How to send video to projector, audio to hifi, wirelessly with zero or matching latency?

[Richdw]

Hi All,

I thought I'd ask to see if someone has overcome this technical issue, as it seems fairly likely to occur when a projector is used.

I have a projector on one side of the room, and my hifi setup on the other. Independently, they both work great. I can use a wired connection from my laptop etc to either device and have good quality audio or video. I can have both BUT only if both a wired. The issue arises when I want both at the same time WITHOUT having a wire going across the room OR latency in the audio. I can connect via bluetooth to the hifi and keep the HDMI connection from my laptop to the projector, but this throws the audio out of sync with the video due to the latency of bluetooth. I believe casting/streaming also carries a latency cost. I can't connect to the projector via bluetooth, as this would be too much data for bluetooth to handle (as far as I can tell from researching the topic).

Acceptable outcome:
-Keep the wired HDMI video connection from laptop to projector.
-Stream/cast/bluetooth audio to the hifi. For watching films I'm happy with "acceptable" SQ.
-Either add delay to the video, or remove latency from the audio, in order to keep them synced.

Ideal outcome:
-Wireless HD (1080p or more) video connection to projector.
-Wireless HQ (better than bluetooth) audio connection to hifi.
-Perfect syncing between the two.
-No limit to what audio or video can be sent. i.e: I want screen mirroring to the projector and all audio output to the hifi.
-Works with most devices.

So has anyone solved this without wires or latency? It seems like a common enough scenario, given that projectors are inherently situated away from audio sources.

I've done some research on Chromecast devices, Apple TV, and Raspberry Pi, but I want to hear what others have come up with and found to work, before I part with too much cash

Any help would be much appreciated.

Thanks!

 

[Neddy]

Yes, go for it.

I've been using wireless HDMI transmitters to my projector for over a decade. About a year back I upgraded to this:
https://www.monoprice.com/product?p...MIibLwh6zc6wIVhcDACh3hvQUUEAQYASABEgLiaPD_BwE
(Mine might be a bit older version - I don't recall paying that much.)

It works fine, but, with the one I have, found that around 25-30' it has trouble getting through closet walls?
I'm using an Oppo103 HDMI1 (video only) as a source, and it's analog audio outputs, via an ADC/USB into my PC system (and back out to a DAC again). (!!!)

So, you'd think, that if latency were a major issue, this setup would accentuate it!

So far I've watched two different movies, and have not noticed any lip-synch/delay issues at all - though I have to admit I totally forgot to look for it specifically - so more 'eval' to do yet. I have to assume there is some, but whatever it is, it didn't call attention to itself in 'casual' watching. More 'testing' to follow.

So, yes, I can recommend the tech, if not a particular product (they seem to introduce newer versions every year or so?).

I started out using a huge and ugly RS-485 conversion scheme to get wires the 75-100' or so required to snake around the room to the projector. It worked. Sort of. Then I tried one of the early Brite-View wireless units - that worked quite well for nearly 10 yrs, but died a heat death of some sort (I now power down all those systems when not in use).

Well worth the 'more dang dongles' and power supplies and fiddly 'will it synch?' setup/use worries!

PS. Another oddity of my setup - I'm using a - now pretty old - Sony projector that does 'only' 1080i. (I don't watch movies that often, so the lamps I bought new, now NLA, still have lots of life left!) and the Oppo 103 does a great job at 'converting' 1080p to 1080i for transmission to the projector.

Ain't nothing like having a near TOTL audio system, and watching BR movies on a 12' screen.


Edit: no suggestions about the audio side of your dilemna, sorry.

 

[pjug]

I'm not really up on this; how much latency is too much? Won't cheap bluetooth xmitters/receivers solve this?
e.g. they talk about synchronized audio and video here: https://www.aptx.com/aptx-low-latency

 

[Richdw]

Thanks for the replies so far.

@Neddy I'd not heard of wireless HDMI transmitters/receivers before so that's a new avenue to explore. I wonder if using two receivers connected to the projecter and hifi respectively, would allow for a synced timing? I also wonder if any laptop has this ability built-in, as it seems handy!

@pjug I'd not spotted the Low-latency version of aptx before. Interesting solution. Could work as a cheap way to get synced audio for watching a film. Shame that the trade-off seems to be audio quality, but there's always a trade-off I'll look in to an affordable aptx-LL transmitter/receiver set.

Has anyone else tried a solution to this issue?

