Audio sync adjustment in real-time?

[laurenglenn]

With all video capturing hardware I've ever used (including my old ATI, and basically any MPEG hardware capture), dropped frames always seem to get files out of sync when editing later on.

Something that I'd love to see added is an Audio delay adjustment in real-time. This way, if you see that when playing your recorded video or imported MPEGs that your audio is slightly out-of-sync due to background processes stealing CPU time, you can "push" the audio sync to delay the audio a little bit. It would be nice, especially with very long recordings (2hrs. or so).

I imagine the MPEG stream could be paused, the adjustment could be made, and then playback would resume..... I don't know. It's just a thought....

Lauren

P.S. My Creative DVCR original software would always have this sync problem when you export the video (especially when there were dropped frames and the like)...

[Narflex]

That's been in there since V1.0. Go to the Audio tab in Setup and change "Audio Playback Delay (msec)" to the desired delay.

[ruel]

Originally posted by laurenglenn
With all video capturing hardware I've ever used (including my old ATI, and basically any MPEG hardware capture), dropped frames always seem to get files out of sync when editing later on.

(...snip...)

P.S. My Creative DVCR original software would always have this sync problem when you export the video (especially when there were dropped frames and the like)...

FYI, for those who don't know about the Creative software, the audio sync has always been a scourge of problems for those folks who want to edit the exported video files or who wanted to burn the exported video files to DVD/SVCD with people banging their heads against the wall in trying to figure out how to get the sound in sync. If you do a search over at AVSforum, you will see a bunch of people who came up with different solutions, but although one solution may work for one person that solution may not necessarily work for someone else. (Jeff mentioned during testing that the Creative VBDVCR needs to compensate in its synchronization routines through some special calls and there is no public information like a developer's kit that would have info about the special calls. So if those special calls were known then other third-party editing software could be fixed to better accomodate the Creative videos without all of the different workarounds that people use.) Otherwise, the Creative exported video is fine with the sound in sync when you watch the recording in the Creative software and if you watch the exported video file "as is" without any further editing or conversion. It's when you do any editing, conversion, or manipulation of the exported video file is when the sound sync problems are introduced. I've taken the easy way out with the exported files by leaving them "as is" such as with half-hour TV shows recorded at the "good" setting copying them to CD (a half-hour show recorded at the "good" setting can easily fit on a CD for storage) or by divxing the video and then changing the framerate on the divx file to sync the sound. But that's for archiving the videos made by the original Creative software to the harddrive or to CD and not necessarily for playing on a standalone DVD player without any further massaging of the file.

[Narflex]

Can you point me to or explain exactly the problem people are having when editing? That shouldn't be occurring because the files I'm creating are synced.....but there's something interesting about the Creative card I just remembered that was giving me issues.

I think they use scene change detection in their encoder which causes you to have variable GOP lengths. If the editing software isn't smart about this and always assumes a constant GOP size (like my mux used to do until I realized this), then you're going to end up with some random sync issues that would make you do this

What do you ya think? I know Provideo has a constant GOP size and we haven't heard of any sync issues with that card for awhile. And they both use the same multiplexor in Sage to create the MPEG2 files.

[laurenglenn]

Originally posted by Narflex
Can you point me to or explain exactly the problem people are having when editing? That shouldn't be occurring because the files I'm creating are synced.....but there's something interesting about the Creative card I just remembered that was giving me issues.

I think they use scene change detection in their encoder which causes you to have variable GOP lengths. If the editing software isn't smart about this and always assumes a constant GOP size (like my mux used to do until I realized this), then you're going to end up with some random sync issues that would make you do this

All I know is that the Creative card never really worked well for me. It's not your software that's at fault. It's the card, IMO. They haven't had a software update and to get an MPEG file, you need to mux it which always goes out of sync for me especially when there's video corruption.

I'm glad you guys tried to get it to work, and you did to a point. I just broke down and bought a Hauppauge PVR-250 which is syncing up much better and causing me less audio drift (which I blame the DVCR card for). Unfortunately, the remote is not nearly as good as the Creative one... But at least it works for me without problems.

Unfortunately, most MPEG-2 editors that I've found are expensive for good ones. The demos of them and the inexpensive ones really don't edit well if the video is captured directly into MPEG, at least the ones I've tried. I used to use MyFlix 3 for MPEG-1, but even that went out of sync. It must just be something with MPEG streams, like you said.

Anyway, I'm a happy user of SageTV and my new Hauppauge card.

Thanks for all your help.
Lauren

[dkardatzke]

Lauren,

Did you PVR-250 come with the silver or black remote?

[laurenglenn]

It came with the black remote. So far, everything has been in sync with this card. I've left it running for hours and it hasn't been out of sync yet.

I have a wireless keyboard and mouse, and have been using them to control SageTV. One day, I'll get the IRMan, but for now, I'll make the best of what I have.

Lauren

[dkardatzke]

That's too bad because they've been shipping recent PVR-250 cards with the PVR-350 silver remote. It's got a much better button selection.

The IRMan is nice, works perfect with my universal remote.

[laurenglenn]

Originally posted by dkardatzke
That's too bad because they've been shipping recent PVR-250 cards with the PVR-350 silver remote. It's got a much better button selection.

The IRMan is nice, works perfect with my universal remote.

It figures....

Anyway, I'm still glad it's working.

If no one buys my old DVCR card (listed on half.com ), I may just try out that dual-tuner support you guys added...

It's OK, though. The PVR-350 remote looks nice, but I like remotes with a different type of layout. Maybe I'll get the ATI remote and use Girder (which I think supports it).

Lauren