• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0

SDL - inconsistent timing of sounds...?

4 posts in this topic

I'm trying to make an application which functions as a metronome, clicking at a rate of 60 BPM. I'm having issues though - if i use Mix_PlayChannel() to play a 'click' sound once every 1000ms, i seem to get something very different than a steady one click per second.

I recorded the sound output in Audacity and compared clicks, and they seem to be spread out by as little as 900ms and sometimes as much as 1100ms for no reason that I can see. I assumed something must have been thrown off somewhere, so in the function that plays the sound I added:

void play_click() {
    std::cout << "click on note " << n << " at " << SDL_GetTicks() << " ticks\n";
    Mix_PlayChannel( -1, metronome, 0 );

The output this gives me is this:

click on note 1 at 1116 ticks
click on note 2 at 2116 ticks
click on note 3 at 3116 ticks
click on note 4 at 4116 ticks
click on note 5 at 5116 ticks
click on note 6 at 6116 ticks
click on note 7 at 7116 ticks
click on note 8 at 8116 ticks
click on note 9 at 9116 ticks
click on note 10 at 10116 ticks
click on note 11 at 11116 ticks
click on note 12 at 12116 ticks
click on note 13 at 13116 ticks
click on note 14 at 14116 ticks
click on note 15 at 15116 ticks

So yeah, I'm thoroughly confused. The application reports that it is triggering the sound every time at a precisely 1000ms interval without even a millisecond's variance - but when you actually listen to the sound it outputs, it's all over the place.

Are there inherent timing problems with sound in SDL that I wasn't aware of or have i just done something dumb (I suspect the latter?)

Thank you for any help

Share this post

Link to post
Share on other sites

how many samples are being mixed at a time?...


basically, check the last parameter for Mix_OpenAudio().

rather than, say, 4096, try something like, say, 1024, and maybe see if it is any better...


Share this post

Link to post
Share on other sites

We probably can't help much if we can't tell how you initialized the audio system.


yeah... I mostly just made an educated guess... real code generally beats guesses though...


Share this post

Link to post
Share on other sites

I think if you don't have a realtime OS you cannot guarantee that timing is perfectly accurate. The problem could also be your soundcard. Musicians have external soundinterfaces with ultra low latency but this is just a guess. For windows you could try asio drivers and for linux the jack audio system.

Edited by sbradl

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  
Followers 0