Changing audio from 96 KHz to 48 KHz in timeline

I just completed editing together an 8 minute piece that combines live music and interviews. I was noticing some minor sync issues and when I exported the project via Quicktime, it was pretty clearly off sync in parts. That's when I discovered that the while the music was at 48 KHz, the interview audio was at 96 KHz. I'm assuming that's my problem. My question is, is it possible to fix this in FCPX, or do I have to do what I fear and fix the audio outside of FCPX, reimport it and sync it up piece by piece with the interview footage? Is there an easier route? Thanks in advance.

I'd use Compressor to transcode it to AIFF 48kHz, 16-bit audio.

Is that going outside of FCPX and reimporting and resyncing the audio? Or is there a way to send it to Compressor from the timeline?

You can just do a batch conversion in Compressor of all your interview footage. Change the audio to 48 kHz and 16 bit, keep the video the same codec. I'm not sure if it will try to recompress your video (if it does, I would make a separate picture export with the unconverted clips). After the conversion is done, you can relink to your new clips and hopefully everything works. This is if you're lazy and don't want to figure out which clips you used. Another way would be to look at the "used" clips and just convert those.

You can actually send to compressor from the timeline by going into preferences and adding a compressor setting as a destination. Also, you can do a master export and set "open with" to compressor. Either way you can set an in and out point to only export that section. However, if you only want to convert your interview audio, you'll want to match back to the original clip and export the audio from there rather than the timeline.

Thanks so much. This is working and will save me some serious time. Gracias.

So I converted everything over to 48 KHz/16 bit. It's all in sync in the timeline. However, when I export to Quicktime H264, it's out of sync still. Any thoughts?

I guess that may be because I'm exporting the proxy media and my original media is off a series of Canon digitals which means it's H264 which FCPX doesn't seem fond of. However, when I go to change the setting in the project, it won't let me change the render. Do I just re-render the timeline as optimized/original? Will that solve the problem? Or is t here a way to make only the clips in the timeline prosres? Don't have space to make all my media prores. Again, thanks.

You should always export with optimized/original set, except perhaps when you're bumping out a low-res rough cut or something like that. FCPX should be fine with native H.264 files from Canon cameras, which is very common. Unless your machine is very slow, you should be fine with native.

Your timeline setting should probably be at least set to ProRes 422 which I consider to be a baseline for mastering. Even though your original clips are H264, in the end it will output to ProRes if you export a master file. If you export it as ProRes 422, is it still out of sync when you play that in quicktime?

By the way, if you're using simple H264 files from a Canon DSLR, you don't really need to make proxy files. With modern machines, proxies are best when dealing with 4K and up media. In general, if you're having sluggish performance with a camera codec, try optimizing media instead.

I just changed my timeline to optimized/original and re-rendered. Exported to quicktime and still have sync issues. Not sure I know what's happening here. Should I re-render as prores HQ?

Hm, very odd that it would be in sync in the timeline but not output in sync. If you match back an interview clip to your event, you're sure the clip now says 48 kHz in the 'sample rate' field? You have to add 'sample rate' as a column for that to show up. Perhaps turn off all audio enhancements to your clips that have the sync problem also, just so you can isolate the problem. Btw, ProRes HQ probably won't help, but it wouldn't hurt either.

Thanks. It seems to be just the interview clips at the head of the piece. So I replaced them and am now rendering in prores HQ. Then I will output and keep my fingers crossed...

Odd, the quicktime file doesn't seem to have the audio locked down. When I first play the file, it's pretty out of sync. But if I pause it, back it up again, what was just a moment ago out of sync is now back in sync. Not sure if that's a memory issue or something else. I wonder if it will keep sync once I upload it online...

Try opening your master file in Quicktime 7 instead of the newest version of Quicktime. See if your audio is now in sync. I have had issues with slight audio sync misalignments that play back perfectly in the timeline but are off when played in Quicktime. Opening and exporting the final from QT7 has always solved the problem for me and I have never been able to figure out why this is.

Yeah, still slightly out of sync in 7, too. Just at the top. Baffling. Uploading it now to see if it stays in sync once it's streaming.