latency during playback ProRes vidoes in Vegas Pro 23

marcinzm wrote on 1/8/2026, 3:56 PM

Hello,

I used Prodad Mercalli software to stabilize footage. I exported videos files in ProRes mov files in Prodad Mercalli SAL version. I changed mov extension into mp4 extension and then I imported all these stabilized footage into Vegas Pro 23 (latest build).

When I play these ProRest files in Vegas Pro 23 I see that audio is not synchronized with video. I see some latency between audio and video. I noticed that after i.e. 5-10 minutest of working in Vegas, this latency disappears. These files are ok and are well stabilized when I playback them outside Vegas in external software player.

I don`t know what it happened.

When I had Nvidia RTX 4070 super and I have never such issue before.

I have Nvidia RTX 5090 and I saw this issue only when I have this graphics card. I don't know if it is because of this graphics card.

Can you advice me anything how to fix this issue?

Regards

Marcin

Comments

3POINT wrote on 1/8/2026, 4:35 PM

I used Prodad Mercalli software to stabilize footage. I exported videos files in ProRes mov files in Prodad Mercalli SAL version. I changed mov extension into mp4 extension and then I imported all these stabilized footage into Vegas Pro 23 (latest build).

What are you doing exactly? What's the format of the original footage and what are you exporting out of Mercalli SAL?

Also I wouldn't use ProRes in VP23 at the moment, since VP23 interprets Prores wrongly.

marcinzm wrote on 1/8/2026, 4:42 PM

The original footage is 4K 50p 4:2:2 200 Mbps HEVC (from Sony FX3 video camera). I click in Mercalli SAL analysing footage then I export stabilized footage to ProRes 4K 50p 4:2:2.

I didn't know that ProRes files are interpreted well in VP23.

3POINT wrote on 1/8/2026, 7:35 PM

Which version of Mercalli SAL do you use (6)? Try to export directly in a mp4 format. Mercalli SAL has several options to export the stabilized result. AFAIK VP23 has a colorshift issue with ProRes.

RogerS wrote on 1/8/2026, 7:51 PM

ProRes should be mov and not mp4. This audio issue is puzzling though. ProRes doesn't decode with the GPU so the model shouldn't be an issue.

23 has gamma issues with some variants like 4444. Judge your 422 footage at best/full quality and it should look right.

marcinzm wrote on 1/9/2026, 1:09 AM

I have been using proDAD Mercalli 6.0.629 64Bit Standard version. I have never had such issue before. It started to appear when I changed GPU, but as you wrote it is not GPU change problem. I have been chaning mov to mp4 extension and doing such way for more than 2 years and I have never had any problems before with latency between audio and video during playback. When I render such project it is ok, so the problem is only with playback. Changing to quarter proxy files playback doesn't help either.

RogerS wrote on 1/9/2026, 1:24 AM

Thank you.

Could you share a short sample file please? I'd like to see if other systems have the same problem.

bitman wrote on 1/9/2026, 8:08 AM

@marcinzm With my RTX5090 I need to enable legacy AVC decoding for VP23 or I will encounter the occasional frame out order. Support for the HW decoding using 5090 series card in Vegas is not fully supported to its potential and probably has less "test miles" than 30 or 40 series NVIDEA cards (if any for the RTX 5090 in particular). Rendering is OK, and really fast with this card, I never had an issue with that.
I do use Mercalli V6 OFX plugin, works fine, but switching from legacy decoding to the default decoding means you have to analyze again. I do not know if switching to legacy decoding will help in your case, though, as I use source camera material AVC 4K 8bit 4.2.0 25fps to turn into full HD 25fps 1080p on the timeline.

marcinzm wrote on 1/9/2026, 8:15 AM

@RogerS

Here is the link to the short sample:

https://marcinzmyslowski.synology.me:444/download.php?plik=audio_and_video_out_of_sync.mp4

The file is 1.6 GB.

marcinzm wrote on 1/9/2026, 8:47 AM

@bitman

I did the same test as you. I have just enabled legacy AVC decoding in VP23 and playback is going smoothly without out of order.

RogerS wrote on 1/9/2026, 8:49 AM

Thank you very much for the file.

I just loaded it into 23.356. At first playback it seemed fine. Then I cut it up and moved the parts around the timeline. The playback still seems fine, everything is in sync. This is with my desktop RTX 5070 with driver 581.57.
Legacy decoding is disabled.