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Blotchy MP4 export render
Hello everyone,
I’ve run into an issue recently with footage I’ve captured using a capture card. The capture format is MP4 (h.264) @ 1680×1050 / 15,000 kbps / 30 fps but the issue I believe is not with the captured footage. It looks great playing back the raw footage and when I import to Sony Vegas I let Sony choose the settings to match the imported footage. So far no problems.
Where the problem I’m having arises is in the export quality of the file. I’ve been using the attached “Render settings” but instead of CBR I was using VBR (average bit rate 8,000,000 and max at 12,000,000) as VBR appears to be the most widely recommended setting for youtube uploads. I got the 8,000,000 and 12,000,000 average and max settings from a few sites and videos saying that youtube compresses all videos to have a max of 12,000,000. However, using those VBR settings I’ve been getting some blotchiness on the last two videos I’ve uploaded. Please see the VBR image to get an idea of the blotchiness I’m experiencing.
This blotchiness isn’t found in every frame. It happens at random intervals but it is consistent throughout the export render.
Now when I set it to CBR (10,000,000) I get none of the blotchiness. Please see the same frame but as a CBR render. Obviously the file is significantly larger (187MB VBR to 220MB CBR).
Project Properties settings:
Render As settings:
I’ve tried to get VBR to work with my latest videos by trying out CPU vs CUDA processing, switching baseline to high vs main, switching project full screen render settings between good and best, and lastly I disabled resample and also tried smart resample but the blotchiness doesn’t seem to respond to any changes there. The switch to CBR is the only thing that’s seemed to work to rid my videos of said blotchiness. What I’d like to know, is there a setting I might be missing when trying to export VBR that would help eliminate that blotchiness? I do like the smaller file sizes that VBR allows for but I’d prefer not to sacrifice quality. I hope I’ve provided enough information. Any input would be greatly appreciated.
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6 Replies
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I am always confused why people dont supply VIDEO samples so we can see the problem.
anyways here are my suggestions
turn on 2 pass
up the bitrate if needed
use CBR is CBR produces the results you want -
2-pass all the way, and please post a sample video.
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Hi Michael,
Your response is much appreciated. I felt the CBR and VBR image stills did a good job conveying the blotchiness that I’m speaking about. I will upload a video that shows in more detail what I’m referring to.
I’ll give VBR a go with a higher bitrate. Are there any bitrate settings you’d recommend for uploading to youtube? The capture bitrate is 20,000,000. I’ve heard that youtube can only handle a max of 16,000,000.
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[Ryan Wuerfel] “re there any bitrate settings you’d recommend for uploading to youtube? The capture bitrate is 20,000,000. I’ve heard that youtube can only handle a max of 16,000,000.”
not Michael here, but have you tried the built-in Youtube renderer and uploader in Vegas Pro 12 ? what do you not like about it ? it does a pretty good job rendering with the most appropriate bitrate considering Youtube restrictions and re-compression.
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Thank you for your response.
The built in youtube renderer, in my opinion, takes significantly longer to upload to youtube. Also, I sort of like having full control over the final image. Bit nitpicky in that regard.
So it looks like both of your suggestions to go two pass solved the issue. Either CBR of 10,000,000 or VBR with two pass works for the mp4 format that I like exporting in. I’ve uploaded a 3 minute clip that displays the blotchiness I was referring to. Just waiting for the moderator to approve it.
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good to hear, you know 2-pass renders for professional edits are a must in my book even if the difference is negligible in most cases, there’s always that random split-second pixelation and/or dithering 2-pass can actually fix.
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