I'm looking at developing an application for the WP7 platform which accepts an audio stream from a computer and outputs that stream on the phone speaker. This involves either dealing with the audio encoding / decoding myself, or somehow passing off an audio stream to the WP7 platform.
I've struggled so far to find any raw audio output API's and I am not sure what I have to do on the server (computer) side to get the phone to just deal with the audio stream.
I have looked at a few MSDN articles, but I can't quite tell if they do what I want. If somebody could point me in the right direction that would be great!
I think the MediaStreamSource class does what I'm looking for, and the MediaStreamSource.ReportGetSampleCompleted method appears to confirm this, but nowhere does it say clearly that it can be used for raw audio.
If you need any information, or if you have any suggestions of better ways to do this that would also be appreciated!
You should be able to use the XNA.Framework.Audio namespace SoundEffect to get a soundeffect instance from a raw audio stream. Which should usually be a standard PCM format.
This post on microphone by Charles Petzold could be useful.
An excerpt
In contrast, classes in the Microsoft.Xna.Framework.Audio namespace
work with uncompressed audio data in the standard PCM format, which is
the same method used for audio CDs and Windows WAV files.
Related
I am trying to create a radio app, which contains a collection of MP3-stream urls. However, I have run into some trouble streaming (or playing back) the audio.
I am trying to connect to a raw data stream like the ones you plug into VLC. An example url is http://mp3.ht-stream.net/;80 (just plugged this one and a few others into VLC and it worked perfectly). Basically your standard internet radio feed.
I have created the AudioPlaybackAgent, filled in what I think is needed to get this up and running, and everything works fine when I stream regular .mp3 files over the internet. But when I try to connect to these streams, it doesn't do (or play) anything.
I reckon it could be because I'm not using an AudioStreamingAgent (with a MediaStreamSource implementation), but that stuff is a bit too advanced for me, and as I understood after some hours searching the interwebs, mp3 streams could use the AudioPlaybackAgent instead.
Any advice on how I can make this work? Will I have to use an AudioStreamingAgent instead? Is there any open source examples as to how I implement this mysterious MediaStreamSource class? Should I scrap my great idea? Any answers will be greatly appreciated.
My AudioPlayer.cs code is available here if you'd like a peek - but it's mostly the standard stuff.
You can't easily play audio from the provided link because of this is not a regular audio file. This is SHOUTcast stream.
You can check some open source implementations and to figure out how to work with this audio stream. For example: Shoutcast MediaStreamSource.
So I can say that you need to implement a lot of stuff in your app to play this stream. There is no quick and easy way.
Look at the Background Audio Streamer sample.
Does anyone have this working? I believe I have the CodecPrivateData messed up, but I can't find any WAVEFORMTEX FormatTags that seem to work. I tried 0xFF00, 0x1016, and 0x0116. I used the MSDN documentation to complete the rest of the string.
I found this in MMReg.h (WAVE_FORMAT_MPEG_ADTS_AAC 0x1600) which would have a FormatTag(0x0016). You would think this is what I should use, but that does not work either.
When using 0xFF if I avoid the adts headers in the stream GetSampleAsync get called repeatedly but there is no playback. I know the stream is good because I can play it in FooBar, VLC, and Window Media Player. When I stick the raw AAC into an MP4 container it works fine in silverlight so I know that the AAC setting are supported by silverlight.
Can someone supply me with a hex CodecPrivateData string that worked for them?
Edit:
This is an example of PrivateCodecData hex string that I think should work:
0x1016010080BB0000E02E0000010000000E000100FE0000000000000000001190
This string goes straight from OpenMediaAsync() to CloseMedia() without even trying a sample. The MSDN documentation example does the same thing found here. I would expect it to at least try a sample before closing.
Silverlight seems to be not compliant with AAC and ADTS wrapper...
If you analyze your MP4 file (with MediaInfo for example), you will see AAC for audio but without ADTS wrapper. This is why Silverlight can read in this case your AAC audio embedded in a MP4 file.
So you need to remove the ADTS header for each audio sample before calling ReportSampleCompleted() in the MediaStreamSource. The ADTS header consists of 7 or 9 bytes (without or with CRC). For more informations about the ADTS header, see this link.
Obviously, you need to adapt your CodecPrivateData string with the right FormatTag. Here is mine for a AAC LC 48KHz #96Kbps file : FF00020080BB0000E02E0000040010000200
I need to convert an AMR (Adaptive Multi-Rate) audio file recorded in a phone (as a Stream object) to a PCM uncompressed wav audio Stream so it can be processed afterwards for speech recognition. The Speech Recognition doesn't like the AMR format. This is going to be a server application using the Microsoft Speech Platform. I am not sure about using the ffdshow or similar libraries in a .
Right now I am researching NAudio and DirectShowNet to see if they can help me accomplish this but was hoping someone can point in the right direction.
