NAudio Object reference not set to an instance of an object - c#

Referring to this question, I have used the code from it: Play audio from a stream using C#
However, I get an error "Object reference not set to an instance of an object" running in debug. I have assigned Url's to a combo box, and when I choose the first choice, opening an ASX stream, the program crashes, giving me the above in debugger.
Any ideas? I have tried doing some fixing with the code below, but I don't think I'm getting the idea, since it still isn't working.
Edit:// It doesn't recognize Mp3FileReader however there are no errors/warnings, it isn't green as it normally would be, am I missing a library?
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Net;
using NAudio.Wave;
using NAudio;
public static void PlayMp3FromUrl(string url)
{
using (Stream ms = new MemoryStream())
{
using (Stream stream = WebRequest.Create(url).GetResponse().GetResponseStream())
{
byte[] buffer = new byte[32768];
int read;
while ((read = stream.Read(buffer, 0, buffer.Length)) > 0)
{
ms.Write(buffer, 0, read);
}
}
ms.Position = 0;
Mp3FileReader fr = new Mp3FileReader(ms);
WaveStream blockAlignedStream = new BlockAlignReductionStream(WaveFormatConversionStream.CreatePcmStream(fr));
if(ms != null)
{
using (WaveOut waveOut = new WaveOut(WaveCallbackInfo.FunctionCallback()))
{
waveOut.Init(blockAlignedStream);
waveOut.Play();
while (waveOut.PlaybackState == PlaybackState.Playing)
{
System.Threading.Thread.Sleep(100);
}
}
}
else
{
MessageBox.Show("blockAlignedStream variable was null!");
}
}
}

The code sample you are using is not a good example of how to play an MP3 from a stream. There are multiple problems with the code. Either use the technique described in this article, or you may be able to make use of the new MediaFoundationReader which can play from a URL.

Related

Unable to use fileInfo and fileStream in PCL project for Xamarin Project

I'm currently facing an issue with using fileInfo and fileStream related codes in my Xamarin PCL Project as Visual Studio will give an error saying that the type or namespace name 'FileInfo' could not be found.
I have already included the using System; and using system.IO statements in the code but it is still not working.
using System;
using System.IO;
using IPShare.Models;
using IPShare.ViewModels;
using Xamarin.Forms;
using System.Net;
using System.Resources;
using System.Text;
using System.Threading.Tasks;
using PCLStorage;
using System.Net.Http;
namespace IPShare.Views
{
public partial class ItemsPage : ContentPage
{
ItemsViewModel viewModel;
private async void OnButtonClicked(object sender, EventArgs e)
{
// Load file meta data with FileInfo
FileInfo fileInfo = new FileInfo(path);
// The byte[] to save the data in
byte[] data = new byte[fileInfo.Length];
// Load a filestream and put its content into the byte[]
using (FileStream fs = fileInfo.OpenRead())
{
fs.Read(data, 0, data.Length);
}
// Delete the temporary file
fileInfo.Delete();
}
}
}
As I'm new to xamarin and C# any help would be greatly appreciated.
The the forum thread linked to below says that FileInfo class is not available in PCL's (It's dated 2013, so this may be outdated).
How to use System.IO.File or similar for cross platform projects in PCLs?

simple program to convert image to byte array in c# and display that array

here is my program that i have written
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Data;
namespace ConsoleApplication7
{
class Program
{
static void Main(string[] args)
{
Image img = Image.FromFile("C:\\images.JPG");
byte[] bArr = imgToByteArray(img);
}
public byte[] imgToByteArray(System.Drawing.Image Imagein)
{
byte[] data = null;using (System.IO.MemoryStream ms = new MemoryStream())
{
Imagein.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
data = ms.ToArray();
}
return data;
}
}
}
now when i build the program it shows error
an object reference is required for the non static field, method or property 'Program.imgToByteArray(Image)'
The error is pretty clear, you can't access non static methods in a static context (method).
You have two options to fix this issue.
Option 1
Make your function/method a static function.
public static byte[] imgToByteArray(System.Drawing.Image Imagein)
{
...
}
Option 2:
Create an instance of Program and access the method.
new Program().imgToByteArray(img);
Since you want to print byte array in console (not sure why?) you could do something like this.
Console.WriteLine(string.Join(",", bytearray);
Make the imgToByteArray method static.
There is really no other rational option.
Regarding Option 2 from #Hari Prasad answer you considered an "possible option": You would be creating new class instance to call a member of this instance from a static class member that is the main entry point of the application which is pretty hardcore and given the code design guildelines i.e. https://msdn.microsoft.com/en-us/library/ms245046.aspx it is something you shouldn't.

