MP3 Tag Reader

Yes, yes, there is no shortage of apps that read the metadata tags inside MP3 files, but it seemed like a fun exercise.

I have long used, and highly recommend, MP3TAG to view and edit the metadata tags in my MP3 files, but got to wondering how it was doing the magic that it does.

I loaded an MP3 into the nifty online hex file viewer HexEd.it, and presto! there were the tags. I searched around on Stack Overflow and got inspiration and a leg up from How to read Id3v2 tag. I found a wealth of further details on the ID3v2 Developer Information page, and was off to the races.

But then...I noticed that my MP3 files also had old school ID3v1 tags, so I added support for those.

And then...while normalizing the volume level on my MP3 files using MP3Gain, I found that it added old school APEv2 tags to the files, so I added support for these as well.

Application Command Line Options

The command line options are:

Usage: Mp3TagReader [options]

Options:
  -?|-h|--help                   Show help information.
  -fs|--fileSpec <FileSpec>      The location of the MP3 file(s). Wildcards may be used. If a folder is provided, all
                                 MP3 files in the folder will be selected.
  -sf|--sortFrames               If provided, Id3v2 frames will be sorted by Id; otherwise they will appear in physical
                                 order. Helpful if you are diffing the JSON output.
  -of|--outputFolder[:<Folder>]  Optional destination folder to write output JSON file(s). If omitted, the MP3 source
                                 folder will be used.                                 

Command Line Examples

This command does not specify an output folder, so the JSON output is written to the console (see below for an example of the output):

> Mp3TagReader -fs "c:\Music\U2\War\01 Sunday Bloody Sunday.mp3"

This command does not specify an output folder, so the JSON output is written to the console with the ID3v2 frames in sorted order:

> Mp3TagReader -fs "c:\Music\U2\War\01 Sunday Bloody Sunday.mp3" -sf

This command produces c:\Music\U2\War\01 Sunday Bloody Sunday.json:

> Mp3TagReader -fs "c:\Music\U2\War\01 Sunday Bloody Sunday.mp3" -of

This command produces c:\tags\01 Sunday Bloody Sunday.json:

> Mp3TagReader -fs "c:\Music\U2\War\01 Sunday Bloody Sunday.mp3" -of:c:\tags

This command outputs JSON for each MP3 in the folder to the console:

> Mp3TagReader -fs "c:\Music\U2\War\*.mp3"

Example JSON Output

Since the output is so verbose, here is just one example. It corresponds to the first command line example above:

{
  "Mp3File": "c:\\Music\\U2\\War\\01 Sunday Bloody Sunday.mp3",
  "Tags": [
    {
      "Type": "Id3v2",
      "TagSize": 310894,
      "Header": {
        "HeaderSize": 10,
        "FramesSize": 310884,
        "Version": "ID3v2.3.0",
        "Flags": []
      },
      "Frames": [
        {
          "Id": "TALB (Album/Movie/Show title)",
          "Size": 21,
          "Flags": [],
          "Text": "War"
        },
        {
          "Id": "TPE1 (Lead performer(s)/Soloist(s))",
          "Size": 19,
          "Flags": [],
          "Text": "U2"
        },
        {
          "Id": "TCOM (Composer)",
          "Size": 77,
          "Flags": [],
          "Text": "Adam Clayton ???·????? ????????"
        },
        {
          "Id": "TCON (Content type)",
          "Size": 53,
          "Flags": [],
          "Text": "Indie / Alternative"
        },
        {
          "Id": "TLEN (Length)",
          "Size": 18,
          "Flags": [],
          "Text": "279426"
        },
        {
          "Id": "TIT2 (Title/songname/content description)",
          "Size": 55,
          "Flags": [],
          "Text": "Sunday Bloody Sunday"
        },
        {
          "Id": "TRCK (Track number/Position in set)",
          "Size": 13,
          "Flags": [],
          "Text": "1"
        },
        {
          "Id": "TYER (Year)",
          "Size": 16,
          "Flags": [],
          "Text": "1983"
        },
        {
          "Id": "APIC (Attached picture)",
          "Size": 308379,
          "Flags": [],
          "MimeType": "image/jpeg",
          "PictureType": "0x03 (Cover (front))",
          "Description": "",
          "PictureDataLength": 308355
        },
        {
          "Id": "MCDI (Music CD identifier)",
          "Size": 134,
          "Flags": [],
          "CdTableOfContentsLength": 124
        },
        {
          "Id": "PRIV (Private)",
          "Size": 24,
          "Flags": [],
          "OwnerIdentifier": "PeakValue",
          "PrivateDataLength": 4
        },
        {
          "Id": "PRIV (Private)",
          "Size": 27,
          "Flags": [],
          "OwnerIdentifier": "AverageLevel",
          "PrivateDataLength": 4
        },
        {
          "Id": "0000 (Padding placeholder)",
          "Size": 2048
        }
      ]
    },
    {
      "Type": "Id3v1",
      "Title": "Sunday Bloody Sunday",
      "Artist": "U2",
      "Album": "War",
      "Year": "1983",
      "Comment": "",
      "Track": 1,
      "Genre": 255
    }
  ]
}