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trying to re-encode for quality and much smaller file size

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Jon Iverson
trying to re-encode for quality and much smaller file size
on Dec 25, 2015 at 10:24:01 am

I have a 15 min 1080p Go Pro movie file that was recently re-encoded to the highest quality H.264/AVC mp4 after removing some shaking in proDAD Mercalli V4. Since this ended up being a large file (10 GB), and I also wanted to do some editing, I imported in Sony Vegas Pro 12, then tried to render when done as MainConcept AVC/AAC mp4. Despite my efforts to decrease file size, like editing down to 7 minutes and decreasing resolution from 1080 to 720p, I'm still ending up with a file around 1 GB at variable bitrate settings of 20,000,000 for maximum and average bps. If I decrease bitrate too much, the video starts to get blocky and looks bad to try watching. The goal is for Youtube posting at some point, but I'd like to get the file size down under 300 MB if possible and yet retain quality at 720p. Perhaps there's a setting I'm missing or even a different codec, so would appreciate any suggestions as to how to proceed. I also have access to After Effects CC and Virtualdub.

Thanks in advance,

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Ivan Myles
Re: trying to re-encode for quality and much smaller file size
on Dec 26, 2015 at 2:54:25 am

YouTube allows high bitrate uploads. Is the 300MB file size arbitrary or is there a constraint behind it (like upload bandwidth, for example)?

The equivalent bitrate to meet your file size requirement for a 7 minute duration is 5.7 Mb/s. This is OK (though not maximum quality) for 1280x720 at 24-30fps, but a little low for 50-60fps.

In general, when encoding set maximum bitrate to 1.5-2X average bitrate, use a key frame distance of 1/2 frame rate, and enable 2-pass VBR encoding.

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