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| -rw-r--r-- | www/devmaster/lesson2.html | 4 | ||||
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| -rw-r--r-- | www/devmaster/lesson4.html | 4 | ||||
| -rw-r--r-- | www/devmaster/lesson5.html | 2 | ||||
| -rw-r--r-- | www/devmaster/lesson6.html | 2 | ||||
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| -rw-r--r-- | www/devmaster/lesson8.html | 427 |
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diff --git a/www/devmaster/lesson1.html b/www/devmaster/lesson1.html index e3be401..ffa1eff 100644 --- a/www/devmaster/lesson1.html +++ b/www/devmaster/lesson1.html @@ -1,7 +1,7 @@ <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> -<title>Untitled Document</title> +<title>Lesson 1: Single Static Source</title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <link rel="stylesheet" type="text/css" href="general.css"> </head> diff --git a/www/devmaster/lesson2.html b/www/devmaster/lesson2.html index 089205d..88a8756 100644 --- a/www/devmaster/lesson2.html +++ b/www/devmaster/lesson2.html @@ -2,7 +2,7 @@ <head> -<title>DevMaster.net - OpenAL Tutorials: Lesson 2</title> +<title>Lesson 2: Looping and Fade-away</title> </head> @@ -171,4 +171,4 @@ real quick and easy tutorial. It won't get too much more complicated at this poi </tr> </table> </body> -</html>
\ No newline at end of file +</html> diff --git a/www/devmaster/lesson3.html b/www/devmaster/lesson3.html index 05f0a5d..17ae9ba 100644 --- a/www/devmaster/lesson3.html +++ b/www/devmaster/lesson3.html @@ -1,7 +1,7 @@ <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> - <title>DevMaster.net Game Development</title> + <title>Lesson 3: Multiple Sources</title> </head> <body> <div Align=center> @@ -295,4 +295,4 @@ OpenAL Tutorials from DevMaster.net. Reprinted with Permission.<br> </tr> </table> </body> -</html>
\ No newline at end of file +</html> diff --git a/www/devmaster/lesson4.html b/www/devmaster/lesson4.html index 5084d2c..f3cf6a8 100644 --- a/www/devmaster/lesson4.html +++ b/www/devmaster/lesson4.html @@ -1,7 +1,7 @@ <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> - <title>DevMaster.net Game Development</title> + <title>Lesson 4: A Closer Look at ALC</title> </head> <body> <div Align=center> @@ -163,4 +163,4 @@ alc.alcCloseDevice(device); </table> <p align="justify"> </p> </body> -</html>
\ No newline at end of file +</html> diff --git a/www/devmaster/lesson5.html b/www/devmaster/lesson5.html index 66c3524..ad4d98b 100644 --- a/www/devmaster/lesson5.html +++ b/www/devmaster/lesson5.html @@ -1,7 +1,7 @@ <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> -<title>Untitled Document</title> +<title>Lesson 5: Sources Sharing Buffers</title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <link rel="stylesheet" type="text/css" href="general.css"> </head> diff --git a/www/devmaster/lesson6.html b/www/devmaster/lesson6.html index 4d557ea..0f85423 100644 --- a/www/devmaster/lesson6.html +++ b/www/devmaster/lesson6.html @@ -1,7 +1,7 @@ <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> -<title>Untitled Document</title> +<title>Lesson 6: Advanced Loading and Error Handles</title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <link rel="stylesheet" type="text/css" href="general.css"> </head> diff --git a/www/devmaster/lesson7.html b/www/devmaster/lesson7.html index 9b3dfd0..ff3a5ba 100644 --- a/www/devmaster/lesson7.html +++ b/www/devmaster/lesson7.html @@ -1,7 +1,7 @@ <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> -<title>Untitled Document</title> +<title>Lesson 7: The Doppler Effect</title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <link rel="stylesheet" type="text/css" href="general.css"> </head> diff --git a/www/devmaster/lesson8.html b/www/devmaster/lesson8.html new file mode 100644 index 0000000..4d68908 --- /dev/null +++ b/www/devmaster/lesson8.html @@ -0,0 +1,427 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html> +<head> + <title>Lesson 8: Ogg/Vorbis Streaming</title> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <link rel="stylesheet" type="text/css" href="general.css"> +</head> +<body> + +<div align="center"> + <img id="NavBar" src="http://games.dev.java.net/images/navbar2p.gif" usemap="#NavBar_MAP" nofinside="~! ~!" align="top" border="0" height="64" hspace="0" vspace="0" width="800"> </div> + +<map name="NavBar_Map"> +<area shape="rect" alt="Projects" coords="356,14,440,46" href="http://games.dev.java.net" target="_self"> +<area shape="rect" alt="Wiki" coords="643,14,695,46" href="http://wiki.java.net/bin/view/Games"> +<area shape="rect" alt="Weblogs" coords="562,15,624,46" href="http://weblogs.java.net/weblogs/project/games"> +<area shape="rect" coords="463,16,541,45" href="http://www.javagaming.org/cgi-bin/JGNetForums/YaBB.cgi" target="_top" alt="Forums"> +<area shape="rect" alt="JavaGames Home" coords="147,16,334,48" href="http://community.java.net/games"> +<area shape="rect" alt="Java.net" coords="21,15,128,46" href="http://www.java.net" target="_self"> +</map> + + +<br> + + +<br> + + +OpenAL Tutorials from DevMaster.net. Reprinted with Permission.