CODEWITHSUNDEEP
delphimp3bitrate
Kermia
Kermia

Reputation: 4221

How to get MP3 file Bitrate ? (Delphi)

how can i get bitrate of a MP3 File ?

Upvotes: 7

Views: 4344

Answers (3)

Matthias Alleweldt
Matthias Alleweldt

Reputation: 2453

Have a look at TAudioFile.GetMp3Info in Read MP3 info (just ignore the german description)

Upvotes: 4

Avo Muromägi
Avo Muromägi

Reputation: 1593

MP3 Bitrate is stored in the 3rd byte of frame header so an option would be to search for the first byte with a value 255 (in theory there's should be no other bytes with all bits set to 1 before that) and bitrate should be stored two bytes after that. Following code does this:

program Project1;

{$APPTYPE CONSOLE}

uses
  Classes, SysUtils;

const
  BIT_RATE_TABLE: array [0..15] of Integer =
    (0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 0);

var
  B: Byte;
begin
  with TFileStream.Create(ParamStr(1), fmOpenRead) do begin
    try
      Position := 0;
      repeat
        Read(B, 1);
      until B = 255;
      Position := Position + 1;
      Read(B, 1);
      Writeln(BIT_RATE_TABLE[B shr 4]);
    finally
      Free;
    end;
  end;
end.

Note that this only finds bitrate of the first frame.

You can find more detailed info from here

Upvotes: 5

Nick Hodges
Nick Hodges

Reputation: 17138

You'll have to create a Delphi structure to read the MP3 file format.

That format is defined here:

http://en.wikipedia.org/wiki/MP3#File_structure

This link: http://www.3delite.hu/Object%20Pascal%20Developer%20Resources/id3v2library.html

appears to contain Delphi code for reading the format as well.

More basically, every file has a format, and generally you need to create a data structure to map that format. You then use file reading code to map the data in the file on top of structure that defines the file format.

Upvotes: 3

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