Re: [Flightgear-devel] doppler volume
James Sleeman wrote Hi Maik, Maik Justus wrote: the effect you are discussing is not the Doppler effect, but just the Yes, I know it's not a function of the Doppler itself, but I was thinking more along the lines of the volume drop off, if it were better, might help the convincingness of the Doppler, if you see what I mean. volume as a function of the distance. Every aircraft has its own sound definition including the distance, where the volume is halved (reference-dist) and the distance where the volume is cutted off (max-dist). Hmm, interesting. It seems that a great many aircraft do not define these values at all. Is there a default definition for these somewhere, is one calculated by openal maybe in the absence of these specific settings? At the end of this message is a quick grep showing the aircraft which do not define reference-dist. Quite a list. Just to clarify on the reference-dist, is it that this value is a diminishing effect, that is for reference-dist of 1 after distance 1 the volume is half original, after distance 2 the volume is 1/4 original (half of a half), distance 3 it's an 1/8th (half of a quarter). Or is it simply that at that specific distance, and for infinity beyond until max-dist the volume is always half the original? snip ... In simgear\source\simgear\sound\xmlsound.cxx I see that default values for reference-dist and max-dist seem to be specifed. It seems possible that these default values are no longer honoured. I think they worked at one time. It is going to be extremely tedious and time consuming to explicitly apply specific values to _every_ sound in fg. I would think that the attenuation of sound in air is amenable to mathematical calculation. Surely we shouldn't be guessing at some arbitrary reference distance? Vivian -- This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] doppler volume
Hello, James Sleeman schrieb am 22.01.2009 01:14: Hi Maik, ... Just to clarify on the reference-dist, is it that this value is a diminishing effect, that is for reference-dist of 1 after distance 1 the volume is half original, after distance 2 the volume is 1/4 original (half of a half), distance 3 it's an 1/8th (half of a quarter). yes, exactly. Maik -- This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] doppler volume
Hi, Maik Justus schrieb am 22.01.2009 13:45: Hello, James Sleeman schrieb am 22.01.2009 01:14: Hi Maik, ... Just to clarify on the reference-dist, is it that this value is a diminishing effect, that is for reference-dist of 1 after distance 1 the volume is half original, after distance 2 the volume is 1/4 original (half of a half), distance 3 it's an 1/8th (half of a quarter). yes, exactly. not exactly, it's 1/8th at distance 4 (doubled distance result in half volume). Maik -- This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] doppler volume
Hi Vivian, Vivian Meazza schrieb am 22.01.2009 11:17: I would think that the attenuation of sound in air is amenable to mathematical calculation. Yes it is. (at lest if your distance to the sound source is large compared to the size of the source). Surely we shouldn't be guessing at some arbitrary reference distance? The problem is, we don't know, which distance the author was thinking about, as he defined/recorded the sound. For in-cockpit sounds the distance from the sound source to the cockpit may be a good guess, for out-of cockpit sounds the typical viewing distance of the aircraft could be a good guess, too. Therefore we will have two different guesses for e.g. the engine sound (as long as there are no different sounds defined for cockpit and external view)... Vivian Maik -- This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] doppler volume
* Maik Justus -- Thursday 22 January 2009: Vivian Meazza schrieb am 22.01.2009 11:17: I would think that the attenuation of sound in air is amenable to mathematical calculation. Yes it is. But it depends on the frequency pattern, no? So we'd need to analyze the spectrum ... time to use libfftw3. :-) I don't see why adding these values to the sound config should be such a problem. Don't we specify animation parameters to the smallest detail? Why should sound be different? OTOH, I would support global default values max-dist and reference-dist in preferences.xml, which an aircraft could override. And finally, every sound definition can still define its own values like before. JFTR: The bo105 sets these values since a while. :-P m. -- This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] doppler volume