<br> + + +<br> + + + +<table style="border-collapse: collapse;" id="AutoNumber1" bgcolor="#666699" border="0" cellpadding="0" cellspacing="0" height="12" width="100%"> + + + <tbody> + + <tr> + + + <td height="12" valign="middle" width="47%"> + + <p><b><font color="#ffffff">OpenAL + Tutorials</font></b></p> + + </td> + + + <td align="right" height="12" valign="middle" width="53%"> + + <p align="right"><a href="http://devmaster.net/"><font color="#66ff99">DevMaster.net</font></a></p> + + </td> + + + </tr> + + + + + </tbody> +</table> + + +<p class="title" align="left"><span class="title"><font size="5">Ogg/Vorbis Streaming +</font></span><font size="4"><br> + + +<b>Lesson 8</b></font></p> + + + +<p class="title" align="right"> <span class="author">Author: <a href="mailto:[email protected]"><font color="#888888">Jesse + Maurais<br> + + + </font></a></span>Adapted for Java by: <a href="mailto:[email protected]"><font color="#888888">Krishna + Gadepalli</font></a></p> + + +<p></p> + + + +<p><a href="http://download.java.net/media/joal/webstart/joal-lesson8.jnlp">Launch the Demo via Java Web Start</a> (not working yet)</p> + + + +<p align="justify">This is a translation of <a href="http://www.devmaster.net/articles/openal-tutorials/lesson8.php"> +OpenAL Lesson 8: OggVorbis Streaming Using The Source Queue</a> +tutorial from <a href="http://devmaster.net/">DevMaster.net</a> to JOAL. + +</p> + +<p> +<cite>"This software is based on or using the J-Ogg library available + from http://www.j-ogg.de and copyrighted by Tor-Einar Jarnbjo."</cite> + +</p> + +<h3>An Introduction to OggVorbis</h3> + + + +<p>Ever heard of Ogg? There's more to it than a funny sounding name. It's the +biggest thing to happen for audio compression since mp3's (also typically used +for music). Hopefully, one day, it will replace mp3's as the mainstream standard +for compressed audio. Is it better than mp3? That is a question that is a little +more difficult to answer. It's a pretty strong debate in some crowds. There are +various arguments about compression ratio vs. sound quality which can sometimes +get really cumbersome to read through. I personally don't have any opinion on +which is "better". I feel the evidence in either case is arguable and not worth +mentioning. But for me the fact that Ogg is royalty free (which mp3 is not) wins +the argument hands down. The mp3 licensing fee is by no means steep for +developers with deep pockets, but as an independent working on a project in your +spare time and on minimal resources, shelling out a few grand in fees is not an +option. Ogg may be the answer to your prayers.</p> + + + +<h3>Designing Your OggVorbis Streaming API</h3> + + +<p>Without further ado let's get to some code.</p> + + +<p>This tutorial will be written in Java and has two main classes: +<a href="https://joal-demos.dev.java.net/source/browse/joal-demos/src/java/demos/devmaster/lesson8/OggDecoder.java?view=markup"><var>OggDecoder</var></a> and +<a href="https://joal-demos.dev.java.net/source/browse/joal-demos/src/java/demos/devmaster/lesson8/OggStreamer.java?view=markup"><var>OggStreamer</var></a>. The +<var>OggDecoder</var> class is wrapper on the <a href="http://www.j-ogg.de">J-Ogg</a> library to decode an Ogg/Vorbis stream and will not be described in this +tutorial. <var>OggStreamer</var> which is the main class doing most of the working for streaming using OpenAL is explained below. + +</p> + +<pre class="code"> // The size of a chunk from the stream that we want to read for each update.<br> private static int BUFFER_SIZE = 4096*8;<br></pre> + + + +<p>'<var>BUFFER_SIZE</var>' defines how big a chunk we want +to read from the stream on each update. You will find (with a little +experimentation) that larger buffers usually produce better sound quality since +they don't update as often, and will generally avoid any abrupt pauses or sound +distortions. Of course making your buffer too big will also eat up more memory. +Making a stream redundant. I beleive 4096 is the minimum buffer size one can +have. I don't recommend using one that small. I tried, and it caused many +clicks.