For my school project I would like to know if anyone can help me in finding a way of outputting sound in real time through the speakers of my PC.
This has to be donevia my sound Card while at the same time playing with parameters of the signal being played such as phase, amplitude, waveform etc?
I would prefere a library under the C++ language if possible and on the Windows plateform for practical reasons. Ofcourse Linux is also possible.
Most importantly I would also like to send a different waveforms through each speaker as to create stationary waves as can be seen through this experiment:
www.youtube.com/watch?v=T56waxJ7bB8
One interesting possibility is to use JACK. It works under Linux, Windows and OSX and provides low-latency access to audio output. It also allows for the output to be arbitrarily routed to some other program.
JACK's programming model is very simple - the only kind of data supported is a single channel of 32-bit floats, so rather than fiddling with manually interleaving data channels, you can instead provide separate instances of left and right audio sine wave generators and route each to the appropriate output channel.
Also, as a minor point of interest, JACK2 is written in C++ (although the external API is still C). I'd recommend starting with the JACK wiki and perhaps modifying one of the simple example clients to do what you're attempting.
There are a few APIs to do this.
For Windows XP and up use DirectSound
For Windows Vista/7/8 and up use WASAPI
There are some cross-platform APIs like OpenAL and SDL.
Search the web for some examples. Play around with those APIs and examples for a while and see how you do.
Related
I've received a dk 3200 kit recently. I know it's old but I would like to start using it to have more of a challenge than just arduino. It came with the board, an st flashlink FL-101B and some cables. I do not have the install disc, but I found the software for psd soft express online. It doesn't work with current windows 7 64bit. If I could use my arduino to program it, that would be great! Or maybe just do it through USB or the parallel ports? I've read that st provides a stm32 library used to help make code. If that works for my mcu, I'll use that.
Thanks
ST is a company that loves to re-organize their website and break links, but a data sheet for a part of what seems to be the same family as on your board is available from a toolchain vendor at:
http://www.keil.com/dd/docs/datashts/st/upsd321x_ds.pdf
On page 118 this seems to indicate that programs can be loaded using JTAG In System Configuration commands, which may be somewhat standardized though quick searching isn't producing a lot of leads. A reference is also made to ST's AN1153 which would be worth trying to locate a copy of, however it's not entirely clear if that will say anything about the programming, or if it only covers the additional two optional signals which have been added for hardware acceleration of the interface.
In theory, if you can find sufficient information about this device (looking at related devices may provide clues) then you should be able to craft a programming from an Arduino or anything else that can be adapted to twiddle bits at the appropriate voltage/threshold levels.
In practice, you may be better off trying to find an old Windows XP box, or even trying to run that software on a virtual/emulated environment and trap the I/O access either to proxy or to figure out what it is doing and reverse engineer your own programmer.
But unless you have a large installed base of boards using these chips, or particular need some unusual feature of them (I thought I saw something about a built-in CPLD?) it's really not going to be worth the effort.
My commercial embedded C++ Linux project requires playing wav files and tones at individual volume levels concurrently. A few examples of the sounds:
• “Click” sounds each time user presses screen played at a user-specified volume
• Warning sounds played at max-volume
• Warning tones requested by other applications at app-specified volume level (0-100%)
• Future support for MP3 player and/or video playback (with sound) at user-specified volume. All other sounds should continue while song/video is playing.
We're using Qt as our UI framework which has QtMultimedia and Phonon support. However, I heard the former has spotty sound support on Linux and the latter is an older version and may be deprecated in an upcoming Qt release.
I've done some research and here are a few APIs I've come across:
KDE Phonon
SFML
PortAudio
SDL_Mixer
OpenAL Soft
FMOD (though I'd prefer to avoid license fees)
ALSA (perhaps a bit too low-level...)
Other considerations:
Cross-platform isn't required but preferred. We'd like to limit dependencies as much as possible. There is no need for advanced features like 3D audio or special effects in the foreseeable future. My team doesn't have much audio experience so ease-of-use is important.
Are any of these overkill for my application? Which seems like the best fit?
Update:
It turns out we were already dependent on SDL for other reasons so we decided on SDL_Mixer. For other Embedded applications, however, I'd take a long at the PortAudio/libsndfile combo as well due to their minimal dependencies.
libao is simple, cross-platform, Xiphy goodness.
There's documentation too!
Usage is outlined here - simple usage goes like this:
Initialize (ao_initialize())
Call ao_open_live() or ao_open_file()
Play sound using ao_play()
Close device/file using ao_close() and then ao_shutdown() to clean up.
Go for PortAudio. For just plain audio without unneeded overhead such as complex streaming pipelines, or 3D, it is the best lib out there. In addition you have really nice cross-platform support. It is used by several professional audio programs and has really high quality.
i have used SDL_Mixer time and time again, lovely library, it should serve well for your needs, the license is flexible and its heavily documented. i have also experimented with SFML, while more modern and fairly documented, i find it a bit bulky and cumbersome to work with even tho both libraries are very similar. imo SDL_Mixer is the best.
however you might also want to check out this one i found a few weeks ago http://www.mpg123.de/, i haven't delved too much into it, but it is very lightweight and again the license is flexible.
There is a sound library called STK that would meet most of your requirements:
https://ccrma.stanford.edu/software/stk/faq.html
Don't forget about:
FFmpeg: is a complete, cross-platform solution to record, convert and stream audio and video.
GStreamer: is a library for constructing graphs of media-handling components. The applications it supports range from simple Ogg/Vorbis playback, audio/video streaming to complex audio (mixing) and video (non-linear editing) processing.
