Audio file formats

[David Conley]

I want to use 5.1 surround for my halloween display. I have found how to encode to a digital stream on the fly and now I need to be able to process some type of audio through LOR without folding the audio down to stereo. Is there a specific format that will pass through unchanged, or possibly a way of preventing LOR from folding it down? Does LOR utilize an embeded media player to process the audio that I can override a codec in leu of AC3filter?

[bob]

LOR uses Windows Media Player to play media files. I have never tried 5.1, and I don't really know much about it, but with one minor exception, mentioned below, any filtering or "folding down" that occurs will occur due to WMP, or possibly your sound card, not due to LOR.

The following file types are supported (though not all of them will work with the Beat Wizard, the VU Wizard, the MIDI Wizard, nonstandard playback speeds, or the waveform display, and video files will only display video with license levels higher than "Basic"):

• AIF
  • *.aif
  • *.aifc
  • *.aiff

  [*]AVI

  • *.avi
    
• MIDI
  • *.mid
  • *.midi
  • *.rmi

  [*]MPEG Audio

  • *.mp2
  • *.mp3
  • *.mpa
• MPEG Video
  • *.mpe
  • *.mpeg
  • *.mpg
  • *.m1v
    

  [*]Sound

  • *.au
  • *.snd
• WAV
  • *.wav

  [*]Windows Media Audio

  • *.wma
• Windows Media Video
  • *.asf
  • *.wm
  • *.wmv

The "minor exception": In some cases, if you want to play the media file at a nonstandard speed, LOR will discover that it cannot do so, but that it can convert the file into a format which it can play at a nonstandard speed. In this case, it will offer to convert it for you; you don't have to say yes. And even if you do say yes, LOR only uses the converted file to play at nonstandard speed; when you play at normal speed, LOR will use the original file.

[David Conley]

Thanks, Bob. I'll have to play some more. I remember reading that LOR simply passes the audio to WMP, but I wasn't sure where I heard it from. I have used a multichannel .wav directly through WMP and got the desired effect. Then I took the same file and used it as the source for a sequence and the audio came out, not folded, but simply missing the extra 4 channels. As I'm writing this I realize that folded was the wrong term to use. I have several more things to try now. I just wanted to get a warm fuzzy that I'm not just wasting time trying to get this to work.

[bob]

Hmmm, well, after thinking about it a little more, I probably shouldn't have said so confidently that any flattening would be due to something other than LOR:

What I should have said, and what I'm totally confident in, is that we don't tell WMP "only play two channels" or "don't play all the channels" or anything like that. We just tell WMP "play".

I assumed that just telling WMP "play" will cause it to play all the channels into the track. However, I guess it's possible that we might have to explicitly tell it "play all six channels", and if we don't explicitly say to do so, then it will just play the left and right channels.

I still believe that we don't have to do that, but I don't know 100% for sure.

[David Conley]

I'll do some experimenting with different options. I can also disable all codecs except for AC3filter ans see what that does. I'll have time to play this weekend. I'll post my results. Maybe this is the beginning of a feature request.

[David Conley]

Got it! The 6 channel .wav file works. WMP did an update that changed AC3filter in the codec priority list, but resetting the priority didn't work. I had to uninstall and then reinstall the filter. At first the audio through LOR was folded down (it really was this time) then I checked the filter default config. It was set for 2 channel. I set it for Dolby Pro Logic II and all was right with the world. Now I can program 32 channels of special effects based on 6 independent audio tracks. Halloween is going to be AWSOME this year!

[George Simmons]

And in a perfect world, someone will come along and translate this thread into plain English for the rest of us...

[David Conley]

Just because this is way too much fun to keep to myself, I'll translate.

I want to be able to place audio at 5 different props for my display. 1 channel in the front of my garage, 1 channel in the rear of the garage (with these I can create extreme stereo effects as well as provide a voice for the guy in the electric chair), 1 channel on the front porch (I have 2 skeletons in rocking chairs there), 1 channel in the middle of the graveyard (there is a coffin, half out of the ground with it occupant there), and 1 channel near the end of the driveway (pinhead on a 5 foot pneumatic piston resides there).

I have a Sound Blaster Audigy card in the computer and a Sony digital receiver connected to it (digital is the only way i will be ably to get the 5.1 surround) I can't get the power that I need by just using the sound card outputs. LOR does not currently support digital audio formats (the most popular is AC3) so i did some research and found AC3Filter. It is a CODEC for Media Player that is specifically designed for digital audio. The key feature that I need is the ability to convert and analog audio (in this case a WAV file) to digital AC3 on the fly (as it is playing). I got this to work and then didn't touch it for well over a month (I had to knock out some honey-do items).

Little did I know that during that time media player performed an update that affected the priority of this CODEC. Another one was put as the primary (thanks Microsoft). When I returned to my experiment I was not ably to get the audio to work properly through LOR. It was disregarding the extra channels. Only the two front stereo channels would play. After talking with "Admin Bob" I began looking around and found the changes that Media Player had made to the CODEC list. Putting AC3Filter at the top of the priority list didn’t fix it so I decided to uninstall and reinstall the CODEC.