</p> + + +<p>So why should we even bother with streaming? Why not load the whole file into +a buffer and then play it? Well, that is a good question. The quick answer is +that there is too much audio data. Even though the actual Ogg file size is quite +small (usually around 1-3 MB) you must remember that is compressed audio data. +You cannot play the compressed form of the data. It must be decompressed and +formatted into a form OpenAL recognizes before it can be used in a buffer. That +is why we stream the file.</p> + + + +<pre class="code"> /**<br> * The main loop to initialize and play the entire stream<br> */<br> public boolean playstream() { ... }<br><br> /**<br> * Open the Ogg/Vorbis stream and initialize OpenAL based<br> * on the stream properties<br> */<br> public boolean open() { ... }<br><br> /**<br> * OpenAL cleanup<br> */<br> public void release() { ... }<br><br> /**<br> * Play the Ogg stream<br> */<br> public boolean playback() { ... }<br><br> /**<br> * Check if the source is playing<br> */<br> public boolean playing() { ... }<br><br> /**<br> * Update the stream if necessary<br> */<br> public boolean update() { ... }<br><br> /**<br> * Reloads a buffer (reads in the next chunk)<br> */<br> public boolean stream(int buffer) { ... }<br><br> /**<br> * Empties the queue<br> */<br> protected void empty() { ... }<br></pre> + + + +<p>This will be the base of our Ogg streaming api. The public methods are +everything that one needs to actually get the Ogg to play. Protected methods are +more internal procedures. I won't go over each function +just yet. I believe my comments should give you an idea of what they're for.</p> + + + +<pre class="code"> // Buffers hold sound data. There are two of them (front/back)<br> private int[] buffers = new int[2];<br> <br> // Sources are points emitting sound.<br> private int[] source = new int[1];<br> <br> private int format; // OpenAL data format<br> private int rate; // sample rate<br></pre> + + + +<p>First thing that I want to point out is that we have 2 buffers dedicated to +the stream rather than the 1 we have always used for wav files. This is +important. To understand this I want you to think about how double buffering +works in OpenGL/DirectX. There is a front buffer that is "on screen" at any +given second, while a back buffer is being drawn to. Then they are swapped. The +back buffer becomes the front and vice versa. Pretty much the same principle is +applied here. There is a buffer being played and one waiting to be played. When +the buffer being played has finished the next one starts. While the next buffer +is being played, the first one is refilled with a new chunk of data from the +stream and is set to play once the one playing is finished. Confused yet? I'll +explain this in more detail later on.</p> + + + +<pre class="code"> public boolean open() {<br> oggDecoder = new OggDecoder(url);<br><br> if (!oggDecoder.initialize()) {<br> System.err.println("Error initializing ogg stream...");<br> return false;<br> }<br> <br> if (oggDecoder.numChannels() == 1)<br> format = AL.AL_FORMAT_MONO16;<br> else<br> format = AL.AL_FORMAT_STEREO16;<br> <br> rate = oggDecoder.sampleRate();<br><br> ...<br> }<br></pre> + + + +<p>This creates a decoder for Ogg file, initializes it and grabs some information on the file. We extract the OpenAL format +enumerator based on how many channels are in the Ogg and then make a not of the sample rate.</p> + + + +<pre class="code"> public boolean open() {<br> ...<br><br> al.alGenBuffers(2, buffers, 0); check();<br> al.alGenSources(1, source, 0); check();<br><br> al.alSourcefv(source[0], AL.AL_POSITION , sourcePos, 0);<br> al.alSourcefv(source[0], AL.AL_VELOCITY , sourceVel, 0);<br> al.alSourcefv(source[0], AL.AL_DIRECTION, sourceDir, 0);<br> <br> al.alSourcef(source[0], AL.AL_ROLLOFF_FACTOR, 0.0f );<br> al.alSourcei(source[0], AL.AL_SOURCE_RELATIVE, AL.AL_TRUE);<br><br> ...<br> }<br></pre> + + + +<p>You've seen most of this before. We set a bunch of default values, position, +velocity, direction... But what is rolloff factor? This has to do with +attenuation. I will cover attenuation in a later article so I won't go too +in-depth, but I will explain it basically. Rolloff factor judges the strength of +attenuation over distance. By setting it to 0 we will have turned it off. This +means that no matter how far away the Listener is to the source of the Ogg they +will still hear it. The same idea applies to source relativity.