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This topic comprises 3 pages: 1 2 3
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Author
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Topic: Drive-In Wifi Sound?
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Jack Ondracek
Film God
Posts: 2348
From: Port Orchard, WA, USA
Registered: Oct 2002
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posted 02-28-2019 12:58 PM
quote: Terry Monohan
Wow Wi Fi STEREOPHONIC SOUND for the drive inn.
The trailer trash crowd will love It with their cracked loud rattled boom box speakers in their old cars.
The neighbor houses may not like all the extra bass sound coming from the lot late at night If the theatre is close in town and not way out in the boondocks.
That's a bit harsh, Terry. Been a while since you attended one?
As most drive-ins have moved beyond carload pricing and sub-run presentations, admission rates have steadily inched toward shouting distance of market levels. That alone has eliminated the crowd that's looking for deep discounts... possibly the "trailer trash" group you're referring to.
Beyond that, I'd challenge you to find anyone at a modern drive-in that came out with the kind of busted, crackly-sounding radio you've stereotyped them into. If you think this is what a well-managed drive-in is like today, you're still living in the '60s.
It's far more common to see substantial investments in auto-stereo systems show up out here. We constantly have to be on the lookout for subwoofers, some of which have the capacity to loosen your teeth. That certainly was not the case 30 years ago.
The loaner radios we have available are not provided for the "cool factor", but a functional courtesy for those who find their radios don't work properly or, perhaps, forgot them. We don't give them out for free, but rent them for a reasonable fee. That prevents us from being expected to provide for our customers audio reception by default.
As for wifi, fm, delays, etc:
FM, done right, doesn't carry much past the confines of the theatre. There is no license available for drive-ins, as the FCC doesn't recognize our usage as something that requires regulation. That said, it's incumbent on us not to rise above their radar. There have been a very few cases where an owner felt the need to broadcast drive-in music and show schedules across town. That's very risky, however, and there have only been a small handful of those cases in the past 20 years or so.
Analog FM has no more inherent delay than hard-wired speakers. If you're using some analog processing to corral dynamic range, latency is not a factor. The use of some digital processors does introduce some delay and, depending on how much, you might need to consider advancing the audio a bit in your server(s). Even then, the brain can tolerate a small amount without offense.
WIFI is another animal, as each step in the chain, from the audio source to whatever encoder you're using, to the network radio, a possible app and finally, the phone itself, introduces latency, even if only a very small amount. That can be managed, to a point, by advancing the server audio, if you also have some form of processing to delay the audio back to its original timing for your FM feed. For certain, your WIFI signal has to be locally generated. I don't think there's any possible way you could send your audio out to a commercial streaming server and have it come back in any condition to sync up to your visual.
Last year, we started working with a company that makes an encoder that might work for drive-ins... eventually. The major problem with the concept, I believe, is that it is far more complex than most drive-in operators are going to want to tolerate, just to be a bit more "cool" and let the teenagers use their phones for the audio. By trade, I'm a radio broadcast engineer, and even I suspect it would be more trouble than it would be worth for me.
Some phones have FM chips in them, using the headphone wires as an antenna. The "Nextradio" app allows those phones to tune a drive-in's FM signal in real-time, making the phone as useful as any other car or portable radio. No participation is required from the drive-in, other than to send out the same signal it intends for customer car and/or portable radios.
It's the streaming concept that's difficult to manage, due to the latency issues and adding unnecessary complexity to a digital booth that some owners still don't completely trust.
Fact is, most people are thrilled just to have a drive-in within a reasonable distance from their home. Frankly, I seriously doubt I've ever lost a customer because I wasn't "cool enough" to be able to shove my audio into their cell phone... or because I don't have 3D, or 7.1 digital, or D-Box, or Atmos, or dancing pandas, etc.
Analog FM works just fine. Don't like it? You could always go back to those old window speakers. Now THAT was a lot of fun!
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 03-01-2019 01:41 AM
The latency issue while it may be solvable in theory, in practice it may actually be unsolvable. There are WAY to many layers and variables. It's not like you can measure the latency of the system and then just simply dial up the right amount of delay.
With WiFi, the latency will VARY from moment to moment. It doesn't just sit there at a given number, and given that you are talking about a myriad number of different devices of all types and of multiple service providers on the user end, each with it's own level of impact on the transmitted WiFi signal, meticulous tweaking may very well be able to get lipsync in some devices, but then what do you do about the other couple of dozen customers? Oh yeah, and those few customers who do get lipsync for a few minutes, will no doubt lose it in the next few minutes.
Whereas the shifting latency is pretty much inconsequential to the user of wifi when it is being used for what it was intended, video and audio both being transmitted together. In this application, the two are independent, so the shifting latency becomes visible to the end user almost immediately as audio will float as if on a wave to and fro...in lipsync, out of lipsync...in lipsync, out of lipsyc, and at different rates for ALL of the DI customers.
