H.264 is Magic (2016) • Hacker News Board

Re: H.264 is Magic (2016)

#81

Post by bool3max » Thu, Mar 17, 2022, 4:24 PM UTC

delusional wrote: post #58

airstrike wrote: post #24

> "a technical walkthrough" > "Suppose you have some strange coin - you've tossed it 10 times, and every time it lands on heads. How would you describe this information to someone? You wouldn't say HHHHHHHHH. You would just say "10 tosses, all heads" - bam! You've just compressed some data! Easy. I saved you hours of mindfuck lectures." Ahh, my favorite kind of technical walkthrough. Love it

Doesn't that description basically presuppose that you already understand compression? "HHHHHHHHHH" is 10 characters, but "10 tosses, all heads" is 21. Already understanding compression, I of course know that the second part could be efficient if encoded properly, but someone actually needing the explanation probably wouldn't know that. It's not really wrong, and not really an "oversimplification" as the parent artic…

That was an example, intended for humans. It is much quicker to say "10 tosses, all heads", than it is to say "HHHHHHHHHH".

A computer example might explain that it takes less storage to store "10H" (i.e. the integer 10 followed by the character H), than it is to store 10 H characters in a sequence.

Re: H.264 is Magic (2016)

#82

Post by adzm » Thu, Mar 17, 2022, 4:35 PM UTC

yboris wrote: post #49

PSA: For images, there's a finally successor to jpeg: JPEG XL (.jxl) - has lossy and lossless mode; is progressive (you can download just the first parts of the bitstream to get a lower resolution image; and other benefits!) https://jpegxl.info/

Lossless JPEG transcoding is the killer feature moving forward from existing images. I can't wait for jxl's broad adoption.

Re: H.264 is Magic (2016)

#83

Post by dang » Thu, Mar 17, 2022, 4:36 PM UTC

H.264 is Magic – a technical walkthrough - https://news.ycombinator.com/item?id=17101627 - May 2018 (1 comment)

H.264 is Magic - https://news.ycombinator.com/item?id=12871403 - Nov 2016 (219 comments)

Re: H.264 is Magic (2016)

#84

Post by wccrawford » Thu, Mar 17, 2022, 4:38 PM UTC

oefrha wrote: post #75

Cthulhu_ wrote: post #65

Earlier quoted context omitted.

Do you believe the person posting is guilty of "creating accounts routinely"? Or just one for this app and one 'main' account? I don't see an issue with creating multiple accounts as long as they're not used for abuse, e.g. spam or trolling, or cause technical issues, e.g. creating millions of accounts. I mean if done right you'd never know or care.

This person is totally guilty of violating the rule on self promotion: > Please don't use HN primarily for promotion. It's ok to post your own stuff occasionally, but the primary use of the site should be for curiosity. Promoting your app in every single otherwise okay comment is certainly distasteful.

I'm usually pretty critical of self-promotion, but in this case they gave a real world example of how they did something related to the article's contents. They didn't even provide a link or an app name, just said that you could find it in their history if you were curious.

I think that's about the best you can do not to promote your product while trying to give real-world examples of things that are being discussed.

Re: H.264 is Magic (2016)

#85

Post by Markoff » Thu, Mar 17, 2022, 4:45 PM UTC

tmp65535 wrote: post #10

Fabrice Bellard's BPG image format uses H.265's keyframe compressor: https://bellard.org/bpg/ Here is a side-by-side visual comparison: http://xooyoozoo.github.io/yolo-octo-bugfixes/#ballet-exerci... Amazing. I ported his BPG decoder to Android ARM for a pornographic app. See my comment history for details. It reduced data transfer by more than 60%.

Why would anyone use such exotic unsupported format when there is WebP, AVIF or JPEG XL, which are all much more supported and better? It's shame they are not natively supported by most of the camera Android apps.

Re: H.264 is Magic (2016)

#86

Post by mikepurvis » Thu, Mar 17, 2022, 4:47 PM UTC

kalleboo wrote: post #51

throw0101a wrote: post #42

Earlier quoted context omitted.

> Even to this day I still do not believe Apple will support AV1 decode, at least not until Google forced the AV1 usage. Even though they joined AOM four years ago: * https://venturebeat.com/2018/01/04/3-reasons-apple-just-join... * https://appleinsider.com/articles/18/01/04/apple-joins-allia... * https://bitmovin.com/apple-joins-av1-codec-consortium/ * https://www.streamingmedia.com/Articles/ReadArticle.aspx?Art...

Apple is also on the Blu-ray board of directors but AFAIK have never supported either playback or mastering of Blu-ray in any of it's products.

Isn't their non-support more a consequence of the fact that they haven't shipped a single product with an optical drive since 2012? Like, you can obviously plug a $100 external Blu-Ray writer into any of their computers, but I think between the competition with their own digital distribution platform and the "bag of hurt" that is DRM nonsense, I can understand them not being interested in explicitly supporting it but still caring about the direction that it takes since they are a media and devices company, and the decisions made there impact them.

Re: H.264 is Magic (2016)

#87

Post by tmp65535 » Thu, Mar 17, 2022, 4:51 PM UTC

Markoff wrote: post #85

tmp65535 wrote: post #10

Fabrice Bellard's BPG image format uses H.265's keyframe compressor: https://bellard.org/bpg/ Here is a side-by-side visual comparison: http://xooyoozoo.github.io/yolo-octo-bugfixes/#ballet-exerci... Amazing. I ported his BPG decoder to Android ARM for a pornographic app. See my comment history for details. It reduced data transfer by more than 60%.

Why would anyone use such exotic unsupported format when there is WebP, AVIF or JPEG XL, which are all much more supported and better? It's shame they are not natively supported by most of the camera Android apps.

In my case, the year was 2017. Early 2017.

How many of those formats were available on all Android phones in 2017?

Answer: None.

Re: H.264 is Magic (2016)

#88

Post by lnanek2 » Thu, Mar 17, 2022, 4:51 PM UTC

yboris wrote: post #49

PSA: For images, there's a finally successor to jpeg: JPEG XL (.jxl) - has lossy and lossless mode; is progressive (you can download just the first parts of the bitstream to get a lower resolution image; and other benefits!) https://jpegxl.info/

As a mobile developer I generally see WEBP getting served to Android devices and HEIC to Apple devices. Is there any advantage to JPEG XL over those?

If our app supported older iOS devices, maybe JPEG would be needed as a fallback, but it seems like JPEG XL wouldn't be compatible with old devices anyway, right?

Re: H.264 is Magic (2016)

#89

Post by rayiner » Thu, Mar 17, 2022, 4:51 PM UTC

This is an awesome introduction to video coding, though it’s thin on motion compensation: https://users.cs.cf.ac.uk/Dave.Marshall/Multimedia/node259.h...

An elucidating exercise is to use python to do a DCOS or wavelet transform on an image and then quantize it to look at the results. It’s a few hundred lines of code if that and gives you a solid idea of the significance of working in the frequency domain and how that makes compression much easier.

Re: H.264 is Magic (2016)

#90

Post by atum47 » Thu, Mar 17, 2022, 4:52 PM UTC

Back in college when I was taking Digital Image Processing class we discussed h.264. Truly impressive technology no doubt. This article goes in much more detail about it, job well done.