Audio Sync Issues

I’m not sure if this has been posted yet or not - but I’d like to clarify some of my findings while using my WDTV Gen2 to playback my video collections.

I haven’t had a ton of issues, but I have noticed the A/V sync issues and the issues concerning the subtitle playback.

The subtitles problems are an easy explanation.   There’s no way WD can keep up with the changing formats and if the sub authors don’t ensure backwards compatability, you get horrid subs.   I’ve converted subs for the sheer sake of getting them to work on the WDTV.   It’s annoying.

I don’t work for WD, but I do want to say this, so don’t flame me about it.   If you’re wondering why you can play your MP4 files with AAC on VLC, MPC, WMP etc. without sync issues, you need look no further then the software you’re using to play it back with.   If you have FFDshow installed, you can actually check this in action.   The software that runs on your PC automatically corrects for defects and audio delay issues encountered when it plays the files for you.

I doubt the WDTV has the capability to do this in real time, nor the amount of memory required to buffer this properly.   This isn’t an excuse, just an answer as I troll the forums looking for some new firmware myself.

I believe you can watch the audio delay being corrected in real-time with FFDShow while you play back your video in your favourite player.   I also think VLC can display this too.   Most computers with high clock rates, multi-cores and large memory can easily provide the power to correct this.  And be aware that there are many “bad” encodes of video on the internet. 

My experience when I come across these files that my WDTV Gen2 won’t play is simply re-encode the audio into PCM or AC3.   Both of those are fairly stable standards.   You can easily extract your audio out of a MKV, re-encode and inject it back in.   Since MKV is a container format, you can extract the audio from your MP4 files, re-encode it, inject everything into an MKV file and set the new audio to another audio channel.    Making an MKV out of any file doesn’t take a long time.   The audio encoding might, though. 

A hassle, I know, but if you paid for the player and are like me (using to play my whole video collection) you might want to invest in some transcoding knowledge to ensure you get the most bang for your buck.   For the most part, I enjoy the fact that my encodes play smoothly on this device.

Hopefully this can help you understand and help you a bit.   The WDTV is a pretty good player and I’m still enjoying it.   I hope you can too.

Good luck everyone.

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I wasn’t overly clear on the first post, but here’s a cap of a very badly encoded Akira backup I made years ago.   You can see the sync issues in Media PLayer Classic being corrected in real time.

Image1.jpg

I believe that’s per video frame - or group of mpeg frames, or something like that.   Either way, it gets multiplied without the program trying to fix it in real time.   Eventually, the audio gets way out of whack, and you have a sync issue.

I know there are other reasons for this as well, but without going into too much detail, this kind of thing happens all too often with messy encodes and video converters that don’t adhere to standards.

Good luck.

I have great picture quality with MKV files. They work perfectly well when I play them on my computer. When I go to play these files through my WD Player, the picture is excellent but there is no sound. Any where I can find instructions on how to correct this? Sounds complicated as I am new to all this.

Thanks

JF

johnnyf, look for any of the posts dealing with “header compression” in Matroska files, and using MKVmerge (with compression set to “none” for all tracks) to fix the problem.