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Author Topic: Drive-In Wifi Sound? Dustin Grush Film Handler Posts: 14 From: Johnstown, PA, USA Registered: Apr 2018 posted 02-22-2019 09:50 AM                     Hello, Does anyone have any experience with the new Drive-In WiFi sound system being offered by Total Cinema Solutions? Anyone planning on trying it this season? I had a brief conversation with a salesperson and remain unconvinced that the "delay" issue has been resolved. I had been toying with a DIY solution to this, all theoretical at this point, and it seems that the additional processing for a RTP type stream would be too long. We constantly have people asking for this, and wondering why the "FM receiver" app on their iPhone doesn't pick up the sound. Thanks in advance. I would also like to point out that I am in no way affiliated with TCS nor am I trying to cast doubt on their product. On the contrary actually, If it actually works it looks like we will be in the market for 2 of them.  |  IP: Logged Barry Floyd Phenomenal Film Handler Posts: 1079 From: Lebanon, Tennessee, USA Registered: Mar 2000 posted 02-22-2019 11:02 AM                        I've never seen that system before, so I can't really tell you anything about it. I know Sennheiser makes a similar system called Cinema Connect. It does both audio and descriptive text for hearing impaired. I called once about the Sennheiser system, and was told it was not available to the US Cinema market... which I think was a load of BS. I was the perfect system to use in a drive-in setting. One thing I've heard from others about trying to develop such a system as "streaming audio" for drive-ins was "Latency". The more customers connected to the system, the worse the latency issue became. I would be curious as to what something like this system costs and how well it performs. Our customers ask us constantly for wifi streaming of audio, so hopefully this system might work out IF the costs are reasonable. EDIT: After looking over the system on-line, I called them and spoke with "Brian". He said they have sold several systems in the last week to 4 other drive-ins, the SACO in Maine, the Black River in New York State, and the Starlite in Wichita. I'd probably wait a couple of weeks and call up some of these other drive-in owners and see how it works. For the price, it's really not that expensive. I've wasted a whole lot more money on stupid stuff over the years than what this system costs.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 02-22-2019 11:17 AM                        What would be the advantage over FM?  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 02-22-2019 11:27 AM                     In general, it is not impossible to solve the latency issue in digital cinema, as technically, it is easy to shift audio back and forth in relation to the image. The only important thing is keeping latency constant and not going up and down. Also, streaming and broadcasting techniques usually can solve the issue of few vs. many devices using the service. However, you need expensive access points that are able to deal with that many clients simultaneously. I don't know how many of the average drive in clients/cars use traditional fm radios in the US nowadays. I would think that FM is still the way to go, and probably also a lot cheaper and more solid in operation than a Wifi based solution. But, many people may simply consider it 'cool' to use their phones instead of the old radio. They may think the sound is better because 'it's digital'... - Carsten  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 02-22-2019 11:45 AM                     The advantage could be that you can support multi-channel audio and the digital signal could boost the quality. In practice, it's not that simple. Latency will not be your friend, there is a lot of stuff involved that will make it difficult to get the latency correct for all things involved: - Wifi itself incurs latency, also there is a considerable challenge to get good in-car quality all over the field and also to serve all clients simultaneously. - If you serve everybody with a unicast stream, even bandwidth can become a potential problem. Broadcast over wifi isn't all that reliable too. - Encoding and streaming will introduce latency, although this part is the part that's the most easy to compensate for, since it can quite easily be measured. Also, by creating a "fake buffer", any large jitter in the system can be compensated. - Your mobile phone will introduce latency in the networking stack, the decoding/processing stack and then also in the playback stack. - You probably don't want to play it on the wacky speakers of your mobile phone, so you connect it to Bluetooth... e.g. that of the in-car Bluetooth system. This will not only incur the latency of the phone, Bluetooth itself, but also that of the car Bluetooth and stereo system. With so many layers of unknown in between, lipsync audio will become an afterthought. For subtitling, it will work, but subtitles are far more graceful than audio. And besides all earlier mentioned arguments: Don't forget the extra level of customer support for telephones not working, car Bluetooth systems not pairing with the phone, people forgetting to connect to the correct Wifi network, phones not connecting to the correct wifi network, outdated phones, phones with issues, etc. etc...  |  IP: Logged Dustin Grush Film Handler Posts: 14 From: Johnstown, PA, USA Registered: Apr 2018 posted 02-22-2019 01:35 PM                     Thanks for all of the replies. Good to see I'm not alone in my skepticism. This is in no way going to replace FM. For the "why" question: We get some walk-ins who don't think to bring a radio. We also get people who rarely use their FM radio in their car and only discover its broken when they try to listen to the movie. Others want to "walk around and see their friends" and still listen to the movie. There is also probably the "cool factor." This unit is getting its audio from the 8-channel output that would be timed with the FM modulator. We use a JSD-60 and I don't believe that there is a way to delay channels individually, but could be wrong about this. They do make "delay boxes" for placing speakers in a large room and having them all sync, but that isn't offered in their package. Latency is the word that I was trying to use before but couldn't think of. As far as troubleshooting the system this would have to be treated as a "if it works then great, if not use something else for tonight" because I rarely have time to troubleshoot things that aren't mission critical for the night, and I hate to do things that way. Thanks again for the replies.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 02-22-2019 02:22 PM                     I guess it's better (though not 'cooler'...) to hand out portable fm radios. Maybe you can buy some from china that look like an iPhone ;-) I also remember that there are cheap mobile phone headsets that include a simple fm radio. - Carsten  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 02-22-2019 02:31 PM                     I work part time on occasion at our local ozoner and I get people coming in if there is an app available for the sound, and do get asked if we have WiFi. I tell them that using WiFi is impossible due to the delay issues.  |  IP: Logged Dustin Grush Film Handler Posts: 14 From: Johnstown, PA, USA Registered: Apr 2018 posted 02-22-2019 02:52 PM                     Carsten, We do have a few radios that we hand out, free of charge, with a drivers license as collateral. This has worked rather well over the past few years that we have done it, and I have yet to have one go missing. At one point I even had out local screen print shop look into getting personalized ones with our logo, but the minimum order was ridiculous. Monte, Up until now that has been my answer as well. Of course I occasionally get the "well it works at so-and-so drive-in..." Its even funnier when they tell me that it works at our other location, not realizing that the two are under the same ownership, just with a different name.  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 02-22-2019 04:17 PM                        quote: Scott Norwood What would be the advantage over FM? Avoiding FCC regulatory and licensing requirements would be my guess.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 02-22-2019 05:34 PM                     When you trace the equipment used through Google, you'll see that they use dedicated Wifi-Access points that specifically enable simultaneous streaming to many users. The manufacturer also has technotes on typical latencies down to individual typical smartphone processing latencies (typically, half as long on iPhones compared to typical Android devices). Now, for a drive in, you would certainly need to support both FM radio and Wifi simultaneously, with both needing specific audio delays. It can be done, if you set your server to output audio earlier than video, then feed the audio towards the FM transmitter through a PA delay line set to the typical overall Wifi system latency, and a non-delayed version towards the Wifi system. So, the audio comes out of the server too early, the Wifi system latency brings it back in sync, and the additional delay line for the fm transmission 'simulates' the WiFi latency over the fm, so both FM and Wifi audio arrive at approximately the same time. At first, it is probably not a big deal to start such a system, as only few people will be using it simultaneously. The question ist, will it really be trouble-free if a higher number of users hook up to it. Will there ever be a significant number of Wifi users? Also, if people ask for it, you need to direct them to a dedicated app. No big deal, you can show a slide during preshow, with the app name, a QR-code, etc. They will need to be able to download this app on site. Hard so say wether they will be prepared or able to download this through their 3G/4G (...) network connection (coverage?), or through your Wifi. In the latter case, your audio Wifi will also need to supply an internet connection. Their audio server also allows to supply internet, so, techwise, that is