public static void OutputShuffledFrames(Mp3 shuffled, Mp3 unshuffled, byte[][] shuffledFrames, string filename)
{
//counters
int j = shuffled.dataStart;
int f = 0;
//get metadata in the new file
if (shuffled.dataStart != 0)
{
for (int i = 0; i < shuffled.dataStart; i++)
{
shuffled.mp3Bytes[i] = unshuffled.mp3Bytes[i];
}
}
//fill frames
while (f < shuffled.numFrames)
{
if (shuffledFrames[f] == null)
{
break;
}
//get frame
for (int k = 0; k < shuffled.frameLength; k++)
{
shuffled.mp3Bytes[j] = shuffledFrames[f][k];
j++;
}
f++;
}
File.WriteAllBytes("E:/Documents/GitHub/ENSE496-Assignment4/Mp3FrameShuffler/" + filename + ".mp3", shuffled.mp3Bytes); //output frame-shuffled file
}
public static byte[][] GetFrameArray(Mp3 mp3)
{
int i = mp3.dataStart; //reset iterator to start of first header
byte[][] frames = new byte[mp3.numFrames][];
//intialize array columns
for (int k = 0; k < frames.Length; k++)
{
frames[k] = new byte[mp3.frameLength];
}
int f = 0; //frame tracker
bool newFrame;
//iterate through mp3 again to collect all the frames into an array
while (f < mp3.numFrames)
{
byte[] frame = new byte[mp3.frameLength]; //current frame
//ensure i does not extend out of range of the array
if (i >= mp3.mp3Bytes.Length - 1)
{
break;
}
//get frame
//ensure we are at the start of a frame
if (mp3.mp3Bytes[i] == mp3.syncWord[0] && mp3.mp3Bytes[i + 1] == mp3.syncWord[1])
{
newFrame = true;
//iterate though and collect the frame
for (int j = 0; j < mp3.frameLength; j++)
{
frame[j] = mp3.mp3Bytes[i];
i++;
//ensure we aren't going out of range again
if (i >= mp3.mp3Bytes.Length)
{
break;
}
}
}
//if we aren't increment and continue looping
else
{
i++;
newFrame = false;
}
//if we were infact at a new frame, then it will be populated and can be added to the 2d array
if (newFrame)
{
frames[f] = frame;
f++;
}
}
return(frames);
}
public static void OutputAllData(Mp3 shuffled, Mp3 unshuffled, byte[] shuffledData, string filename)
{
//get metadata in the new file
if (shuffled.dataStart != 0)
{
for (int i = 0; i < shuffled.dataStart; i++)
{
shuffled.mp3Bytes[i] = unshuffled.mp3Bytes[i];
}
}
//insert shuffled mp3 data after id3 tag, if there is one
for (int i = shuffled.dataStart; i < unshuffled.mp3Bytes.Length; i++)
{
shuffled.mp3Bytes[i] = shuffledData[i - shuffled.dataStart];
}
File.WriteAllBytes("E:/Documents/GitHub/ENSE496-Assignment4/Mp3FrameShuffler/" + filename + ".mp3", shuffled.mp3Bytes); //output frame-shuffled file
}
public static void GetMp3Data(Mp3 mp3)
{
int i = 0;
int temp;
//get mp3 data
//check for ID3 header
if (mp3.mp3Bytes[i] == 49 && mp3.mp3Bytes[i + 1] == 44 && mp3.mp3Bytes[i + 2] == 33)
{
//find end of ID3 header
while (mp3.mp3Bytes[i] == mp3.syncWord[0] && mp3.mp3Bytes[i + 1] == mp3.syncWord[1])
{
i++;
}
mp3.dataStart = i; //get index of where the id3 header ends
}
//ensure we are at the start of the mp3 data
while (mp3.mp3Bytes[i] != mp3.syncWord[0] || mp3.mp3Bytes[i + 1] != mp3.syncWord[1])
{
i++;
}
mp3.dataStart = i;
mp3.numFrames++;
temp = i - 1;
i = i + 1;
//count iterations until next header
while (mp3.mp3Bytes[i] != mp3.syncWord[0] || mp3.mp3Bytes[i + 1] != mp3.syncWord[1])
{
i++;
}
mp3.frameLength = i - temp;
mp3.numFrames = (mp3.mp3Bytes.Length - mp3.dataStart) / mp3.frameLength;
}
static void Main(string[] args)
{
int key = 802797117; //shuffling key - taken from requirement 3
Mp3 mp3 = new Mp3();
mp3.mp3Bytes = File.ReadAllBytes("E:/Documents/GitHub/ENSE496-Assignment4/Mp3FrameShuffler/mp3.mp3"); //get file
mp3.syncWord[0] = 0xff; //mp3 sync word first byte
mp3.syncWord[1] = 0xfb; //mp3 sync word second byte
//get mp3 data
GetMp3Data(mp3);
byte[][] frames = GetFrameArray(mp3);
//
//SHUFFLE DATA BY FRAMES
//
byte[][] shuffledFrames = Shuffle(frames, mp3.numFrames, mp3.frameLength, key);
//create new mp3 for export
Mp3 mp3Shuffled = new Mp3();
mp3Shuffled.mp3Bytes = new byte[mp3.mp3Bytes.Length];
mp3Shuffled.frameLength = mp3.frameLength;
mp3Shuffled.numFrames = mp3.numFrames;
mp3Shuffled.dataStart = mp3.dataStart;
OutputShuffledFrames(mp3Shuffled, mp3, shuffledFrames, "mp3Shuffled");
//
//UNSHUFFLE DATA BY FRAMES
//
byte[][] unshuffledFrames = Unshuffle(shuffledFrames, mp3.numFrames, mp3.frameLength, key);
//create new mp3 for export
Mp3 mp3Unshuffled = new Mp3();
mp3Unshuffled.mp3Bytes = new byte[mp3.mp3Bytes.Length];
mp3Unshuffled.frameLength = mp3.frameLength;
mp3Unshuffled.numFrames = mp3.numFrames;
mp3Unshuffled.dataStart = mp3.dataStart;
OutputShuffledFrames(mp3Unshuffled, mp3, unshuffledFrames, "mp3Unshuffled");
//
//SHUFFLE ALL DATA
//
byte[] mp3Data = new byte[mp3.mp3Bytes.Length - mp3.dataStart];
//get data minus ID3 tag
for (int i = mp3.dataStart; i < mp3.mp3Bytes.Length; i++)
{
mp3Data[i - mp3.dataStart] = mp3.mp3Bytes[i];
}
byte[] shuffledData = ShuffleAll(mp3Data, key);
//create new mp3 for export
Mp3 mp3ShuffledData = new Mp3();
mp3ShuffledData.mp3Bytes = new byte[mp3.mp3Bytes.Length];
mp3ShuffledData.frameLength = mp3.frameLength;
mp3ShuffledData.numFrames = mp3.numFrames;
mp3ShuffledData.dataStart = mp3.dataStart;
OutputAllData(mp3ShuffledData, mp3, shuffledData, "mp3ShuffledData");
//
//UNSHUFFLE ALL DATA
//
byte[] unshuffledData = UnshuffleAll(shuffledData, key);
//create new mp3 for export
Mp3 mp3UnshuffledData = new Mp3();
mp3UnshuffledData.mp3Bytes = new byte[mp3.mp3Bytes.Length];
mp3UnshuffledData.frameLength = mp3.frameLength;
mp3UnshuffledData.numFrames = mp3.numFrames;
mp3UnshuffledData.dataStart = mp3.dataStart;
OutputAllData(mp3UnshuffledData, mp3, unshuffledData, "mp3UnshuffledData");
}
