Very simple question. In the MSDN documentation for the DirectSound API they state that when my application is in focus it will be the only audible program. This is exactly what I want to happen, however when setting this flag and playing sound through my application, I can still hear the background music on my computer.
So the question is, why? Is it because the application playing the background music using a different low level API, and thus different mixing buffers? Or is there some other little trick i need to tweak in order to become the only audible application.
I asked a similar/related question here, with no response. But once again if you don't know the answer to the specific DirectSound question, but you know a way of becoming the only audible application with a different API let me know!
Thanks, I'm on Windows XP 32Bit Professional, if it makes a difference.
A long time ago, the Windows developers realized that allowing one application to have total control of the audio system (whereby muting other apps) was a bad idea. And then they subsequently deprecated many of these "exclusive" and foreground/background mode flags. I believe this behavior change goes all the way back to DirectX 7.1 (WinME) and then formally everywhere on DX 8. This was 10 years ago.
Imagine your video conferencing app becoming muted when you switched the foreground application to an app that ran audio in some sort of exclusive mode. Not being able to reliably hear anyone when switching between apps is not a great experience.
As a matter of fact, prior to DX 8, many popular voice-comm apps for multi-player gaming would continually sniff for the foreground window handle and use that for the call to SetCooperativeLevel such that they wouldn't get muted.
I think it would be interesting to know, "what is that you really want to do?" that makes you assume you need total control of the audio output.
On Vista and higher, there is the WASAPI api for low-level audio. I believe there is a concept of "exclusive" mode but I don't know if trumps other apps using the sound card. YMMV.
Related
I want to try some C and C++ programming with audio processing, such as synthesizers, chorus, delay etc, but I only know working with a console as output. I wish to have, instead of a console application, a window that would be capable of sending an audio signal to the speakers, running the code at the background and working with it in a similar way as it goes with printf: every time I would call the "output function", it would send to the speakers (or sound card) a sample value, indicating current oscilator position. This output operation could be executed every time it is requested or in the end of a built in loop. Doing all this with a high sample rate would be just great.
I think I could do all this using AudioWorker on Web Audio API, plus a flexible GUI on HTML5 canvas, but I'm new at this API and I'm not sure whether its resulting sound quality is good enough.
Thanks in advance.
Edit: I use Windows 8.1, but any answer for other platform is welcome.
Edit2: Any programming languages other than C, C++ or JavaScript suggestions are also welcome.
I do lots of sound synthesis with the Web Audio API and I think it sounds great. Javascript is really all you need. Well, if you want to use audio files, you need a web server to serve those audio files, but the audio synthesis all happens in javascript.
It doesn't matter so much what OS you use, but different browsers have different levels of support for the web audio API. Chrome tends to have the best support, and Internet Explorer definitely has the worst support.
I've been looking into dimming a screen on a Windows platform from my program. I know that there's a SetMonitorBrightness API that allows this, but the issue for me is that it would be nice to be able to dim the screen on Windows XP as well (which that API does not support) and also dim screens on desktop computers.
So I did some research and found this utility that seems to dim my screen on a Windows XP desktop without a problem. I tried to contact the author to find out how they implemented the dimmer but I did not hear back from them.
So I was curious to hear from developers on this site, how do you think they managed to dim the screen when the SetMonitorBrightness API is not supported?
PS. I am a newbie developer myself trying to write an energy saving program for our small business. It is a nonprofit organization and we don't have funds to hire a Windows developer to do this for us. Most of our computers are Windows XP desktops, so as you can see I can't use SetMonitorBrightness API as it is widely documented on the web.
Thanks in advance.
In the case that you cite, have a look at the screensaver with Dependancy Walker. My guess is that they create a full screen window and use SetLayeredWindowAttributes() to set a semi-opaque setting for the window, thus making the screen appear dimmed. I doubt it would save you much money.
You might want to look into the DDC protocol which allows you to control aspects of some monitors. The MS API that allows you to do this can be found roundabout here: http://msdn.microsoft.com/en-us/library/windows/hardware/ff570290%28v=vs.85%29.aspx and you should look at the I2C functions too.
Alternatively you could look for a ready made library to do the DDC stuff for you, such as http://www.nicomsoft.com/products/i2c/. They too have a dimmer application that is free for personal use and non-free for commercial use. They may even allow you to use it for free if you contact them and explain it's for a non-profit organisation.
If you are trying to do this as an energy saving program why not use a screensaver setting that turns the monitor off after a certain period of idleness? In any case
Forgive me if this information is outdated, but I have done this in the past using SetDeviceGammaRamp. The 'Get' version is available too for state saving and restore. I have seen it used in C# programs through, so it might still be relevant albeit not too common anymore.
I've had a desire to learn at least a tiny bit about programming hardware for quite some time now and thought I'd ask here to get some starting points. I am a reasonably accomplished programmer with Delphi and Objective-c experience but have never even listened to a device port / interupt (I dont even know the terminology) let alone programmed a piece of hardware.