</p> + + + +<pre class="code"> public void release() {<br> al.alSourceStop(source[0]);<br> empty();<br><br> al.alDeleteSources(1, source, 0); check();<br> al.alDeleteBuffers(2, buffers, 0); check();<br> }<br></pre> + + +<p>We can clean up after ourselves using this. We stop the source, empty out any +buffers that are still in the queue, and destroy our objects. + +</p> + +<pre class="code"> public boolean playback() {<br> if (playing())<br> return true;<br> <br> if (!stream(buffers[0]))<br> return false;<br> <br> if(!stream(buffers[1]))<br> return false;<br> <br> al.alSourceQueueBuffers(source[0], 2, buffers, 0);<br> al.alSourcePlay(source[0]);<br> <br> return true;<br> }<br></pre> + + + +<p>This will start playing the Ogg. If the Ogg is already playing then there is +no reason to do it again. We must also initialize the buffers with their first +data set. We then queue them and tell the source to play them. This is the first +time we have used '<var>alSourceQueueBuffers</var>'. What it does basically is give the +source multiple buffers. These buffers will be played sequentially. I will +explain more on this along with the source queue momentarily. One thing to make +a note of though: if you are using a source for streaming never bind a buffer to +it using '<var>alSourcei</var>'. Always use '<var>alSourceQueueBuffers</var>' consistently.</p> + + + +<pre class="code"> public boolean playing() {<br> int[] state = new int[1];<br> <br> al.alGetSourcei(source[0], AL.AL_SOURCE_STATE, state, 0);<br> <br> return (state[0] == AL.AL_PLAYING);<br> }<br></pre> + + +<p>This simplifies the task of checking the state of the source. </p> + + + +<pre class="code"> public boolean update() {<br> int[] processed = new int[1];<br> boolean active = true;<br><br> al.alGetSourcei(source[0], AL.AL_BUFFERS_PROCESSED, processed, 0);<br><br> while (processed[0] > 0)<br> {<br> int[] buffer = new int[1];<br> <br> al.alSourceUnqueueBuffers(source[0], 1, buffer, 0); check();<br><br> active = stream(buffer[0]);<br><br> al.alSourceQueueBuffers(source[0], 1, buffer, 0); check();<br><br> processed[0]--;<br> }<br><br> return active;<br> }<br></pre> + + +<p>Here is how the queue works in a nutshell: There is a 'list' of buffers. When +you unqueue a buffer it gets popped off of the front. When you queue a buffer it +gets pushed to the back. That's it. Simple enough?</p> + + +<p>This is 1 of the 2 most important methods in the class. What we do in this +bit of code is check if any buffers have already been played. If there is then +we start popping each of them off the back of the queue, we refill the buffers +with data from the stream, and then we push them back onto the queue so that +they can be played. Hopefully the Listener will have no idea that we have done +this. It should sound like one long continuous chain of music. The '<var>stream</var>' +function also tells us if the stream is finished playing. This flag is reported +back when the function returns.</p> + + + +<pre class="code"> public boolean stream(int buffer) {<br> byte[] pcm = new byte[BUFFER_SIZE];<br> int size = 0;<br><br> try {<br> if ((size = oggDecoder.read(pcm)) <= 0)<br> return false;<br> } catch (Exception e) {<br> e.printStackTrace();<br> return false;<br> }<br><br> ByteBuffer data = ByteBuffer.wrap(pcm, 0, size);<br> al.alBufferData(buffer, format, data, size, rate);<br> check();<br> <br> return true;<br> }<br></pre> + + +<p>This is another important method of the class. This part fills the buffers +with data from the Ogg bitstream. It's a little harder to get a grip on because +it's not explainable in a top down manner. '<var>oggDecoder.read</var>' does exactly what you may +be thinking it does; it reads data from the Ogg bitstream. The <a href="http://www.j-ogg.de/">j-ogg</a> library does all +the decoding of the bitstream, so we don't have to worry about that. This +function takes a <var>byte</var> array as an argument and will decode atmost the capacity of +this array. </p> + + +<p>The return value of '<var>oggDecoder.read</var>' indicates several things. If the value of the +result is positive then it represents how much data was read. This is important +because '<var>read</var>' may not be able to read the entire size requested (usually +because it's at the end of the file and there's nothing left to read). Use the +result of '<var>read</var>' over '<var>BUFFER_SIZE</var>' in any case. If the result of '<var>read</var>' +happens to be negative then it indicates that there was an error in the +bitstream. If the result happens to equal zero then there is nothing left in the file to play.