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Old 12-30-2019, 07:41 AM   #1
drew
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Default Can I replicate Vimeo's video rate reduction in REAPER?

Hi vid experts!

I'm comparing a file I'm exported from REAPER with the results of an upload to Vimeo and HD download of that transcoded vid.

Top of each image shows VLC stats, with REAPER source props underneath.

I see the rate reduces from 17062 kb/s to 5531 kb/s (the HD 1080p setting in Vimeo). Is there a way to set this in REAPER renders?

I've never known what the Video codec quality % control in the render dialog actually corresponds to. Is that about bitrate?

(I'm also puzzled as to why "Media data size" & "Content bitrate" sizes are way bigger for the smaller file, but that's not really a REAPER question!)

Finally, other than manually renaming, is there a way (yet) to make output extension .MP4 when exporting?

Thanks for any tips!

Drew

BEFORE:


AFTER:
Attached Images
File Type: png Stats Pre Vimeo.png (19.8 KB, 134 views)
File Type: png Stats Post Vimeo.png (19.8 KB, 144 views)
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Old 12-31-2019, 04:36 AM   #2
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Hi Drew,

The Video Codec % value is for fixed quality scale (VBR- Variable Bit Rate) video encoding where the encoder tries to maintain the quality of the video by adjusting the bit rate based on the complexity of the video it’s analysing. In x264 terms this would be setting the -crf (Constant Ratefactor) value where lower values (less than the default 23) produce better quality, larger file size videos. I am not sure how the REAPER percentage correlates with the CRF value.

VLC Player’s Statistics page’s "Content Bitrate" shows the current combined (video + audio) bit rate. I’m guessing that, because REAPER uses a variable bit rate based on video image complexity, when you took the screen shot of the VLC stats page the video wasn’t very complex – hence the low bit rate.

I am not too sure what coding constraints Vimeo uses to transcode submitted videos. They could be CBR - Constant Bit Rate, or constrained variable bit rate. I’ll have to download and analyse a Vimeo video. See Vimeo’s Compression Guidelines on Vimeo for a bit more insight.

I recommend using MediaInfo to analyse both the file you submitted to Vimeo and the downloaded Vimeo file. It will give you an idea as to what the coding constraints might have been.

Is there any particular reason why you’re wanting to match the Vimeo encoding? If you’re using Vimeo as a method to get your videos transcoded, I would suggest you look at HandBrake – it’s free, easy to use and uses the award winning x264 encoder to encode H.264 video streams.

Since REAPER 5.985 you’ve been able to save H.264 videos as .MP4 – check out this REAPER Blog video.

All the best,

Andrew
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Old 12-31-2019, 01:30 PM   #3
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Thanks for that detailed response, Andrew!

I hadn't noticed you can now override the extension when specifying filename. That's v. useful. Thx.

I have used FFMPEG on command line with the -crf parameter in the past, but when the value is high enough to result in a small file size, comparable to that of the Vimeo output, the picture quality is never as good.

I had just thought I might be missing a way to set CBR & tweak bitrate within the render settings.

I guess if I do use Handbrake or FFMPEG CLI to achieve this, I should render lossless out of REAPER and work with that, rather than H.264 and then again to reduce? Though I don't know how much that would actually show up.

Many thanks once again for your insight.

Cheers,

Drew
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Old 12-31-2019, 03:00 PM   #4
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Yeah, exporting an uncompressed file out of REAPER and then using a more configurable encoder to export to your specification seems to be the way to go.

If you’re familiar with the ffmpeg command line, you could try out the following line. Obviously replacing the square bracketed stuff (maybe even without the quotes "") with your input and output filenames.
Code:
ffmpeg -i "[INPUT_FILE_NAME]" -c:v libx264 -pix_fmt yuv420p -profile:v high -level 4.2 -preset medium -tune film -bf 3 -g 50 -sc_threshold 20 -x264-params force-cfr=1:bitrate=5000:vbv-bufsize=5000:vbv-maxrate=5500 -c:a aac -b:a 384k -movflags faststart -y "[OUTPUT_FILE_NAME].mp4"
The command will produce a relatively predictable output file size, though it is still variable in nature. It’s a starting point! There are loads of other options you could add and then tweak for better visuals, like “subme”, “deblock”, “me”, and “ref”. Sadly, all my notes and links to helpful encoding website are on my computer at work.

Good luck!
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