Please help a designer - sound issue 
Author Message
 Please help a designer - sound issue

Hi, I'm a graphics designer and I dabble in the web, but mainly I'm a film
person. I've been trying to build a 3D world, but am having no luck getting
a sound file to play. If you would could you please see if you can find
anything wrong with my .WRL file at www.magicnet.net/~xavier/test.wrl I
would really appreciate it if you could tell me what I've done wrong (or
more appropriately what my Max2 exporter has done wrong) Thank you.

CS



Sat, 01 Jul 2000 03:00:00 GMT  
 Please help a designer - sound issue

Note for anyone else that's trying to get this url, the actual address
is:

www.magicnet.net/~xavier/test.WRL

I looked at the wrl file and the AudioClip node and Sound node looked
fine.  However the sound file (back.wav) is not in a format recognized
by any of my audio programs, and therefore certainly not by CosmoPlayer
and almost certainly not by any other vrml browser.  I suggest using one
of the more standard wav formats like straight uncompressed wav (i.e.,
PCM).

-Dave

Quote:

> Hi, I'm a graphics designer and I dabble in the web, but mainly I'm a film
> person. I've been trying to build a 3D world, but am having no luck getting
> a sound file to play. If you would could you please see if you can find
> anything wrong with my .WRL file at www.magicnet.net/~xavier/test.wrl I
> would really appreciate it if you could tell me what I've done wrong (or
> more appropriately what my Max2 exporter has done wrong) Thank you.

> CS

--


A Silicon Graphics Company  |   http://reality.sgi.com/chamber
  Phone: (650) 933-6414     |          http://doh.engr/


Sat, 01 Jul 2000 03:00:00 GMT  
 Please help a designer - sound issue

Quote:

>Note for anyone else that's trying to get this url, the actual address
>is:

>www.magicnet.net/~xavier/test.WRL

My apologies for the incorrect URL, yes the WRL should have been
capitalized. It slipped my mind that I had capitalized it due to an odd
error where my browser (Cosmo Player 2 with Internet Explorer 4) would not
load worlds without the extension capitalized. And thank you Mr Chamberlin
for the prompt and correct answer. It was most helpful. After experimenting
with different sound formats, I have found a format that works,
unfortunately I am faced with a new conundrum. The file now is 400 kb large.
Certainly this is not appropriate for a VRML world. Would anybody have any
suggestions as how to further diminish it's size? Other of course than
cutting the content short, it would not be possible. The clip contains a
song loop that absolutely must be at that duration. I would as always
welcome any comments.

CS



Sun, 02 Jul 2000 03:00:00 GMT  
 Please help a designer - sound issue

Quote:

> unfortunately I am faced with a new conundrum. The file now is 400 kb large.
> Certainly this is not appropriate for a VRML world. Would anybody have any
> suggestions as how to further diminish it's size? Other of course than
> cutting the content short, it would not be possible. The clip contains a
> song loop that absolutely must be at that duration.

I *was* going to suggest compressing it using MPEG Layer-II audio
compression.  However since you note that it must loop and the loop
point must be at the duration, you may have a problem.  The difficulty
with MPEG compression is that if your clip is not an exact multiple of
the packet size, then a little bit of silence will be tacked on to the
end.  So if you have a clip that depends on the end exactly matching the
beginning, you're most likely out of luck because you're probably going
to get a little slice of silence when it loops.  However, if you can
author the clip such that it fades out at the end and fades in at the
beginning, then you won't notice it.  If you can't do that, things get
tricky.  One option might be to try using ADPCM compression under WAV.
However not many audio utilities provide this as an export option.  I'm
not sure how much compression AVI provides, but you might also try
encoding it using AVI (with no video).  If the audio is not
high-fidelity, then you can also try using either mu-law or a-law
compression.

The ideal solution would be to use AIFC with MPEG Layer-II as the
encoding scheme.  AIFC allows you to specify the exact duration, so you
could avoid the silence-padding problem that MPEG Layer-II normally
has.  Unfortunately ActiveMovie/DirectShow does not currently support
AIFC so this is not an option.  We (CosmoSoftware) are looking into
writing an ActiveMovie filter node that could handle AIFC-wrapped MPEG
Layer-II audio, but that would be for a future release.

And in general, you can follow the following suggestions for reducing
the size of your audio clips:

1) Never use stereo if it's going to be spatialized.  You're just
sending down information that's going to get thrown away (you can only
spatialize a mono signal)
2) Only use as high a sampling rate as is necessary to adequately
represent your audio clip.  For example, if you have very low energy in
the frequency bands above 11Khz, then there's no sense in using anything
higher than 22Khz sampling rate (your sampling rate must be twice as
high as the highest frequency you wish to preserve).  For voice, which
generally has very low energy above 4Khz, even 8Khz sampling rates are
adequate.  Every time you half the sampling frequency, you half the size
of your file.  So a 44Khz sampled signal will be 4 times as large as an
11Khz sampled signal.
3) If possible, use MIDI.  While MIDI won't work for many situations, it
is very well suited for background music tracks and other music-related
audio.  The "compression" for MIDI is phenomenal (I'm using the word
compression loosely here since MIDI isn't a compression algorithm).  For
example, you could have a 3 minute music clip that's only 20k!

-Dave

--


A Silicon Graphics Company  |   http://reality.sgi.com/chamber
  Phone: (650) 933-6414     |          http://doh.engr/



Sun, 02 Jul 2000 03:00:00 GMT  
 
 [ 4 post ] 

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