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Old 27th August 2021, 00:31   #1  |  Link
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Compression Experiments - The Wolverine: 33.10 mbps Blu-ray vs 1.80 mbps encode

I've continued to play with x265 and thought I'd try a simple experiment: how much can a film be compressed until it's subjectively unwatchable, and at what point does the encode remain watchable and retain most details, but with the lowest possible bitrate? (far lower bitrate than any reasonable person would use to encode a film)

Video Rationale
I chose The Wolverine as it's relatively modern, contains a diverse range of studio sets and locations, and has modern, 'natural' grain (by this I mean there is a small amount of grain).

- Source
Video: Blu-ray AVC @ 33.10 mbps
Audio: DTS-HD Master Audio 7.1 @ 5.34 mbps
Total Size: 42.65 GB

- Encode
Video: x265 (modified Fast profile, 3-pass) @ 1.8 mbps
Audio: E-AC3 @ 640 kbps
Total Size: 1.96 GB

I'm incredibly impressed considering it's a 138 minute film under 2GB with 640 kbps 5.1 audio and, for the most part, acceptable quality - certainly when watching on a TV and not comparing individuals frames on a 32" professional calibrated 10-bit 4K display. It's certainly not transparent and not something I would encode for my physical -> digital archive, but this was just a test.

I chose 1.8 mbps after doing a number of tests and settled on a 3-pass encode in order to make sure sure I extracted every bit of detail possible, given the heavily restricted bitrate.

I welcome your views. Again, this was just an experiment I found to be a fun project, but also a needed distraction whilst experiencing a trigeminal neuralgia attack.

I deliberately looked for scenes where the compression is noticeable (e.g. textures missing detail or having a flat appearance). A good example of this is the scene with the bear (fifth set of images). And yes, there are 'dirty borders' that I would fix for an encode I intend to keep.

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Last edited by tonemapped; 27th August 2021 at 00:34. Reason: Added statement about dirty pixel borders
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low-bitrates, multi pass, wolverine, x265

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