writing bytes from file directly to memorry

[Shurikn]

I have a C++ code that do this(write from a file directly to memory)

it reads a wave file and store it in memory so it can be changed... here's my Wave.h file:

struct EnteteWave
{
char chunkID [4];
int chunkSize;
char format [4];
char subchunk1ID [4];
int subchunk1Size;
short audioFormat;
short numChannels;
int sampleRate;
int byteRate;
short blockAlign;
short bitsPerSample;
char subchunk2ID [4];
int subchunk2Size;
};
class FichierWave
{
public:
FichierWave();
~FichierWave();
int LireFichier(char *nomFic);
int EcrireFichier(char *nomFic); 
double CalculerDuree();
short GetNbCanaux();//number of chanel
int GetFreqEch();
short GetNbBitsPerEch();
int GetByteRate();
short *donneeG;//left channel data
short *donneeD;//right chanel data
private:
EnteteWave *entete;
int nbSamples;
char *nomFichier;
};

 

I reand from the file and write to memory using this code:

 

int FichierWave::LireFichier(char *nomFic)
{
nomFichier = nomFic;
FILE *fp;
fp = fopen(nomFichier, "rb");
if (! fp)
	return 1;
int validation = fread(entete, sizeof(EnteteWave), 1, fp);
if (validation != 1)
	return 2;
if (strncmp(entete->chunkID,"RIFF", 4) != 0)
{
	fclose(fp);
	return 3;
}
if (strncmp(entete->format, "WAVE", 4) != 0)
{
	fclose(fp);
	return 4;
}
if (strncmp(entete->subchunk1ID, "fmt ", 3) != 0)
{
	fclose(fp);
	return 5;
}
if (entete->audioFormat != 1)
{
	fclose(fp);
	return 6;
}
if (strncmp(entete->subchunk2ID, "data",4) != 0)
{
	fclose(fp);
	return 7;
}
if (entete->subchunk2Size <= 0)
{
	fclose(fp);
	return 8;
}
...
...

 

I tryed to code something similar in C#, but I dont think it'll work because first: to replace char I used byte, but if I say:

if(entete.chunkID=="RIFF")

will it see the Bytes as an array of char?... here how i trye to do it in c#:

((actually in my c# program I try to read trough all visible media types so here's the exemple of a jpg))

[structLayout(LayoutKind.Sequential)]
public struct EnTeteJPG
{
	[MarshalAs(UnmanagedType.ByValArray, SizeConst=2)]
	public byte[] SOI;
	[MarshalAs(UnmanagedType.ByValArray, SizeConst=2)]
	public byte[] JFIFMarker;
	[MarshalAs(UnmanagedType.ByValArray, SizeConst=2)]
	public byte[] length;
	[MarshalAs(UnmanagedType.ByValArray, SizeConst=5)]
	public byte[] identifier;
	[MarshalAs(UnmanagedType.ByValArray, SizeConst=2)]
	public byte[] version;
	public byte units;
	[MarshalAs(UnmanagedType.ByValArray, SizeConst=2)]
	public byte[] Xdensity;
	[MarshalAs(UnmanagedType.ByValArray, SizeConst=2)]
       public byte[] Ydensity;
       public byte Xthumbnail;// 0 = no thumbnail
	public byte Ythumbnail;// 0 = no thumbnail
}

I try to write it that way:

public int LireFichier(string nomFichier)
	{
		this.nomFichier=nomFichier;
		FileStream stream=new FileStream(nomfichier,FileMode.Open);
		BinaryReader reader=new BinaryReader(stream);
		entete=reader.ReadByte(sizeof(EnTeteJPG));
		reader.Close();
		stream.Close();

		if(entete.SOI!=&HFFD8)
		{
			return 0;
		}
		if(entete.JFIFMarker!=&HFFE0)
		{
			return 0;
		}
		if(entete.identifier!=&H4A46494600)
		{
			return 0;
		}
		return 1;
	}

i used various exemple from this site to help me write this code (mainly the marshalling things, which by the way dont work yet....)

 

so I am close to doing this right? I saw that there is a way to use pointers in c#, maybe I could try with that... anyone can help?

[Shurikn]

As I suspected, this code is not working I had to change this:

this.nomFichier=nomFichier;
		FileStream stream=new FileStream(nomfichier,FileMode.Open);
		BinaryReader reader=new BinaryReader(stream);
		entete=reader.ReadByte(sizeof(EnTeteJPG));
		reader.Close();
		stream.Close();

 

to this:

this.nomFichier=nomFichier;
		FileStream stream=new FileStream(nomFichier,FileMode.Open);
		BinaryReader reader=new BinaryReader(stream);
		entete=reader.ReadByte(Marshal.SizeOf(EnteteAVI));
		reader.Close();
		stream.Close();

 

because he didnt seem to like me useing SizeOf, the compilator was saying to use Unsafe or marshal.SizeOF

so i chosed Marshal.SizeOf, but now, it tells me the the Marshal.SizeOf is expecting an object and not a class, but that's not how it work in c++...

 

the other error I get are this:

if(entete.chunkId!=Convert.ToByte("RIFF"))
{
return 0;
}

I get the error:

C:\Documents and Settings\Nicolas Dufour\Mes documents\Visual Studio Projects\ZoneMedia\AVI.cs(27): Operator '!=' cannot be applied to operands of type 'byte[]' and 'byte'

 

so as I suspected, he dont see an array of byte as chars... so I dont really know how to handle this here... please anyone can help?

[snarfblam]

Your post was big and it hurt my head. I hope these might help: To convert a string to bytes with one byte per character (like a C++ char), use the System.Text.ASCIIEncoding class. There are tutorials that can be found with google that show how to read/write structs to a file using the FileStream class. This example is in VB but it should be easy to translate to C#.

[Shurikn]

Thank you! and sorry for hurting your head like that, but I wanted my message to be as clear as possible and dont have people asking me: can you post this or post that