It seems like a futile endeavor that really serves no purpose, especially with FM in cars which for years has been working pretty flawlessly. And even cars of 10-15 years vintage come with more and more sophisticated sound systems that are able to deliver very good stereo separation at heart pumping volume levels. DIs pretty much have a system that's work fine for their needs for decades. They have even ironed out even the minor pesky issues like dealing with cars that drive in without a working radio. Bottom line, the current FM system works remarkable well.
I would consider it a much better marketing strategy and investment to spend a few extra $$ incorporating Dolby's Virtual Surround circuitry, encoding a surround channel in the two channel FM transmission signal. It's simple, it's cheap and it gives the DI a great marketing hook: The (put name here) Drive-In now has Dolby 360 Degree Virtual Surround -- even better than the local godzillaplex -- because the sound engulfs you...is all around you in your car! What can a DI hawk about a WiFi system? "WiFi will give the same two channels of audio, probably not even able to deliver the same fidelity as FM and then there's the "cool" effect that all movies will look like they were made in Japan with the actors looking like they have been dubbed."
The FM delivery system has stood the test of time. It works; it's reliable; it doesn't nearly have as many variables in the way of it functioning properly as does WiFi. But the main thing is, it fits very well that great old adage, If it aint broke, son, don't try to fix it!"
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Marcel Birgelen
Film God
Posts: 3357
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012
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posted 03-01-2019 03:45 AM
quote: Frank Angel
I would consider it a much better marketing strategy and investment to spend a few extra $$ incorporating Dolby's Virtual Surround circuitry, encoding a surround channel in the two channel FM transmission signal. It's simple, it's cheap and it gives the DI a great marketing hook
The question is how you make it work in your average car, that doesn't have the matrix decoder available to demux the surround and potential center channel?
Or you upgrade Carsten's idea and hand-out soundbars, a separate sub woofer and a speaker for your surround channel. Doesn't sound (sorry) all that practical... ![[Wink]](wink.gif)
I think the only real benefit of digital transmission is that it can potentially increase the playback quality, but ever so slightly. Internationally, DAB+ is becoming the standard for digital radio transmission, but in the US it's mostly "HD Radio". Potential problems are spectrum licensing issues and very expensive equipment, compared to plain analog FM transmitters.
The quality boost going from a good analog system to a digital system will be negligible. In my car, with a "premium" sound system, I can hardly distinguish between compressed DAB+ and good FM. It's only very apparent when the signal goes out of reach. While digital will induce hard drops, analog FM will either slowly fade away into the background noise or be overpowered by an interfering radio station.
Keep in mind that digital radio might also introduce extra latency due to internal buffers, both at the encoding but also at the decoding end.
While "HD Radio" and DAB+ both support some forms of surround sound, I doubt many in-car system are capable of extracting and rendering it accordingly.
The surround part feels to be the only compelling reason for me, to even try to implement a digital solution, but it fails at a potential very low adoption rate of in-car sound systems.
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Jack Ondracek
Film God
Posts: 2348
From: Port Orchard, WA, USA
Registered: Oct 2002
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posted 03-01-2019 06:54 AM
Install soundbars... I like that!
As Marcel suggests, HD radio does indeed introduce latency... a lot of it. Depending on how it's set up, I've seen everything from a few seconds to over 40.
In the US, the term "HD Radio", for both AM and FM, refers to a process that one company holds the monopoly on. "Ibiquity" won out over other digital processes after lawsuits were threatened when the FCC tried to dictate (like FM stereo) the winning method. AC-Delco decided it was too expensive to put decoders for the 3 or 4 competing methods in their radios and, after heavy investments into Ibiquity by Disney and, I think, NBC/Universal, "decided" to support only the Ibiquity method.
To-date, the installed base continues to be spotty and, due to lack of interest by the car-buying public, does not seem to be growing, like FM did in the 70's or color TV did in the '60s. There are only a couple of desktop options, and you have to look around to find them. So long as that continues to be the case, HD will be a "chicken and egg" situation. Broadcasters won't really want to invest in something that few will actually hear, and the public won't see much value in investing in the few available receiver options.
For broadcasters and certainly smaller economies, like the drive-in business, the transmission equipment is horrendously expensive, is generally available only to licensed broadcasters and, if you're using more than the first (HD-1) channel, you have to pay licensing royalties to Ibiquity to have the extra subchannels unlocked.
I don't believe there will ever be an HD-type solution aimed directly toward drive-ins. The numbers simply are not there. Beyond current analog FM broadcast technology, any options will continue to be adapted from products intended for other industries.
The other issue is user penetration. Because of the cost and (in mildly rugged terrain) reception issues, HD has only taken a foothold in larger communities, and even then, a small one.
In the Seattle market, nearly all of the major commercial FM stations are HD equipped and, though they've tried, none of them claim to be making any kind of financial return on their investments. For the most part it's been an image thing... keeping up with the competition, so to speak.
