通过AVMetadataMachineReadableCodeObject从Aztec条形码读取原始字节会产生意外结果 [英] Reading raw bytes from an Aztec barcode via AVMetadataMachineReadableCodeObject yields unexpected result
问题描述
我一直在研究iOS阅读器应用程序，用于德国铁路（德国铁路）使用的特殊条形码。它是Aztec条形码的一种变体，用于连接DSA签名字符串和zlib缩减的有效负载。
当我得知 AVMetadataMachineReadableCodeObject时，我被卡住了没有用于读取条形码中包含的原始字节的公共方法，字符串方法总是使zlib压缩数据乱码。
幸运的是，< a href =https://stackoverflow.com/a/36957666/3625228>这个答案让我朝着正确的方向前进。可以使用KVO访问（私有）字节，因为我目前不希望在App Store上分发应用程序，这是完美的。
尽管我差不多不存在的 Swift 和 Objective-C 知识我设法让它工作，你可以在样本中看到码。但是条形码中存储在 NSData 中的字节与预期结果不匹配！我怀疑我使用的zlib库（
这就是我需要的
使用正确的条形码阅读器（我使用bcTester 5）扫描时产生以下字节：
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
如您所见， offset 68（ 78 9C ）开始一个有效的zlib流。如果您在此处拆分数据和膨胀zlib的数据，它返回一个字符串这样的：
U_HEAD01005300802P9QAN-40501201514560DEDE0080ID0200180104840080BL020357031204GW3HEMP906012015060120151021193517S0010018Fernweh客票natS00200012S0030001AS00900051-0-0S01200010S0140002S2S0150006BerlinS0160011NeumünsterS0210038B -Hbf 8:16 ICE794 / HH-Hbf 10:16 IC2224S0230013Krull AndreaS026000213S0270019 *************** 0484S0280013Andrea＃Krull S031001006.01.2015S032001006.01.2015S035000511160S0360003271
测试NSData
如果我使用bcTester返回的字节手动构建字节数组，一切都按预期工作， zlib数据正确膨胀。以下是我测试的方法：
让testArray = [UInt8]（arrayLiteral：0x23,0x55,0x54,0x30,0x31,0x30 ，0x30,0x38,0x30,0x30,0x30,0x30,0x30,0x31,0x30,0x2C,0x02,0x14,0x1C，0x3D，0xE9,0x2D，0xCD，0x5E，0xC4,0xC0,0x56,0xBD，0xAE，0x61,0x3E ，0x54,0xAD，0xA1,0xB3,0x26,0x33,0xD2,0x02,0x14,0x40,0x75,0x03,0xD0,0xCF，0x9C，0xC1,0xF5,0x70,0x58,0xBD，0x59,0x50,0xA7,0xAF，0xC5 ，0xEB，0x0A，0xF4,0x74,0x00,0x00,0x00,0x00,0x30,0x32,0x37,0x31,0x78,0x9C，0x65,0x50,0xCB，0x4E，0xC3,0x30,0x10,0xE4,0x53,0x2C,0x71 ，0x43,0x4A，0xD9,0xF5,0x2B，0x36,0xB7,0x84,0x04,0x52,0x01,0x55,0x51,0x40,0x1C,0x51,0x01,0x23,0x2A，0x42,0x0E，0x21,0x15,0x3F，0xC7 ，0x8D，0x1F，0x63,0x36,0x11,0x52,0x2B，0x7C，0xF1,0x78,0x76,0x76,0x66,0xBD，0xF7,0x8F，0x4D，0x5D，0x54,0xC4,0x44,0xCE，0x10,0x05,0xD2 ，0xEB，0x78,0x5B，0xAC，0x32,0x7B，0xB4,0x77,0xC8,0x11,0x6B，0x62,0xC7,0xD6,0x79,0xAA，0xEA，0xAA，0x16,0xE1,0xB2,0 x22,0x4D，0xC4,0x01,0xAD，0x36,0x58,0x61,0xCA，0x6B，0x30,0xC6,0xE5,0x64,0xA0,0xB6,0x97,0x0F，0xA6,0xA9,0x6F，0xD6,0x71,0xDF，0xC7， 0xCF，0x3E，0x7F，0x37,0x93,0x66,0x8E，0xC6,0x71,0xDE，0x92,0x4C，0xC0,0xE1,0x22,0x0D，0xFD，0x57,0x7A，0xCB，0xEE，0xB6,0xCF，0xEF，0x69， 0x54,0xFD，0x66,0x44,0x05,0x31,0xD0,0x03,0x18,0x01,0x05,0x40,0x04,0x70,0x9C,0x51,0x46,0xAD，0x38,0x49,0x33,0x00,0x86,0x20,0xDD， 0x42,0x88,0x04,0x22,0x5F，0xA6,0xA1,0xDB，0xF6,0x78,0x79,0xD4,0x79,0x95,0x76,0x1F，0x3F，0xDF，0xFD，0xE7,0x98,0x86,0x16,0xB1,0x30， 0x0B，0x65,0xD6,0x3C，0xBD，0x2A，0x15,0xCE，0xD8,0xAB，0xE5,0x79,0x9D，0x47,0x7B，0xDA，0x34,0x13,0xC7,0x34,0x73,0x5A，0x6B，0x0B，0x35， 0x72,0xD9,0x5C，0x0D，0xBB，0xAE，0x53,0xAA，0xE8,0x5F，0x86,0xB4,0x01,0xE9,0x25,0x8D，0x0D，0x50,0x8E，0x72,0x3C,0x39,0x3C,0xB2,0x13， 0x94,0x82,0x74,0xCE，0x2D，0xC7,0xB3,0x41,0x8B，0xED，0x4C，0x9F，0xF5,0x0B，0xE2,0x85,0x6C， 0x01,0x8C，0xFE，0xC7,0xB8,0xE9,0x87,0x8C，0xD9,0xF1,0x90,0x28,0xA3,0x73,0xFE，0x05,0x6D，0xDE，0x5F，0xF1）
