@D7K - Can you elaborate on the settings to change? All I did was set the bitrate Max/Avg to 60,000,000 and the result is a clip of the same size as the sum of all the clips I used. The default setting for MAGIX AVC is max 48,000,000 and average 24,000,000, which produces a much reduced file size, but in one area (used as a comparison) I noticed pixelation whereas the original does not. For this reason I wanted to find some default settings in Vegas Pro 16 that would render to the highest possible quality, which would be to the same level as the original clip(s). Seems that the bitrate is the key.

I make also the same files but choose for that task the free app MP4 joiner from https://www.mp4joiner.org/en/ and with that tool you can also split the mp4's without any loss and it works much faster than an edit program.

Vegas is an encoder. It's purpose is to change your inflated camera source into deliverable (playable) video. In order to do this it compresses the video to a smaller size, using a  different  codec than the original.

Preserving the source bitrate is not a goal, nor is it the "key" in modern encoding. The goal is to preserve the source quality (up to 99.5%) in a file that will be smaller, as well as playable in a mainstream consumer environment.

That said, 24Mbps sounds a bit low. Raise it closer to the maximum, say, 30-40 Mbps, and keep in mind that software encoders are still considered generally better quality than hardware.

Also, different encoders give different results. A great one to try is x265 in Happy Otter Scripts.

The job of preserving the bitrate and format of the original is that of a muxer (spelling is correct), not an encoder.

I recently got a GoPro Hero 7 Black. I tested it by making a few clips of 4K @ 25fps. I tried to render all clips into one to get the best possible quality. However, the standard settings was using MAGIX AVC (or HEVC) 4K, but the quality was good, but not the same as the original video.

To my opinion, MAGIX AVC may render the fastest but also the worst. I always see a lot of artifacts in areas with almost the same colour, which I don't see when rendering with other codecs, like XAVC.

Today I tested 2160p50 (100mbps) footage from my Osmo Pocket, render with Magix AVC to 1080p50 (20mbps average) and with XAVC also to 1080p50 (66mbps). Then I also used that XAVC render as source for Handbrake (normal template) to render to AVC 1080p50 (17.8mbps). The difference in quality between Magix AVC and Handbrake AVC output is enormous, despite the higher bitrate of Magix AVC. With other words, quality is not always a result of higher bitrates.

To my opinion, MAGIX AVC may render the fastest but also the worst. I always see a lot of artifacts in areas with almost the same colour, which I don't see when rendering with other codecs, like XAVC.

@3POINT Presumably that's because the Magix codec is dropping the minimum bitrate too low and the user has no control over this. The common recommendation (from Musicvid and others) is to set the average and highest bitrates relatively close.

Presumably that's because the Magix codec is dropping the minimum bitrate too low

Nope. In my tests it does this even with constant bitrate.

With other words, quality is not always a result of higher bitrates.

I cannot agree more.

To aim quality you have to choose better encoders.