Develop Reference

NAudio Loopback Record Crackle Sound Error

I'm recording sound via the WasapiLoopbackCapture and write it to an MP3-File via the NAudio.Lame lib:
LAMEPreset quality = LAMEPreset.ABR_320;
audiostream = new WasapiLoopbackCapture();
audiostream.DataAvailable += stream_DataAvailable;
audiostream.RecordingStopped += stream_RecordingStopped;
mp3writer = new LameMP3FileWriter(Environment.GetEnvironmentVariable("USERPROFILE") + #"\Music\record_temp.mp3",
audiostream.WaveFormat, quality);
audiostream.StartRecording();
When the user presses the stop-recording-button, I save the MP3 and stop the recording:
mp3writer.Flush();
audiostream.Dispose();
mp3writer.Dispose();
All works fine, except that the output file has some disturbing crackle noises in it. (See here for example). I think it might be the case, that my computer is a bit to slow to do the process of compressing and writing the audio data in realtime, so some of the values get lost, but that is just my guess
Edit: When recording to WAVE, the errors dont appear.
What may be the problem here and how could I possibly solve it / work around it?

start off by saving your audio to a WAV file. Does that have crackles in it? If so the crackles are coming from the soundcard. If not, they are coming from the encoding to MP3 code.

C# Reading Video Metadata in Windows (Title,description,year)

Hey everyone just trying to make a program that browses video files and reads the title and description from the files metadata. I found some docs from microsoft here giving whats needed but how do I access these functions? what using namespaces are needed in c#? I would love any help that can be provided.

In that link you posted, scroll to the bottom and click "Shell Metadata Providers". There's more more information and some sample C++ code.
Here are some other relevant links:
Reading/Writing metadata of audio/video files
http://www.codeproject.com/Articles/14535/Accessing-WMF-metadata-with-C
https://social.msdn.microsoft.com/Forums/pt-BR/0f36a3b2-4d3d-4842-88a4-bea493bbbace/read-video-filemov-avi-mpg-etc-meta-data?forum=csharpgeneral
https://web.archive.org/web/20170225230114/https://stackoverflow.com/questions/7396265/c-sharp-to-read-properties-of-video-files
Sorry I can't give you anything more concrete, however it looks like some tag libraries (i.e. for reading MP3 metadata) may work as well, as the metadata for videos seems to be stored in a similar, if not identical, format. That being said, you can give TagLib# a shot.
https://www.nuget.org/packages/taglib/

I've made a simple C# code (portable to Unity, too) csatomreader. It's optimized for speed and can read the atoms over HTTP, too.
E.g. Get title:
using (FileStream stream = new FileStream(fileName, FileMode.Open))
{
var mp4Reader = new AtomReader(stream);
string value = mp4Reader.GetMetaAtomValue(AtomReader.TitleTypeName);
Console.WriteLine($"{atomTypeName}: {value}");
}
If you need to get more metadata values at once, then iterate over ParseAtoms(), e.g. see the GetMetaAtomValue() source.

Make correct URI for WP Game Library

I am trying to create a library with sounds in it, but I cant get the URIs to work, if I use a online uri like
new Uri("http://www.archive.org/download/BrahmsViolinConcerto-Heifetz/03Iii.AllegroGiocosoMaNonTroppoVivace.mp3")
it works fine, so the issue is linking correctly to my folders in my project
My in my WP Game Librarys folder I have \Sounds\letters and in that folder is a sound named a.wma
My Method for loading this is
public void PlayLetter(string letter)
{
try
{
Initialize();
FrameworkDispatcher.Update();
var uri = new Uri(#"/Sounds/letters/" + letter + ".wma", UriKind.Relative);
var song = Song.FromUri("sound", uri);
MediaPlayer.Play(song);
}
catch(Exception e)
{
Console.WriteLine(e.ToString());
}
}
And I of course give it string "a" as a parameter when it fails
I have also included the sound file in my project like
I just get a
A first chance exception of type 'System.InvalidOperationException' occurred in Microsoft.Xna.Framework.dll
But its an uri problem I am certain as I tried a online URI that worked just fine
Also I am in doubt of 2 things, is MediaPlayer the right thing to use in a game? And can a library play sounds (Or even contain them)

