I need to develop WinForms app, which will be able to decrypt a media file (a movie) and then play it without saving decrypted file to the HDD (the decrypted file finally will be stored in the memory stream) The problem is, how then play that movie from the memory stream ? Is it possible ?
It is possible, but I expect you will need to write your own DirectShow filter to do so, which once created will act as a file reader (implementing the IFileSourceFilter interface), and, as the video plays, will read successive frames from the file, decrypt them, and pass them up to the next filter.
This will only work however if the file is encrypted in a sequential form (i.e. each individual frame is encrypted as a seperate entity). Otherwise, you will have to decrypt the entire file at once, which could be intensive, slow, and probably have to hit the hard drive to store the end file.
But anyway, this link should get you started: http://msdn.microsoft.com/en-us/library/dd375454%28VS.85%29.aspx
I'm afraid that in order to create the DirectShow filter, you will need to use C++, and it isn't the easiest API to get your head around.
An alternate way to do it may be to use the Windows Media Format SDK, which allows you to pass custom video packets to a renderer in real time. There is also a good interop library for C# (WindowsMediaLib)
First of all, it's a good idea to encrypt source video piece by piece. So the encrypted video file is a set of encrypted parts. Just split original file into parts of the same size and encrypt them.
Here the scheme (OutputStream is a stream of encrypted video file, InputStream is original file stream, ChunkSize is a size of each part in the original file, also we write some metadata: sizes of original and encrypted pieces):
using (BinaryWriter Writer = new BinaryWriter(OutputStream))
{
byte[] Buf = new byte[ChunkSize];
List<int> SourceChunkSizeList = new List<int>();
List<int> EncryptedChunkSizeList = new List<int>();
int ReadBytes;
while ((ReadBytes = InputStream.Read(Buf, 0, Buf.Length)) > 0)
{
byte[] EncryptedData = Encrypt(Buf, ReadBytes);
OutputStream.Write(EncryptedData, 0, EncryptedData.Length);
SourceChunkSizeList.Add(ReadBytes);
EncryptedChunkSizeList.Add(EncryptedData.Length);
}
foreach (int SourceChunkSize in SourceChunkSizeList)
Writer.Write(SourceChunkSize);
foreach (int EncryptedChunkSize in EncryptedChunkSizeList)
Writer.Write(EncryptedChunkSize);
}
Such metadata will help to find encrypted part rapidly.
Secondly, don't decrypt encrypted data in each read request. Cache it: video playing in the most case is just a sequential reading.
The tricky part is how to play encrypted video file. You may write either a DirectShow filter (video specific solution), or check a 3rd party product (multipurpose solution): BoxedApp, a virtualization SDK. What's cool is that they have an article that shows how to solve exact your task, look: http://boxedapp.com/encrypted_video_streaming.html
Related
I'm having a go at modifying an existing C# (dot net core) app that reads a type of binary file to use Azure Blob Storage.
I'm using Windows.Azure.Storage (8.6.0).
The issue is that this app reads the binary data from files from a Stream in very small blocks (e.g. 5000-6000 bytes). This reflects how the data is structured.
Example pseudo code:
var blocks = new List<byte[]>();
var numberOfBytesToRead = 6240;
var numberOfBlocksToRead = 1700;
using (var stream = await blob.OpenReadAsync())
{
stream.Seek(3000, SeekOrigin.Begin); // start reading at a particular position
for (int i = 1; i <= numberOfBlocksToRead; i++)
{
byte[] traceValues = new byte[numberOfBytesToRead];
stream.Read(traceValues, 0, numberOfBytesToRead);
blocks.Add(traceValues);
}
}`
If I try to read a 10mb file using OpenReadAsync(), I get invalid/junk values in the byte arrays after around 4,190,000 bytes.
If I set StreamMinimumReadSize to 100Mb it works.
If I read more data per block (e.g. 1mb) it works.
Some of the files can be more than 100Mb, so setting the StreamMinimumReadSize may not be the best solution.
What is going on here, and how can I fix this?
Are the invalid/junk values zeros? If so (and maybe even if not) check the return value from stream.Read. That method is not guaranteed to actually read the number of bytes that you ask it to. It can read less. In which case you are supposed to call it again in a loop, until it has read the total amount that you want. A quick web search should show you lots of examples of the necessary looping.
I have a task for work, I need to convert a local .wav file into 2 separate PCM files.