possible, if your site has internet connectivity. Patrons request for Wifi may also be generic, as I suppose many patrons would love to use a free Wifi on your site before or during the screening. But that's a different service. One potential issue is that smartphones usually stick to either 3G/4G OR Wifi, but not both. If they connect to your audio Wifi, and that Wifi offers no internet connection, attempts to download the app will fail, as that Wifi is a dead end. Patrons would need to switch back and forth between different connection types in order to download the app, and then to receive audio. Then when they receive audio, they will be offline, and wonder why... So, all in all, there are many reasons why you should expect complaints or requests for help. Are you prepared to deal with all these smartphones your patrons will probably stick out towards you? - Carsten  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 02-22-2019 06:01 PM                        Even if the delay thing is solved, this would only work for D-cinema. Not for live events, film, video game night, etc., since there would be no way to advance the sound in order to delay it later. That may or may not actually be a problem for most drive-ins, but it would at least be a consideration. My inclination would be to think that it is more trouble that it is worth. I haven't seen a car without an FM radio since I was a kid (AM-only was the default then), and the technology (FM) seems to work well, without requiring technical support for the customers. I've seen drive-ins that have a row or two of field speakers in addition to FM for those who don't have or want to use their car radios. Is the FCC thing really an issue with drive-ins? I thought that low-power broadcasting was legal as long as it doesn't carry off of the property and doesn't affect licensed stations' signals. Is this not the case?  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 02-22-2019 06:08 PM                     Well, you could probably pay some extra $ to delay the image as well. At least for some typical live event broadcast technology, that should be possible (satellite, IP streaming). How many DIs do live alternative content? by the way - within the EU, from 2020 all new cars need to have an analog and digital combo radio. That is mandatory - a radio MUST be in every new car sold. - Carsten  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 02-28-2019 05:16 AM                     Another comment towards possible latency issues: This document from one of these Wifi-live sound companies suggests typical device specific streaming audio latencies for Android and iOS devices being in the 170-460 ms range. https://www.listentech.com/wp-content/uploads/2017/05/LTN0012_Wifi-Latency-Tech-Note_042717.pdf The document is not precise as to wether the given values are 'device-only', or, full system (audio-input of encoding server - > mobile device headphone output). Whatever - in order to compensate for this delay/latency, the cinema server has to advance the audio against the video during playout so that it will arrive at the client in sync time. A Doremi has an adjustment range of -200 (earlier) to +200ms (later). I know other servers to allow e.g. -250ms to +250ms. For HD-SDI systems, the image processing will usually introduce a delay of 2-4 frames (no idea for IMB/IMS) for the video anyway, so, for a Doremi, the maximum effective Wifi latency correction ('predelay') possible is in the 250-280ms range (audio adjustment range plus inherent image delay). So, if those figures in the above document are correct and depict full system latency, it may just work decently for typical iOS devices. If a patron experiences an audio delay in the range of 200-250ms, that is certainly not tolerable, especially if the user uses e.g. a bluetooth connection into his car audio system which introduces another delay in the 50-100ms range (which is typical number). If typical latencies experienced in the field, as depicted in that document, really vary between 170ms and 460ms (and I expect even more variations under non-optimal reception, heavy load, etc.), that range alone is unacceptable because you can only compensate for an average fixed delay, not for every individual user. But if one or multiple patrons experience a sync error of e.g. 200-300ms, that is unacceptable. I'm not saying it wouldn't be possible, but, these are questions that a company offering these systems for 'cinema' use must be able to answer. They also need to be able to explain dual system aspects (as parallel FM/Wifi use with their specific delay needs). - Carsten  |  IP: Logged Terry Monohan Master Film Handler Posts: 379 From: San Francisco CA USA Registered: May 2014 posted 02-28-2019 07:43 AM                     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. Time to bring back the old Eprad 3ch stereo in car speakers from the early 1950's for a new retro generation to enjoy and put on the dash board! I have a question was or is the FM sound system stereo multi channel?  |  IP: Logged

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