</p> + + + +<p> The last part of this method is the call to '<var>alBufferData</var>' +which fills the buffer id with the data that we streamed from the Ogg using '<var>read</var>'. +We employ the '<var>format</var>' and '<var>rate</var>' values that we set up earlier</p> + + + +<pre class="code"> protected void empty() {<br> int[] queued = new int[1];<br> <br> al.alGetSourcei(source[0], AL.AL_BUFFERS_QUEUED, queued, 0);<br> <br> while (queued[0] > 0)<br> {<br> int[] buffer = new int[1];<br> <br> al.alSourceUnqueueBuffers(source[0], 1, buffer, 0);<br> check();<br><br> queued[0]--;<br> }<br><br> oggDecoder = null;<br> }<br></pre> + + +<p>This method will will unqueue any buffers that are pending on the source. </p> + + + +<pre class="code"> protected void check() {<br> if (al.alGetError() != AL.AL_NO_ERROR)<br> throw new ALException("OpenAL error raised...");<br> }<br></pre> + + +<p>This saves us some typing for our error checks.</p> + + + +<h3>Making Your Own OggVorbis Player</h3> + + +<p>If you're with me so far then you must be pretty serious about getting this +to work for you. Don't worry! We are almost done. All that we need do now is use +our newly designed class to play an Ogg file. It should be a relatively simple +process from here on in. We have done the hardest part. I won't assume that you +will be using this in a game loop, but I'll keep it in mind when designing the +loop. </p> + +<p>This should be a no-brainer. </p> + + +<pre class="code"> + public boolean playstream() { + if (!open()) + return false; + + oggDecoder.dump(); + + if (!playback()) + return false; + + while (update()) { + if (playing()) continue; + + if (!playback()) + return false; + } + + return true; + } +</pre> + +<p>The program opens the stream, dumps some stream information and then +will continually loop as long as the '<var>update</var>' method continues to +return true, and it will continue to return true as long as it can successfully +read and play the audio stream. Within the loop we will make sure that the Ogg +is playing.</p> + +<h3>Answers To Questions You May Be Asking</h3> + + +<h4>Can I use more than one buffer for the stream?</h4> + + +<p>In short, yes. There can be any number of buffers queued on the source at a +time. Doing this may actually give you better results too. As I said earlier, +with just 2 buffers in the queue at any time and with the cpu being clocked out +(or if the system hangs), the source may actually finish playing before the +stream has decoded another chunk. Having 3 or even 4 buffers in the queue will +keep you a little further ahead in case you miss the update.</p> + + +<h4>How often should I call ogg.update?</h4> + + +<p>This is going to vary depending on several things. If you want a quick answer +I'll tell you to update as often as you can, but that is not really necessary. +As long as you update before the source finishes playing to the end of the +queue. The biggest factors that are going to affect this are the buffer size and +the number of buffers dedicated to the queue. Obviously if you have more data +ready to play to begin with less updates will be necessary.</p> + + +<h4>Is it safe to stream more than one Ogg at a time?</h4> + + +<p>It should be fine. I haven't performed any extreme testing but I don't see +why not. Generally you will not have that many streams anyway. You may have one +to play some background music, and the occasional character dialog for a game, +but most sound effects are too short to bother with streaming. Most of your +sources will only ever have one buffer attached to them.</p> + + +<h4>So what is with the name?</h4> + + +<p>"Ogg" is the name of Xiph.org's container format for audio, video, and +metadata. "Vorbis" is the name of a specific audio compression scheme that's +designed to be contained in Ogg. As for the specific meanings of the words... +well, that's a little harder to tell. I think they involve some strange +relationship to Terry Pratchett novels. Here is a little page that goes into the +details.</p> + +<table style="border-collapse: collapse;" id="AutoNumber2" bgcolor="#666699" border="0" cellspacing="1" width="100%"> + + + <tbody> + + <tr> + + + <td width="40%"> + + <p dir="ltr"><font color="#ffffff" size="2">© 2003 DevMaster.net. + All rights reserved.</font></p> + + </td> + + + <td width="60%"> + + <p align="right" dir="ltr"><font size="2"><a href="mailto:[email protected]"> + <font color="#ffffff">Contact us</font></a><font color="#ffffff"> if you + want to write for us or for any comments, suggestions, or feedback.</font></font></p> + + </td> + + + </tr> + + + + </tbody> +</table> + + +<p> </p> + + +</body> +</html> |