wav-file-info
Version:
Lightweight Node.js WAV file info helper
102 lines (86 loc) • 3.69 kB
JavaScript
// Hi Welcome to WFI by David Jones / RackFX, LLC
var fs = require('fs');
var wfi = {}
wfi.infoByFilename = function(filename, cb){
var stats = fs.statSync(filename)
var buffer = new Buffer(40); // first 40 bytes are RIFF header
fs.open(filename, 'r', function(err, fd) {
if(err) return cb(err); // error probably TODO:check this!
// ex error -
// { [Error: ENOENT: no such file or directory, open './test.wav'] errno: -2, code: 'ENOENT', syscall: 'open', path: './test.wav' }
var read_result = {}
// this a list of sequenced bytes in the 40 byte header. This builds the read_result object.
// Property name / Data type / Length
var reads = [
['riff_head', 'string', 4],
['chunk_size','uinteger', 4],
['wave_identifier', 'string', 4],
['fmt_identifier', 'string', 4],
['subchunk_size','integer',4],
['audio_format','integer',2],
['num_channels','integer',2],
['sample_rate','uinteger',4],
['byte_rate','integer',4],
['block_align','integer',2],
['bits_per_sample','integer',2],
//['uhm','integer',2],
['data_identifier','string', 4],
//['sub_chunk2_size', 'integer', 4],
]
fs.read(fd, buffer, 0, 40, 0, function(err, num) {
var i=0;
var pointer = 0;
function read_wav(){
var read = reads[i];
i++;
if(read[1]=='string'){
read_result[read[0]] = buffer.toString('ascii', pointer , pointer + read[2]);
pointer = pointer + read[2]; // pointer = pointer plus # bytes
}
else if(read[1]=='integer'){
read_result[read[0]] = buffer.readUInt16LE(pointer, read[2])
pointer = pointer + read[2];
}
else if(read[1]=='uinteger'){
read_result[read[0]] = buffer.readInt32LE(pointer, read[2])
pointer = pointer + read[2];
}
if(i < reads.length) { return read_wav()}
else { return fs.close(fd, post_process); }
}
//console.log(i)
read_wav();
}); // end fs.read
function post_process(){
var error = false;
var invalid_reasons = []
if (read_result.riff_head != "RIFF") invalid_reasons.push("Expected \"RIFF\" string at 0" )
if (read_result.wave_identifier != "WAVE") invalid_reasons.push("Expected \"WAVE\" string at 4")
if (read_result.fmt_identifier != "fmt ") invalid_reasons.push("Expected \"fmt \" string at 8")
if (
(read_result.audio_format != 1) && // Wav PCM
(read_result.audio_format != 65534) && // Extensible PCM
(read_result.audio_format != 2) && // Wav
(read_result.audio_format != 6) && // Wav ALAW
(read_result.audio_format != 7) && // Wav MULAW
(read_result.audio_format != 22127) && // Vorbis ?? (issue #11)
(read_result.audio_format != 3)) // Wav
invalid_reasons.push("Unknown format: "+read_result.audio_format)
if ((read_result.chunk_size + 8) !== stats.size) invalid_reasons.push("chunk_size does not match file size")
//if ((read_result.data_identifier) != "data") invalid_reasons.push("Expected data identifier at the end of the header")
if (invalid_reasons.length > 0) error = true;
if (error) return cb({
error : true,
invalid_reasons: invalid_reasons,
header: read_result,
stats: stats
});
cb(null, {
header: read_result,
stats: stats,
duration: ((read_result.chunk_size) / (read_result.sample_rate * read_result.num_channels * (read_result.bits_per_sample / 8)))
});
}
});
}
module.exports = wfi;