To start with what I would like to be able to do is,
Buy a simple bit of kit with 2,3 or 10 buttons
Plug the device into my pc via USB
Listen to the device and write some code to do something once the button is pressed.
I reckon this is a good place to start, anyone got pointers on hardware to buy or how I could start this?
I like the Arduino, easy to use, open source and a great community!
Good to get started with, and uses a subset of C/C++.
Also, has alot of addon hardware available, like GPS, Bluetooth, Wifi etc
My experiences with Arduino have been nothing but good, from the point you get it out of it's box (and install the free compiler on either Windows / Mac / Linux), to building your first 'sketch' (a project or application for the Arduino).
Making an application is easy, you have a Setup Method, which is called on startup, and then a loop method which is looped while the Arduino is running.
Then all you have to do is hook either inputs or outputs up to the pins on the Arduino board, tell the code what they are and hopefully you'll get the desired output.
One other really good thing about the Arduino (and others I'm sure) is that you now have a use for those old broken printers, or 2x CD-Rom's that no one wants, and every other little bit of out dated technology. It's amazing what you can find in a server room!
Now, I have only worked on small projects, like plugging in an LCD, and reading the room temp and various projects like that. But based on what I have done, I am happy with the Ardunio, it gives a good base to embedded programming and if it's not enough, you can always go bigger!
My 2 cents!
There's also the hot-off-the press netduino which uses the .NET Micro Framework and Microsoft Visual C# Express. I don't know that's it's better than the Arduino but it's another option.
Why don't you start with AVR programming for microprocessors. Yeh it might be a bit too low level. but I know many people that have started with it for hardware programming. you could find a compiler here. http://winavr.sourceforge.net/ and a good tutorial here: http://www.ladyada.net/learn/avr/
The previous poster mentioned the Arduino, but you should also consider a Teensy. It's basically the same thing, but price is a little better. You also have the option of using it in "Arduino" mode, or raw AVR mode. I don't know if Arduinos give you both options.
There is a comparison page where you can see the Teensy has some better hardware. The built-in USB gives it much better performance.
I would definitely suggest trying out various microcontrollers. Arduino Controllers are nice and have a number of tutorials.
However, its not your only option. In school, I worked with Microchip PICs, which are also quite nice for the hobbyist scene. The nice thing about the PIC was that our microcontrollers textbook supported it, so we got to see the application as we were learning the theory.
If I understand your question right, you are not interested in embedded programming. You want to buy something that works from the begining and control it from Windows.
When it comes to buttons, there is not much to do in Windows. These are HID controls and Windows handles all the interfacing for you. Nothing too exciting there.
In that case you can grab any Joystick and use the DirectInput (a part of the DirectX tech.) to interact with it. With force feedback you can do some cool stuff.
A more fun project would be to buy a Wii control and write some fun applicartions.
Look at this site to get some ideas of what I mean:
http://johnnylee.net/projects/wii/
Since Windows has no support for a Wii contrller, you really get to do some work here :)
I see that you like Delphi, so you can take a look at AvrCo Multitasking Pascal for AVR. You can try it at http://www.e-lab.de. MEGA8/88 version is free. There are tons of drivers, simulator, JTAG online debugger and programmer with visualization of all standard devices (for a startup, you can make a simple LPT programmer with just a few resistors). It can also make programs for all Arduino devices out there, since AVR is in their hearth. Atmel's STK500 is a good beginner board, with leds, switches, and few other peripherals. If you prefer open source, then WinAVR with GCC could be your path.
As already mentioned, Arduino is a good choice. The community is large and helpful. The nice thing is that you can transition right to a "real" language by using the GCC port for AVR micros, if you want. On my latest project I did this - prototype most of it with Arduino, then re-write it in C.
Starting with buttons and LEDs is a great idea. Build some confidence in working with basic hardware first, before modding the Wii!
Some links:
Windows GCC cross compiler (1 step install) for AVR: WinAVR
A Arduino clone kit
Adafruit is another good source of starter hardware and tech advice
The embedded StackOverflow
Any program you already write interacts with hardware, there's the monitor, keyboard, mouse, speaker etc. Getting a simple setup where your program can deal with buttons on a USB device will not teach you that much about working with hardware. It's partly a question of how low you want to go in the software stack and how much you want to learn about what happens at the point where the software ends.
Get yourself a copy of "The Art of
Electronics". It's a relatively easy read and covers everything between Ohm's law and the microprocessor and will give you a good idea of what the complete system does.
Read it.
Check out Digikey. You can buy anything hardware related from resistors, capacitors, IC's, low cost boards easily online and for reasonable prices.
Other replies mentioned Microchip PIC and Atmel AVR which are small and simple microcontrollers. Both companies have a wealth of application notes, check out their web site, read through some app notes. You can get low cost evaluation boards for the above or something like the Arduino mentioned in other replies. Consider designing and building your own board to force yourself to learn the basics. Find a friend who is an EE or serious hobbyist who wouldn't mind helping you with some tips.
