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handle JUNK in your CHUNK #10

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167 changes: 92 additions & 75 deletions wav-file-info.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2,92 +2,109 @@
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!
wfi.infoByFilename = function(filename, cb) {
var stats = fs.statSync(filename)
var buffer = new Buffer(80); // 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 = {}
// 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],
// 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) {
];


fs.read(fd, buffer, 0, 80, 0, function(err, num) {

var i=0;
var pointer = 0;
function read_wav(){
var read = reads[i];
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'){
i++;

switch (read[1]) {
case 'string':
read_result[read[0]] = buffer.toString('ascii', pointer, pointer + read[2]);
pointer += read[2]; // pointer = pointer plus # bytes
break;
case 'integer':
read_result[read[0]] = buffer.readUInt16LE(pointer, read[2])
pointer += read[2];

// move past the JUNK chunk and backup our index in the reads process to properly get the next chunk
if (read_result.fmt_identifier === 'JUNK' && read[0] == 'subchunk_size') {
// JUNK chunk is the subchunk size + 1 unused byte when the subchunk size is an odd number
pointer += read_result.subchunk_size + (read_result.subchunk_size % 2);
// backup, backup
i--;
i--;
}
break;
case 'uinteger':
read_result[read[0]] = buffer.readInt32LE(pointer, read[2])
pointer += read[2];
break;
}

if (i < reads.length) {
return read_wav();
}
else {
return post_process();
}

read_result[read[0]] = buffer.readUInt16LE(pointer, read[2])
pointer = pointer + read[2];
}
else if(read[1]=='uinteger'){
}
//console.log(i)
read_wav();
}); // end fs.read

read_result[read[0]] = buffer.readInt32LE(pointer, read[2])
pointer = pointer + read[2];
}
if(i < reads.length) { return read_wav()}
else { return post_process(); }
function post_process() {
var error = false;
var invalid_reasons = []

}
//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) && (read_result.audio_format != 3)) invalid_reasons.push("Unknwon 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 (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) && (read_result.audio_format != 3)) invalid_reasons.push("Unknwon 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 (invalid_reasons.length > 0) error = true;
if (error) return cb({
error: true,
invalid_reasons: invalid_reasons,
header: read_result,
stats: stats
});

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)))
});
}
});
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;