Blackmagic Forum

Creating proxy media from a file with a different (video) frame rate seems to yield audio rate issues.

I created a new project (timeline 24fps) and dragged in two video files: one with 23.976fps (H.264 High L4.0, with AAC) and one with 30fps (H.264 High L4.1, with AAC). I have the project set to "choose automatically" for optimized media and proxy media resolution; both formats are to be DNxHR HQX.

* I drag the two clips to the timeline one above the other. They play properly - the two people singing stay in sync across 2.5 minutes. I delete the clips from the timeline.

* I select both files, right click and Generate Optimized Media. I drag the two clips to the timeline. They play properly again. I delete the clips from the timeline.

* I select both files, right click and Generate Proxy Media. I drag the two clips to the timeline. The VIDEO is in sync. But the 30fps file audio is now pitched lower, timed slower, and it reaches "end of clip" partway through the singing.

This looks like a bug with proxy media.

My experience is similar. However, check your audio sample rate in the original footage of the 30 FPS file. I'll bet it is at 44.1kHz.

When I did experiments after initially thinking that the problem was the frame rate, it seemed clear that it's about the audio sample rate.

When I went into the disk and found the actual rendered proxy files, they were all rendered with a 48kHz sample rate. The original files that had 48kHz sample rates themselves played fine when proxies were made, then turned on. The files that had 44.1kHz sample rates played back out of sync and pitched down when the proxies (now rendered at 48kHz) were turned on.

However, if I took the proxies of the 44.1kHz originals out of the proxy location and imported them simply as files, they played back fine, all in sync and proper pitch.

So I think there is something in the proxy system that is expecting an exact copy of the specs of the original, so that it plays back a 48kHz sample rate as if it were 44.1kHz, and that makes it out of sync and pitched differently.

There was a previous post on this, but it is still not solved in Beta 3. The solution, it seems to me, would be simply to make sure that the proxy generation system rendered the sample rate in the proxy as contained in the original. Then the proxy playback, which is clearly expecting that sample rate, would be happy, and so would we.

@Michael, you are correct sir. 44.1KHz on the problem files that started me on this excursion. Thanks for the extra info.

This issue continues in 17 beta 4.

I hope it can be addressed. Making and using proxies is a great new feature, but flawed.

This is still going on in Beta 5.

I keep hoping.

Same her, just installed beta 5. Still running out of sync, I posted about it when 17 was out.
I thought it was mentioned in the new fixes that it was addressing the optimized clips as well?


Yasir
Resolve beta 5, 16GB iMac, Catalina

Issue exists in the 17.0 release.

Issue had changed in 17.1.

Audio is now in Sync but pitched lower.

Come on guys this has been an issue for ages

I came here because I just had the exact same annoying issue. I just wanted to change my workflow from the optimized media to proxy media, because you can't see anymore if there is already any optimized media.
And now I got disappointed because none of my proxy files I rendered the last hour plays at its original speed in Resolve. I now used optimized media for these clips again and have come to terms with the fact that I can't see the generated media status or path.

Is it really that hard to fix this? Just point the playback sample rate to the new generated files instead of to the original one. Can't be a task for more than 30 minutes...

Just bumping this because it's a huge pain

Yes, this error and many other errors have been known for a long time.Users report bugs even in the beta phase, but they are not fixed. Instead, there are always new versions, new features and even more new bugs. That is really annoying.

same here

Just found this bug. It seems like it has been around for a long time. Hope they fix it soon it pretty much makes the Proxy workflow useless for me.

Just came across this problem myself... a pity because the proxy media feature has been working really well for me otherwise.

Wondering if anyone has gone to the trouble to generate proxies using external tools and then referenced back into Resolve? That's my next step as a workaround... although not convinced it will work if it's the proxy system expecting a 48k sample rate. Shall endeavour to report back my results.

michhes wrote:Just came across this problem myself... a pity because the proxy media feature has been working really well for me otherwise.

Wondering if anyone has gone to the trouble to generate proxies using external tools and then referenced back into Resolve? That's my next step as a workaround... although not convinced it will work if it's the proxy system expecting a 48k sample rate. Shall endeavour to report back my results.

I end up importing the footage I want to proxy twice (as a copy), proxying one and then using the second for the audio. adds a few seconds on so it's not the end of the world, would be nice if it worked though it's been a bug for a while now

Using ffmpeg and the command below, I manually generated a DNxHR proxy file:

ffmpeg -i "source.mov" -c:v dnxhd -profile:v dnxhr_lb -c:a aac -b:a 128k -ar 48000 proxy.mov

Note my source was 44.1 kHz audio as noted above so I'm resampling that to 48kHz. Both the original and proxy file playback fine and sound fine in VLC.

In resolve, I right-clicked the file in question in the bin (so the original source file I'd imported previously) and selected Unlink Proxy Media and then Link Proxy Media... and selected my newly-created proxy file.

Same result as before: audio plays back at a lower pitch.

Unfortunately seems like this is an issue with the Proxy feature in Resolve... maybe it's looking at the original file or only wants to play 48 kHz, who knows.

17.4.2. Still here.

Still having this Exact problem, Sample at 44.1 kHz
Resolve 17.4.3 Free version

Keep in mind, Your Resolve Timeline is defaulted to 48 kHz, therefore you could try to change to match you recorded footage in 44.1 kHz, I think this is causing the syncing issue.
Most cell phone will shoot 44.1 kHz , to help make a file slightly smaller.

Before you bring your footage in, after setting up for a new project, go to Project Settings Shift-9 and select the last task Fairlight
you can apply any of the different sample rates to match the footage you are bringing in.

I still think BMD needs to take a closer look at Proxy, Optimized media and sync.
I have been having issues, and I know once I get my new iMac M1xxx, will not have those issues and might never have to use proxy etc.

If you want to change your 44.1 kHz footage to 48 kHz then try using Handbrake.

regarding Optimized media, the latest manual it notes that by creating a new Bin and placing optimized file, so you can tell which clip is optimized.
We need to hear from some user that has a powerful machine and how it handles proxy media?

I'm on an iMac, 16 BG (late 2015)

The release notes for 17.4.6 appear to claim resolution on this issue:

What's new in DaVinci Resolve 17.4.6
...
• Addressed audio issues with proxies generated for non-48KHz clips.
...