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I'm asking in relation to the vse as a standalone, as well as the 3d viewport.

Where can I specify what chroma subsampling I want for my output? i.e. 4:4:4 vs 4:2:2 vs 4:2:0?

Are presets applied to each of the render options that aren't otherwise visible? What are these options?

I feel like I'm missing something. Is chroma subsampling a "physical" film only thing? I know you can select the sampling for your 3d renders, but I mean that's variable whereas chroma subsampling is like 3 main options. I'm guessing those are different things.

Do 3d renders not follow the convention of chroma subsampling. And when just using the video sequence editor then, do I not get the option of specifying a chroma subsampling? Is the chroma subsampling of the input video respected when output from the the vse?

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    $\begingroup$ That would depend on the codec you choose to encode. $\endgroup$
    – user1853
    Commented Mar 11, 2019 at 5:24
  • $\begingroup$ can you elaborate on what each codec provides then. As I stated in the OP I don't have this information nor do I know where I'd find it. $\endgroup$
    – kite
    Commented Mar 15, 2019 at 5:18

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That would depend on the codec you choose to encode.

As an extremely simplified explanation:

When you render an image, Blender generates the information for Red Green and Blue and Alpha in 32bit float. Which is a lot of information. That image is not compressed in any way and all color information is available before processing to be encoded and saved.

Why not save then all of that information?

Not only it would take a lot of disk space, but you would need an extremely powerful device to play that amount of information in real time and sustain uninterrupted video streaming.

Compression schemes or codecs were invented to deal with the problem. Codecs allow for smaller files and facilitate playback at a steady framerate.

The efficiency and quality of the pictures is then determined by the codec used in the compression. Compression means that some information has to be thrown out.

In other words: when you choose a codec, you are choosing a way to discard information from an image.

One of the many ways is by using less information on the red and blue channels of the image than the green channel.

From the Wikipedia:

Chroma subsampling is the practice of encoding images by implementing less resolution for chroma information than for luma information, taking advantage of the human visual system's lower acuity for color differences than for luminance.

Different codecs use different ways to do chroma subsampling

For example, ProRes can have many flavors: 422, or 4444. ProRes422-variants use Chroma subsampling of 4:2:2 at 10 Bit Color depth. ProRes 4444 samples color in the 4:4:4 schema with a color depth of 12 Bit. Most DnxHD codecs use 422 but the ones with the higher bit depth will use 444. Different variants of Mpeg4 or H.265 will use 422 or 444.

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  • $\begingroup$ Okay....but I still have no idea what I'm getting when I choose each render option in blender. What's ProRes in blender terms, is that one of the render options? Blender only supports 8 bit depth with its ffmpeg video formats. $\endgroup$
    – kite
    Commented Mar 15, 2019 at 7:04
  • $\begingroup$ Blender uses FFmpeg to encode. Do a search on your favorite search engine to understand what encoding is and learn about codecs. $\endgroup$
    – user1853
    Commented Mar 15, 2019 at 18:33
  • $\begingroup$ I already know what codecs are and all of what you explained. Re-read my OP. You covered what I wanted in your last segment but only gave educated guessed and no specifics which is what I wanted. Atm I'm stuck rendering each option and using ffmpeg to determine what the chroma sampling for each turns out as. Is this information not available somewhere? H.264 for example has many different versions...on blender its just "h.264....version h.264" How am I supposed to know its 8 bit by default? How am I suppposd to know if its 4:2:0 or 4:2:2 by default. Where is this listed? That's what I want $\endgroup$
    – kite
    Commented Mar 16, 2019 at 2:53

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