Inspiring

Question

Why is multicam so choppy?

Forum|Forum|3 years ago
May 18, 2022
2 replies
2052 views

My laptop was upper-middle-end maybe 4 years ago. Premiere pro says there is some compatibility issue with the video card. Still, the program runs.

I've got seven podcast clips, 50 minutes long, that I am multicaming. I can do it, but it is mega laggy. The 1/8 and 1)16th options for the previews are not available, but I have taken off the master preview cam option (so it only shows the seven multicams select from).

Is there anything I can do to make it less laggy? I can deal with bad quality video in the preview, it's just that it hangs a lot.

This topic has been closed for replies.

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Dave_DIRAuthor

Inspiring

So where I'm at right now is I'm transcoding the files to NDxHQX 1080p 29.97.

For the next one I'll see if I can get OBS to output to NDx, otherwise I'll have to remux the mkv to a mp4, then transcode to NDx for 3 of the files. For the facecam, since I can't run two OBS without everything shutting down, we're using our phones. And one mov from iPad for room shot. Maybe 500gb of NDx files altogether, and one night of doing all the transcoding.

There an easier way to make the multicam less choppy?

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Phillip Harvey

Community Expert

You can use FFMPEG to record to ProRes or DNX straight out of OBS, but since those are high bitrate, high quality video codecs it will be a lot more demanding on your system to record them. It's up to you if you want to try to accommodate that, but I would personally just record into a decent quality H264 and plan to use proxies for your editing process. I would also recommend not remuxing with OBS, as the process of going from MKV to MP4 with their remux will introduce Variable Framerate, which is like poison to editing software and is giong to cause a lot more headaches for you. If you record directly into the TS container rather than MKV you'll get all the same pros as the MKV container without having to remux. You can import the TS files directly into Premiere.

On the note of Variable Framerate, keep in mind that while phones can look great, they record very problematic video when it comes to working with it in post production. Phones do record into variable framerate, which means you're going to have issues with audio syncing (which you absolutely do not want if you are trying to sync up multiple streams over a long period of time), not to mention other performance and errors that you get from the VFR. Particularly with 4K on a phone you'll usually be recording in HEVC, which is also a very unoptimized editing codec. And also be sure to turn off HDR settings on the phones as that will be another layer you'll need to address in post production. Often to get phone media into a good and stable shape you need to transcode it to correct the variable framerate at minimum, if not also getting it into a better editing codec and changing the color space at the same time.

In general the answer to your question has already been stated by others: proxies.

Playing 7 streams of video simultaneously is a lot of work for a computer, so you want that video to be super easy to work with. Also note that the playback resolution pulldown menu is going to have a minimal effect on the performance here because your computer still has to do the hard part - decoding the video - before it can play it back at a lower resolution.

Edit: I also wanted to address a question you posted earlier that I didn't see answered. Importing 100GB+ videos to Premiere is not an issue. File size in general is not really an indication as to whether it's going to be easy or difficult for Premiere to play, and in fact if you are going to try to make an assumption based on file size it would tend to be the opposite of what you think. Small file size = efficiently compressed and requiring more computing power to decompress (play). Whereas a larger file size would indicate an intraframe video codec (every frame exists individually), which is a lot easier for the computer to "understand."

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Phillip Harvey

Community Expert

Much appreciated! I will look into proxies tonight. We have 8 webcams sitting around, but our computers can't handle multiple OBS's so we had to resort to our phones for the face vids. For next time I'll check out the HDR setting and turn it off, but for now I'm transcoding the whole lot to NDx

I'll also look up what the TS container is, that I should use instead of mkv, I don't remember seeing that setting. Are TS files edit friendly like NDx? ... I mean will they allow for smoother Multicam? Or does Multicam generally only work well (with seven 50min long files) with NDx?

Much appreciated

TS is just a container, like MKV, MP4, AVI, FLV, etc. The video codec inside of the container is H264 (so no, it isn't edit-friendly like DNX, but you can still make a proxy of it into something edit-friendly.)

When you Remux (also called Rewrap) you are just taking the video and audio codecs from inside of the container and putting them into another container. If it helps you can think of it like taking things out of one box and putting them into another box.

The container doesn't have a whole lot to do with the performance/optimization of the codec inside, except that you can maybe infer what the video codec might be inside the container (often when people say "it's an mp4," they are essentially saying, "it's h264.") But take the .MOV container as an example. Inside an MOV container you could have the HEVC/H265 video codec, which is terrible for video editing, or you could have ProRes, which is great for video editing. So the container or file extension does not paint the full picture and it isn't the same as the codec.

Ann Bens

Community Expert

Might want to consider using proxies.

Or convert footage to an edit friendly codec.

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Dave_DIRAuthor

Inspiring

So I use Adobe Media converter to transcode the files to ndxhd. The files are already 4-5gb, I'm expecting to fill a terabyte with these new files.

I don't get why video is so resource heavy. '93 was the first handheld digital video recorder. Was that alien technology? 30 years later I can't run two instances of OBS without 16 gigs of RAM shutting down, and I can't multicam 7 videos. Not sure why I need a $10K rig just to post produce a home recorded podcast video, 2000 freaking 22.

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ah.photo

Inspiring

As digital recording technologies and computers have evolved, so has video quality, and the demands of the compression techniques used to encode them.

There is more data being recorded in videos, even with OBS, compared to 1993 digital video recorders. To accomodate that data, more resource-intensive codecs are used. To add fuel to the fire, these newer codecs like H.264/H.265 are designed for delivery to minimize the space needed for the file, even further requiring more robust encode/decode processes.

So even though computers have advanced, so have the demands of the technology. Plus you say you're trying to decode 7 video streams at once? That will be a factor as well and why leveraging proxies and codecs optimized for editing (like ProRes or DNx) are crucial. It's important even when working with higher end machines too.

To answer your other question, you should be able to import the files into Premiere Pro, but if you are reading 7 streams at once of high bandwidth video, you may run into problems if you're using a slow HDD. Not only do you need to account for decoding, but also the bandwidth your drive can support in reading multiple video files at once.

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