Now the symptom changed. My audio was now being folded. This means that the rear channels were being played by the front channels and the center channel was being split between the front channels. All of the audio was being heard, but only from the front (stereo) speakers. A quick look at the configuration of the CODEC revealed that it installed with a default of stereo. I changed it to Dolby Pro Logic II and everything was happy.

Now all of my props can have a voice and I can place sound effects to coincide with visual effects. For example: My electric chair has rope lights outlining it. There is a small fog machine behind it and a pneumatic reciprocating piston attached to the tailbone of the convict. Here is the sequence of events: The room darkens and a single pinhole spotlight shines on the convict. A voice pronounces the sentence and asks if the convict has any last words. The convict struggles (slight piston motion) and proclaims that he’ll be back. The sound effect (the speaker is near the chair) plays the sound of an electric charge building up. The rope lights begin to pulse slowly at very low intensity. The piston shakes slightly as the convict struggles to get free. Then the juice kicks in and the loud electric sizzling sound begins as the rope lights jump to full intensity and pulse quickly. The convict begins thrashing wildly and screaming. The fog machine provides a little fog to simulate smoke and then it all stops suddenly except for the sound of a heartbeat slowing until it stops. The pin-spot dims as the heartbeat fades. The whole event takes less than a minute and will replay 5 times during the track. The total track time will be about 10 minutes. There are several other things that are going on in other parts of the display. It’s going to be the best Halloween yet.

[George Simmons]

Thanks for the translation. Sorry I won't be able to check out your display - sounds like a real killer...

[ChrisBMacon]

David,



When you record your audio with the PC, do you tell it what channel to play it on?



Hello, Chris Brooks here. I haven't purchased LOR yet, but in the process. I'm wanting to build an outdoor surround sound display with viewers in the center. I want to place the 5 speakser (ampped up course), in the yard. What I'm not clear on is if using movie audio clips, how to get it to LOR in surround sound and only play the audio.

[David Conley]

I have spent much time on this concept. It's a delicate balance of software and hardware. First you need to create a multi-track audio file. I used Audacity. It's open source and very easy to work with. Don't try to specify the channels at this time. the best you can do is save a multi-track wave file. Once you have the file, make another version that has been folded down to stereo. You will need this one to use when creating the sequence. LOR will burp if you try to display a waveform for the multi-track file. Use the stereo one for programming and substitute the final version once the sequence is complete. LOR will pass it through just fine.

Now that you have a multi-track wave you need to encode it into surround. I acquired a copy of Cool Edit Pro before Adobe scarfed it up and made it expensive. Look around and you may still be able to find it. I'm sure there are other programs out there, but this one works very nicely. It comes with a spatial visualizer where you can place your audio anywhere in the room. I hava one effect where a man who is breathing hard is walking slowly around the room. You'd swear that he's passing right by you. I also use it to dedicate speakers to specific voices so that the characters in my front yard talk to each other. There really is no limit to what you can do. I have two separate systems working this year so that I have 10 channels and 2 LFE channels all at the same time. For compatibility with most surround amplifiers I export the final surrount file in WMA format. It appears to work the best.

Next problem is getting the audio from LOR to the speakers. In order to get the true surround input, you need to provide a digital surround format to the receiver. I'm using 2 different receivers and both are happy with the same type of sound card. Just be sure that they have a digital input and will at least decode Dolby Pro Logic II. The sound card is the Sound Blaster Audigy. It's an older card and is easy to find on eBay for about $30. Make sure the one you get has a digital output. You'll also need a digital audio cable and most likely a mono male 3.5mm to RCA female adapter (radio shack, $2). This card is capable of passing encoded digital audio without messing with it. All of the special features need to be disabled in order for it to pass the audio properly.

Now you need something that will digitally encode the WMV file, on the fly, as it leaves LOR and pass it to the sound card and then to the receiver and the speakers. AC3 Filter (again, open source) is free and is an amaizing little plug-in for WMP. Once installed, go to your control panel and make sure the it is the #1 priority audio codec. You'll know if it's working if when you play your WMA file a little AC3 filter icon appears in your tray. double click on it and you'll be able to tweak your settings as the file plays. Let me know if or when you get to this point. There's more to this process, but you've got more than enough for now. This is not something you have ready for Sunday.



Good luck...I'l be listening.

[bob]

LOR will burp if you try to display a waveform for the multi-track file.

Could you please send me (bob@lightorama.com) an example of such a file, so I can look into how LOR reacts to it? Thanks.

[David Conley]

The actual files I use are well over 100M in size, but I snipped a 10 second clip for you. It was compiled using Cool Edit Pro. LOR displays "can't initiate conversion" when you try to show the waveform. It will play, but it makes it hard to program without the waveform to look at. I tried the same thing with a WMA file and had much better success, but I wonder if it will suffer from the same decompression delays that occur with MP3's. The WMA is about 1/10th the size of the WAV. By the way...flattening is not a problem with either. They both make it to the sound card unaffected. I didn't try doing any wizards with either of the formats so I don't know how they will react. Have fun.

Attached files 10 sec sample.zip

[bob]

Thank you!