The typical thing in XNA would be to use a SoundEffectInstance:
http://msdn.microsoft.com/en-us/library/microsoft.xna.framework.audio.soundeffectinstance.aspx
Unfortunately SoundEffectInstance only works with wav files. If you want to play back longer music files - you can use a MediaElement - but that allows for playback of a single compressed audio file at a time only. Another option might be to play compressed from the MediaLibrary using the MediaPlayer class. You could also save your own compressed audio file in the MediaLibrary to play it from there. See:
http://msdn.microsoft.com/en-us/library/microsoft.xna.framework.media.medialibrary.songs.aspx

How to capture screen to be video using C# .Net?

I know there are lots of question like this.
But I don't want to use the Windows media encoder 9 because it's a problem to get one, and then it is no longer supported.
I know that, one possibility is to capture lots of screenshots and create a video with ffmpeg but I don't want use third party executables.
Is there are a .net only solution?

the answer is the Microsoft Expression Encoder. It is according to my opinion the easiest way to record something on vista and windows 7
private void CaptureMoni()
{
try
{
Rectangle _screenRectangle = Screen.PrimaryScreen.Bounds;
_screenCaptureJob = new ScreenCaptureJob();
_screenCaptureJob.CaptureRectangle = _screenRectangle;
_screenCaptureJob.ShowFlashingBoundary = true;
_screenCaptureJob.ScreenCaptureVideoProfile.FrameRate = 20;
_screenCaptureJob.CaptureMouseCursor = true;
_screenCaptureJob.OutputScreenCaptureFileName = string.Format(#"C:\test.wmv");
if (File.Exists(_screenCaptureJob.OutputScreenCaptureFileName))
{
File.Delete(_screenCaptureJob.OutputScreenCaptureFileName);
}
_screenCaptureJob.Start();
}
catch(Exception e) { }
}

Edit Based on Comment Feedback:
A developer by the name baSSiLL has graciously shared a repository that has a screen recording c# library as well as a sample project in c# that shows how it can be used to capture the screen and mic.
Starting a screen capture using the sample code is as straight forward as:
recorder = new Recorder(_filePath,
KnownFourCCs.Codecs.X264, quality,
0, SupportedWaveFormat.WAVE_FORMAT_44S16, true, 160);
_filePath is the path of the file I'd like to save the video to.
You can pass in a variety of codecs including AVI, MotionJPEG, X264, etc. In the case of x264 I had to install the codec on my machine first but AVI works out of the box.
Quality only comes into play when using AVI or MotionJPEG. The x264 codec manages its own quality settings.
The 0 above is the audio device I'd like to use. The Default is zero.
It currently supports 2 wave formats. 44100 at 16bit either stereo or mono.
The true parameter indicates that I want the audio encoded into mp3 format. I believe this is required when choosing x264 as the uncompressed audio combined in a .mp4 file would not play back for me.
The 160 is the bitrate at which to encode the audio.
~~~~~
To stop the recording you just
recorder.Dispose();
recorder = null;
Everything is open source so you can edit the recorder class and change dimensions, frames per second, etc.
~~~~
To get up and running with this library you will need to either download or pull from the github / codeplex libraries below. You can also use NuGet:
Install-Package SharpAvi
Original Post:
Sharp AVI:
https://sharpavi.codeplex.com/
or
https://github.com/baSSiLL/SharpAvi
There is a sample project within that library that has a great screen recorder in it along with a menu for settings/etc.
I found Screna first from another answer on this StackoverFlow question but I ran into a couple issues involving getting Mp3 Lame encoder to work correctly. Screna is a wrapper for SharpAVI. I found by removing Screna and going off of SharpAvi's sample I had better luck.