let testData = NSData（bytes ：testArray，length：testArray.count）
我解决了这段时间以前在Xamarin / C＃中，但Swift的想法也是如此。 encodedData 和 ReadCode 方法取自ZXing lib。希望它有所帮助。
它适用于读取和解码小和大票证代码，但iOS SDK中的默认Aztec阅读器不够用，所以最后我们继续与Manateeworks的读者。我现在可以看到iOS 10 SDK没有任何改善。
public override void DidOutputMetadataObjects（AVCaptureMetadataOutput captureOutput，AVMetadataObject [ ] metadataObjects，AVCaptureConnection连接）
{
foreach（metadataObjects中的AVMetadataMachineReadableCodeObject元数据）{
var d1 =（metadata.ValueForKey（（NSString）_ internal））;
var d2 =（d1.ValueForKey（（NSString）basicDescriptor））;
var data =（d2.ValueForKey（（NSString）BarcodeRawData））;
var str = data.ToString（）。Trim（）。Trim（new [] {'<'，'>'}）。替换（，）;
var bitarray = new bool [str.Length * 4];
for（var i = 0; i< str.Length / 2; i ++）{
int value = Convert.ToInt32（str.Substring（i * 2,2），16）;
bitarray [i * 8 + 0] =（值& 1）> 0;
bitarray [i * 8 + 1] =（值& 2）> 0;
bitarray [i * 8 + 2] =（值& 4）> 0;
bitarray [i * 8 + 3] =（值& 8）> 0;
bitarray [i * 8 + 4] =（值& 16）> 0;
bitarray [i * 8 + 5] =（值& 32）> 0;
bitarray [i * 8 + 6] =（值& 64）> 0;
bitarray [i * 8 + 7] =（值& 128）> 0;
}
var pabData = encodedData（bitarray）;
parent.scanFinished（true，pabData）;
}
}
enum ZXAztecTable
{
ZXAztecTableUpper，
ZXAztecTableBinary，
ZXAztecTableDigit
};
public byte [] encodedData（bool [] bitArray）
{
var result = new List< byte> （）;
int endIndex = bitArray.Length;
ZXAztecTable latchTable = ZXAztecTable.ZXAztecTableUpper; //表格最近锁定到
ZXAztecTable shiftTable = ZXAztecTable.ZXAztecTableUpper; //用于下一次读取的表
int index = 0;
while（index< endIndex）{
if（shiftTable == ZXAztecTable.ZXAztecTableBinary）{
if（endIndex - index< 5）{
break;
}
int length = ReadCode（bitArray，index，5）;
指数+ = 5;
if（length == 0）{
if（endIndex - index< 11）{
break;
}
length = ReadCode（bitArray，index，11）+ 31;
指数+ = 11;
}
for（int charCount = 0; charCount< length; charCount ++）{
if（endIndex - index< 8）{
index = endIndex; //强制外循环退出
break;
}
字节码=（字节）ReadCode（bitArray，index，8）;
result.Add（code）;
指数+ = 8;
}
//回到我们在
shiftTable = latchTable中的任何模式;
} else {
int size = shiftTable == ZXAztecTable.ZXAztecTableDigit？ 4：5;
if（endIndex - index< size）{
break;
}
ReadCode（bitArray，index，size）;
指数+ =大小;
latchTable = shiftTable;
shiftTable = ZXAztecTable.ZXAztecTableBinary;
}
}
返回result.ToArray（）;
}
public int ReadCode（bool [] bitArray，int startIndex，int length）
{
int res = 0;
for（int i = startIndex; i< startIndex + length; i ++）{
res<< = 1;
if（bitArray [i]）{
res | = 0x01;
}
}
返回res;
}
I have been working on an iOS reader app for a special kind of barcode used by Deutsche Bahn (german rail) for a while now. It is a variant of Aztec barcode that concatenates a DSA signature string and a zlib deflated payload.
