For those interested in this topic, I highly recommend the approachable but more extensive technical introduction at https://github.com/leandromoreira/digital_video_introduction
H.264 is Magic (2016)
31–40 of 229 posts
Re: H.264 is Magic (2016)
#32Does anything interesting happen if you take the frequency domain representation of an image, represent the frequency domain as an image itself, and compress that with some sort of image compression? For example, encode the frequency domain representation as a low quality JPEG, and then undo the steps to turn it back into the "original". How do the JPEG artifacts on the frequency domain manifest in the resulting imag…
With only a slight compression, the image would go shit or totally unrecognizable.
A quick album (there are captions):
Re: H.264 is Magic (2016)
#33H.264 patents are not expiring yet, if anyone was wondering. 2027 seems to be when that happens. On the other hand, I believe H.263 patents already expired, and MPEG-4 ASP (DivX etc.) is expiring this year.
I often wonder what we could do with a truly patent free codec once all the H.264 patent expired.
Re: H.264 is Magic (2016)
#34Does anything interesting happen if you take the frequency domain representation of an image, represent the frequency domain as an image itself, and compress that with some sort of image compression? For example, encode the frequency domain representation as a low quality JPEG, and then undo the steps to turn it back into the "original". How do the JPEG artifacts on the frequency domain manifest in the resulting imag…
This wouldn't work well because in the frequency domain representation, different "pixels" have very different importance for the overall appearance of the image: The pixels at the center of the frequency domain representation represent low frequencies, so compressing them will drastically alter the appearance of the image. On the other hand, the corners/edges of the frequency domain representation represent high frequencies, i.e. image details that can be removed without causing the image to change much. That's the crucial benefit of the Fourier transform for compression: it decomposes the image into important bits (low frequencies) and relatively less portant bits (high frequencies). Applying compression that doesn't take that structure into account won't work well.
Re: H.264 is Magic (2016)
#35Fabrice 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%.
Bro. Why are you promoting so much an app that barely does anything (opens a series of images from a hosting), as 'pornographic application that change your life'?
This account exists ONLY to talk about that app. Every one of my projects is isolated from the others by using different accounts, etc. We should all be meticulous about compartmentalizing our online identity.
This app uses an unusual image codec (BPG) which illustrates that if you control the encoder and decoder, you can choose a format with no mainstream support. I think it is a good point.
Re: H.264 is Magic (2016)
#36Earlier quoted context omitted.
Isn’t that exactly what HEIC is?
It looks like BGP actually predates HEIC. HEIC technical document finalise in 2015. The GitHub mirror of BGP has history back to 2014.
I'm not saying which one is earlier as I have no idea, but comparing these two dates doesn't seem to be a good way.
Implementation of HEIC existed before its documentation finalized.
Re: H.264 is Magic (2016)
#37Earlier quoted context omitted.
Yeah, in this era of mobile device dominance i think hardware decoding is key. Suspect Apple will add it then suddenly the Android SoC folks will suddenly consider it a priority and not before.
Apple won't add it; they traditionally ignore free codecs, and even if they implement them, it is so limited, so it is usable only in the narrow situation, where it is required (see Opus, for example). On the PC side, decoding is supported by Intel (since Tiger Lake), Nvidia (since 30x0) and AMD (since RDNA2). On the mobile side, it is supported by bunch of mobile chip vendors, like Mediatek or Samsung; so you can ha…
Apple is even a governing member of the alliance behind AV1 (https://en.wikipedia.org/wiki/Alliance_for_Open_Media), so the case could be different than with previous free codecs.
Re: H.264 is Magic (2016)
#38Does anything interesting happen if you take the frequency domain representation of an image, represent the frequency domain as an image itself, and compress that with some sort of image compression? For example, encode the frequency domain representation as a low quality JPEG, and then undo the steps to turn it back into the "original". How do the JPEG artifacts on the frequency domain manifest in the resulting imag…
With only a slight compression, the image would go shit or totally unrecognizable. A quick album (there are captions): https://imgur.com/a/7yHPzRH
Thanks, this is exactly what I wanted to see.
Re: H.264 is Magic (2016)
#39H.264 patents are not expiring yet, if anyone was wondering. 2027 seems to be when that happens. On the other hand, I believe H.263 patents already expired, and MPEG-4 ASP (DivX etc.) is expiring this year.
I often wonder what we could do with a truly patent free codec once all the H.264 patent expired.
Probably ask what we could do with H.269 (or whatever the common tech of the time is) when that is no longer encumbered by patents!
Re: H.264 is Magic (2016)
#40Very intuitive explanations. Love it!