Sound quality issues when using NAudio to play several wav files at once

My objective is this: to allow users of my .NET program to choose their own .wav files for sound effects. These effects may be played simultaneously. NAudio seemed like my best bet.
I decided to use WaveMixerStream32. One early challenge was that my users had .wav files of different formats, so to be able to mix them together with WaveMixerStream32, I needed to "normalize" them to a common format. I wasn't able to find a good example of this to follow so I suspect my problem is a result of my doing this part wrong.
My problem is that when some sounds are played, there are very noticeable "clicking" sounds at their end. I can reproduce this myself.
Also, my users have complained that sometimes, sounds aren't played at all, or are "scratchy" all the way through. I haven't been able to reproduce this in development but I have heard this for myself in our production environment.
I've played the user's wav files myself using Windows Media and VLC, so I know the files aren't corrupt. It must be a problem with how I'm using them with NAudio.
My NAudio version is v1.4.0.0.
Here's the code I used. To set up the mixer:
_mixer = new WaveMixerStream32 { AutoStop = false, };
_waveOutDevice = new WaveOut(WaveCallbackInfo.NewWindow())
{
DeviceNumber = -1,
DesiredLatency = 300,
NumberOfBuffers = 3,
};
_waveOutDevice.Init(_mixer);
_waveOutDevice.Play();
Surprisingly, if I set "NumberOfBuffers" to 2 here I found that sound quality was awful, with audible "ticks" occurring several times a second.
To initialize a sound file, I did this:
var sample = new AudioSample(fileName);
sample.Position = sample.Length; // To prevent the sample from playing right away
_mixer.AddInputStream(sample);
AudioSample is my class. Its constructor is responsible for the "normalization" of the wav file format. It looks like this:
private class AudioSample : WaveStream
{
private readonly WaveChannel32 _channelStream;
public AudioSample(string fileName)
{
MemoryStream memStream;
using (var fileStream = File.OpenRead(fileName))
{
memStream = new MemoryStream();
memStream.SetLength(fileStream.Length);
fileStream.Read(memStream.GetBuffer(), 0, (int)fileStream.Length);
}
WaveStream originalStream = new WaveFileReader(memStream);
var pcmStream = WaveFormatConversionStream.CreatePcmStream(originalStream);
var blockAlignReductionStream = new BlockAlignReductionStream(pcmStream);
var waveFormatConversionStream = new WaveFormatConversionStream(
new WaveFormat(44100, blockAlignReductionStream.WaveFormat.BitsPerSample, 2), blockAlignReductionStream);
var waveOffsetStream = new WaveOffsetStream(waveFormatConversionStream);
_channelStream = new WaveChannel32(waveOffsetStream);
}
Basically, the AudioSample delegates to its _channelStream object. To play an AudioSample, my code sets its "Position" to 0. This code that does this is marshalled onto the UI thread.
This almost works great. I can play multiple sounds simultaneously. Unfortunately the sound quality is bad as described above. Can anyone help me figure out why?

Some points in response to your question:
Yes, you have to have all inputs at the same sample rate before you feed them into a mixer. This is simply how digital audio works. The ACM sample rate conversion provided by WaveFormatConversion stream isn't brilliant (has no aliasing protection). What sample rates are your input files typically at?
You are passing every input through two WaveFormatConversionStreams. Only do this if it is absolutely necessary.
I'm surprised that you are getting bad sound with NumberOfBuffers=2, which is now the default in NAudio. Have you been pausing and resuming, because there was a bug where a buffer could get dropped (fixed in the latest and will be fixed for NAudio 1.4 final)
A click at the end of a file can just mean it doesn't end on a zero sample. You would have to add a fade out to eliminate this (a lot of media players do this automatically)
Whenever you are troubleshooting a bad sound issue, I always recommend using WaveFileWriter to convert your WaveStream into a WAV file (taking care not to produce a never ending file!), so you can listen to it in another media player. This allows you to quickly determine whether it is your audio processing that is causing the problem, or the playback itself.