I was stuck, when I learned that the AVMetadataMachineReadableCodeObject had no public method for reading the raw bytes contained in the barcode and the string methods always garbled the zlib-compressed data.
Luckily, this answer sent me in the right direction. The (private) bytes can be accessed with KVO, and as I don't currently expect to distribute the app on the App Store, that was perfect.
Despite my almost non-existent Swift and Objective-C knowledge I managed to get this to work, as you can see in the sample code. But the bytes from the barcode that are stored in NSData don't match the expected result! I suspected the zlib library I use (DeflateSwift) was not working, so I built a test case, which worked fine.
My question is: what am I doing wrong? Do I need to further process the raw bytes to get to the expected result (see below)? How raw exactly are the bytes that are stored in the AVMetadataMachineReadableCodeObject? Can anyone point me in the right direction? Any help is appreciated.
Here is my code (which is a sad mashup of Swift and Objective-C)
if let metadataObject = metadataObjects.first {
let readableObject = metadataObject as! AVMetadataMachineReadableCodeObject;
let rawReadableObject = readableObject.valueForKeyPath("_internal.basicDescriptor")!["BarcodeRawData"] as? NSData;
if let rawBytes = rawReadableObject {
let barcodeData = rawBytes; // or use testData instead
let barcodeSplit:Int = 68;
let barcodeLength:Int = barcodeData.length;
let barcodeHeader:NSData = barcodeData.subdataWithRange(NSRange(location: 0, length: barcodeSplit))
let barcodeZlibContent:NSData = barcodeData.subdataWithRange(NSRange(location: barcodeSplit, length: (barcodeLength-barcodeSplit)))
let count = barcodeZlibContent.length / sizeof(UInt8)
var array = [UInt8](count: count, repeatedValue: 0)
barcodeZlibContent.getBytes(&array, length:count * sizeof(UInt8))
print("\(barcodeLength)kb")
print(barcodeHeader)
print(barcodeZlibContent)
var inflater = InflateStream()
var (inflated, err) = inflater.write(array, flush: true)
if err != nil{
fatalError("\(err!)")
}
if let ticketString = String(bytes: inflated, encoding: NSUTF8StringEncoding) {
print(ticketString)
} else {
print("not a valid UTF-8 sequence")
}
}
}
This is what I get
The bytes returned from AVMetadataMachineReadableCodeObject are
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
Here is the sample barcode of a Deutsche Bahn ticket I used for testing.
