Vastly different bit rates with same settings [SOLVED]

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zvon
Posts: 3
Joined: Sun Jul 02, 2017 10:29 am

Vastly different bit rates with same settings [SOLVED]

Post by zvon » Sun Jul 02, 2017 10:39 am

Hi, I'm using HandBrake 1.0.7 and I'm currently encoding my blu rays of Back to the Future 1-3. I'm using the same settings on all of them, but the first one got encoded with overall bit rate 12.7 Mb/s and has 11 GB whereas the second one has 7 026 Kbps and 5 GB. The source files have nearly identical attributes (the second one is slightly larger and has slightly higher bit rate) so my question is this - how can I have such big difference in resulting encode while using the same settings?

My encode settings:

Code: Select all

 HandBrakeCLI -i "$SOURCE" -o "$DEST" -f av_mkv -e x265_10bit --encoder-preset slow -q 18.0 --cfr --audio-lang-list "eng" --all-audio --aencoder "copy:aac" --audio-copy-mask "aac" --audio-fallback "av_aac" --mixdown "5point1" 
Last edited by zvon on Sun Jul 02, 2017 11:01 am, edited 1 time in total.

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s55
HandBrake Team
Posts: 9589
Joined: Sun Dec 24, 2006 1:05 pm

Re: Vastly different bit rates with same settings

Post by s55 » Sun Jul 02, 2017 10:58 am

The complexity of the two video streams is different.

As an extreme example, If you shoot a 1 minute video where your filming someone just talking and not moving much, the video will be drastically smaller than another 1 minute video where the camera pans 360 degrees over the same period. The second video in this example as much more happening so requires a higher bit-rate to maintain all that extra data. In the first example, because large parts of the frames are unchanged, you can gain much higher compression without losing quality.

zvon
Posts: 3
Joined: Sun Jul 02, 2017 10:29 am

Re: Vastly different bit rates with same settings

Post by zvon » Sun Jul 02, 2017 11:01 am

Ah, I see, thank you :)

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BradleyS
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Re: Vastly different bit rates with same settings [SOLVED]

Post by BradleyS » Sun Jul 02, 2017 12:42 pm

Additionally, noisy/grainy videos will produce larger output with constant quality encoding. You can use one of the denoise filters to help remedy this.

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