Q: Is it normal that Audio Airplay doesn't sync with Video?

Network latency from this sort of data stream will be in the manner of <5ms, not 2 seconds. Buffering of the audio may occur but with the high bandwidth of modern 802.11x connections, it is very unlikely to be needed or to cause a delay. As an example, I can simultaneously stream multiple HD videos across my network to multple devices, both wired and wireless with no perceptible lag. It's apparent that Apple does have airplay streaming with zero lag if you use Apple based audio protocols and programs. All audio/video streams get demuxed at some point. You can't send it to the hardware through the HAL (hardware abstraction layer) without splitting it. I'm sure Apple could fix this if they tried.

My goal is to play YouTube video on my PC and have the video in sync with audio going to an Airport Express. To be precise the audio  is going via Airfoil (pc tool to send any audio source to Airplay receiver) to Airport Express which is in bridged mode and is hooked up to a Power over Ethernet switch. Audio is going from the Airport with analogue RCA cable to an Onkyo receiver. The PC is connected to a Zyxel router, the latter is also connected to another Power over Ethernet switch and all are happily on the same LAN (no wi-fi involved in the Airplay streaming as far as I know).

Well video and audio are out of sync! (Quelle surpise..) 

I have been experimenting with a tool for PC called Tuneblade.Tuneblade replaces Airfoil in the scenario above.  It has an option to play audio without the use of the 2 second buffer. This noticeably improves the sync issue, but not there yet. According to the Tuneblade blog - http://tuneblade.com/blog/ - Apple TV 3 should have dramatically lower "Minimum AirPlay audio latency". Is there any truth in this claim? Would buying an Apple TV 3 resolve my issue? Would latency (and A/V syncing in my described scenario)  with Apple TV be better also without using the Tuneblade tool? I'm asking this because everyone complaining here is using Airport Expres and not Apple TV.

I think there is some BS involved with the lag appearing while playing streaming videos via any kind of browser. I mean, I use AirPlay with both my Mac and two iDevices - one on iOS 7 and one on iOS 6. The iOS can handle youtube videos no problem at all, and the Mac with much more computing capabilities doesn't handle it. Besides, I noticed that while the system (Maverics) is set to use laptop's speakers and iTunes has the AirPlay option activated inside the application the music plays without a lag. But if I switch to AirPlay on a system level (option-click on a sound icon on toolbar), even iTunes gets delayed. That I cannot understand:(

This has been bugging me for ages.

Obviously the VLC delay is great for videos - but you can also use for youtube by pasting in the URL.

Now for netflix / iplayer etc.

Is it just me or has this been fixed??

selecting the airport express as output device (option click on volume on menu bar)

now plays youtube and vimeo videos in chrome are totally in sync.

Thanks for you tip about the safari plugin, did you have to change any of the plugin settings for it to work? I had a look in the settings but dont undetstand much of it.

I'd like to know if this sync problem is fixed under mavericks? Or is it still there?

this is really terrible. I went out to buy a wireless speaker that i can use for many different applications... i had in mind the logitech UE boom bluetooth speaker, this is around 120€, when i went to the shop and tested a few speakers and spoke with the sales guys, they all told me airplay airplay airplay, its so much better quality than bluetooth.... which after listening to a few different options agreed and went for a bose sound touch using airplay... for 375€... a treat for myself. only to get home and find this horrific lag...what the ****... it seems to be ok from the iPhone using netflix, but from the iMac its unusable. gutted. i advise anyone out there to get something with bluetooth, yeah the sound quality is maybe compressed or whatever, but if your using wireless speakers its not like your looking for studio quality anyway.. really crappy. bad apple.

oh its there in mavericks

What about Netflix.com ? That's not flash.

Hello. I still have the same problem with airplay. youtube and netflix 2 secs lag. Now I'm using Chrome and everything is synced . not the best solution but Chrome "it just works"

I have spent a few hours trying to resolve this issue, the same exact issue a majority of you are having.  My issue: Audio lags behind video from my iMac (maverick) about 3-4 seconds when streaming to airplay (via airport express).  I spent time resetting the router, checking firmware, doing a SMC reset and a PRAM reset, configuring the "radio channels" but nothing seemed to work.  Eventually, I realized the problem wasn't with the hardware but it seems it has something to do with the software.  I ended up identifying the problem to be flash, and since i use chrome (latest version) i downloaded an extension that is called magicaction and when I added it i enabled force player type "HTML5" as well as "SpeedBooster" then when I went back to youtube to play video (after closing and reopening Chrome after the extension install) there was no lag when the videos played back.  I was surprised at how it worked, but it solved my problem.  I have yet to try other players but I would assume it may be issues with the Audio / Video Codec's that are used.

I am still having the issue with normal video files. disappointing.

Just my 2cents.

With the latest update this issue was solved. Try youtube on safari and see how it works.

Even after YEARS being present taking part of OS X, DVD Player and Airplay, both native Apple products, STILL do not play in sync! Even in the lastest OS X 10.10 Yosemite.

Why, why, why!!!

It has been one year since the last posting, but I ran into this thread, having trouble with netflix videos played in safari and sound streamed via Airport Express 1. Gen to my Hifi-System. Since maybe others still run into the same issues and this thread, here is the solution I found for myself:

Neither Safari nor Firefox will play Netflix videos on a mac without a lag between sound and video (youtube etc. seems fine, don't know why). Fortunately Googles Chrome browser does so for Netflix.

Hope this will help someone the way it helped me.

P.S. All systems software is updated to the latest version.