This is what I need
When scanned with a proper barcode reader (I used bcTester 5) this yields the following bytes:
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
As you can see, at offset 68 (78 9C) begins a valid zlib stream. If you split the data here and inflate the zlib data, it returns a string like this:
U_HEAD01005300802P9QAN-40501201514560DEDE0080ID0200180104840080BL020357031204GW3HEMP906012015060120151021193517S0010018Fernweh-Ticket natS00200012S0030001AS00900051-0-0S01200010S0140002S2S0150006BerlinS0160011NeumünsterS0210038B-Hbf 8:16 ICE794/HH-Hbf 10:16 IC2224S0230013Krull AndreaS026000213S0270019***************0484S0280013Andrea#Krull S031001006.01.2015S032001006.01.2015S035000511160S0360003271
Test NSData
If I build the byte array manually using the bytes returned from bcTester, everything works out as expected and the zlib data inflates correctly. Here is how I tested:
let testArray = [UInt8](arrayLiteral: 0x23, 0x55, 0x54, 0x30, 0x31, 0x30, 0x30, 0x38, 0x30, 0x30, 0x30, 0x30, 0x30, 0x31, 0x30, 0x2C, 0x02, 0x14, 0x1C, 0x3D, 0xE9, 0x2D, 0xCD, 0x5E, 0xC4, 0xC0, 0x56, 0xBD, 0xAE, 0x61, 0x3E, 0x54, 0xAD, 0xA1, 0xB3, 0x26, 0x33, 0xD2, 0x02, 0x14, 0x40, 0x75, 0x03, 0xD0, 0xCF, 0x9C, 0xC1, 0xF5, 0x70, 0x58, 0xBD, 0x59, 0x50, 0xA7, 0xAF, 0xC5, 0xEB, 0x0A, 0xF4, 0x74, 0x00, 0x00, 0x00, 0x00, 0x30, 0x32, 0x37, 0x31, 0x78, 0x9C, 0x65, 0x50, 0xCB, 0x4E, 0xC3, 0x30, 0x10, 0xE4, 0x53, 0x2C, 0x71, 0x43, 0x4A, 0xD9, 0xF5, 0x2B, 0x36, 0xB7, 0x84, 0x04, 0x52, 0x01, 0x55, 0x51, 0x40, 0x1C, 0x51, 0x01, 0x23, 0x2A, 0x42, 0x0E, 0x21, 0x15, 0x3F, 0xC7, 0x8D, 0x1F, 0x63, 0x36, 0x11, 0x52, 0x2B, 0x7C, 0xF1, 0x78, 0x76, 0x76, 0x66, 0xBD, 0xF7, 0x8F, 0x4D, 0x5D, 0x54, 0xC4, 0x44, 0xCE, 0x10, 0x05, 0xD2, 0xEB, 0x78, 0x5B, 0xAC, 0x32, 0x7B, 0xB4, 0x77, 0xC8, 0x11, 0x6B, 0x62, 0xC7, 0xD6, 0x79, 0xAA, 0xEA, 0xAA, 0x16, 0xE1, 0xB2, 0x22, 0x4D, 0xC4, 0x01, 0xAD, 0x36, 0x58, 0x61, 0xCA, 0x6B, 0x30, 0xC6, 0xE5, 0x64, 0xA0, 0xB6, 0x97, 0x0F, 0xA6, 0xA9, 0x6F, 0xD6, 0x71, 0xDF, 0xC7, 0xCF, 0x3E, 0x7F, 0x37, 0x93, 0x66, 0x8E, 0xC6, 0x71, 0xDE, 0x92, 0x4C, 0xC0, 0xE1, 0x22, 0x0D, 0xFD, 0x57, 0x7A, 0xCB, 0xEE, 0xB6, 0xCF, 0xEF, 0x69, 0x54, 0xFD, 0x66, 0x44, 0x05, 0x31, 0xD0, 0x03, 0x18, 0x01, 0x05, 0x40, 0x04, 0x70, 0x9C, 0x51, 0x46, 0xAD, 0x38, 0x49, 0x33, 0x00, 0x86, 0x20, 0xDD, 0x42, 0x88, 0x04, 0x22, 0x5F, 0xA6, 0xA1, 0xDB, 0xF6, 0x78, 0x79, 0xD4, 0x79, 0x95, 0x76, 0x1F, 0x3F, 0xDF, 0xFD, 0xE7, 0x98, 0x86, 0x16, 0xB1, 0x30, 0x0B, 0x65, 0xD6, 0x3C, 0xBD, 0x2A, 0x15, 0xCE, 0xD8, 0xAB, 0xE5, 0x79, 0x9D, 0x47, 0x7B, 0xDA, 0x34, 0x13, 0xC7, 0x34, 0x73, 0x5A, 0x6B, 0x0B, 0x35, 0x72, 0xD9, 0x5C, 0x0D, 0xBB, 0xAE, 0x53, 0xAA, 0xE8, 0x5F, 0x86, 0xB4, 0x01, 0xE9, 0x25, 0x8D, 0x0D, 0x50, 0x8E, 0x72, 0x3C, 0x39, 0x3C, 0xB2, 0x13, 0x94, 0x82, 0x74, 0xCE, 0x2D, 0xC7, 0xB3, 0x41, 0x8B, 0xED, 0x4C, 0x9F, 0xF5, 0x0B, 0xE2, 0x85, 0x6C, 0x01, 0x8C, 0xFE, 0xC7, 0xB8, 0xE9, 0x87, 0x8C, 0xD9, 0xF1, 0x90, 0x28, 0xA3, 0x73, 0xFE, 0x05, 0x6D, 0xDE, 0x5F, 0xF1)
let testData = NSData(bytes: testArray, length: testArray.count)
I solved this some time ago in Xamarin/C#, but the idea is the same for Swift too. The encodedData and ReadCode methods are taken form ZXing lib. Hope it helps.
