Slides out of sync with speaker video/audio

[benbucksch]

In the recording for my talk, the (big) slides appear 14 seconds too early, compared to the speaker video video and audio. The video review system allows me to adjust the audio sync. But if I changed that, the voice and the speaker image would be out of sync. It's just the big slides that are out of sync.

Actual result:

• The review system gives me no way to adjust the sync of the slides.

Expected result:

• The slides and speaker video are in sync automatically
• If not, the review system gives me a way to adjust the slides compared to the speaker video and audio. (For this feature, the sync between speaker video and audio stays as-is and is not altered.)

I was told that is a limitation of the video setup at FOSDEM. Is that because the system merges the videos immediately at the recording time? If so:

Proposals:

• Record slides and speaker video separately, then merge them later with the software, so that it's possible to adapt the sync later via the review system. (This would also allow to change the speaker video size, another desirable feature.)
• If not possible, then use ffmpeg to cut out the speaker video, make 2 videos out of it (slides will have white background instead of speaker video), then stitch them back together with the new sync.

[yoe]

On Mon, Feb 05, 2024 at 07:23:41AM -0800, Ben Bucksch wrote:

In the recording for my talk, the (big) slides appear 14 seconds too early, compared to the speaker video video and audio. The video review system allows me to adjust the audio sync. But if I changed that, the voice and the speaker image would be out of sync. It's just the big slides that are out of sync.

Actual result:

• The review system gives me no way to adjust the sync of the slides.

  Expected result:

• The slides and speaker video are in sync automatically

• If not, the review system gives me a way to adjust the slides compared to the speaker video and audio. (For this feature, the sync between speaker video and audio stays as-is and is not altered.)

  I was told that is a limitation of the video setup at FOSDEM. Is that because the system merges the videos immediately at the recording time?

Yes, that's correct.

If so:

Proposals:

• Record slides and speaker video separately, then merge them later with the software, so that it's possible to adapt the sync later via the review system. (This would also allow to change the speaker video size, another desirable feature.)

This unfortunately requires a lot more storage space and a lot more work, neither of which are very desirable.

 * If not possible, then use ffmpeg to cut out the speaker video, make
   2 videos out of it (slides will have white background instead of
   speaker video), then stitch them back together with the new sync.

We are not set up to do this, unfortunately (884 talks! we're happy we can publish most of them within a couple of weeks...).

However, if you wish to do this yourself, you can! Just download the video which you see when you review it (there's a download link right there), edit it in an editing program of your choice, and then let me know so I can give you an upload link into the system.

Alternatively, if you prefer, we can also add an "apology" note. This would add a slide to the video similar to the second one at https://github.com/FOSDEM/video/issues/233, wherein we explain the situation. This would appear just after the opening slide but before the main video.

If you don't think either of these two options are appropriate or required, then you can just continue reviewing the current video as normal.

Kind regards,

-- @.***{be,co.za} wouter@{grep.be,fosdem.org,debian.org}

I will have a Tin-Actinium-Potassium mixture, thanks.

[benbucksch]

Hey Wouter, thanks for the response. I didn't mean to ask you to do the work manually. This was a feature request for the software system. If not feasible, then so be it.