I'm working on the sound part of an interactive installation that would need an event to be triggered by osc an undefined number of times, making the sound linked to it overlaps instead of being rewinded and started again.
Would it be possible to do that without needing to make an array of loadings of the same sound?
I'm actually trying to do it with processing and minim library.
Do you think it would be easier to achieve it with another programming software? I've found myself in the same difficulties trying to do it with puredata. Any tip or clue would be extremely welcome.
Thanks a lot.
You will need multiple readers ([tabread~] resp [tabplay~] in Pd; i don't know about Processing/minim, but the same principle applies) to read the table multiple times (in parallel), where each one can be started separately.
However, you only need a single instance of your data array (e.g. [table]), as the various readers can access the same array independently.
Can you use Java libraries in Processing? Processing is built on Java, yes?
If you can, I have a library you can use, supporting a class I call AudioCue available via github. This is modeled on a Java Clip but with additional capabilities. It allows multiple, concurrent playback. AudioCue also has real time controls for volume, panning and playback speed, in case you want to play around with adding some more interactivity to your installation.
I would love to know if it can be used with Processing. Please follow up with me if you try this route. I'd like to see it done, and can possibly assist.
If Processing allows you to send PCM directly out for playback, then the basic algorithm is the store the audio data in an array, and create pointers or cursors (depending on your preferred terminology) that independently iterate through that array. This is the main basis of the algorithm I use for AudioCue, with the PCM being routed out via a Java SourceDataLine.
I can't seem to find any information regarding the process that Ableton uses to efficiently detect atonal percussion and convert it into MIDI. I assume feature extraction and onset detection algorithms are executed, but I'm intrigued as to what algorithms. I am particularly interesting how its efficiency is maintained for a beatboxed input.
Cheers
Your guesses are as good as everyone else's - although they look plausible. The reality is that the way this feature is implemented in Ableton is a trade secret and likely to remain that way.
If I'm not mistaken Ableton licenses technology from https://www.zplane.de/ for these things.
I don't exactly know how the software assigns the different drum sounds, but the chapter in the live manual Convert Drums to New MIDI Track says that it can only detect kick, snare and hi-hat. An important thing is that they are identified by the transient Markers. For a good result you should manually check and adjust them. The transient Markers look like the warp Markers, but are grey.
compared to a kick and a snare for example, a beatboxed input is likely to have less difference between the individual sounds and therefore likely to be harder for Ableton to individually extract the seperate sounds (depends on the beatboxer). In any case, some combination of frequency and amplitude - more specifically(Attack, Decay, Sustain, Release) as well as perhaps the different overtone combinations that account for differences in timbre are going to be the characteristics that would have to be evaluated in order to separate the kick snare and hihat .
Before this feature existed I used gates and hi/low pass filters to accomplish a similar task. So perhaps Ableton's solution is not as complicated as we might imagine.
I'm working on an app which needs to draw with OpengGL at a refresh rate at least equal to the refresh rate of the monitor. And I need to perform the drawing in a separate thread so that drawing is never locked by intense UI actions.
Actually I'm using a NSOpenGLView in combination with CVDisplayLink and I'm able to achive 60-80FPS without any problem.
Since I need also to display some cocoa controls on top of this view I tried to subclass NSOpenGLView and make it layer-backed, following LayerBackedOpenGLView Apple example.
The result isn't satisfactory and I get a lot of artifacts.
Therefore I've solved the problem using a separate NSWindow to host the cocoa controls and adding this window as a child window of the main window containing the NSOpenGLView.
It works fine and I'm able to get quite the same FPS as the initial implementation.
Since I consider this solution quite like a dirty hack, I'm looking for an alternative and more clean way of achiving what I need.
Few days ago I came across NSOpenGLLayer and I thought that it could be used as a viable solution for my problem.
So finally, after all this preamble, here comes my question:
is it possible to draw to a NSOpenGLLayer from a separate thread using CVDisplayLink callback?.
So far I've tried to implement this but I'm not able to draw from the CVDisplayLink callback. I can only -setNeedsDisplay:TRUE on the NSOpenGLLayer from the CVDisplayLink callback and then perform the drawing in -drawInOpenGLContext:pixelFormat:forLayerTime:displayTime: when it gets automatically called by cocoa. But I suppose that this way I'm drawing from the main thread, isn't it?
After googling for this I've even found this post in which the user claims that under Lion drawing can occur only inside -drawInOpenGLContext:pixelFormat:forLayerTime:displayTime:.
I'm on Snow Leopard at the moment but the app should run flawlessly even on Lion.
