Skip to content
This repository has been archived by the owner on Dec 10, 2022. It is now read-only.

Commit

Permalink
Merge pull request #6 from moffatman/master
Browse files Browse the repository at this point in the history 
Fix frame sizes, Read correct text encoding, NNBD
  • Loading branch information
@sanket143
sanket143 authored Jul 17, 2021
2 parents f23238e + 719b32b commit f0e236e
Show file tree
Hide file tree
Showing 3 changed files with 217 additions and 35 deletions.
248 changes: 215 additions & 33 deletions lib/id3.dart
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,15 +5,160 @@ import 'dart:convert';

import 'src/const.dart';

class MP3ParserException implements Exception {
String cause;
MP3ParserException(this.cause);
String toString() {
return this.cause;
}
}

class _MP3FrameParser {
List<int> buffer;
int pos = 0;
int lastEncoding = 0x00; // default to latin1
_MP3FrameParser(this.buffer);
List<int> readUntilTerminator(List<int> terminator,
{bool aligned = false, bool terminatorMandatory = true}) {
if (remainingBytes == 0) {
return [];
}
for (int i = pos;
i < buffer.length - (terminator.length - 1);
i += (aligned ? terminator.length : 1)) {
bool foundTerminator = true;
for (int j = 0; j < terminator.length; j++) {
if (buffer[i + j] != terminator[j]) {
foundTerminator = false;
break;
}
}
if (foundTerminator) {
final start = pos;
pos = i + terminator.length;
return buffer.sublist(start, pos - terminator.length);
}
}
if (terminatorMandatory) {
throw MP3ParserException(
"Did not find terminator $terminator in ${buffer.sublist(pos)}");
} else {
return buffer.sublist(pos);
}
}

String readLatin1String({bool terminator = true}) {
return latin1
.decode(readUntilTerminator([0x00], terminatorMandatory: terminator));
}

String readUTF16LEString({bool terminator = true}) {
final bytes = readUntilTerminator([0x00, 0x00],
aligned: true, terminatorMandatory: terminator);
// final utf16les = List<int?>((bytes.length / 2).ceil());
final utf16les = List.generate((bytes.length / 2).ceil(), (index) => 0);

for (int i = 0; i < bytes.length; i++) {
if (i % 2 == 0) {
utf16les[i ~/ 2] = bytes[i];
} else {
utf16les[i ~/ 2] |= (bytes[i] << 8);
}
}
return String.fromCharCodes(utf16les);
}

String readUTF16BEString({bool terminator = true}) {
final bytes =
readUntilTerminator([0x00, 0x00], terminatorMandatory: terminator);
// final utf16bes = List<int?>((bytes.length / 2).ceil());
final utf16bes = List.generate((bytes.length / 2).ceil(), (index) => 0);

for (int i = 0; i < bytes.length; i++) {
if (i % 2 == 0) {
utf16bes[i ~/ 2] = (bytes[i] << 8);
} else {
utf16bes[i ~/ 2] |= bytes[i];
}
}
return String.fromCharCodes(utf16bes);
}

String readUTF16String({bool terminator = true}) {
final bom = buffer.sublist(pos, pos + 2);
if (bom[0] == 0xFF && bom[1] == 0xFE) {
pos += 2;
return readUTF16LEString(terminator: terminator);
} else if (bom[0] == 0xFE && bom[1] == 0xFF) {
pos += 2;
return readUTF16BEString(terminator: terminator);
} else if (bom[0] == 0x00 && bom[1] == 0x00) {
pos += 2;
return "";
} else {
throw MP3ParserException(
"Unknown UTF-16 BOM: $bom in ${buffer.sublist(pos)}");
}
}

String readUTF8String({bool terminator = true}) {
final bytes = readUntilTerminator([0x00], terminatorMandatory: terminator);
return Utf8Decoder().convert(bytes);
}

void readEncoding() {
if (buffer[pos] < 20) {
if (lastEncoding == 0x01) {
// Do not modify the BOM, 0x01 must apply to each field
pos++;
} else {
lastEncoding = buffer[pos++];
}
}
}

String readString({bool terminator = true, bool checkEncoding: true}) {
if (checkEncoding) {
readEncoding();
}
if (pos == buffer.length) {
return '';
}
if (lastEncoding == 0x00) {
return readLatin1String(terminator: terminator);
} else if (lastEncoding == 0x01) {
return readUTF16String(terminator: terminator);
} else if (lastEncoding == 0x02) {
return readUTF16BEString(terminator: terminator);
} else if (lastEncoding == 0x03) {
return readUTF8String(terminator: terminator);
} else {
throw MP3ParserException(
"Unknown Byte-Order Marker: $lastEncoding in $buffer");
}
}

List<int> readBytes(int length) {
pos += length;
return buffer.sublist(pos - length, pos);
}

List<int> readRemainingBytes() {
return buffer.sublist(pos);
}

int get remainingBytes {
return buffer.length - pos;
}
}

class MP3Instance {
List<int> mp3Bytes;
Map<String, dynamic> metaTags;
late final List<int> mp3Bytes;
final Map<String, dynamic> metaTags = {};