It works well for reading and decoding both "small" and "large" ticket codes, but the default Aztec reader in iOS SDK is not good enough, so in the end we went on with the reader from Manateeworks. I can see now that it did not get any better with iOS 10 SDK.
public override void DidOutputMetadataObjects (AVCaptureMetadataOutput captureOutput, AVMetadataObject[] metadataObjects, AVCaptureConnection connection)
{
foreach (AVMetadataMachineReadableCodeObject metadata in metadataObjects) {
var d1 = (metadata.ValueForKey ((NSString)"_internal"));
var d2 = (d1.ValueForKey ((NSString)"basicDescriptor"));
var data = (d2.ValueForKey ((NSString)"BarcodeRawData"));
var str = data.ToString ().Trim ().Trim (new [] { '<', '>' }).Replace (" ", "");
var bitarray = new bool[str.Length * 4];
for (var i = 0; i < str.Length / 2; i++) {
int value = Convert.ToInt32 (str.Substring (i * 2, 2), 16);
bitarray [i * 8 + 0] = (value & 1) > 0;
bitarray [i * 8 + 1] = (value & 2) > 0;
bitarray [i * 8 + 2] = (value & 4) > 0;
bitarray [i * 8 + 3] = (value & 8) > 0;
bitarray [i * 8 + 4] = (value & 16) > 0;
bitarray [i * 8 + 5] = (value & 32) > 0;
bitarray [i * 8 + 6] = (value & 64) > 0;
bitarray [i * 8 + 7] = (value & 128) > 0;
}
var pabData = encodedData (bitarray);
parent.scanFinished (true, pabData);
}
}
enum ZXAztecTable
{
ZXAztecTableUpper,
ZXAztecTableBinary,
ZXAztecTableDigit
};
public byte[] encodedData (bool[] bitArray)
{
var result = new List<byte> ();
int endIndex = bitArray.Length;
ZXAztecTable latchTable = ZXAztecTable.ZXAztecTableUpper; // table most recently latched to
ZXAztecTable shiftTable = ZXAztecTable.ZXAztecTableUpper; // table to use for the next read
int index = 0;
while (index < endIndex) {
if (shiftTable == ZXAztecTable.ZXAztecTableBinary) {
if (endIndex - index < 5) {
break;
}
int length = ReadCode (bitArray, index, 5);
index += 5;
if (length == 0) {
if (endIndex - index < 11) {
break;
}
length = ReadCode (bitArray, index, 11) + 31;
index += 11;
}
for (int charCount = 0; charCount < length; charCount++) {
if (endIndex - index < 8) {
index = endIndex; // Force outer loop to exit
break;
}
byte code = (byte)ReadCode (bitArray, index, 8);
result.Add (code);
index += 8;
}
// Go back to whatever mode we had been in
shiftTable = latchTable;
} else {
int size = shiftTable == ZXAztecTable.ZXAztecTableDigit ? 4 : 5;
if (endIndex - index < size) {
break;
}
ReadCode (bitArray, index, size);
index += size;
latchTable = shiftTable;
shiftTable = ZXAztecTable.ZXAztecTableBinary;
}
}
return result.ToArray ();
}
public int ReadCode (bool[] bitArray, int startIndex, int length)
{
int res = 0;
for (int i = startIndex; i < startIndex + length; i++) {
res <<= 1;
if (bitArray [i]) {
res |= 0x01;
}
}
return res;
}
这篇关于通过AVMetadataMachineReadableCodeObject从Aztec条形码读取原始字节会产生意外结果的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