Am I missing something?
Yes, it is possible, though not recommend. Call display on the layer from within your CVDisplayLink. This will cause canDrawInContext:... to be called and if it returns YES, drawInContext:... will be called and all this on whatever thread called display. To make the rendered image visible on screen, you have to call [CATransaction flush]. This method has been suggested on the Apple mailing list, though it is not completely problem free (the display method of other view may get called on your background thread as well and not all views support rendering from a background thread).
The recommend way is to make the layer asynchronous and render the OpenGL context on main thread. If you cannot achieve a good framerate that way, since your main thread is busy elsewhere, it is recommend to rather move everything else (pretty much your whole application logic) to other threads (e.g. using Grand Central Dispatch) and only keep user input and drawing code on the main thread. If your window is very big, you may still not get anything better than 30 FPS (one frame ever two screen refreshes), yet that comes from the fact, that CALayer composition seems a rather expensive process and it has been optimized for more or less static layers (e.g. layers containing a picture) and not for layers updating themselves 60 FPS.
E.g. if you are writing a 3D game, you are advised not to mix CALayers with OpenGL content at all. If you need Cocoa UI elements, either keep them separated from your OpenGL content (e.g. split the window horizontally into a part that displays only OpenGL and a part that only displays controls) or draw all controls yourself (which is pretty common for games).
Last but not least, the two window approach is not as exotic as you may think, that's how VLC (the video player) draws its controls over the video image (which is also rendered by OpenGL on Mac).
I am currently helping someone with a reaction time experiment. For this experiment reaction times on the keyboard are measured. For this experiment it might be important to know, how much error could be introduced because of the delay between the key-press and the processing in the software.
Here are some factors that I found out using google already:
The USB-bus is polled at 125Hz at minimum and 1000Hz at maximum (depending on settings, see this link).
There might be some additional keyboard buffers in Windows that might delay the keypresses further, but I do not know about the logic behind those.
Unfortunately it is not possible to control the low level logic of the experiment. The experiment is written in E-Prime a software that is often used for this kind of experiments. However the company that offers E-Prime also offers additional hardware, that they advertise for precise reaction-timing. Hence they seem to be aware about this effect (but do not tell how large it is).
Unfortunately it is necessary to use a standart keyboard, so I need to provide ways to reduce the latency.
any latency from key presses can be attributed to the debounce routine (i usually use 30ms to be safe) and not to the processing algorithms themselves (unless you are only evaluating the first press).
If you are running an experiment where millisecond timing is important you may want to use http://www.blackboxtoolkit.com/ to find sources of error.
Your needs also depend on the nature of your study. I've run RT experiments in Eprime with a keyboard. Since any error should be consistent on average across participants, for some designs it is not a big problem. If you need to sync up the data though with something else (like Eye tracking or EEG) or want to draw conclusions about RT where specific magnitude is important then E-Primes serial resp box (or another brand, though I have had compatibility issues in the past with other brand boxes and eprime) is a must.
I am in the process of developping a game, and after two months of work (not full time mind you), I have come to realise that our specs for the game are lacking a lot of details. I am not a professional game developper, this is only a hobby.
What I would like to receive help or advices for is this: What are the major components that you find in games, that have to be developped or already exists as librairies? The objective of this question is for me to be able to specify more game aspects.
Currently, we had specified pretty much only how we would work on the visual, completely forgetting everything about game logic (AI, Entities interactions, Quest logic (how do we decide whether or not a quest is completed)).
So far, I have found those points:
Physics (collision detection, actual forces, etc.)
AI (pathfinding, objectives, etc.)
Model management
Animation management
Scene management
Combat management
Inventory management
Camera (make sure not to render everything that is in the scene)
Heightmaps
Entities communication (Player with NPC, enemy, other players, etc)
Game state
Game state save system
In order to reduce the scope of this queston, I'd like it if you could specifically discuss aspects related to developping an RPG type of game. I will also point out that I am using XNA to develop this game, but I have almost no grasp of all the classes available yet (pretty much only using the Game component with some classes that are related to it such as GameTime, SpriteBatch, GraphicDeviceManager) but not much more.
You have a decent list, but you are missing storage (save load), text (text is important in RPGs : Unicode, font rendering), probably a macro system for text (something that replaces tokens like {player} with the player characters name), and most important of all content generation tools (map editor, chara editor, dialog editor) because RPGs need content (or auto generation tools if you need ). By the way have links to your work?
I do this exact stuff for a living so if you need more pointers perhaps I can help.
I don't know if this is any help, but I have been reading articles from http://www.gamasutra.com/ for many years.
