Workaround for audio drop-off — Davinci Resolve

Unfortunately, while editing video files in Davinci Resolve yesterday, I wasted almost half the day and scratched my head for a few hours until I got a solution. So, I’d like to leave an article here for someone who may encounter the same issue.

Tl;dr,

If you lose audio data while exporting, you should try detaching the audio data from the source:

> C:\path\to\ffmpeg.exe -i video-captured.mov audio-only.wav

and re-attach it to the video in Resolve.

I recorded an exciting interview but had a trouble while editing it later…

Davinci Resolve

Once, I had been familiar with Final Cut and iMovie on my Mac, but I already switched to Windows now, so I have to handle video files on it too. According to my great friend’s recommendation, I started using Davinci Resolve recently. This application was totally amazing! I can’t believe that it is provided for free. I was just enjoying this application for a while until...

Davinci Resolve 15

No audio exported!

…yesterday, there was something strange. The video file exported from Resolve had no audio data except for the first 30 seconds. In a preview, it was fine, and of course, the original MP4 file included audio data as well. Only when exported from Resolve, it will happen. What?

“It might depend on the file format?” I guessed. But, exporting as MP4 or MOV or other formats affected nothing. I lost audio in every video format while exporting. Then, I googled the solution through the internet, but I couldn’t find any hints. “OK, I will solve it by myself.” I made up my mind.

Input file format?

To clarify this issue, I tried the same with other video sources:

- MP4: some files work fine, but some others not.
- MOV: no issue (at this point).
- AVI: oh! Not supported in Resolve.

It seemed that MOV file worked fine at least, but I’m not sure though. So I converted my problematic MP4 files into MOV by FFMPEG command with audio re-encoding. But, unfortunately, it wasn’t the solution.

Windows Camera App

If the format was independent from the issue, how about devices or applications which the video came from? “Ah, I might have realized a possibility.”

Windows 10 Camera App

For the sake of simplicity, our whole video system which includes four cameras and a switcher is designed to be recognized as an integrated web camera through USB 3.0. It comes with many merits: we don’t need to install drivers, and also even a Chromebook can record videos through it. Anyway, to record the video, I used “Camera” app in Windows 10 just because it is included as a part of the OS. And I found that only the videos recorded in “Camera” had the issue with Resolve.

He should be the first suspect.

Workaround 1 (not worked)

Finding a suspect was not a goal. I just needed a good “export”. So, putting the real reason aside, some workaround was needed.

My concern was my PC environment. My laptop is equipped with 16GB RAM and Core i7 but not perfect for video editing, I know. And the original source was a little bit long: more than two hours. So, to reduce the load for such RAMs and CPUs, I split it into multiple, relatively short lengthed, files by FFMPEG:

> C:\path\to\ffmpeg.exe -i video-captured.mov -c copy -map 0 -segment_time 00:20:00 -f segment chunked-%03d.mov

Although some clips worked better after combining on Resolve, some clips lost their audio only after the first six seconds. It seemed so unstable. This could not be a solution. Sigh.

Workaround 2 (not worked)

I focused on its unstability. Temporally, I brought the heavy machine for VR (Oculus Rift) and install Davinci Resolve and set it up all as my laptop environment. It has a lot of memory, CPU power and GPU power. I hoped a miracle would happen with such a blutal force. But, it didn’t work either.

Workaround 3 (worked!)

Ok, then, our last resort would be spiliting the file into video and audio completely. By the command below, I extracted only its audio data from our problematic video file:

> C:\path\to\ffmpeg.exe -i video-captured.mov audio-only.wav

The point was WAV format which is an uncompressed data format, I think. It should have no issue theoretically. I didn’t want to do this “split” because I was afraid that it could break the sync between video and audio. But, If there was no other way, I should have tried it. And, fortunately, it worked finally.

To select only a audio track, turn off “link” before. Then you can delete it exclusively.

Conclusions

I’m not sure which was correct: the data generated by Camera app was corrupted, or the combination of it and Resolve was bad. Anyway, the best way to avoid this issue is not to use Camera app on Windows 10. There’re some other options to capture videos as you know.

But, if you have only a video file, and it’s difficult to record it again, then, try the Workaround 3 above.


By the way, the video I recorded is here. Check it out!

A deep talk about Manga with Ooi-san, Nakano-san and Nakamata-san who are the author of these books. The books and this talk are in Japanese.