/// Member Functions
MP3Instance(String mp3File) {
var file = File(mp3File);
mp3Bytes = file.readAsBytesSync();
metaTags = {};
mp3Bytes = File(mp3File).readAsBytesSync();
}

bool parseTagsSync() {
Expand Down Expand Up @@ -55,7 +200,7 @@ class MP3Instance {
break;
}

frameSize = parseSize(frameHeader.sublist(4, 8));
frameSize = parseSize(frameHeader.sublist(4, 8), major_v);
frameContent = mp3Bytes.sublist(cb + 10, cb + 10 + frameSize);

if (FRAMESv2_3[latin1.decode(frameName)] == FRAMESv2_3['APIC']) {
Expand All @@ -67,32 +212,59 @@ class MP3Instance {
'base64': ''
};

var offset = 0;

for (var i = 1; i < frameContent.length; i++) {
if (frameContent[i] == 0) {
apic['mime'] = latin1.decode(frameContent.sublist(1, i));
offset = i;
break;
}
final frame = _MP3FrameParser(frameContent);
frame.readEncoding();
apic['mime'] = frame.readLatin1String();
apic['description'] = frame.readString();
apic['base64'] = base64.encode(frame.readRemainingBytes());
metaTags['APIC'] = apic;
} else if (FRAMESv2_3[latin1.decode(frameName)] == FRAMESv2_3['USLT']) {
final frame = _MP3FrameParser(frameContent);
frame.readEncoding();
final language = latin1.decode(frame.readBytes(3));
String contentDescriptor;
contentDescriptor = frame.readString(checkEncoding: false);
final lyrics = (frame.remainingBytes > 0)
? frame.readString(checkEncoding: false, terminator: false)
: contentDescriptor;
if (frame.remainingBytes == 0) {
contentDescriptor = '';
}
apic['picType'] = frameContent[++offset].toString();

for (var i = offset + 1; i < frameContent.length; i++) {
if (frameContent[i] == 0) {
apic['description'] =
latin1.decode(frameContent.sublist(offset + 1, i));
offset = i;
break;
metaTags['USLT'] = {
'language': language,
'contentDescriptor': contentDescriptor,
'lyrics': lyrics
};
} else if (FRAMESv2_3[latin1.decode(frameName)] == FRAMESv2_3['WXXX']) {
final frame = _MP3FrameParser(frameContent);
metaTags['WXXX'] = {
'description': frame.readString(),
'url': frame.readLatin1String(terminator: false)
};
} else if (FRAMESv2_3[latin1.decode(frameName)] == FRAMESv2_3['COMM']) {
final frame = _MP3FrameParser(frameContent);
frame.readEncoding();
final language = latin1.decode(frame.readBytes(3));
final shortDescription = frame.readString(checkEncoding: false);
final text =
frame.readString(terminator: false, checkEncoding: false);
if (metaTags['COMM'] == null) {
metaTags['COMM'] = {};
if (metaTags['COMM'][language] == null) {
metaTags['COMM'][language] = {};
}
}

apic['base64'] = base64.encode(frameContent.sublist(offset));
metaTags['APIC'] = apic;
metaTags['COMM'][language][shortDescription] = text;
} else if (FRAMESv2_3[latin1.decode(frameName)] == FRAMESv2_3['MCDI'] ||
FRAMESv2_3[latin1.decode(frameName)] == FRAMESv2_3['RVAD']) {
// Binary data
metaTags[FRAMESv2_3[latin1.decode(frameName)] ??
latin1.decode(frameName)] = frameContent;
} else {
var tag =
FRAMESv2_3[latin1.decode(frameName)] ?? latin1.decode(frameName);
metaTags[tag] = latin1.decode(cleanFrame(frameContent));
metaTags[tag] =
_MP3FrameParser(frameContent).readString(terminator: false);
}

cb += 10 + frameSize;
Expand Down Expand Up @@ -127,26 +299,36 @@ class MP3Instance {
return false;
}

Map<String, dynamic> getMetaTags() {
Map<String, dynamic>? getMetaTags() {
return metaTags;
}
}

int parseSize(List<int> block) {
int parseSize(List<int> block, int major_v) {
assert(block.length == 4);

var len = block[0] << 21;
len += block[1] << 14;
len += block[2] << 7;
len += block[3];
int len;
if (major_v == 4) {
len = block[0] << 21;
len += block[1] << 14;
len += block[2] << 7;
len += block[3];
} else if (major_v == 3) {
len = block[0] << 24;
len += block[1] << 16;
len += block[2] << 8;
len += block[3];
} else {
throw MP3ParserException("Unknown major version $major_v");
}

return len;
}

List<int> cleanFrame(List<int> bytes) {
List<int> temp = new List<int>.from(bytes);

temp.removeWhere((item) => item < 1);
temp.removeWhere((item) => item < 1);

if (temp.length > 3) {
return temp.sublist(3);
Expand Down
2 changes: 1 addition & 1 deletion pubspec.lock
View file
Original file line number Diff line number Diff line change
Expand Up @@ -345,4 +345,4 @@ packages:
source: hosted
version: "2.1.16"
sdks:
dart: ">=2.2.2 <3.0.0"
dart: ">=2.12.0 <3.0.0"
2 changes: 1 addition & 1 deletion pubspec.yaml
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ version: 0.1.8
homepage: https://github.com/sanket143/id3

environment:
sdk: ">=2.1.0 <3.0.0"
sdk: '>=2.12.0 <3.0.0'

dev_dependencies:
test: ^1.6.5

0 comments on commit f0e236e

Please sign in to comment.