 

[Neddy]

Need a head-scratching smiley

Yes, indeed, you could try using two HDMI transmitters, one for video, one for audio (you'd need two HDMI sources, or a splitter to feed them with). Might want check specs carefully to make sure they can handle two in the same room?
Costs add up quickly for that.

You didn't mention what your hifi accepts as inputs, or whether this is a multi-channel or stereo only system, or where the laptop sits relative to the two (halfway in between, or viewing position, I'm guessing?).
More info on that would be helpful?
(I have this 'nightmare' use case in mind where you're doing video conferencing with this setup?)

Let's assume 'worst case' - hifi analog inputs only, multi-channel, laptop at viewing position, say halfway between both:

So you could do the aptx-LL + HDMI transmitter approach, but that's a lot of 'dongles' to have sitting next to your laptop, and, FWIW, I've had a pretty miserable experience with aptx in general, and worse with BT in general (YMMV).
(Too bad your laptop doesn't have AptX LL built in)

Or, just run (analog?) audio wires from your laptop to your hifi?

Or, get an HDMI splitter (more dongles!) and run dual HDMI from your laptop, 1 to wireless HDMI, 2 to hifi?
(I have also used various HDMI splitters, and they are pretty reliable...but.. More Dongles!)

So, I hate to say it, but my best guess is that the best/cheapest most reliable solution for you would be just buy a used Opp103 or similar (but, they've gone up in used prices - $300-$600?? there may be other players that might work, depending on your setup), plus a wireless HDMI transmitter.
Here's why:
1. The Oppo has an HDMI Input (if you are really laptop source material bound, or for streamer things like Roku.)
That would mean a single HDMI cable to Oppo, from there, HDMI or analog to Hifi, and HDMI to wireless transmitter.

2. The Oppo103 has both HDMI A/V and HDMI Video only outputs (Split AV) as well as analog outputs (and TOSlink, for stereo) - so will work with just about any HiFi.
Place the Oppo (or other player) near your Hifi, and use the HDMI transmitter for projector video only.

3. Works with a remote (not to mention smart phone apps, etc).
This is pretty much how the 'head end' of my system is setup, and, once you get everything working, it's pretty much simple & reliable (or at least as these things get).

I know this isn't what you were hoping/looking for - more info might help simplify options.
At least the wireless HDMI solution is known, works well, and you have a variety of options for that.

Hope this helps a little?

 

[Richdw]

Let's assume 'worst case' - hifi analog inputs only, multi-channel, laptop at viewing position, say halfway between both:

@Neddy That pretty much describes my setup at present, albeit with a bluetooth receiver connected to one of the analog inputs, for when the wired connection is not practical. Thanks for the suggestions, I'll definitely look in to the Oppo103 type solution, although, as you say, the HDMI connection to the hifi may require some thought.

I'm curious as to whether anyone has tried using chromecast or similar to solve my dilemma?

 

[pjug]

I'd not spotted the Low-latency version of aptx before. Interesting solution. Could work as a cheap way to get synced audio for watching a film. Shame that the trade-off seems to be audio quality, but there's always a trade-off I'll look in to a?

I see that LLAC is another codec, possibly better audio quality than Apt-X LL. It seems this is included with newer versions of Android, but unfortunately I am not finding transmitter and receiver dongles that have this.

https://en.wikipedia.org/wiki/LHDC_(codec)
LLAC[edit]
Low Latency Audio Codec (LLAC) is also called LHDC LL. It is based on the high definition wireless audio technology from LHDC, but designed for low latency and features an auto detect gaming mode. Savitech claims LLAC has end-to-end latency of around ~30ms. LLAC supports bitrates of 400/600 kbit/s, bit-depth of up to 24 bit and sample rate of up to 48 kHz. LLAC has no hardware requirement for the transmitter.[6]

 

[Richdw]

Just to update, and possibly get further information....

I've purchased one Chromecast Audio (CCA) and one Chromecast 3 (CC3). I've connected the CCA to my hifi and the CC3 to the projector. Individually, they are great. I can cast various audio outputs to both devices, and do so simultaneously. However I cannot send video to the CC3 whilst simultaneously sending the movie's audio to the CCA. This is clearly a pain, but I was warned of this issue..... ...and yet I had hope that the clear niche where this issue occurs (projector+hifi) would mean that someone somewhere has created a workaround/hack to work with a CCA and CC3. Alas, I am yet to find that hack!