I have managed to read the file into a WavStream or into a Byte[] but have no knowledge on how to convert each channel to a separate file, without losing the headers.
Sample Code will be highly appreciated.
Thanks,
Nokky.
P.S
This is the code I used.
public void WavToPcmConvert(string filePath)
{
string fileName = Path.GetFileNameWithoutExtension(filePath);
using (var reader = new WaveFileReader(filePath))
{
using (var converter = WaveFormatConversionStream.CreatePcmStream(reader))
{
WaveFileWriter.CreateWaveFile(, converter);
}
}
}
In a PCM file, samples are interleaved left, right. Assuming you have 16 bit samples, this means you get two bytes left channel, two bytes right, and so on.
So create two WaveFileWriters, then read a second's worth of audio from converter, loop through the bytes you've read, and write alternating pairs into each WaveFileWriter. Keep going until you get to the end of your input stream (converter.Read returns 0).
I'm trying to reimplement an existing Matlab 8-band equalizer GUI I created for a project last week in C#. In Matlab, songs load as a dynamic array into memory, where they can be freely manipulated and playing is as easy as sound(array).
I found the NAudio library which conveniently already has Mp3 extractors, players, and both convolution and FFT defined. I was able to open the Mp3 and read all its data into an array (though I'm not positive I'm going about it correctly.) However, even after looking through a couple of examples, I'm struggling to figure out how to take the array and write it back into a stream in such a way as to play it properly (I don't need to write to file).
Following the examples I found, I read my mp3's like this:
private byte[] CreateInputStream(string fileName)
{
byte[] stream;
if (fileName.EndsWith(".mp3"))
{
WaveStream mp3Reader = new Mp3FileReader(fileName);
songFormat = mp3Reader.WaveFormat; // songFormat is a class field
long sizeOfStream = mp3Reader.Length;
stream = new byte[sizeOfStream];
mp3Reader.Read(stream, 0, (int) sizeOfStream);
}
else
{
throw new InvalidOperationException("Unsupported Exception");
}
return stream;
}
Now I have an array of bytes presumably containing raw audio data, which I intend to eventually covert to floats so as to run through the DSP module. Right now, however, I'm simply trying to see if I can play the array of bytes.
Stream outstream = new MemoryStream(stream);
WaveFileWriter wfr = new WaveFileWriter(outstream, songFormat);
// outputStream is an array of bytes and a class variable
wfr.Write(outputStream, 0, (int)outputStream.Length);
WaveFileReader wr = new WaveFileReader(outstream);
volumeStream = new WaveChannel32(wr);
waveOutDevice.Init(volumeStream);
waveOutDevice.Play();
Right now I'm getting errors thrown in WaveFileReader(outstream) which say that it can't read past the end of the stream. I suspect that's not the only thing I'm not doing correctly. Any insights?
Your code isn't working because you never close the WaveFileWriter so its headers aren't written correctly, and you also would need to rewind the MemoryStream.
However, there is no need for writing a WAV file if you want to play back an array of byes. Just use a RawSourceWaveStream and pass in your MemoryStream.
You may also find the AudioFileReader class more suitable to your needs as it will provide the samples as floating point directly, and allow you to modify the volume.
I will like to compress a file before sending it through the network. I think the best approach is 7zip because it is free and open source.
How I use 7zip with .net?
I know that 7zip is free and that they have the source code in c# but for some reason it is very slow on c# so I rather call the dll 7z.dll that comes when installing 7zip for performance reasons. So the way I am able to eassily marshal and call the methods in 7z.dll is with the help of the library called sevenzipsharp . For example adding that dll to my project will enable me to do:
// if you installed 7zip 64bit version then make sure you change plataform target
// like on the picture I showed above!
SevenZip.SevenZipCompressor.SetLibraryPath(#"C:\Program Files\7-Zip\7z.dll");
var stream = System.IO.File.OpenRead(#"SomeFileToCompress.txt");
var outputStream = System.IO.File.Create("Output.7z");
SevenZip.SevenZipCompressor compressor = new SevenZip.SevenZipCompressor();
compressor.CompressionMethod = SevenZip.CompressionMethod.Lzma2;
compressor.CompressionLevel = SevenZip.CompressionLevel.Ultra;
compressor.CompressStream(stream, outputStream);
that's how I use 7zip within c#.
Now my question is:
I will like to send a compressed file over the network. I know I could compress it first then send it. The file is 4GB so I will have to wait a long time for it to compress. I will be wasting a lot of space on hard drive. then I will finally be able to send it. I think that is to complicated. I was wondering how it will be possible to send the file meanwhile it is being compressed.
