I want to capture all audio that is played to the user (all sounds together). Currently I'm working on Windows but it would be nice if the code was cross-platform (but not necessarily). Is it possible to do it with OpenAL? How? Code examples would be great.
Language: C++
The only way to do this I believe is to create a replacement audio device driver that receives all audio requests, and then forwards them to the original device driver. There are a number of existing applications that work in this way including Freecorder, MP3myMP3 Recorder, SoundTap and Wondershare to name but a few (Google "Streaming Audio Recorder").
As for cross-platform, I would say not a chance since it is OS driver model dependent.
Depending on what you have in your system, some (not all) sound cards offer a "Stereo Mix" feature, which can be used like any other recording device. This is basically exactly what you want, as it is literally a mix of all stereo sounds being played.
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Does anyone know how to programmatically capture the sound that is being played (that is, everything that is coming from the sound card, not the input devices such as a microphone).
Assuming that you are talking about Windows, there are essentially three ways to do this.
The first is to open the audio device's main output as a recording source. This is only possible when the driver supports it, although most do these days. Common names for the virtual device are "What You Hear" or "Wave Out". You will need to use a suitable API (see WaveIn or DirectSound in MSDN) to do the capturing.
The second way is to write a filter driver that can intercept the audio stream before it reaches the physical device. Again, this technique will only work for devices that have a suitable driver topology and it's certainly not for the faint-hearted.
This means that neither of these options will be guaranteed to work on a PC with arbitrary hardware.
The last alternative is to use a virtual audio device, such as Virtual Audio Cable. If this device is set as the defualt playback device in Windows then all well-behaved apps will play through it. You can then record from the same device to capture the summed output. As long as you have control over the device that the application you want to record uses then this option will always work.
All of these techniques have their pros and cons - it's up to you to decide which would be the most suitable for your needs.
You can use the Waveform Audio Interface, there is an MSDN article on how to access it per PInvoke.
In order to capture the sound that is being played, you just need to open the playback device instead of the microphone. Open for input, of course, not for output ;-)
If you were using OSX, Audio Hijack Pro from Rogue Amoeba probably is the easiest way to go.
Anyway, why not just looping your audio back into your line in and recording that? This is a very simple solution. Just plug a cable in your audio output jack and your line in jack and start recordung.
You have to enable device stero mix. if you do this, direct sound find this device.
I am currently on linux and I am playing around with rtmidi. Now I was able to play a sound though my digital piano but I am wondering if I can also output the sound though my speakers?
When my digital piano is not connected I still get one device with getPortCount(); I assumed that is my audio driver. The device name is Midi Through:0 which is somewhat strange.
But I don't hear any sound and I am not sure if that is the intended behavior. Can I play midi sounds though my audio driver with rtmidi? Or do I need another library for this?
To convert MIDI commands into real sounds, you need a synthesizer.
Sound cards stopped having a built-in hardware synthesizer in the last millenium.
You need a software synthesizer, such as Fluidsynth or Timidity.
RtMidi is, as quoted from this website, a realtime midi input/output API. It does not say it is an audio API or library therefore it probably isn't. So yes, you will need another library or API for this, I recommend OpenAL.
My company is currently working on what could be called an audio analysis program which needs to process to multiple audio inputs (8 or so) in real time. This means that we need a framework that can handle multichannel audio interface devices that have up to 8 input channels. On top of this, the framework should be as portable as possible. We actually started our development using Java but it ran into issues with the sound API.
When looking for alternate ways to do what we need, I started thinking about using C++ and Qt. I have some experience with both, but I've never done anything remotely similar (in any language for that matter)
Now, the question is, can Qt/Phonon handle audio interfaces/sound cards with over 2 input channels (assuming that the OS can see the devices just fine)? Would it dependent on the backend being used?
Phonon as no input function. it's for playback only if i'm right. but if you want to process input audio you can use QAudioInput. I've used it with just one audio input but I think this constructor with the right QAudioDeviceInfo could do what you want.
