mp3-header
v0.1.4
Published
Parsing of MP3 headers including Xing table.
Downloads
145
Readme
Node.js MP3 Header Parsing
npm install mp3-header
Full working example (mp3)
const fs = require("fs");
const Mp3Header = require("mp3-header").Mp3Header;
const HEADER_LENGTH = 4;
fs.open("filename.mp3", 'r', function(err, fd) {
var buffer = new Buffer(HEADER_LENGTH);
// The offset in the mp3 file where there is a valid MP3 frame
var offset = 0;
fs.read(fd, buffer, 0, HEADER_LENGTH, offset, function(err, bytesRead, buffer) {
if (err) {
return fs.close(fd);
}
var header = new Mp3Header(buffer);
if (header.parsed && header.is_valid) {
console.info("MP3 Sample Rate: ", header.mpeg_samplerate);
}
fs.close(fd);
});
});
Full working example (XING)
const fs = require("fs");
const XingHeader = require("mp3-header").XingHeader;
const MAX_FRAME_LENGTH = 2881; // Theoretical max mp3 frame length
fs.open( "filename.mp3", 'r', function(err, fd) {
var buffer = new Buffer(MAX_FRAME_LENGTH);
// The offset in the mp3 file where there is a valid Xing header
var offset = 0;
fs.read(fd, buffer, 0, MAX_FRAME_LENGTH, offset, function(err, bytesRead, buffer) {
if (err) {
return fs.close(fd);
}
var header = new XingHeader(buffer);
if (header.parsed && header.is_valid) {
console.info("Number of audio frames: ", header.xing_frames);
}
fs.close(fd);
});
});
Classes
The package exports two classes for parsing MP3 file headers: Mp3Header
and XingHeader
.
Mp3Header
is the one that takes care of parsing the MPEG header of an MP3 audio frame, and provides informations about the encoding.
XingHeader
is an extension Mp3Header
that also takes care of parsing the metadata related to the Xing table of the MP3 file.
Properties
Once you parse a header, these are the properties you can access from the package classes:
| Parameter | Type | Present in | Example |
| -------------------------- | -------- | ------------ | --------- |
| parsed
| Boolean | Both | true
|
| is_valid
| Boolean | Both | true
|
| mpeg_version
| Integer | Both | 2
|
| mpeg_layer
| Integer | Both | 3
|
| mpeg_has_padding
| Boolean | Both | true
|
| mpeg_channels
| Integer | Both | 1
(mono) or 2
(stereo) |
| mpeg_bitrate
| Integer | Both | 128000
|
| mpeg_samplerate
| Integer | Both | 44100
|
| mpeg_num_samples
| Integer | Both | 1152
|
| mpeg_frame_length
| Integer | Both | 384
|
| xing_offset
| Integer | XingHeader
| 21
|
| xing_frames
| Integer | XingHeader
| 223
|
| xing_bytes
| Integer | XingHeader
| 43008
|
| xing_keyword
| String | XingHeader
| Xing
(VBR) or Info
(CBR) |
| xing_flags
| Integer | XingHeader
| |
| xing_has_frames
| Boolean | XingHeader
| true
|
| xing_has_bytes
| Boolean | XingHeader
| true
|
| xing_frames_offset
| Integer | XingHeader
| |
| xing_bytes_offset
| Integer | XingHeader
| |
Run test suite
grunt test
More info
- https://www.codeproject.com/Articles/8295/MPEG-Audio-Frame-Header
- http://gabriel.mp3-tech.org/mp3infotag.html
License
MIT