Is it possible in Firefox OS to create a filtering application such as a fancy equalizer which can apply its filter to all audio going to the device audio outputs independent of the source of that audio?
No, you only have control over sound that your apps create at the moment. No way of plugging into the device audio output.
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I'm trying to share the computer's audio via webRTC and GetUserMedia, but I don't know if it is possible to obtain this stream.
On Linux and Firefox, when I request the GetUserMedia with the following constrains
navigator.mediaDevices.getUserMedia({video: false, audio:true})
In the popup I can choose alsa_output.pci and share the computer's audio. But when I tried on Chrome/Chromium or I changed to Windows neither Firefox nor Chrome show me any option to capture the internal audio, only my headset microphone.
Are there any option for the getUserMedia or any workaround to get this audio? I tried all the examples of WebRTC samples and Muaz's examples but no one displayed me this option, only Firefox under Linux.
There's no way to do this from the JavaScript code.
In Windows, you just have to use as input for WebRTC Stereo mix (or Wave out mix on some laptops/sound cards). If you don't have it on your list of recording devices, try to update your sound card driver. If you do have it in the list, but it is marked as Currently unavailable, then right click on it and select Set as Default Device. This would make it available.
If your sound card doesn't support Stereo mix, then you can use something like Virtual Audio Cable.
As I understand it, streaming via bluetooth is handled via the A2DP profile. While the SBC codec is default, A2DP supports AAC, MP3, and a few other Codecs.
My question is, since spotify files are in the OGG VORBIS format (OGG Container, Vorbis Codec), what is the best way to handle streaming via Bluetooth without quality loss? Is there a specific A2DP implementation? Are folks like Jambox, etc just using the SBC implementation?
Spotify's streaming format is an implementation detail to all clients, and making the assumption that it's OGG Vorbis is not something you should do, and in some circumstances is actually a false assumption.
Since you've managed to use every single Spotify tag in your question, I don't know which platform you're developing for. However, the correct thing to do is take the PCM data the Spotify playback library gives you and use whatever playback stack your target platform gives you. On Android, iOS, Mac OS, etc the system will handle audio output devices for you, including Bluetooth streaming.
I am to test voice recognition programs. Some which I have access to the code and others where I don't.
Sadly my (beautiful) voice is not perfect, so when I am reading a text it sounds slightly different each time. Which makes the testing difficult and time consuming. Giving that I can tweak a lot of parameters.
So I was wondering if there was a way to record my own voice (already done). And then play it as normal microphone input so the voice recognition program I am testing will see it as microphone input.
This would also help greatly if it could be done programatically in C#. So I can in my own code specify when to play what.
To play it from speakers and have the voice recognition programs listen to the microphone is not an option, because it is not the same sound on different computers/speakers/microphones.
Thanks.
Edit:
What i have found so far is to use a software sound Card simulator. But I haven't been able to find a suitable one.
Just as there are printer drivers that do not connect to a printer at all but rather write to a PDF file, analogously there are virtual audio drivers available that do not connect to a physical microphone at all but can pipe input from other sources such as files or other programs.
I hope I'm not breaking any rules by recommending free/donation software, but VB-Audio Virtual Cable should let you create a pair of virtual input and output audio devices. Then you could play an MP3 into the virtual output device and then set the virtual input device as your "microphone". In theory I think that should work.
If all else fails, you could always roll your own virtual audio driver. Microsoft provides some sample code but unfortunately it is not applicable to the older Windows XP audio model. There is probably sample code available for XP too.
I have developed a pretty complex audio software for my client with plugins for Winamp, Windows Media player and VST. Now the client is interested in some method to avoid maintaining the multitude of plugins, we have no way to support all the media players out there.
The client does not care for Unix/Mac yet, so I can look only at Windows XP and Vista/7/
Basically, what we need is a way to always reliably intercept as much audio stream protocols as possible (well, except maybe ASIO, that's another story, I guess), then pass this audio through our custom effects engine and then route back to the default audio device, whatever it is.
Now I am thinking, what options do I have (theoretically).
I could use hooks. I need to hook globally older vaweOut and also DirectSound.
But will this still work on Vista/7?
I could use a virtual driver, like the author of the Virtual Audio Cable did:
http://software.muzychenko.net/eng/vac.htm
Seems a pretty daunting task. Anyway, the client will contact the author of VAC to see if he agrees to sell his source code for a reasonable price.
This driver could install itself as a default audio output device, intercept the audio stream from Windows, and pass it back to default device. Hmm, but what about various DirectSound audio buffers, do I have to mix them myself or is there any way I could tell Windows mixer to mix all for me and pass a single mixed audio stream?
It seems, this custom driver will of course kill all the hardware audio acceleration, but we can live with that, if we warn our customers about this issue.
As I understand, the most current Windows driver standard is WDF.
But maybe it does not work for audio on Windows Vista/7?
I know, Vista/7 has a different audio stack from XP.
If I can do it using WDF, what driver should I write - kernel mode or user mode?
Maybe I am missing more elegant and simple options to intercept, process and route audio on Windows?
Try Virtual Audio Streaming SDK. Also virutal sound card and let you read/process audio data in realtime.
http://www.virtualaudiostreaming.net/sdk-license.html
I have written an application that receives media files from a central server and plays those files according to a playlist. All works well.
A client has contacted us and wants to use our application to play some audio files as presentations in a kiosk-style application. So far, so good, our application can handle this no problems.
He has requested as a potential feature that we would have a number of headphone sockets at the front of the kiosk. Each headphone socket would play the same audio presentation in a different language.
I have come up with the idea of encoding a single audio file with the presentation in multiple languages, and each language in a different channel. We would then require a sound card that could decode each channel and output it on a different headphone socket.
Thing is, while I'm think the theory is sound, I have absolutely no idea whether this is feasible and what would be required to pull it off.
Any ideas?!
As a side-note: the application uses Media Player as the underlying component to handle the playback of audio and video. I'd appreciate any help as to the software we could use to generate the multi-channel audio stream and the hardware (USB sound card would be fine) that we could use to decode the stream.
Thanks!
You need to use multiple files not channels, its going to be way easier that way.
Instead of using Media Player use DirectShow (on .NET you have DirectShow.NET), In DirectShow you have the notation of Multiple files on the same graph.
You will be able to control to which audio device play which files, and your Play, Pause, Stop commands will be preformed on all files without you need to worry about syncing.
There are many samples on how to build media player like with DiectShow, extending them to use multiple files should be really easy.
For HW take a look at this (USB with 8 output channels)
I think with Shay's hardware you've got a complete solution:
Encode a 7.1 file with a different mono voice track on each channel.
Use the 8 channel output device in 7.1 mode, with a different headset in each port, and you've got it. Or, if you only have 6 languages, a 5.1 file would work. Many PC's have 5.1 outputs built in, you'd only need 3 splitters to break out the left and right channels from each jack.
You can do the encoding with Windows Media Encoder, or other pro audio tool.