FLAC Audio Causes Failure

It seems that Video AI can’t handle files (mkv in my case) with a FLAC audio stream. I converted LPCM in handbrake to FLAC and VideoAI fails the job when trying to process it. Remuxing file without the FLAC audio stream and having VideoAI works fine. The mkv file contained a FLAC 2.0 channel and a AC3 2.0 channel. I tried remuxing the MKV with the AC3 as the first channel and FLAC as the second and it still failed. So it seems that have a FLAC audio stream in the MKV causes the problem with the job failing.

Thank you for bringing this to my attention! Can you please share the file you are using that is causing the failure?

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I uploaded the file. I just used Big Buck Bunny and encoded the audio as 16 bit FLAC. It fails right away.

Hi Chris,

I downloaded the file and ran a quick test export. Looks like using ‘Copy’ as the audio setting and selecting an mkv container will transfer the FLAC audio track without issue. Could you share the export settings you’re using in Video AI to see if there’s an incompatible option selected? Thanks!

I’m exporting Prores LT to a .mov container. Perhaps .mov does not support FLAC? I am upscaling using Artemis.

That’s right, .mov containers do not support FLAC audio. If you’d like to keep a lossless audio track in a .mov I’d recommend using LPCM instead. FLAC will work fine within .mkv but we do not currently support ProRes LT video tracks within .mkv since they are generally not accepted in editing software.

Good to know. Thank you. It would be good though for the software to error out and say something like FLAC audio tracks are not supported in the .mov container. It took ma a few hours to figure out that was the problem. I thought something was wrong with the video source and I ended up re-encoding it a couple of times. Only later did it occur to me that it might be the audio track.

I agree that the messaging around some of these errors could be improved. We are actually in the process of completely redesigning the export menu in Video AI to address a few different feature requests, and one of them will be to only allow valid combinations of video/audio/container to be selected when queuing an export. We hope to have this launched in a future update soon.

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