[hogfan]

Ok, currently running the 11-08 SVN build of XBMC on Xbox. All movie encoded in Handbrake on OSX to MKV with H.264 & AC3 passthrough to keep the original 5.1.

Before yesterday my surround sound wasn't hooked up (recently moved) and I was watching these .MKVs just fine with the 5.1 track being mixed down to stereo.

After hooking up the surround sound and connecting my optical audio cable from Xbox Advanced AV pack to the Yamaha receiver, I enabled AC3 5.1 & DTS in "Configure Audio Hardware", and disabled "downmix to stereo" option. Movies had audio/video sync issues during playback, audio ahead of video. Tested again, same movie in stereo. Same issue. Rolling back version of XBMC didn't fix the problem.

Long story short, a couple of MKVs are on the Xbox, most are not and are on a network share. When I tested 5.1 audio on a MKV that I had already watched (knowing there were no sync problems) that was stored on the Xbox, playback was perfect.

So, it appears that I have audio video sync issues with all mkvs that are being streamed across the network. The share source is on a PC with gigbit ethernet, & my 2WIRE gateway is gigbit. Xbox I think is 1/100 ethernet. Is there a cache setting I can adjust to correct the sync issue. Has anyone seen this issue before? I am moving to HTPC, but need XBOX to get things done until then. Thanks for any suggestions.

-hogfan

[hogfan]

Ok, tested MKVs in MPlayer on OSX and no issues. After re-installing XBMC on the XBOX (needed to be done anyway), I discovered that the A/V sync issue ONLY occurs when using digital audio output. Connecting the Xbox to TV with analog (rca) allows the MKV to play back in sync just fine on XBMC. When running throught optical cable to my Yamaha receiver, I get bad sync issue where audio is ahead video. Yahma receiver has an audio delay setting, but I wouldn't think I should have to use it considering the movies are original framerate, and the AC3 track has been left untouched. Any suggestions? Thanks.

[floepie]

I have the same thing with the SPDIF output from my windows HTPC to receiver. I just started with XBMC, but this issue persists with any software. The audio is about 1/10 second ahead of video. Previously, I've used AC3filter to delay audio 100ms to fix the problem.

[hogfan]

Interesting. Does anybody know what causes this to occur? It's not just the MKV of the movie. The DVD does this as well in XBMC.

[floepie]

I'm still not convinced we have the same problem, but I've always chalked up the difference in timing due to the fact that the 2 devices cannot be timed to the same clock. Perhaps some of the newer receivers can decode DTS/AC3 faster than earlier models could and therefore the audio can be heard that much sooner to the point it becomes somewhat noticeable.