I don't have a perfect set of tools from the beginning, but your list covers most of the usual trouble for RUNNING the game. But have you found out what each one of the items stands for? How much have you made already? "Inventory Management" sounds very heavy, but some games just need a simple "array" of objects. Takes an hour to program + some graphical integration (if you have your GUI Management done already).
How to start planning
When I develop games in my spare time, I usually get an idea because another game lacks this function/option. Then I start up what ever development tool I am currently using and try to see if I can make a prototype showing this idea. It's not always about fancy graphics, but most often it's more about finding out how to solve a certain problem. Green and red boxes will help you most of the way, but otherwise, use Google Images and do a quick search for prototype graphics. But remember that these images are probably copyrighted, so only use them for internal test purposes and to explain to your graphic artists what type of game/graphic you want to make.
Secondly, you'll find that you need to find/build tools to create the "maps/missions/quests" too. Today many develop their own "object script" where they can easily add new content/path to a game.
Many of the ideas we (my friends and I) have been testing started with a certain prototype of the interface, to see if its possible to generate that sort of screen output first. Then we build a quick'n'dirty map/level-editor that can supply us with test maps.
No game logic at this point, still figuring out if the game-engine in general is running.
My first game-algorithm problem
Back when I was in my teens I had a Commodore 64 and I was wondering, how do they sort 10 numbers in order for a Highscore? It took me quite a while to find a "scalable" way of doing this, but I learned a lot about programming too.
The second problem I found
How do I make a tank/cannon fire a bullet in the correct direction when I fly my helicopter around the screen?
I sat down and drew quick sketches of the actual problem, looked at the bullet lines, tried some theories of my own and found something that seemed to be working (by dividing and multiplying positions etc.) later on in school I discovered this to be more or less Pythagoras. LOL!
Years and many game attempts later
I played "Dune" and the later C&C + the new game Warcraft (v1/v2) - I remember it started to annoyed me how the lame AI worked. The path finding algorithms were frustrating for the player, I thought. They moved in direction of target position and then found a wall, but if the way was to complex, the object just stopped. Argh!
So I first sat with large amounts of paper, then I tried to draw certain scenarios where an "object" (tank/ork/soldier) would go from A to B and then suddenly there was a "structure" (building/other object) in the pathway - what then?
I learned about A-star pathfinding (after solving it first on my own in a similar way, then later reading about the reason for this working). A very "cpu heavy" way of finding a path, but I learned a lot from the process of "cracking this nut". These thoughts have helped me a lot developing other game algortimes over time.
So what I am saying is: I think you'll have to think more of:
How is the game to be played?
What does the user experience look like?
Why would the user want to come back to the game?
What requirements are needed? Broadband? 19" monitor with 1280x1024?
An RPG, yes - but will it be multi-user or single?
Do we need a fast network/server setup or do we need to develop a strong AI for the NPCs?
And much more...
I am not sure this is what you asked for, but I hope you can use it somehow?
There are hundreds of components needed to make a game, from time management to audio. You'll probably need to roll your own GUI, as native OS controls are very non-gamey. You will probably also need all kinds of tools to generate your worlds, exporters to convert models and textures into something suitable for your game etc.
I would strongly recommend that you start with one of the many free or cheap game engines that are out there. Loads of them come with the source code, so you can learn how they have been put together as you go.
When you think you are ready, you can start to replace parts of the engine you are using to better suit your needs.
I agree with Robert Gould's post , especially about tools and I'd also add
Scripting
Memory Management
Network - especially replication of game object states and match-making
oh and don't forget Localisation - particularly for text strings
Effects and effect timers (could be magical effects, could just be stuff like being stunned.)
Character professions, skills, spells (if that kind of game).
World creation tools, to make it easy for non-programmer builders.
Think about whether or not you want PvP. If so, you need to really think about how you're going to do your combat system and any limits you want on who can attack whom.
Equipment, "treasure", values of things and how you want to do the economy.
This is an older question, but IMHO now there is a better answer: use Unity (or something akin to it). It gives you 90% of what you need to make a game up front, so you can jump in and focus directly on the part you care about, which is the gameplay. When you run aground because there's something it doesn't do out of the box, you can usually find a resource in the Asset Store for free or cheap that will save you a lot of work.
I would also add that if you're not working on your game full-time, be mindful of the complexity and the time-frame of the task. If you'll try to integrate so many different frameworks into your RPG game, you can easily end up with several years worth of work; maybe it would be more advisable to start small and only develop the "core" of your game first and not bother about physics, for example. You could still add it in the second version.