Strange studio vs camera audio issue

[Jakester]

So recently I was asked to do a quick audition tape for a gig playing drums. 

 

They wanted me to play along with their backing track which was to a click at 120bpm. 

 

I thought I'd be better off recording the audio using a DAW and syncing it with phone camera video so it would have better sound. I've done this before on gig videos so I know how to do it fairly well. 

 

I was using my phone for video at 1080p, and the drums were mic'd into my XR18 into Reaper. The mics were o/hs and kick and snare. The camera was about 1.5m away from the kit. 

 

So I recorded both, did the 'clap' (ahem) to ensure there'd be a defined point to sync the video and audio. 

 

I did a bit of EQing of the drums in Reaper and then bounced it down into a stereo audio file. 

 

I then went in and sync'd the new audio track against the phone audio track, and then deleted the latter. So far, so, good. 

 

However, for some reason I cannot possibly fathom, the video and audio start to go out of sync after about 30 measures. It's only slight, but it continues until about half-way through the track they're both fully a beat out.

 

Now, I can't understand how this has happened. They were both recorded at exactly the same time. The room isn't big enough to get any kind of delay on the sound compared to the video, and in any event the mics were closer than the phone so if anything, the phone audio would be out (but it wasn't).

 

The audio is consistent at 120bpm all the way through, and the processed track still syncs with the Reaper internal metronome. I have a tape saturation plugin on the master so wondered if that could be the issue, but I've re-exported the track without and it's the same issue. Not using any time delay plugins, just EQ, gates and compression. 

 

Unless there's a small space-time vortex in my studio which is causing the light to be delayed in reaching the camera I can't see how this could have possibly happened. I've done this sort of thing loads of times and never had any problems. 

 

Anyone have any ideas?

[BigRedX]

Different sample and/or frame rates between the recorded audio and the video?

 

Check that they are both the same. If this is the problem, I suspect it will be easier to change the audio to match that of the phone video, so find out what that is and then set up the audio inputs so that it matches.

[Jakester]

Thanks.

 

Hmm, don't think so - output render settings was 44.1Khz in Reaper, and that's also the same as the unedited source video file. 

 

Interestingly the rendered video file is coming out at 48Khz, so for some reason iMovie is upsampling the bit rate, but obviously that's after I've had  (and worked around) the sync problems. 

 

I got round it by just splitting and jumping the audio along a frame every now and then, but it's far from ideal! 

 

I may try a different programme to see if it's an issue with iMovie or the audio. 

[paul_c2]

"Phone camera video" sounds like the culprit here. Clearly either the phone video and/or the audio recording aren't playing back at the same rate they were recorded, hence the drift you can perceive from 1 min onwards. I dare say, with the fact that you recorded it in Reaper, unless you made some erroneous slip there, its replaying at the same speed as the original recording. 

 

You'll need to use some kind of video editor to "tweak" the phone camera video's tempo to match the audio track. I am guessing you didn't do a clap at the end too; but there may be a useful reference you can refer to in some trial and error process.

Edited March 30, 2022 by paul_c2

[BigRedX]

IIRC iMovie only supports 48kHz, so you'll need to record your audio to match.

 

Any reason why you're not doing this editing in Reaper?

[Jakester]

1 hour ago, paul_c2 said:

I am guessing you didn't do a clap at the end too; but there may be a useful reference you can refer to in some trial and error process.

 

No, but there's lots of stops, stabs and crashes which make it fairly easy to line up, so ultimately I had to just drop in a couple of very short snips in the audio to help it resync. 

 

15 minutes ago, BigRedX said:

Any reason why you're not doing this editing in Reaper?

 

 

Only that I haven't quite yet figured out how to use the video editing features!  In more seriousness, I couldn't get it to properly import the native video from the iPhone, but will have another crack. 

[BigRedX]

Just now, Jakester said:

Only that I haven't quite yet figured out how to use the video editing features!  In more seriousness, I couldn't get it to properly import the native video from the iPhone, but will have another crack. 

 

Since you mentioned iMovie I assume that you are using a Mac to do this? I was aware that Reaper for Windows requires some additional files to be able to import .mov files (which is what your iPhone will be producing) but I would have thought that the Mac version of Reaper shouldn't need these.

 

Anyway at the moment the easiest way to sort out this problem on any future video recording you need to make would be to to set the project sampling rate in Reaper to 48kHz to match your video.

[Jakester]

35 minutes ago, BigRedX said:

Anyway at the moment the easiest way to sort out this problem on any future video recording you need to make would be to to set the project sampling rate in Reaper to 48kHz to match your video.

Thanks, will do!

[Dood]

The question has been answered already but I have fallen foul of the same before even on high quality cameras. Now I do a sanity check to ensure that all of the source recording kit is set to match each other. In my case, 25fps, 24bit, 48Khz. 

 

Nearly all of my audio editing happens in my DAW that I use to record the multichannel audio. This could include automating the muting of the Lav mic when bass is playing. I drop the separate audio files (Lav Mics, Bass, DI, Room whatever) in to my video editing software along with the multi camera angles (and the onboard camera sound to help with syncing) then once locked I edit my footage in the video app. Some final audio tweaking happens in the same app before exporting my footage. I shoot in 4K and export to 2K unless I am requested otherwise. 

[lowdown]

I'm presuming the OP has looked at the frame rates? if not, try the link below, section 3).

More likely it's the video drifting, not the audio.

Usually this is down to playback mismatch of frame rates.

The DAW (video player) project settings frame rate has to be set to the same frame rate as the video was recorded when playing back in Reaper (or any DAW/audio/video editor).

I'm not a Reaper user, but this chap has a decent step-by-step guide writing with videos/films/pictures.

 

https://howtowritefilmmusic.com/how-to-set-up-reaper-daw-for-film-scoring/

 

[Jakester]

2 hours ago, lowdown said:

I'm presuming the OP has looked at the frame rates? if not, try the link below, section 3).

More likely it's the video drifting, not the audio.

Usually this is down to playback mismatch of frame rates.

The DAW (video player) project settings frame rate has to be set to the same frame rate as the video was recorded when playing back in Reaper (or any DAW/audio/video editor).

I'm not a Reaper user, but this chap has a decent step-by-step guide writing with videos/films/pictures.

 

https://howtowritefilmmusic.com/how-to-set-up-reaper-daw-for-film-scoring/

 

 

Thanks. I daresay the problem could well be the limited 'under the hood' editing functionality in iMovie. I only used that as it's supposed to be quick and simple! 

[skidder652003]

Video editing in Reaper is way easier than iMovie and I've used both and DaVinci Resolve.

 

If you keep it all "in house" in Reaper it will save time and agro with sync issues.

 

I remember having a similar issue and solved it by adjusting the movie playback rate in Reaper.  As I recall, I right clicked on the movie file that was on one track, selected item properties and adjusted the playback rate until it synced up with the audio track. I'm sure there's a YouTube video explaining it .