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Accurate Colors
I am new to Vegas and am obsessive about color accuracy.
I finally got Vegas to export video with accurate colors using the following procedure:
In Vegas, render as: Video for Windows -> Uncompressed
You can then convert it using ffmpeg and the codec of your choice. For example, here it is converted to x264:
ffmpeg -y -i "untitled.avi" -pix_fmt yuv420p -crf 0 -c:v libx264 -vf scale=out_color_matrix=bt709:out_range=full -color_primaries bt709 -color_trc bt709 -colorspace bt709 -r 59.94 output.mp4@REM NOTE: Output range MUST be full.
The pixel format can be 4:2:0, 4:2:2 or 4:4:4.
I have tested the output of this process and the 8 – bit color values are accurate to +/- 3. For example, a color value of 16 might come out anywhere from 13 to 19. I have found that this is as accurate as it gets with 8-bit YUV.
HTH
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7 Replies
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Hi Chris,
Thank You for posting this information.
Would the process be more expedient by using a FrameServer script direct out of Vegas to Handbrake for the x264? Or even better, using the Happy Otter Scripts (HOS) add-on to x264, avoiding the uncompressed render?
In your reference to pixel format, did you mean chroma subsampling, that confuses me?
BTW: HOS is available as a free beta at tools4vegas.com
Best Regards……George
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Hi George –
I haven’t tested the alternatives you suggested so I can’t vouch for them.
All I know is that rendering as “Video for Windows -> Uncompressed” is captive to Vegas. Also, I had handbrake installed on my machine for a short while yesterday and it doesn’t seem to have the fine control that ffmpeg does. Is it possible that handbrake has ffmpeg as its underpinnings?
You need to be able to specify full-range video. I didn’t see a way to do this on handbrake. Ideally these would be built into Vegas and could be executed in one step. No matter; writing a batch file to run ffmpeg is easy to do on Windows and I’m sure it is just as easy on Linux or Mac.
I’ve done all the testing and that’s the hard part.
I don’t know how to write a frame server script to extract video from Vegas. Do you?
Yes, pixel format refers to chroma subsampling.
My ffmpeg script contains -crf 0 which makes ffmpeg quasi lossless. You can use a higher number if more compression/a smaller file is desired. You can also replace x264 with x265 if that is desired.
https://trac.ffmpeg.org/wiki/Encode/H.264
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Also, my script is for video only. It needs to specify an audio codec which is supported by mp4. Let me know if you need help with this.
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Hi Chris,
I don’t need any help, Thank You.
I also don’t write scripts, just use those available from various sources.
Best Regards……George
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Here is a code fragment for 128k aac audio. This will get you started on YouTube.
-c:a aac -b:a 128k
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I have also found that XDCAM exports with accurate colors.
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Update: the above code also works with libx265.
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