Both devices have considerably higher latency than the previous bluetooth setup. Interestingly, when running purely audio to both CCA and CC3, there are options to control the audio delay to ensure audio is synchronised across both devices. I find this a bit strange, knowing I can make both devices play audio perfectly in-sync, and one of them is tailored to output HDMI video. Unfortunately Google does not allow casting video to multiple CC3 devices, otherwise I could solve my issue by doing just that and splitting the audio from one device to my hifi and the video from the other to my projector...Alas.

I see that LLAC is another codec

Thanks @pjug it may be that bluetooth is where I end up again. As you point out, finding devices to send/receive specific codecs soon becomes another challenge.

Thanks all, and please do send suggestions to solve this matter of global importance

 

[Wombat]

Need a head-scratching smiley

Yes, indeed, you could try using two HDMI transmitters, one for video, one for audio (you'd need two HDMI sources, or a splitter to feed them with). Might want check specs carefully to make sure they can handle two in the same room?
Costs add up quickly for that.

You didn't mention what your hifi accepts as inputs, or whether this is a multi-channel or stereo only system, or where the laptop sits relative to the two (halfway in between, or viewing position, I'm guessing?).
More info on that would be helpful?
(I have this 'nightmare' use case in mind where you're doing video conferencing with this setup?)

Let's assume 'worst case' - hifi analog inputs only, multi-channel, laptop at viewing position, say halfway between both:

So you could do the aptx-LL + HDMI transmitter approach, but that's a lot of 'dongles' to have sitting next to your laptop, and, FWIW, I've had a pretty miserable experience with aptx in general, and worse with BT in general (YMMV).
(Too bad your laptop doesn't have AptX LL built in)

Or, just run (analog?) audio wires from your laptop to your hifi?

Or, get an HDMI splitter (more dongles!) and run dual HDMI from your laptop, 1 to wireless HDMI, 2 to hifi?
(I have also used various HDMI splitters, and they are pretty reliable...but.. More Dongles!)

So, I hate to say it, but my best guess is that the best/cheapest most reliable solution for you would be just buy a used Opp103 or similar (but, they've gone up in used prices - $300-$600?? there may be other players that might work, depending on your setup), plus a wireless HDMI transmitter.
Here's why:
1. The Oppo has an HDMI Input (if you are really laptop source material bound, or for streamer things like Roku.)
That would mean a single HDMI cable to Oppo, from there, HDMI or analog to Hifi, and HDMI to wireless transmitter.

2. The Oppo103 has both HDMI A/V and HDMI Video only outputs (Split AV) as well as analog outputs (and TOSlink, for stereo) - so will work with just about any HiFi.
Place the Oppo (or other player) near your Hifi, and use the HDMI transmitter for projector video only.

3. Works with a remote (not to mention smart phone apps, etc).
This is pretty much how the 'head end' of my system is setup, and, once you get everything working, it's pretty much simple & reliable (or at least as these things get).

I know this isn't what you were hoping/looking for - more info might help simplify options.
At least the wireless HDMI solution is known, works well, and you have a variety of options for that.

Hope this helps a little?

 

[Richdw]

View attachment 83440

I have explored this option, and it may be where I go next, but a lot of the HDMI transmitters available are prohibitively expensive, especially if I need 2 of them. Further more, casting is, on the face of it, very energy efficient, compared to wirelessly transmitting via HDMI and/or bluetooth. I could in theory even turn off the device I've cast from whilst watching a film etc. I'll keep the chromecasts either way, for casting music or if I end up with a TV (projector fan noise anyone?..).

 

[Neddy]

Yes, I was shocked at how the prices on the HDMI transmitters jumped up - I did find mine 'on sale' for a decent discount during the holiday season? As for power, my transmitters run off USB power jacks, so not all that bad - and I have them both on power strips I (usually) just turn off when not in use (mostly b/c the 1st gen one I had before these did run awfully hot).

I'd sure be inclined to try one of those plus BT audio - at least it'd be a cheaper test (amazon prime returns anyone?).

My older Sony projector doesn't make objectionable noise (difference between small conference room projectors vs. HT ones?) , except during cool down before shut off....but then I usually play movies Loud, too.

Yes, as soon as you go 'off book' from what the various mfgrs have schemed up (as packages) things get annoying complicated - brain teasers.
Brings to mind WISA audio systems - most of them on offer now are 'packaged' systems; only a few are aimed at 'just want to add wireless surround channels to existing surround sources' and also Not Cheap.
Come to think of it, WISA audio might be (yet another, pricey, more dongl-y) audio option for you
https://www.wisaassociation.org/

Best wishes on solving your globally eminent dilemma!