 1:1 DAR 16:9, 25 fps, 25 tbr, 1k tbn, 1k tbc (default)
    Stream #0.1(eng): Audio: vorbis, 44100 Hz, mono, s16 (default)

But I agree, it would be useful if file showed some information about the video. Please make a feature request in the appropriate channels (which are not on askubuntu).

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ffprobe is giving the correct output for the files the file command is displaying only the word data – Pili Sep 17 '12 at 18:18
It is not a matter of what is useful or if there is another way to display the file type. It's a matter of correctness: what is correct for that linux command to do. Is there a bug? Should the command be upgraded? Is there a problem in my installation?..... – Pili Sep 17 '12 at 18:24
Well, file recognizes that it's a video file of the type webm just fine. Try file --mime your_video.webm and it says your_video.webm: video/webm; charset=binary which is quite correct I'd say. – phoibos Sep 17 '12 at 18:38
NO. And it says: $ file --mime gizmo.webm gizmo.webm: application/octet-stream; charset=binary – Pili Sep 17 '12 at 18:51
It's more like a new feature. New features are not automatically included as they can break things or pull in new dependencies. The functionality may be included in a new upstream release that included much more new features, so this wasn't picked up by the Ubuntu maintainers. Security updates have top priority after release, after that come stable release updates (SRU) and only if necessary new features are included in an already released Ubuntu release. There is a feature freeze deadline during the development process for that. – LiveWireBT Sep 17 '12 at 20:19

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