Because of interference, cost and nearly zero interest from listeners, there are no remaining Seattle-area AM stations broadcasting in stereo. I turned off the last operating AM stereo exciter last Summer. Ironically, the other three (also now off) were news and sports-talk stations... voice-centric formats that sounded much better in stereo!
We're basically back to the same given... for now. Analog FM, done right, is comparable to anything else you could economically send out of your booth.
As for the ongoing desire to somehow get real surround to your car.... our customers have a nagging habit of messing up our extraordinarily well-engineered stereo transmission by merely turning their cars around and viewing the movie from the back end. Just by doing that, right becomes left and left becomes right. It almost makes you want to turn the stereo off and mix it all into one channel.
One owner found a way to inject the 19kHz pilot into his transmitter, even though he had no stereo generator on it. For anyone who cared, their stereo light came on, and most of them believed he was really broadcasting that way.
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 03-01-2019 09:24 AM
quote: Marcel Birgelen
The question is how you make it work in your average car, that doesn't have the matrix decoder available to demux the surround and potential center channel?
That's the beauty of Dolby's Virtual Surround system, Marcel. You supply it with 5 channels, say from a DVD or BluRay, or in this case, outputs from the Cinema Processor and it manipulates the phasing so that the surround channels are folded into the Left Right channels of say a stereo TV set or two channels of a computer audio card, and the phase manipulation causes the two channel playback of the device to create a phantom, illusional surround channel just from two speakers. In order for it to work, the listener needs to be in the sweet spot or near equidistant between the Left and Right speakers.
Beauty of this is that coincidentally, that's pretty much where the occupants of the car (or TV set, at a computer or listening on a headphones) are sitting.
I saw this hawked at a computer show decades ago and it worked surprisingly well. It actually did sound like stuff was coming from behind my head. If you are not setting perfectly centered between the two speakers, the surround audio will shift somewhat, but the illusion is still there until you are at or beyond one side or another of the speakers.
Not sure what happens in cars that put speakers all over the place, but it should still cause some sort of anomaly in the location of sounds in the stereo field since all those speakers in the car still are placed in a way that you hear correct Left and Right stereo location/separation, and that's all Dolby Virtual Surround requires. Sony at one time made a Virtual Surround process for headsets. Feed it 5.1 audio in, and it will give you virtual surround sound in the headset or any two channel playback device. 
But that's not the point -- whatever it is that the Dolby Surround encoder does to psychoacoustically manipulate sounds to create even a slight illusion that patrons are hearing stuff from behind their heads, that's enough of a marketing advantage that will allow the DI to use a very powerful phrase in their ads -- Dolby and Surround Sound. It will help to dispel the notion that DIs have terrible audio, stemming historically from those 4 inch Eprad or Symplex window-hanging speakers. And nowadays, car owners like to brag about their vehicle sound systems, the higher end cars boasting sound systems like Bose or Sony or Bang & Olufsen, etc. They already believe their car audio system delivers great sound. Now the DI is just adding surround to it.
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Marcel Birgelen
Film God
Posts: 3357
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012
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posted 03-01-2019 04:56 PM
quote: Frank Angel
That's the beauty of Dolby's Virtual Surround system, Marcel.
Ah, you were referring to those "psychoaccoustic surround" trickster setups.
Well, those are interesting, but like you mentioned, they really need you to be in the sweet spot to work. Similar tricks are being pulled on "virtual surround" headsets.
Like Scott already mentioned, I don't think you're really sitting in the sweet spot on neither the drivers nor passenger seat. It would still be interesting to see how well it works though.
quote: Scott Norwood
I had to laugh about Jack's comment about people who park backwards. I'd never thought of that, but it is pretty common for people with minivans.
Yeah, I also had a good laugh, but it makes somewhat sense for certain car configurations. I doubt your sound will be any good though.
Maybe, you could offer the backwards channel for them, where left and right are reversed. ![[Smile]](smile.gif)
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 03-01-2019 05:14 PM
Thing is, in today's cars, seems they are able to use multiple speaker placement so that both the driver and the passenger (at least in the front seats) do get a fairly distinguishable stereo soundfield; if I didn't hear stereo in my new car, I would give the car back. I almost gave it back when I found out 1) it didn't have a CD player and 2) the bluetooth receiver (which SHOULD have been able to pair with a neat little CD player, DOESN'T seems they somehow configured it to pair only with effin cellphone...not other Bluetooth stuff.
With this psychoacoustic trickery, it will work as long as you can hear some stereo separation. I've actually never sat in the back seat of my car so I don't know what they hear, but in the end, it's really more about marketing and bragging rights to say you have 360° surround sound at the DI rather than if it actually presents a perfect placement of what's in the surround channels. Let's face it, when you sit in a theatre, depending on your seat location, what you hear in the way of sound location is never going to be exactly where the mixing engineer placed them.
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