How can I determine that a particular file is in fact an MP3 file?

Question

How can I determine that a particular file (which may or may not have an ".mp3" file extension) is in fact an MP3 file? I wish to do this in C#.

C# and file type magic numbers; possibly a duplicate of http://stackoverflow.com/questions/1654846/in-c-how-can-i-know-the-file-type-from-a-byte — kagali-san, Sep 04 '11 at 22:10
If you successfully load it using the solution provided in http://stackoverflow.com/questions/184683/, you might consider it a valid MP3 — Merlyn Morgan-Graham, Sep 04 '11 at 22:11

fvu · Answer 1 · 2011-09-04T22:27:26.890

According to http://www.garykessler.net/library/file_sigs.html an mp3 file will always start with ID3 (hex 49 44 33) However, presence of these bytes only mean that the file is tagged with ID3 information. If this signature is not found, it could be an untagged mp3 file. To determine this, check out the mp3 file structure and you'll see that an mp3 frame starts with the signature ff fb (hex).

So :

if file starts with hex 49 44 33

or

if file starts with hex ff fb

it's safe to assume that it's an MP3.

Rob Agar · Answer 2 · 2011-09-04T22:27:04.457

5

Files often start with a "magic number" to identify the data format. Depending on the format, a file starts with a certain sequence of bytes which is unique to that format. There's no standard to follow so it's not 100% reliable.

As fvu says, the mp3 magic number is 0x49 0x44 0x33

edited Sep 04 '11 at 22:27

answered Sep 04 '11 at 22:18

Rob Agar

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score 5 · Accepted Answer · answered Sep 05 '11 at 02:55

using file extension is not reliable.
the best libary you can use is https://github.com/mono/taglib-sharp it detects most of the common file types. maybe you just want mp3, so you can extract any mp3 related class.
a simpler library you can use is https://github.com/judwhite/IdSharp

score 1 · Answer 4 · edited Jun 02 '13 at 06:04

1

string[] filePath = Directory.GetFiles(fbdialog.SelectedPath.ToString(),".mp3", 
                                       SearchOption.AllDirectories);

foreach (string str in filePath)
{
    MessageBox.Show("It's mp3 file");
}

edited Jun 02 '13 at 06:04

nawfal

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answered Sep 05 '11 at 02:33

Sam Casil

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score -2 · Answer 5 · answered Jun 02 '13 at 06:01

-2

C# code:

bool isMP3(byte[] buf)
{
    if (buf[0] == 0xFF && (buf[1] & 0xF6) > 0xF0 && (buf[2] & 0xF0) != 0xF0) 
    {
         return true;
    }
    return false;
}

answered Jun 02 '13 at 06:01

HexBrowser

1

How can I determine that a particular file is in fact an MP3 file?

5 Answers5

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