Video Studio X8 4K output audio/video sync issue

[hsinhow]

Hi,

I am working on a project with video clips taken by a Sony 4K camcorder (FRD-AX33/XAVC S). As I have issues in editing clips in timeline using the raw XAVC S clips, I have pre-processed my raw video clips into 4K mp4 format. With this extra step, I can go ahead and edit my recordings.

Everything seems went well and I produced my first few 4K videos using VSX8 and I shared them on YouTube (4K 30p mp4 as suggested by YouTube). My audience soon reported to me that I have audio delay problem!! I soon confirmed it and this issue showed up in more than one cases:

1. The original video from X8 looks OK. But the YouTube version (processed by YouTube) has severe audio delay.
2. Some of the output mp4 videos from X8 already have audio sync issue. They seems to occur to clips which is at the end of long recording or clips with more heavy editing like split/transitions/...

For the first one, since the original mp4 from X8 looked generally fine (it has some visible audio delay in one clip in the middle), I used Handbrake to transcode it and then upload the output mp4 to YouTube. This Handbrake version looks much better than the X8 encoded one. This indicated the X8 mp4 encoder has some hidden issues at least with YouTube.

The second case is more annoying and I finally confirmed it should be a X8 bug after many builds and experiments: In the original production timeline, I imported the X8 rendered mp4 into an overlay track and compared the audio waveforms. I can clearly see that the waveform does not align between those two!

It is not clear where the bug comes from and I think it only affects 4K mp4 because I did not have audio/video sync issue when I did 1080p HD project before. This is a big disappointment for X8 as I upgrade it for 4K video production. Now I have to switch or rely other video editors or encoders for proper.

At this moment, I would not recommend X8 for people when will be working on 4K project.

HH

[Ken Berry]

I have never even experimented with 4K although my GoPro Hero can film in it. But I have nothing to play it back on to get the full 4K effect. So I am afraid I can't help with your 4K problem.

However, as far as out of sync audio is concerned, in the past it was usually associated with Video Studio's SmartRender. So if you have SmartRender ticked in your output settings, untick it and see if that improves the situation.

[hansjj]

for seeking the causes online, you may find that editing xavc there we should get the complete structure and the right video codec.

as you said it will be nice to edit the xavc files in MP4 format. so i can sugest you to convert the xavc s clips to mp4 to be edited smoothly. just look for a best xavc s video converter to enjoy more.

[hsinhow]

Thanks for the comments and feedback.

I have tried flipping the SmartRender option and it did not make difference for the problematic video project.

The SmartRender, unfortunately, does have another bug when rendering 4K mp4 files. I have seen more than a few times that, when I click "Start" button and X8 immediately showed "100% complete" and crashed. I have tried to cleanup the X8 working folder (in Document\Corel...\18.0) and it seems does not fix the issue. I am now using 4K option in "AVC/H.264" for my production. I'll then use Handbrake or other video editors (I am evaluating Power Director 13) for final release transcode/build.

Ken: Do you know how to reset or cleanup SmartRender?

I am now using X8 as the XAVC S => mp4 transcoder. I am not sure how much confidence I should have on this process given that X8 have issues in in editing XAVC S footage in timeline. Can hansjj suggest good XAVC S converters? The XAVC S coded is said to be able to handle and hold high bit rate video footage. I would like to maintain the video quality as much as possible.

As a long time user of VideoStudio, I really wish they can address these bugs ASAP.

HH

[Ken Berry]

Ken: Do you know how to reset or cleanup SmartRender?

Sorry. I'm just a user like you... Getting SmartRender to work better is a job for the team who wrote the software in the first place.

[hsinhow]

I think I have identified the root cause of the audio/video sync issue after many 4K video builds.

It is from the VSX8's MPEG4 encoder. Several VSX8's mp4 output video files has the following issues:

1. Some mp4 videos looked fine played using media players. But after uploaded to YouTube, serious audio delay was seen.
2. Some mp4 files has the issue of degrading audio/video sync through the length of the video.

Since mp4 is the standard video format for YouTube, this is a huge bug that Corel needs to fix ASAP. Currently, I have to rely on other encoders or video editors for final mp4 rendering (for the #1 bug condition). For the #2 bug, there is no workaround and I have to use other video editors for the whole project or pre-processing raw (XAVC S in my case) video clips.

BTW, this is not the only bug that VSX8 has for 4K video production. X8 cannot edit XAVC S clips in timeline (on my 2 computers). It is really disappointing!

HH