I want to capture all audio that is played to the user (all sounds together). Currently I'm working on Windows but it would be nice if the code was cross-platform (but not necessarily). Is it possible to do it with OpenAL? How? Code examples would be great.
Language: C++
The only way to do this I believe is to create a replacement audio device driver that receives all audio requests, and then forwards them to the original device driver. There are a number of existing applications that work in this way including Freecorder, MP3myMP3 Recorder, SoundTap and Wondershare to name but a few (Google "Streaming Audio Recorder").
As for cross-platform, I would say not a chance since it is OS driver model dependent.
Depending on what you have in your system, some (not all) sound cards offer a "Stereo Mix" feature, which can be used like any other recording device. This is basically exactly what you want, as it is literally a mix of all stereo sounds being played.
I'm looking for a free, portable C or C++ library which allows me to play mono sound samples on specific channels in a 5.1 setup. For example the sound should be played with the left front speaker whereby all other speakers remain silent. Is there any library capable of doing this?
I had a look at OpenAL. However, I can only specify the position from which the sound should come, but it seems to me that I cannot say something like "use only the front left channel to play this sound".
Any hints are welcome!
I had a look at OpenAL. However, I can only specify the position from which the sound should come, but it seems to me that I cannot say something like "use only the front left channel to play this sound".
I don't think this is quite true. I think you can do it with OpenAL, although it's not trivial. OpenAL only does the positional stuff if you feed it mono format data. If you give it stereo or higher, it plays the data the way it was provided. However, you're only guaranteed stereo support. You'll need to check to see if the 5.1 channel format extension is available on your system (AL_FORMAT_51CHN16). If so, then, I think that you feed your sound to the channel you want and feed zeroes to all the others channels when you buffer the samples. Note that you need hardware support for this on the sound card. A "generic software" device won't cut it.
See this discussion from the OpenAL mailing list.
Alternatively, I think that PortAudio is Open, cross-platform, and supports multiple channel output. You do still have to interleave the data so that if you're sending a sound to a single channel, you have to send zeroes to all the others. You'll also still need to do some checking when opening a stream on a device to make sure the device supports 6 channels of output.
A long time ago I used RTAudio. But I cannot say if this lib can do what you want to archive, but maybe it helps.
http://fmod.org could do the trick too
I use the BASS Audio Library http://www.un4seen.com for all my audio, sound and music projects. I am very happy with it.
BASS is an audio library to provide developers with powerful and efficient sample, stream (MP3, MP2, MP1, OGG, WAV, AIFF, custom generated, and more via add-ons), MOD music (XM, IT, S3M, MOD, MTM, UMX), MO3 music (MP3/OGG compressed MODs), and recording functions. All in a tiny DLL, under 100KB* in size. C/C++, Delphi, Visual Basic, MASM, .Net and other APIs are available. BASS is available for the Windows, Mac, Win64, WinCE, Linux, and iOS platforms.
I have never used it to play different samples in a 5.1 configuration. But, according their own documentation, it should be possible.
Main features
Samples Support for WAV/AIFF/MP3/MP2/MP1/OGG and custom generated samples
Sample streams Stream any sample data in 8/16/32 bit, with both "push" and "pull" systems. File streams MP3/MP2/MP1/OGG/WAV/AIFF file streaming. Internet file streaming. Stream data from HTTP and FTP servers (inc. Shoutcast, Icecast & Icecast2), with IDN and proxy server support and adjustable buffering. ** Custom file streaming ** Stream data from anywhere using any delivery method, with both "push" and "pull" systems
Multi-channel Support for more than plain stereo, including multi-channel OGG/WAV/AIFF files
...
Multiple outputs Simultaneously use multiple soundcards, and move channels between them
Speaker assignment Assign streams and MOD musics to specific speakers to take advantage of hardware capable of more than plain stereo (up to 4 separate stereo outputs with a 7.1 soundcard)
3D sound Play samples/streams/musics in any 3D position
Licensing
BASS is free for non-commercial use. If you are a non-commercial entity (eg. an individual) and you are not making any money from your product (through sales, advertising, etc), then you can use BASS in it for free. Otherwise, one of the following licences will be required.