[Aaron Star]

If you want to record in 5.1 you could look into one of the following solutions:

1.) Get a Zoom H6N with the either the X/Y capsule or the XLR capsule. Then rig your talent with a lav or mono shotgun, and either two stereo mics or mono mics set in an X pattern. Of course there is the Holophone mic at $2K. The .1 channel could be recorded, but normally this is a generated rolled off channel for the low end frequencies only. Normally 5.1 is not recorded, but generated in the final mix.

Then bring all those channels into Vegas, edit, output to AC3-5.1.

5.1 editing in vegas demo.
https://www.youtube.com/watch?t=130&v=KIvYOftIF4c

Only certain codecs support 5.1 channels of audio out of vegas. HDCAM will do 24 PCM mono channels, XDCAM 16 PCM mono, XVAC 8 mono PCM, Windows Media with WMA10 pro supports 7.1 channels in 24bit, AVC would be MP4 plus something like AC-3 muxed by some application that will do it. FFMPEG might be able to mux mp4 video and AC-3 into a new file. You would have to figure out how you are going to display the final, and them conform to that standard.

2.) Canon makes a hot shoe 5.1 microphone for the Vexia line of cameras. This would allow you to run your 2 cameras, then take the audio from one and use it on the other. You could also just use the new Vexia for your footage. The vexia records in 1080.MTS with AC3-5.1 on camera mic only.

https://www.adorama.com/CASMV1.html?utm_term=Other&utm_medium=cpc&utm_campaign=Other&utm_source=adl-umbase

[Aaron Star]

Graham surely got dinged in the helmet, for sticking his head above the parapet. But I would be interested to know if his solution with the eye dropper was close.

[Aaron Star]

Is the audio in the front of video, or behind?

Have you tried not altering the .mp4 and rendering it to something like xdcam, or DV and seeing the problem persists?

[Aaron Star]

Your system is configured more towards Premier, that is why it is working better for you. If you swap that Nvidia card for a 290/390x, you would be able to playback and render faster in Vegas. NVidia is pretty far AMD behind in the OpenCL arena. NV is trying to push people into CUDA which is their proprietary device.

There is also so cut off on Mainconcept support with GPU acceleration. You would have look at your GPU with GPU-z Sensors to see if your GPU is even being used during render. An older AMD card like a 5770, 6970, or maybe even a 7970 supports the MC GPU encoder.

Sony AVC encoder supports OpenCL on both AMD and NV, but the sony encoder only uses GPU for effects, and motion calculations on the encoder. The actual encoding is done on CPU.

Have you run tests on the difference between the Sony and MC encoder?

Maybe render to XDCAM-EX, then handbrake the result?

[Aaron Star]

Use the trimmer to select the media you want to add, then hit TAB to toggle through selecting audio, video, or both. Then drag and drop the selection, or there are buttons to insert the media at the cursor similar to the way AVID works.

[Aaron Star]

What is your final display (where you plan on showing this work?)

[Aaron Star]

I would ask what your final display format is first.

As Wayne suggests, if you downscale everything you lose the ability to crop in on the 4k footage with no loss. However, editing at 1080 in HDCAM-sr-lite or XDCAM422/ex will be much easier on your system if the project is complex.

[Aaron Star]

Depending on your editing system, I would shoot something like 30p or 60p at about 125 to 250th shutter. Then export the frames as still image PNG or TIF sequence. Then import the image sequence as 25p, more frames per second will help animate the slo-mo better. Slowing down 25p will get pretty choppy the lower you go.

Do some tests on the shutter thing, to see how much blur you are going to get based on the action in the scene.

[Aaron Star]

If you are a Vegas editor, you might consider picking a camera that records to Sony Broadcast level codecs like XDCAM422-HD, XAVC-I 10bit-4096×2160-60p. This would allow you straight up timeline performance and stability.

The new Canon 422 codec is basically XDCAM, so that might be a good choice too.

The old Red One is a not so obvious choice, Vegas supports Redcode native, and the image quality of that camera still surpasses $5K cameras due to the 12-bit capture abilities.

[Aaron Star]

I believe you have it backwards. The question is why do most players stretch video levels, which appears to the eye as darker. Vegas is showing you what is in the file, the difference you are seeing is a lack of level correction in the Vegas display. You can add this correction manually, just like the player has it baked in, by adding a Sony levels fx to your preview window then selecting SRGB to Computer RGB. There is also a check box selector for external monitor that will apply this adjustment, this setting is under Preview preferences.

If you where to render to Windows Media format, this format bakes in the level correction automatically. This is one reason people like to use windows media for upload to YouTube, as they get a 1:1 view in the YouTube player. Normally h264 content will appear darker when uploaded to YouTube because the YouTube player is applying the same level correction as the player you posted a screenshot of.

Vegas is a technical application that shows what is in the file at a rudimentary level. It is up to the editor to understand level issues through the display chain.