I've start to write a midi parser https://gist.github.com/rubzyk/8453093
inspired by this article http://vishnumenon.com/2013/06/25/musical-chains-music-generation-with-clojure/
I'm stuck with tempo stuffs, i can't find a way to convert tempo change messages into bpm
i've tried to use the way explained here but it gives me wrong tempi... like 3000+ bpm
any help is welcome
feel free to advice me for some modification/refactoring of the code
Just a suggestion, but why not use java interop for this? Java already has a very solid midi library in javax.sound.midi. I've rolled my own midi library before (not in clojure) and it's tricky to get right with all the bit fiddling.
Another option is midi-clj.
Related
I want to develop an application that would take audio(.wav) as input and display its real time simultaneous frequency spectrum . From what i have looked upon the subject , this requires fourier transform of the waves . Can someone suggest where i should start with ? Possible references and books . I want to learn the details of the implementations of realtime frequency spetrum rather than the development of GUI which i am quite familiar with(in C# and in C++).
There are already many libraries to do FFTs for you. No reason to reinvent the wheel. DirectX has an implementation but it might only be in the most recent version. Here's an open source C library for it.
If you want to understand the math behind it, here's a simple explanation and here's a complicated explanation.
You should begin with opening the wav file, extracting the audio stream and decoding it. There are 3rd party libraries to help on this operation.
Take a look at FFTW.
As far as books go, the classic text book on signal processing is Oppenheim and Schafer's Digital Signal Processing. Its college level but it is quite through. You do need some knowledge of calculus in places.
One should understand a bit of the theory before going off and implementing an application to display something. Here are some free online resources on digital signal processing, which is the basis for understanding FFTs and frequency spectrums, and maybe how not to misuse them.
http://www.dspguide.com/pdfbook.htm
http://www.bores.com/courses/intro/index.htm
http://ccrma.stanford.edu/courses/320/Welcome.html
http://yehar.com/blog/?p=121/
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 was told I have to use winsock, but I dont know where to start. For example, I am trying to access, lets say http://www.newegg.com/, I am trying to get the text title of just the three front page products. Any help is greatly appreciated. :D
I'd also recommend libcurl for this sort of thing.
You can use the cURL command line tool to generate sample code as well, which is helpful for experimentation.
W3.org themselves provide sample C / C++ librarys for Http requests.
Find them here
Specifically, look for HTTPReq.c
Use boost library and poco. They both provide solutions for network programming. Boost also provide spirit library which you can use for parsing data from websites. Poco libraru also provides NetSSL, crypto solutions.
P.S. boost::spirit is not a library for parsing data from websites, it provides solution for parsing strings ...
you need to open a socket.
then you need to do an http get
somewhat like :-
http://www.esqsoft.com/examples/troubleshooting-http-using-telnet.htm
You could use the QNetworkAccessmanager class from Qt framework.
I'm assuming you need to use c++ for a reason, such as integration with existing software, otherwise, as per some of the other suggestions, choosing a language with a more convenient framework (eg: scripting language) would be better suited for the task.
If you would like to avoid getting your hands dirty with WINSOCK, or have the need to run on a platform other than windows, you could look at the using the boost asio library.
The following page contains links to simple sync and async http clients:
http://www.boost.org/doc/libs/1_37_0/doc/html/boost_asio/examples.html
You can find documentation on the library itself at:
http://www.boost.org/doc/libs/1_37_0/doc/html/boost_asio.html
Use c++ if you must, but it might be a lot less painful to use python.
Look at the Python httplib module for how to set the host you want to pull from etc. Python's available for free for most platforms and is enough like C++ that you can probably learn python a heck of a lot faster than you can learn to write a program controlled browser in c++. Well, maybe that's not true for everyone on this site, but I'll bet it's true for "most" of us. I used to get stock quotes updated in near real time from CNN Money years ago and IIRC it was around 100 lines of python code.
Hotei
okay i'm making a game using c++ (for the engine) and openGL, now i've had lots of trouble using cal3d library for importing my 3d max models into my c++ project,
as a matter of fact i dunno where to even start, i can't find any decent guide and their documentation is pure shit really. i've been searching and trying stuff in this for over a month, but i don't even understand the file structure it uses so far :S
i really need some help, r there any other libraries? any decent guide i can use? i'm stuck
thnx alot
Rather than write your own exporter, consider using one of the built-in exporters for FBX, COLLADA, Crosswalk (.XSI), the Quake/Doom3 .MD3/.MD4 format, or even OBJ. It'll be much easier to parse the resulting file format on your end than to write and maintain a brand-new exporter.
Max is a complete pain for any kind of scripting or plugin. I'd suggest using maya instead if at all possible. You'll get better results for animation and rigging, too. I know it's not a direct answer to your question but part of the problem is the info for stuff like this is not easy to come by.
So I understand that there are a few options available as far as parsing straight XML goes: NSXMLParser, TouchXML from TouchCode, etc. That's all fine, and seems to work fine for me.
The real problem here is that there are dozens of small variations in RSS feeds (and Atom feeds too), so supporting all possible permutations of feeds available out on the Internet gets very difficult to manage. I searched around for a library that would handle all of these low-level details for me, but came out without anything.
Since one could link to an external C/C++ library in Objective-C, I was wondering if there is a library out there that would be best suited for this task? Someone must have already created something like this, it's just difficult to find the "right" option from the thousands of results in Google.
Anyway, what's the best way to parse RSS/Atom feeds in an iPhone application?
I've just released an open source RSS/Atom Parser for iPhone and hopefully it might be of some use.
I'd love to hear your thoughts on it too!
"Best" is relative. The best performance you'll need to go the SAX route and implement the handlers. I don't know of anything out there open source available (start a google code project and release it for the rest of us to use!)
Whatever you do, it's probably a really bad idea to try and load the whole XML file into memory and act on it like a DOM. Chances are you'll get feeds that are much larger than you can handle on the device leading to frequent memory warnings and crashes.
I'm currently trying out the MWFeedParser #Michael Waterfall is developing.
Quite easy to set up and use (I'm a beginner iPhone developer).
His sample code for using MWFeedParser to populate a UITableViewController implementation is helpful as well.
take a look at apple's XML Performance sample -- which points to using libXML directly -- for performance and quicker updates to the display. Which may be important if you are working with very large feeds.
Check out my library for parsing Atom feeds, (BSAtomParser) at GitHub. It doesn't care about validating the feed, it does its best at returning whatever is valid. The parser covers most of RFC 4287, even extensions.
Here's my solution: a really simple yet powerful RSS parsing library: https://github.com/H2CO3/RSSKit
Have you looked at TouchCode yet? I don't think it has an RSS processor, but it might give you a start.
http://code.google.com/p/touchcode/
I came accross igasus project on sourceforge today. I haven't used it or really checked it, but perhaps it might help.
From their site:
igagus is a web service for the iPhone that allows aggregation of RSS to be delivered in an iPhone friendly format.
Actually, I was trying to suggest you ask on the TouchCode discussion board, because I remember someone was trying to expand it to support RSS. That might be a decent starting point. But I was being rushed by my wife.
But I see now that TouchCode doesn't have a discussion board. I'd still ask the author, though, he might know what came of that effort.
This might be a reasonable starting point for you. Atom support isn't there yet, but you could help out?