I bought my first pair of Bluetooth headphones recently (this one). It's working well, except there's a noticable audio lag when watching videos. This is true whether I play them on my Macbook Pro or my Treo 755p. Is this just something that always happens when using A2DP, or is there something else going on?

On the Treo, I can sorta understand why there would be lag, as I have to use Softick Audio Gateway to use A2DP, and I figured there's some encoding delay. But on my Macbook Pro, I assumed it would be real-time or close to it, but the lag makes movies unwatchable. Anyone ever have these sorts of problems, and is there anything I can do to fix?

Is it possible the delay is in the headphone side of things, in which case you're probably screwed.

It might not help, but you an tweak the a/v sync in VLC. According the manual it work in either lead or lag mode to make the audio in the headphones match the video on the screen.

Yeah, mplayer will do that too, but there are so many different things that play video (flash players, quicktime, etc.) that I don't want to rely on the player doing lag compensation if I can help it.

As for the delay being on the headphone side, who would buy these things if there was really that much lag by design? There's not nearly that much lag with my bluetooth keyboard, that's for sure. Yeah, stereo audio is going to be higher bandwidth than my typing speed, but if the latency is that bad, it seems like something a lot more people would have mentioned in the Amazon reviews and so forth.

Personally, I don't know how it could ever not have lag. I assume the bluetooth headset must buffer the audio to some extent. How is it supposed to then sync the audio to the video which is being decoded by a completely different device/program?

I don't think you'll be able to get the AV in sync without making some adjustments to affect the video delay. What I wonder is if there's any type of existing signaling standard for players that may be A2DP savvy to handle this automagically.

I'm also not sure how much delay you're talking about, but we (humans) can generally perceive audio that's off by even a small fraction of a second. I'm talking like 100 milliseconds in some cases.

There's a noticeable latency in the headphones as it decodes the SBP-encoded audio, and in good headphones there'll be buffering too. There's no back-channel: no way for the player end to work out what the headphone latency is. A2DP is never going to work for video except with players which can deliberately advance the audio track by an adjustable amount, and even then it probably won't stay synchronised as the headphone DAC clock can drift relative to the player.

When listening to music, you don't really care about latency -- or, at least, you care a lot less; you probably wouldn't even notice 0.5s audio-only latency, but that's plenty enough to destroy video.

HFP for phone hands-free kits is deliberately a lower-latency protocol, but at the cost of much lower streaming audio quality.

Peter

Okay, as long as it's a case of unrealistic expectations, I can breathe easier. This would be a great thing for the OS to pick up on, though. Presumably the OS has some idea of the current latency of both the video playback and audio, and could sync them. Oh well.

I switched over to HFP and the audio quality was unacceptable, and there were many more stutters/drop-outs than A2DP. So, I guess I'll just bring along a pair of wired headphones for video. Wish I'd realized this before I bought the headphones, though.

It's possible, but perhaps most of the people buying them are only using them for audio?

I've had a few sets of bluetooth headphones, and only used them for audio, so I can't compare your experience to mine. I returned or abandoned all three sets, though, and not because of quality, but because of range. I know bluetooth is designed for personal networking and everything, but I had problems when my headphones were on my head and my mp3 player was in my pants pocket. I tried changing the side I carried it on, and even carrying the player in my shirt pocket, but it would only play clearly when the player had direct line of sight.

Hopefully the Bluetooth 3 spec will do better on the audio side.

Related question:

If I want to watch TV at night, I have to turn the volume down so as to not wake up my daughter. Unfortunately, at that point, the TV is competing with the background noise of the fridge, the air conditioner, and so forth. Clearly, headphones are the answer.

Ahh, but which sort of headphones?

My current receiver has a phono jack, but it's not specified what happens if the source material is Dolby 5.1. How does it construct the stereo downmix? Some newer receivers have Dolby Headphone coding, which I assume tries to create a virtual surround experience. But I'm not aware of any receivers doing Dolby Headphone and A2DP wireless at the same time.

There are some headphones (e.g., Pioneer DIR800C's) that claim to do it all, integrated, but I'd rather use my nice Grado Labs old-school wired headphones, either with some kind of wireless adapter, or just a long cord from the couch to the receiver on the other side (although that could certainly be awkward).

This is all bound up in my eventual migration to Bluray and an HDMI-switching receiver, and that's all waiting until I feel like there's enough content available in Bluray that it's worth the bother.

You could check out the AKG Hearo 999, which is now discontinued. It got really good reviews for its surround processing and for its wireless headphones, but it also has a headphone jack for your Grados.