Audio Sync Issue from iMac to 720p TV

I'm having audio sync issues when I play movies from my iMac on my HD TV.

I have a 2010 27" iMac w the i5 and 4 Gb mem. I bought the minidisplay port to DVI converter cable. I run 3 feet of DVI and then convert to ~5 ft of HDMI cable. Two audio configurations have the same result. One is 6 feet mini-stereo right to speakers. Second is 6 feet mini-stereo to RCA stereo in on TV. The TV is 720p HD but it is DLP.

The same movies seemed synced with audio and video when I watch on my iMac. When I watch on the TV, the audio is a few fractions of a second ahead of the video. The problem seems slightly worse when I watch in Front Row as opposed to iTunes but that might be my imagination. I mirror the displays while watching on the TV.

Any suggestions?

You mean you're running an adapter into a DVI cable and then a dvi to hdmi adapter and then a hdmi cable? Really bad idea and that's your issue.

You need to grab one of these in the length you need - link.

Thanks for the quick reply. Yes. I am converting just as you say. Before I bought one of the cables you suggested, I tested it tonight on a DVD playing in the iMac displaying on the TV in my config with the DVI->HDMI w speakers plugged directly into the iMac (as opposed to playing a m4v file converted from a DVD).

I just watched all of the Da Vinci Code (2 hr 29 mins) with perfect audio sync.

Additionally, the audio is always quiet when I watch from m4vs files. From the DVD, it was significantly louder.

I use HandBrake to convert my DVDs (even verified by my someday possible brother-in-law FBI guy) to m4vs.

What am I missing here? Perhaps my iMac can't keep up with playing an m4v on two screens (because DVDs have some hardware acceleration?) Why would the minidisplay->DVI->HDMI effect m4v files more than DVDs?

And why does the audio directly from the DVD kick the m4v's ****?

thanks.

i am currently using the miniDV out to HDMI with the converter setup and haven't had any sync issues when playing from my macbook to my t.v. However, I have had loads of problems with audio sync when I am converting old videos that don't have timecodes. Someone on this forum finally explained to me that I needed to adjust the sequence presets in FCP to match the audio/video I was working with and to export with the same settings. Bottom line the audio was at 12bit and I was exporting at 16bit. Video started out fine but about 30 minutes in noticeable sync issues. I don't know what kind of video you are working with or if this in anyway relates to your problem...

But, I have the same connection setup as you and currently have no problems with sync...even when playing DVD's (commercial or homemade).