Melchior FRANZ Subject: Re: [Flightgear-devel] doppler volume * Maik Justus -- Thursday 22 January 2009: Vivian Meazza schrieb am 22.01.2009 11:17: I would think that the attenuation of sound in air is amenable to mathematical calculation. Yes it is. But it depends on the frequency pattern, no? So we'd need to analyze the spectrum ... time to use libfftw3. :-) Well even taking some arbitrary mid frequency would be better than a wild guess. I don't see why adding these values to the sound config should be such a problem. Don't we specify animation parameters to the smallest detail? Why should sound be different? And usually there are default values. OTOH, I would support global default values max-dist and reference-dist in preferences.xml, which an aircraft could override. And finally, every sound definition can still define its own values like before. I don't see any particular merit is setting the value in preferences.xml, but it would be nice if the default values worked as designed, no matter where they are set. JFTR: The bo105 sets these values since a while. :-P Well done, but what do you base the values on? Vivian -- This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] doppler volume
* Vivian Meazza -- Thursday 22 January 2009: Melchior FRANZ I don't see any particular merit is setting the value in preferences.xml, but it would be nice if the default values worked as designed, no matter where they are set. It's always nice to have default values changeable, rather than hard-coded. So a property is the right choice. And preferences.xml is the place to initialize properties. And then, these values might have to be changed at runtime: Sound propagation also depends on the atmosphere, the terrain, etc. Probably nobody would ever bother, but having the possibility doesn't hurt either. JFTR: The bo105 sets these values since a while. :-P Well done, but what do you base the values on? Real life experience and guessing. That's not much worse than an unscientific calculation. If somebody doesn't like the values, just complain and I might change them. m. -- This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
[Flightgear-devel] doppler volume
The doppler effect (which I currently have working through the USE_SOFTWARE_DOPPLER define) has never sounded very real to my ear. Recently I've wondered if it might be to do with the volume dropoff not being enough. It's hard to subjectively quantify the dropoff in the flyby, but for example if we switch to tower view, it seems you can always hear the aircraft no matter how far away you get, for example, I was 100 miles from the tower and yet I had no trouble hearing the aircraft at all. Is the dropoff (if there is one at all, perhaps my mind is filling in the blank and making one), configurable at all through some property, I couldn't find one? It would be good to be able to play around with the numbers and see if it makes an improvement to the subjective convincingness of the doppler effect. --- James Sleeman -- This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] doppler volume
Hi James, the effect you are discussing is not the Doppler effect, but just the volume as a function of the distance. Every aircraft has its own sound definition including the distance, where the volume is halved (reference-dist) and the distance where the volume is cutted off (max-dist). The volume as a function of the distance is calculated by Openal. Therefore we need to know the aircraft, with wich you have the wrong effect and the kind of sound (most probably the engine sound?). If the sound configuration for this specific sound has reasonable definition for reference-dist we need to know your operating system and openal version. With this information other users can check, if they have the same problem. Maybe we can drill it down to a openal problem or maybe the distance passed to openal is wrong... Unfortunately I actually do not have a running flightgear; therefore I can not perform tests. Maik James Sleeman schrieb am 21.01.2009 13:46: The doppler effect (which I currently have working through the USE_SOFTWARE_DOPPLER define) has never sounded very real to my ear. Recently I've wondered if it might be to do with the volume dropoff not being enough. It's hard to subjectively quantify the dropoff in the flyby, but for example if we switch to tower view, it seems you can always hear the aircraft no matter how far away you get, for example, I was 100 miles from the tower and yet I had no trouble hearing the aircraft at all. Is the dropoff (if there is one at all, perhaps my mind is filling in the blank and making one), configurable at all through some property, I couldn't find one? It would be good to be able to play around with the numbers and see if it makes an improvement to the subjective convincingness of the doppler effect. --- James Sleeman -- This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] doppler volume