If you want to learn more about PC hardware you can take a look at some simple device drivers (e.g. printer or serial port) under Windows (download the WinDDK), Linux or even DOS. Programming under something like DOS on a PC allows for relatively easy interaction with the PC hardware, you can use a printer port to read push buttons etc.
Links (I'm a new user so I can't link directly):
www.amazon.com/Art-Electronics-Paul-Horowitz/dp/0521370957
www.digikey.com/
www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2879
www.atmel.com/products/avr/
I'm developing a musical game, it's like a singstar but instead of singing, you have to play the recorder. It's called oFlute, and it's still in early development stage.
In the game, I capture the microphone input, then run a simple FFT analysis and compare the results to typical recorder's frequencies, thus getting the played note.
At the beginning, the audio library I was using was RtAudio, but I don't remember why I switched to PortAudio, which is what I'm currently using. The problem is that, from time to time, either it crashes randomly or stops capturing, like if there were no sound coming from the microphone.
My question is, what's the best option to capture microphone input on Linux? I just need to open, read, and close a flow of bytes from the microphone.
I've been reading this guide, and (un)surprisingly it says:
I don't think that PortAudio is very good API for Unix-like operating systems.
So, what do you recommend me?
PortAudio is a strange choice given the other options.
I would personally abstract away from everything and use GStreamer. Audio can be a horrible mess on Linux (speaking as a long term sufferer). Letting Gstreamer deal with that lets you forget about it, move along and not have to think about it again.
OpenAL is probably the most popular for game dev though and it should support most systems (although you will have "fun" getting it playing nice with PulseAudio).
I'd certainly make sure you're developing for the most popular setup (which is PulseAudio at the moment, I reckon) so you don't end up in a situation where you release and you're plunged into a pool of people moaning about the sound not working.
And don't listen to the nonsense about PulseAudio - it might be new and it might take up a few more resources than a barebones ALSA system but it's certainly not mired with latency issues. Asking people to remove it isn't an option with modern desktop distros as it's so tightly integrated (and useful too).
When I run this code:
MIXERLINE MixerLine;
memset( &MixerLine, 0, sizeof(MIXERLINE) );
MixerLine.cbStruct = sizeof(MIXERLINE);
MixerLine.dwComponentType = MIXERLINE_COMPONENTTYPE_SRC_WAVEOUT;
mmResult = mixerGetLineInfo( (HMIXEROBJ)m_dwMixerHandle, &MixerLine, MIXER_GETLINEINFOF_COMPONENTTYPE );
Under XP MixerLine.cChannels comes back as the number of channels that the sound card supports. Often 2, these days often many more.
Under Vista MixerLine.cChannels comes back as one.
I have been then getting a MIXERCONTROL_CONTROLTYPE_VOLUME control and setting the volume for each channel that is supported, and setting the volumne control to different levels on different channels so as to pan music back and forth between the speakers (left to right).
Obviously under Vista this approach isn't working since there is only one channel. I can set the volume and it is for both channels at the same time.
I tried to get a MIXERCONTROL_CONTROLTYPE_PAN for this device, but that was not a valid control.
So, the question for all you MMSystem experts is this: what type of control do I need to get to adjust the left/right balance? Alternately, is there a better way? I would like a solution that works with both XP and Vista.
Computer Details: Running Vista Ultimta 32 bit SP1 and all latest patches. Audio is provided by a Creative Audigy 2 ZS card with 4 speakers attached which can all be properly addressed (controlled) through Vista's sound panel. Driver is latest on Creative's site (SBAX_PCDRV_LB_2_18_0001). The Vista sound is not set to mono, and all channels are visable and controlable from the sound panel.
Running the program in "XP Compatibility Mode" does not change the behaviour of this problem.
If you run your application in "XP compatibility" mode, the mixer APIs should work much closer to the way they did in XP.
If you're not running in XP mode, then the mixer APIs reflect the mix format - if your PC's audio solution is configured for mono, then you'll see only one channel, but if you're machine is configured for multichannel output the mixer APIs should reflect that.
You can run the speaker tuning wizard to determine the # of channels configured for your audio solution.
Long time Microsoftie Larry Osterman has a blog where he discusses issues like this because he was on the team that redid all the audio stuff in Vista.
In the comments to this blog post he seems to indicate that application controlled balance is not something they see the need for:
CN, actually we're not aware of ANY situations in which it's appropriate for an application to control its balance. Having said that, we do support individual channel volumes for applications, but it is STRONGLY recommended that apps don't use it.
He also indicates that panning the sound from one side to the other can be done, but it is dependent on whether the hardware supports it:
Joku, we're exposing the volume controls that the audio solution implements. If it can do pan, we do pan (we actually expose separate sliders for the left and right channels).
So that explains why the MIXERCONTROL_CONTROLTYPE_PAN thing failed -- the audio hardware on your system does not support it.