Using a video as the sound track for a sequence

[algerdes]

I'm doing some experiments to ready for later this year.  I have a sequence for "Let it Go" from the movie Frozen.  It has been noticed that the lipsync to the .mp3 that is used isn't quite on. In fact, it is almost 1/4 second off.  Since the sequence uses the video to drive a P10 panel, I switched over to the .mp4 as the audio source.

After doing so, the sync between the visual and the audio was still noticeably out, almost 1/2 second.  I went outside xLights and ran the video "normally" (via the computer's program) and it was dead on.  The exact video that we set to use in xLights.

Reading back threads on this subject, one would think that this should work.

What is the secret to getting videos correctly synced? Using xLights 2022.25.

[Bwinter]

I use video (MP4) for many years (multiple different videos), without any problems.  The file is located on my master/main RPi, which is connected to both my projector and transmitter.

Do you know which is actually the problem--the video or the audio?

[algerdes]

I am still in the sequencing stage.  The video is located in the "video" folder of the sequence files.  When played directly (via the player in Windows) it is fine. When played via xLights in the sequencer it is out of sync.

Further research (reading) brings up some interesting conversations about the VLC player (used in xLights?) perhaps not presenting correctly.  I'm still digging into it.

[Stormyblade]

I have the song 'Into the Unknown' from Frozen 2 (my daughter picked this special version off YouTube as it has the special audio intro from the singer Aurora at the start) . In my case, I've stripped out the audio from the video, used the resulting mp3 as the audio for the sequence, and used the mp4 as a video file for the sequence. I just used a free online site that lets you upload a video, strips out the audio, and gives you back an mp3 file. I've also done the same thing for 3 other songs in my show that use video for the full sequence, and in each case I don't have any issues with the audio and video being out of sync. I do *not* have the box 'Use sequence audio as video file and synchronize' checked, and my start time for the video file is set to 0.00 for every song/video/sequence.

After going back and reading through your issue again, let me add something: I know the FPP manual says to upload the full sequence to the Master/Player, and *just* the video file to the Remote device (along with naming it as an mp4 with the exact same name as the mp3 audio file that is used for the sequence). That didn't work for me and I was definitely having sync issues. For me, what is working is that I upload the V2 version to the Master/Player, and the V2 Sparse/zstd version of the sequence to the Remote, and NO video file. I tried testing with the video file still there and was getting stuttering, and just happened to find out that it works as I just described. I don't know why it's working, but it is, and I've gone out several times to verify that everything still runs smoothly. I'd love to have one of the developers tell me how to do this better, but I'm not screwing with anything for the remainder of this season.

[algerdes]

Thanks for that information.

In my case there are no remotes. A single FPP runs the whole show (we have a great wired network between the FPP and all the controllers. One wireless bridge across a parking lot, otherwise all cabled.)

For this investigation (?) we haven't even left the sequencing computer, yet.

[Stormyblade]

Just checking, but you didn't change your media offset by accident, did you? It should be set to 0.

You cannot view this attachment.

[algerdes]

Nope. 
We are not on a RPI/FPP yet. This is still inside the sequencing computer.
The sync is off when playing xLights and viewing the outcome on the computer screen.

Thank you for the reminder about the Media Sequence Offset.  I'll keep it in mind when I do transfer to the FPP.