50GB gives assurances that the BluRays are high quality (but not always. I've seen some horrible BluRay encodings...)
As long as you are going from high quality sources, you should be fine. The issue is each transcoding step is a glorified loop-(find something we think humans can't see and delete it)
In other words: the AV1 encoder in your example works by finding 47GBs of data TO DELETE. It's simply gone, vanished. That's how lossy compression works, delete the right things and save space.
In my experience, this often deletes purposeful noise out of animation (there are often static noise / VHS like effects in animation and film to represent flashbacks, these lossy decoders think it's actually noise and just deleted it all changing the feel of some scenes).
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More importantly: what is your plan with the 50GB BluRays? When AV2 (or any other future codec) comes out, you'll want to work off the 50GB originals and not off the 3GB AV1 compressed copies.
IMO, just work with the 50GB originals. Back them up, play them as is.
I guess AV1 compression is useful if you have a limited bandwidth (do you stream them out of your basement, across the internet and to your phone or something? I guess AV1 is good for that) But for most people just working with the 50GB originals is the best plan
AV1 is not about throwing away more data that the human can’t see. It’s about having better tools.
1. the prediction tools of AV1 are better than those of h265. Better angular prediction, better neighboring pixels filtering, an entirely new chroma from luma prediction tool, an intra-block copying tool, more inter prediction tools, non-square coding units.
2. If the prediction is better, the residuals will be smaller.
3. Those residuals are converted to frequency domain with better tools for AV1 as well (more options than just DCT), so that you have a better grouping of coefficients close to the DC component. (Less zeros interleaving non-zero values.)
4. Those coefficients compress better, with a better entropy coding algorithm too.
You can have exactly the same video quality for h265 and AV1 yet still have a lower bitrate for the latter and with no additional decision made to “find out what humans can’t see.” The only place in the process where you decide to throw away stuff that humans can’t see is in the quantization of the frequency transformed residuals (between step 3 and 4) and the denoising before optional film grain synthesis.
To be clear: you can of course only go down or stay equal in quality when you transcode, due to rounding errors, incompatible prediction modes etc. That’s not under discussion. I’m only arguing about the claim that AV1 is better in general because you throw away more data. That’s just not true.
> In other words: the AV1 encoder in your example works by finding 47GBs of data TO DELETE.
With that reasoning, lossless compression of .wav to .flac destroys >50% of data.
In actuality, you can reconstruct much of the source even with lossy compression. Hell, 320kbps mp3 (and equivalent aac, opus, etc) are indistinguishable from lossless and thus aurally transparant to humans, meaning as far as concerns us, there is no data loss.
Maybe one day we'll get to the point where video compression is powerful enough that we get transparent lossy compression at the bit rates streaming services are offering us.
> In my experience, this often deletes purposeful noise out of animation
AV1 specifically analyzes the original noise, denoises the source then adds back the noise as a synthetic mask / overlay of sorts. Noise is death for compression so this allows large gains in compression ratio.
> AV1 specifically analyzes the original noise, denoises the source then adds back the noise as a synthetic mask / overlay of sorts. Noise is death for compression so this allows large gains in compression ratio.
If said noise still exists after H265.
And there's no guarantee that these noise detection algorithms are compatible with H264, H265, AV1, or future codecs H266 or AV2.
50GB gives assurances that the BluRays are high quality (but not always. I've seen some horrible BluRay encodings...)
As long as you are going from high quality sources, you should be fine. The issue is each transcoding step is a glorified loop-(find something we think humans can't see and delete it)
In other words: the AV1 encoder in your example works by finding 47GBs of data TO DELETE. It's simply gone, vanished. That's how lossy compression works, delete the right things and save space.
In my experience, this often deletes purposeful noise out of animation (there are often static noise / VHS like effects in animation and film to represent flashbacks, these lossy decoders think it's actually noise and just deleted it all changing the feel of some scenes).
--------
More importantly: what is your plan with the 50GB BluRays? When AV2 (or any other future codec) comes out, you'll want to work off the 50GB originals and not off the 3GB AV1 compressed copies.
IMO, just work with the 50GB originals. Back them up, play them as is.
I guess AV1 compression is useful if you have a limited bandwidth (do you stream them out of your basement, across the internet and to your phone or something? I guess AV1 is good for that) But for most people just working with the 50GB originals is the best plan
AV1 is not about throwing away more data that the human can’t see. It’s about having better tools.
1. the prediction tools of AV1 are better than those of h265. Better angular prediction, better neighboring pixels filtering, an entirely new chroma from luma prediction tool, an intra-block copying tool, more inter prediction tools, non-square coding units.
2. If the prediction is better, the residuals will be smaller.
3. Those residuals are converted to frequency domain with better tools for AV1 as well (more options than just DCT), so that you have a better grouping of coefficients close to the DC component. (Less zeros interleaving non-zero values.)
4. Those coefficients compress better, with a better entropy coding algorithm too.
You can have exactly the same video quality for h265 and AV1 yet still have a lower bitrate for the latter and with no additional decision made to “find out what humans can’t see.” The only place in the process where you decide to throw away stuff that humans can’t see is in the quantization of the frequency transformed residuals (between step 3 and 4) and the denoising before optional film grain synthesis.
To be clear: you can of course only go down or stay equal in quality when you transcode, due to rounding errors, incompatible prediction modes etc. That’s not under discussion. I’m only arguing about the claim that AV1 is better in general because you throw away more data. That’s just not true.
> In other words: the AV1 encoder in your example works by finding 47GBs of data TO DELETE.
With that reasoning, lossless compression of .wav to .flac destroys >50% of data.
In actuality, you can reconstruct much of the source even with lossy compression. Hell, 320kbps mp3 (and equivalent aac, opus, etc) are indistinguishable from lossless and thus aurally transparant to humans, meaning as far as concerns us, there is no data loss.
Maybe one day we'll get to the point where video compression is powerful enough that we get transparent lossy compression at the bit rates streaming services are offering us.
> In my experience, this often deletes purposeful noise out of animation
AV1 specifically analyzes the original noise, denoises the source then adds back the noise as a synthetic mask / overlay of sorts. Noise is death for compression so this allows large gains in compression ratio.
> AV1 specifically analyzes the original noise, denoises the source then adds back the noise as a synthetic mask / overlay of sorts. Noise is death for compression so this allows large gains in compression ratio.
If said noise still exists after H265.
And there's no guarantee that these noise detection algorithms are compatible with H264, H265, AV1, or future codecs H266 or AV2.
Thank you for the detailed answer!