After a lot of searching for a solution for this, I am going to use ffmpeg. It provides the AMR-NB (NB=Narrow Band) decoder. There are a lot of c# wrappers for ffmpeg around; most of them abandoned efforts and one that is up to date but is not free. Just running ffmpeg with the basic parameters provides what I need, plus it is really fast.
I don't like the idea of calling an external process to do the conversion, plus I need to save the AMR stream as a file so it can be converted to a wav file but I believe I can make it work efficiently.
What is the best way to convert various audio formats to PCM?
For example: mp3, evrc, ogg vox.
Is there a library out there that will allow me to implement this relatively easily?
EDIT:
I guess my initial question wasn't really what I needed. Most of the libs I have found are file converters. What I need is a block converter, where I pass in a 1Kb block of vox data and it returns its converted PCM block. Of course I’ll have to tell the converter what type of data it is and various pieces of codec information.
The solution I am going for is to save and VOIP formats into a common wav format and to play that conformed file in real time. I thought there should be an easy way to do this because all audio is eventually turned into PCM before it is outputted anyways.
You can use NAudio to pass blocks of compressed audio into any ACM codecs you have installed on your machine. You do need to know how to create the appropriate WAVEFORMAT structure to describe the compressed audio type correctly though.
Check out AVBlocks SDK for .NET. It supports several audio formats, and audio transforms like Multi-channel audio to Stereo audio, resampling and bitrate conversion.
Try modified code from http://alvas.net/alvas.audio,tips.aspx#tip91
static void AnyToWav(string fileName)
{
DsReader dr = new DsReader(fileName);
IntPtr formatPcm = dr.ReadFormat();
byte[] dataPcm = dr.ReadData();
dr.Close();
WaveWriter ww = new WaveWriter(File.Create(fileName + ".wav"), AudioCompressionManager.FormatBytes(formatPcm));
ww.WriteData(formatPcm);
ww.Close();
}
Don't know any lib that does it all but we do mp3->wav using madxlib.
It's free but I suggest paying the $10 for the sdk as it comes with documentation and examples.
There is a c# tutorial on youtube that might be helpful to you. It shows how to use a specific audio library called alvas.audio that really does some neat things with audio. I found the video to be very educational. The audio library is completely written in c#. Watch the video for more details: http://www.youtube.com/watch?v=2DIQECXFPeU
I have a requirement to build a very simple streaming server. It needs to be able to capture video from a device and then stream that video via multicast to several clients on a LAN.
The capture part of this is pretty easy (in C#) thanks to a library someone wrote with DirectShow.Net (http://www.codeproject.com/KB/directx/directxcapture.aspx).
The question I have now is how to multicast this? This is the part I'm stuck on. I'm not sure what to do next, or what steps to take.
There are no filters available that you can plug and use.
You need to do three things here:
Compress the video into MPEG2 or MPEG4
Mux it into MPEG Transport Stream
Broadcast it
There are lots of codecs available for part 1, and some devices can even output compressed video.
The part 3 is quite simple too.
Main problem goes with part 2, as MPEG Transport Stream is patented. It is licensed so that you cannot develop free software based on it (VLC and FFMPEG violate that license), and you have to pay several hundred dollars just to obtain a copy of specification.
If you have to develop it, you need to:
Obtain a copy of ISO/IEC 13818-1-2000 (you may download it as PDF from their site), it describes MPEG Transport Stream
Develop a renderer filter that takes MPEG Elementary Streams and muxes them into Transport Stream
It has to be a renderer as Transport Stream is not a transform filter. There are some kind of outband data (program allocation tables and reference clocks) that need to be sent on a regular basis, and you need to keep a worker thread to do that.
To achieve that you need to setup/write some kind of video streaming server.
I've used VideoCapX for the same purpose on my project. The documentation and support is not top notch, but it's good enough. It's using WMV streaming technology. The stream is called MMS stream. You can view it with any most media player. I've tested with Windows Media Player, Media Player Classics and VLC. If you would like to see it's capability without writing any code just yet, take a look at U-Broadcast, it uses VideoCapX to do the job behind the scene.
I've been using DirectShow.Net for almost 2 years, and I still find it hard to write a streaming server myself, due to the complexity of DirectShow technology.
Other than WMV, you can take a look at Helix Server or Apple Streaming Server. The latter one is not free, so is WMV Streaming Server from Microsoft.
You can also take a look at VLC or Windows Media Encoder to do streaming straight from the application. But so far I find U-Broadcast out do both of the above. VLC has some compatibility issue with codec and playback from non VLC player, WME has problem with starting up capturing device.
Good Luck
NOTE: I'm not associated with VideoCapX or it's company, I'm just a happy user of it.
http://www.codeproject.com/KB/directx/DShowStreamingServer.aspx might help, and http://en.wikipedia.org/wiki/VLC_media_player#cite_note-14
VLC also "should" be able to stream from any device natively.