Hi fellow wiki editors!

To help newly registered users get more familiar with the wiki (and maybe older users too) there is now a {{Welcome to the wiki}} template. Have a look at it and feel free to add it to new users discussion pages (and perhaps your own).

I have tried to keep the template short, but meaningful. /Johan G

Difference between revisions of "FlightGear Newsletter February 2011"

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(Sound files for 3D Audio)
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== Development news ==
 
== Development news ==
 
===Sound files for 3D Audio===
 
===Sound files for 3D Audio===
Recently there seems to be some confusion about what types of sound files are supported for 3D audio rendering. More and more stereo files showed up resulting in reports of soundmanager problems. Let's explain a bit more about how 3D audio works, especially for OpenAL.
+
There seems to be some confusion about what types of sound files are supported for 3D audio rendering. Let's explain a bit more about how 3D audio works.
  
A 3D audio, or spatialized audio, implementation consists of one listener (like the OpenGL viewer) and multiple audio sources. A listener is placed at a specific location and has an orientation (view direction). Sources are placed in the scene at their own location and an emission direction which is used to calculate the sound cone for non omni-directional sounds (sound sources that sound louder in one direction and softer or even quiet in the opposite direction). Sound sources can best be seen as a single dot emitting sound waves.
+
A 3D audio, or spatialized audio, implementation consists of one listener (like the OpenGL viewer) and multiple audio sources. A listener is placed at a specific location and has an orientation (view direction). Sources are placed in the scene at their own location and have an emission direction which is used to calculate the sound cone for non omni-directional sounds (sound sources that sound louder in one direction and softer or even quiet in the opposite direction). Sound sources can best be seen as a single dot emitting sound waves.The relative positions of the sources and the listener is used to calculate where the sources should be positioned in the listeners sound sphere.
  
The relative positions of the sources and the listener are used to calculate where the sources should be positioned in the listeners sound sphere. Now if a sound source would be anything but mono it is almost impossible to guess how to handle all the channels in 3D space;
+
If a sound source would be anything but mono it is almost impossible to guess how to handle all the channels in 3D space;
* do they get mixed together which makes stereo files rather useless anyhow.
+
* Do they get mixed together?
* do the the separate tracks get positioned with a slight offset to each other, which basically means mixing them together at any distance but very near.
+
* Do the tracks get positioned with a slight offset to each other? This in effect means mixing them together when the source is not close to the listener.
* or do they get positioned at the same location but with a sound direction offset of 180⁰, which again means mixing them together for omni-directional sources.
+
* Do they get positioned at the same location but with a sound direction offset of 180⁰? This means mixing them together if the sound is omni-directional.
  
 
There is something to say for any of the choices but you can bet that if one of the three was chosen someone else comes by and wants it to be different.
 
There is something to say for any of the choices but you can bet that if one of the three was chosen someone else comes by and wants it to be different.
  
For this reason it is specified that only mono files will be used for 3D audio processing and stereo files will mixed using the stereo mixer instead. Trying to set a position or direction for a stereo file will result in an error like:
+
For this reason it is specified that only mono files will be used for 3D audio processing and stereo files will be mixed using the stereo mixer instead. Trying to set a position or direction for a stereo file will result in an error like:
 
  ''Failed to load WAV file: Unsupported mode within an otherwise usable file type''
 
  ''Failed to load WAV file: Unsupported mode within an otherwise usable file type''
  

Revision as of 04:58, 5 February 2011

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Welcome to the FlightGear Newsletter!
Please help us write the next edition!
Enjoy reading the latest edition!


We would like to emphasize that the monthly newsletter can not live without the contributions of FlightGear users and developers. Everyone with a wiki account (free to register) can edit the newsletter and every contribution is welcome. So if you know about any FlightGear related projects such as for example updated scenery or aircraft, please do feel invited to add such news to the newsletter.


FlightGear events

Development news

Sound files for 3D Audio

There seems to be some confusion about what types of sound files are supported for 3D audio rendering. Let's explain a bit more about how 3D audio works.

A 3D audio, or spatialized audio, implementation consists of one listener (like the OpenGL viewer) and multiple audio sources. A listener is placed at a specific location and has an orientation (view direction). Sources are placed in the scene at their own location and have an emission direction which is used to calculate the sound cone for non omni-directional sounds (sound sources that sound louder in one direction and softer or even quiet in the opposite direction). Sound sources can best be seen as a single dot emitting sound waves.The relative positions of the sources and the listener is used to calculate where the sources should be positioned in the listeners sound sphere.

If a sound source would be anything but mono it is almost impossible to guess how to handle all the channels in 3D space;

  • Do they get mixed together?
  • Do the tracks get positioned with a slight offset to each other? This in effect means mixing them together when the source is not close to the listener.
  • Do they get positioned at the same location but with a sound direction offset of 180⁰? This means mixing them together if the sound is omni-directional.

There is something to say for any of the choices but you can bet that if one of the three was chosen someone else comes by and wants it to be different.

For this reason it is specified that only mono files will be used for 3D audio processing and stereo files will be mixed using the stereo mixer instead. Trying to set a position or direction for a stereo file will result in an error like:

Failed to load WAV file: Unsupported mode within an otherwise usable file type

Nasal for newbies

New software tools and projects

FlightGear addons and mods

In the hangar

New aircraft

Updated aircraft

Liveries

Scenery corner

Airports

Aircraft of the month

Airport of the month

Screenshot of the month

Piper J3 Cub

Suggested flights

Aircraft reviews

Wiki updates

New articles

<DynamicArticleList>

 type=new
 count=10

</DynamicArticleList>

New aircraft articles

<DynamicArticleList>

 type=new
 count=10
 categoryRoot=Aircraft

</DynamicArticleList>

Most popular newsletters

<DynamicArticleList>

 type=hot
 count=5
 categoryRoot=FlightGear Newsletter

</DynamicArticleList>

Community news

FlightGear on youtube

New tutorials and screencasts

Forum news

Multiplayer

Virtual airlines

Useful links

And finally ...

Contributing

One of the regular thoughts expressed on the FlightGear forums is "I'd like to contribute but I don't know how to program, and I don't have the time". Unfortunately, there is a common misconception that contributing requires programming and lots of free time. In fact, there are a huge range of ways to contribute to the project without needing to write code or spending days working on something.

For ideas on starting to contribute to FlightGear, you may want to check out: Volunteer.

Call for volunteers

The OpenRadar project is looking for a new maintainer.

The TerraGear GUI project is looking for programmers to help create a GUI frontend for TerraGear [1].

The FGFSPM (FlightGear Package Manager) is looking for a new maintainer.

Reminder: Google's Summer of Code 2011

FlightGear project is planning to participate in GSoC 2011. However, doing that really requires a fair amount of work, planning and organizing. This is not something that can be done by a single person. It really needs a coordinated team effort, or otherwise FlightGear won't be able to apply/participate at all, and has not participated in past years.

So all users are invited to help us progress further with our preparations for GSoC 2011. If you have any questions or other feedback, please use the forum to get in touch.

Thanks for reading FlightGear Newsletter February 2011