I got an assignment at work to create a system which will be able to direct sound to different output channels of our sound card. We are using M-Audio ProFire 610, which has 8 channel output and connects through FireWire. We are also using a Mac Mini as our host server and I'm gonna be working in Xcode.
This is the diagram of what I am building:
diagram http://img121.imageshack.us/img121/7865/diagramy.png
At first I thought that Java will be enough for this project, however later on I discovered that Java is not able to push sound to other than default output channels of the sound card so I decided to switch to C++. The problem is that I am a web developer and I don't have any experience in this language whatsoever - that is why I am looking for help from more experienced developers.
I found a Core Audio Primer for ios4 but not sure how much of it I can use for my project. I find it a bit confusing, too.
What steps should I take to complete this assignment? What frameworks should I use? Any code examples? I am looking for any help, hints, tips - well anything that will help me complete this project.
If you're just looking for audio pass-through, you might want to look at something that's already been built, like Jack which creates a software audio device that looks and works just like a real one (you can set it as default output for your app) and then allows you to route each channel anywhere you want (including to other applications).
If you want/need to make your own, definitely go with C++, for which there are many many tutorials (I learned from cplusplus.com). CoreAudio is the low-level C/C++ interface as Justin mentioned, but it's really hard to learn and use. A much simpler API is provided by PortAudio, for which I've worked a bit on the Mac implementation. Look at the tutorials there, make something similar for default input and output, and then to do the channel mapping use PaMacCore_SetupChannelMap, which is described here. You'll need to call it twice, once for the input stream and once for the output stream. Join the mailing list for PortAudio if you need more advice! Good luck!
the primary APIs are at CoreAudio/AudioHardware.h
most of the samples/supporting code provided by apple is in C++. however, the APIs are totally C (don't know if that helps you or not).
you'll want to access the Hardware Abstraction Layer (aka HAL), more details in this doc:
http://developer.apple.com/documentation/MusicAudio/Conceptual/CoreAudioOverview/CoreAudioOverview.pdf
for (a rather significant amount of) additional samples/usage, see $DEVELOPER_DIR/Extras/CoreAudio/
I am writing a small program in C++ that receives mic input and does some simple live audio processing. I have been looking around and the only things I have been able to find that work on Linux are PortAudio, QAudioInput, and fmod.
I am trying to stay away from any super low level programming and use a minimal amount of lines.
Which one of these would fit my needs best?
Check out JUCE. Juce will build on many platforms. JUCE does a lot more than just audio, but it was made with audio programmers in mind. Look at he JUCE demo application and then just chop up the source code from the audio demo to suit your needs. The API documentation is really good also. The abstraction from the low level stuff is good.
I've been trying to wrap my head around embedded. Since I will be self-taught in this specific niche, I realize it will be harder to get a job in the field, so I'm hoping to add a completed project to my resume to prove to potential employers that I've done it and can do it again for them.
Can someone suggest a project that I can undertake as a single person and actually be able to finish, but at the same time not too simple that it doesn't prove anything? Something reasonable that I can aim for.
If you can substantiate your example with a project you worked on yourself, and mention how many people were involved, and how long it took to finish it, that would also help me gauge the difficulty of projects I see in general and rule out the ones that are probably too big for my capacity. It's very difficult to gauge the amount of work a project needs from my position.
You should take a look at the arduino. To quote their site:
Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It's intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments.
There is a really handy playground listing a bunch of personal projects on the arduino, any one of which might fulfil your need to do some embedded development. You can also trawl around the internet (e.g. instructables) to find many other interesting arduino applications -- I particularly like the one building a fancy control system for an espresso machine, and, of course, there is the mandatory fart detecting chair that tweets its findings.
Being an arduino experimenter myself, I can attest to the simplicity and power of this device -- and the great fun you will have playing with it. If you want to get started quickly, I can recommend buying the starter kit from the very helpful people at oomlout.
Are you looking specifically at embedded software development, or are you interested in circuit board design as well?
If it's just software, then I would suggest getting hold of an ARM development board (Possibly the Philips LPC range - sparkfun have some nice ones) that you can program via a bootloader over usb and start hacking. Get one with a display and an ethernet port and you can build up to making some sort of network attached sensor (temperature, water level, object counter, etc). Start out little (turn on a LED from a button) and work your way up.
If you're also into the electronics side of things, I'd suggest something like an MP3 (or WAV) player and maybe stick to the AVR or PIC 8bit microcontrollers (AVR is used on the Arduino) as these are a little easier to deal with than ARM. Here you could start with a usb powered device that streams wav files from a PC serial port out to a pair of headphones, and build up to a battery powered board, feeding data to an MP3 decoder IC from an SD card.
Some things you may want to learn & demonstrate:
Understands the bounds of working with limited resources, including memory management (dynamic and/or static); resource management (locks, semaphores, mutex); multiple tasks (interrupts); and appropriate data structures
Ability to interface with other devices/ICs over various interconnects (analog & digital IO, serial bus (RS232, I2C, SPI))
Ability to sanely structure a program and segment the various modules without producing 'spaghetti' code
Ability to use source and integrate 3rd party libraries where appropriate (think FAT filesystem, or TCP/IP stack)
Misc Tips:
read and understand the datasheets (yes all of them)
code and test on the desktop where possible, but understand that there are differences and bugs will still creep through (this is where it helps to be using a tool-chain that is common with the desktop - GCC is good, but the tools are generally CLI)
use assert a lot - you can flash the line number of a failed assert using a single LED - this is invaluable
Most of all have fun - it still makes me smile when you first get a new component working (display, motor, sensor). Embedded makes the world go round :)