What using statement do I need for WavReader and FlacWriter?

so far I have these using statements:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Net;
using Newtonsoft.Json;
using System.Threading;
using NAudio.Wave;
using System.Diagnostics;
using System.Threading.Tasks;
using System.Runtime.InteropServices;
using Alvas.Audio;
I'm trying to write a wav to flac converter.
Here is the function:
public static void flac_converter()
{
string inputFile = Path.Combine("wav ", input);
string outputFile = Path.Combine("flac", Path.ChangeExtension(input, ".flac"));
if (!File.Exists(inputFile))
throw new ApplicationException("Input file " + inputFile + " cannot be found!");
WavReader wav = new WavReader(inputFile);
using (var flacStream = File.Create(outputFile))
{
FlacWriter flac = new FlacWriter(flacStream, wav.BitDepth, wav.Channels, wav.SampleRate);
// Buffer for 1 second's worth of audio data
byte[] buffer = new byte[wav.Bitrate / 8];
int bytesRead;
do
{
bytesRead = wav.InputStream.Read(buffer, 0, buffer.Length);
flac.Convert(buffer, 0, bytesRead);
} while (bytesRead > 0);
flac.Dispose();
flac = null;
}
}
But I get this error: "The Type of Namespace 'WavReader' cannot be found"
I also get this error: "The Type or Namespace 'FlacWriter' cannot be found"
I know I have to do two things, download the appropriate lib, then all teh DLL files to the reference of the project and also add "using blahBlah;"
However, I don't know what DLL i need, or what using statements I need to get rid of these errors. Anyone know?
change the spelling of wavreader to wavereader. It should work out.

IPTC .NET read/write c# library

I am looking for some library to read/write IPTC metadata from Jpg files.
Open source or paid, doesn't matter.
It should work with .NET 3.5 and c#.
Does anybody know such a library? I googled but haven't found anything.
*http://msdn.microsoft.com/en-us/library/system.windows.media.imaging.aspx
using System;
using System.IO;
using System.Linq;
using System.Windows.Media.Imaging;
namespace wictest
{
class Program
{
static void Main(string[] args)
{
var stream = new FileStream("1.jpg", FileMode.Open, FileAccess.Read);
var decoder = new JpegBitmapDecoder(stream, BitmapCreateOptions.None, BitmapCacheOption.None);
var metadata = decoder.Frames[0].Metadata as BitmapMetadata;
if(metadata != null)
Console.WriteLine(metadata.Keywords.Aggregate((old, val) => old + "; " + val));
Console.ReadLine();
}
}
}
You need to reference PresentationCore.dll and WindowsBase.dll to get access to the System.Windows.Media namespace.

SslStream.DataAvailable not a valid function

I am migrating C# code from using a NetworkStream to SSLStream, however where I use stream.DataAvailable I get the error:
Error 1 'System.Net.Security.SslStream'
does not contain a definition for
'DataAvailable' and no extension
method 'DataAvailable' accepting a
first argument of type
'System.Net.Security.SslStream' could
be found (are you missing a using
directive or an assembly reference?)
now my local MSDN copy does not include DataAvailable as a member of SslStream however http://msdn.microsoft.com/en-us/library/dd170317.aspx says it does have the member DataAvailable.
here is a copy of my code.
using System;
using System.Collections;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using System.Net.Security;
using System.Security.Authentication;
using System.Security.Cryptography.X509Certificates;
using System.IO;
namespace Node
{
public static class SSLCommunicator
{
static TcpClient client = null;
static SslStream stream = null;
static List<byte> networkStreamInput = new List<byte>();
public static void connect(string server, Int32 port)
{
try
{
client = new TcpClient(server, port);
stream = new SslStream(client.GetStream(),false);
...
...
...
public static List<DataBlock> getServerInput()
{
List<DataBlock> ret = new List<DataBlock>();
try
{
//check to see if stream is readable.
if (stream.CanRead)
{
//Check to see if there is data available.
if (stream.DataAvailable)
{
byte[] readBuffer = new byte[1024];
int numberOfBytesRead = 0;
//while data is available buffer the data.
do
{
numberOfBytesRead = stream.Read(readBuffer, 0, readBuffer.Length);
byte[] tmp = new byte[numberOfBytesRead];
Array.Copy(readBuffer, tmp, numberOfBytesRead);
networkStreamInput.AddRange(tmp);
} while (stream.DataAvailable);
...
Also if you have a better way to get my output of the stream in to a managed array (there will be some parsing done on it later in the code) I would love the help. I am using Visual Studio 2008
--EDIT
I just realized I linked to the embedded SDK, this is not a embedded system, so how do I see if data is available in the normal .net SDK?
The page you are looking at is for the .NET Micro Framework.
According to this page for .Net 2.0 and this page for .Net 3.5, there is no DataAvailable property on SSLStream.
Edit: Can't you just call Read() and see if you get anything back? i don't think this will block.

Categories