It seems to be a problem with SevenZipSharp:
Have you considered an alternate library - one that doesn't even require 7-Zip to be installed / available?
From the description posted at http://dotnetzip.codeplex.com/ :
creating zip files from stream content, saving to a stream, extracting
to a stream, reading from a stream
Unlike 7-Zip, DotNetZip is designed to work with C# / .Net.
Plenty of examples - including streaming, are available at http://dotnetzip.codeplex.com/wikipage?title=CS-Examples&referringTitle=Examples .
Another option is to use the 7-Zip Command Line Version (7z.exe), and write to/read from standard in/out. This would allow you to use the 7-Zip file format, while also keeping all of the core work in native code (though there likely won't be much of a significant difference).
Looking back at SevenZipSharp:
Since the 0.29 release, streaming is supported.
Looking at http://sevenzipsharp.codeplex.com/SourceControl/changeset/view/59007#364711 :
it seems you'd want this method:
public void CompressStream(Stream inStream, Stream outStream)
Thank you for considering performance here! I think way too many people would do exactly what you're trying to avoid: compress to a temp file, then do something with the temp file.
CompressStream threw an exception. My code is as follows:
public void TestCompress()
{
string fileToCompress = #"C:\Users\gary\Downloads\BD01.DAT";
byte[] inputBytes = File.ReadAllBytes(fileToCompress);
var inputStream = new MemoryStream(inputBytes);
byte[] zipBytes = new byte[38000000]; // this memory size is large enough.
MemoryStream outStream = new MemoryStream(zipBytes);
string compressorEnginePath = #"C:\Engine\7z.dll";
SevenZipCompressor.SetLibraryPath(compressorEnginePath);
compressor = new SevenZip.SevenZipCompressor();
compressor.CompressionLevel = CompressionLevel.Fast;
compressor.CompressionMethod = CompressionMethod.Lzma2;
compressor.CompressStream(inputStream, outputStream);
inputStream.Close();
outputStream.Close();
The exception messages:
Message: Test method Test7zip.UnitTest1.TestCompress threw exception:
SevenZip.SevenZipException: The execution has failed due to the bug in the SevenZipSharp.
Please report about it to http://sevenzipsharp.codeplex.com/WorkItem/List.aspx, post the release number and attach the archive
In mono for android I have an app that saves images to local storage for caching purposes. When the app launches it tries to load images from the cache before trying to load them from the web.
I'm currently having a hard time finding a good way to read and load them from local storage.
I'm currently using something equivilant to this:
List<byte> byteList = new List<byte>();
using (System.IO.BinaryReader binaryReader = new System.IO.BinaryReader(context.OpenFileInput("filename.jpg")))
{
while (binaryReader.BaseStream.IsDataAvailable())
{
byteList.Add(binaryReader.ReadByte());
}
}
return byteList.toArray();
OpenFileInput() returns a stream that does not give me a length so I have to read one byte at a time. It also can't seek. This seems to be causing images to load much slower than they aughto. Loading images from Resrouce.Drawable is almost instantanious by comparison, but with my method there a very noticable pause, maybe 300ms, for loading a 8kb file. This seems like a really obvious task to be able to do, but I've tried many solutions and searched a lot for advise but to no avail.
I've also noticed this code seems to crash with an EndOfStream exception when not run on the UI thread.
Any help would be hugely appreciated
What do you intend on doing with the List<byte>? You want to "load images from the cache," but you don't specify what you want to load them into.
If you want to load them into a Android.Graphics.Bitmap, you could use BitmapFactory.DecodeStream(Stream):
Bitmap bitmap = BitmapFactory.DecodeStream(context.OpenFileInput("filename.jpg"));
This would remove the List<byte> intermediary.
If you really need all the bytes (for whatever reason), you can rely on the fact that System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal) is the same as Context.FilesDir, which is what context.OpenFileInput() will use, permitting:
byte[] bytes = System.IO.File.ReadAllBytes(
Path.Combine (
System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal),
"filename.jpg"));
However, if this is truly a cache, you should be using Context.CacheDir instead of Context.FilesDir, which is Path.GetTempPath returns:
byte[] cachedBytes = System.IO.File.ReadAllBytes(
Path.Combine(System.IO.Path.GetTempPath(), "filename.jpg"));