Audio sync problem - simultaneous HDMI and analog output

sultanoswing · 2013-11-11 08:51:49

I'm currently running my audio out through my Geforce 460 via HDMI to my A/V receiver. I have a simultaneous stereo analog output running through my ASUS Xonar D2, using Pulseaudio & Amarok as the player (VLC-gstreamer backend).

I use the HDMI and A/V receiver to power my main stereo in my living room, but on occasion when I want music around the house, I use the analog line out to send audio to an FM transmitter.

The problem is, I'm running into audio sync problems. The audio starts out synchronised (at least to the naked ear) but within 20-30 seconds it is noticeably out of sync, with the analog audio (form my FM radio) running around a half second ahead of the HDMI output (my main speakers).

So - where to begin finding where the sync problem is? The receiver? Conversions between 44Khz and 48Khz?

Any help much appreciated - google-foo hasn't turned up anything obvious so far.

schmidtbag · 2013-11-12 18:49:45

I have the same issue with my laptop, though I don't use PA. That being said, I don't see there being an easy alternative. Why not just mute one when you use the other? Or, you could try only doing analog and use an audio splitter cable, which you can get for a couple dollars on ebay. Doing that should get you synchronized audio.

When you really think about it, it's not much of a surprise why an analog audio source would be out of sync with an HDMI audio source. It takes time for the data to be transmitted to the GPU, interpret the audio signal so it can be converted to the HDMI standard, wait for it to synchronize with the video signal, then the TV/receiver has to interpret the signal, convert the audio signal into analog, and play it out the speakers.

sultanoswing · 2013-11-13 06:08:18

Yeah - that was my thought - a very difficult, and probably insoluble problem as it stands. I can't just mute one of the devices as that would defeat the purpose of having multi-room music! Fortunately it's not too noticeable usually, as you can't usually hear the main stereo and the FM radios at the same time, unless you're standing in the right part of the house

The analog splitter cable not really a goer, since running clean, crisp multi-channel HDMI with pass through when needed is the essential goal of the HTPC. So unless I was to switch inputs and or unplug cables...

What I will end out doing, in the absence of a software solution, is hooking the FM transmitter directly to my receiver. I was going to just use the headphone-out jack of the receiver to feed audio to the FM transmitter, but the stoopid receiver can't output audio to external speakers at the same time as the headphone is plugged. To overcome this, I'll probably run a headphone amp off the receiver's RCA outputs, into the FM transmitter. Like this one: http://headamp.com/portable_amps/ae2/, or this one: http://www.amazon.com/Rolls-HA43-Headph … B00102ZOQC

Last edited by sultanoswing (2013-11-13 06:15:11)

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#1 2013-11-11 08:51:49

Audio sync problem - simultaneous HDMI and analog output

#2 2013-11-12 18:49:45

Re: Audio sync problem - simultaneous HDMI and analog output

#3 2013-11-13 06:08:18

Re: Audio sync problem - simultaneous HDMI and analog output

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