Hi Maik, Maik Justus wrote: the effect you are discussing is not the Doppler effect, but just the Yes, I know it's not a function of the Doppler itself, but I was thinking more along the lines of the volume drop off, if it were better, might help the convincingness of the Doppler, if you see what I mean. volume as a function of the distance. Every aircraft has its own sound definition including the distance, where the volume is halved (reference-dist) and the distance where the volume is cutted off (max-dist). Hmm, interesting. It seems that a great many aircraft do not define these values at all. Is there a default definition for these somewhere, is one calculated by openal maybe in the absence of these specific settings? At the end of this message is a quick grep showing the aircraft which do not define reference-dist. Quite a list. Just to clarify on the reference-dist, is it that this value is a diminishing effect, that is for reference-dist of 1 after distance 1 the volume is half original, after distance 2 the volume is 1/4 original (half of a half), distance 3 it's an 1/8th (half of a quarter). Or is it simply that at that specific distance, and for infinity beyond until max-dist the volume is always half the original? Here is the list, checking for max-dist yields basically the same result. for file in *; do fgrep -r reference-dist $file /dev/null; if [ $? != 0 ]; then echo $file - no reference-dist; fi; done 14bis - no reference-dist 707 - no reference-dist 737 - no reference-dist 737-300 - no reference-dist 747 - no reference-dist 747-200 - no reference-dist 787 - no reference-dist a10 - no reference-dist A-10 - no reference-dist A300 - no reference-dist A320 - no reference-dist A320-family - no reference-dist A380 - no reference-dist a4 - no reference-dist A-6E - no reference-dist A6M2 - no reference-dist airwaveXtreme150 - no reference-dist Albatross - no reference-dist Alphajet - no reference-dist an225 - no reference-dist AN-225 - no reference-dist AR-234 - no reference-dist as350 - no reference-dist ASK21 - no reference-dist asw20 - no reference-dist ATC - no reference-dist B-17 - no reference-dist B-1B - no reference-dist B-2 - no reference-dist b29 - no reference-dist b52 - no reference-dist B-52F - no reference-dist BAC-TSR2 - no reference-dist beaufighter - no reference-dist bell206 - no reference-dist Bernard-HV220 - no reference-dist bf109 - no reference-dist bleriot-XI - no reference-dist bocian - no reference-dist Buccaneer - no reference-dist Bugatti - no reference-dist c172x - no reference-dist c182 - no reference-dist c182rg - no reference-dist C-2A - no reference-dist c310u3a - no reference-dist C550B - no reference-dist C684 - no reference-dist CanberraBI8 - no reference-dist Caravelle - no reference-dist Carreidas - no reference-dist Citation - no reference-dist colditz - no reference-dist couzinet70 - no reference-dist dc3 - no reference-dist DerKleineUhu - no reference-dist DH-88 - no reference-dist DH-89 - no reference-dist DO-335 - no reference-dist DO-X - no reference-dist Dragonfly - no reference-dist E3B - no reference-dist ec130 - no reference-dist eurofighter - no reference-dist f104 - no reference-dist F-106-dart - no reference-dist f-14b - no reference-dist f15 - no reference-dist f15c - no reference-dist f16 - no reference-dist f18 - no reference-dist F4U - no reference-dist F80C - no reference-dist F-86 - no reference-dist F-8E - no reference-dist F-8E-Crusader - no reference-dist Farman-IV - no reference-dist fkdr1 - no reference-dist fokker100 - no reference-dist fokker50 - no reference-dist fw190 - no reference-dist harrier - no reference-dist He162 - no reference-dist HondaJet - no reference-dist Hornet - no reference-dist Hunter - no reference-dist Instruments - no reference-dist Instruments-3d - no reference-dist j22 - no reference-dist j3cub - no reference-dist j7w - no reference-dist jeep - no reference-dist ju52 - no reference-dist KC135 - no reference-dist Ki-84 - no reference-dist Lightning - no reference-dist Lockheed-SR71 - no reference-dist Macchi-Castoldi-MC72 - no reference-dist Malolo1 - no reference-dist marchetti - no reference-dist MD11 - no reference-dist MIBS - no reference-dist MiG-15 - no reference-dist Mig-29 - no reference-dist mirage2000 - no reference-dist MPCarrier - no reference-dist NTPS - no reference-dist ogel - no reference-dist OH-1 - no reference-dist ornithopter - no reference-dist OV10_USAFE - no reference-dist P-38-Lightning - no reference-dist p51d - no reference-dist paraglider - no reference-dist payen-pa100 - no reference-dist PC-6 - no reference-dist pc7 - no reference-dist pushback - no reference-dist Rascal - no reference-dist SaabJ35Draken - no reference-dist santa - no reference-dist seahawk - no reference-dist SeaVixen - no reference-dist sgs126 - no reference-dist sgs233 - no reference-dist shuttle - no reference-dist Skyvan - no reference-dist snowplow - no reference-dist
