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What you need to know before touching a video file

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Re: What you need to know before touching a video file

#101

Post by alwa »

snakeboy wrote: post #15
ramesh31 wrote: post #12

Earlier quoted context omitted.

technically correct is the best kind. who cares if it's obnoxious? take the opinions and agree or disagree with them.

It works if you know the person and have a baseline for how much confidence you give their opinions. If it's just a random person on the internet, they need to support their argument.

I mean—they can. They don’t need to give more than they’re already giving we anonymous strangers for free. For all we know, this person wrote this for people they encounter personally or professionally, and we’re just incidentally benefitting.

We as readers should gauge their credibility for ourselves, whether by reputation or by checking the claims. I don’t know who wrote it but it seems basically correct, consistent, and concisely argued to me.

Re: What you need to know before touching a video file

#102

Post by weinzierl »

memoriuaysj wrote: post #96
ErroneousBosh wrote: post #94

Earlier quoted context omitted.

It really is gone. You can predict what you think it might have been, but you can't know what it was.

it's gone in a single still frame but across many consecutive frames, the information is spread out temporaly and can be recovered (partially) the same principle of how you can get a high resolution image from a short video, by extracting the same patch from multiple frames https://en.wikipedia.org/wiki/Video_super-resolution

That looks interesting. Is there ready-made software that can do this? Doesn't have to be easy to use just useable with a time commitment of a few days.

Re: What you need to know before touching a video file

#103

Post by memoriuaysj »

perching_aix wrote: post #100
memoriuaysj wrote: post #85

Earlier quoted context omitted.

this is exactly what "higher" compression levels do (among other things like bigger dictionary) - they try harder, more iterations, to find the optimum combination of available knobs for a particular chunk of data.

Yes, that much was always clear. I just always thought the way these software go about finding those combinations was also standardized on a high level rather than proprietary to each implementation. It is a fairly recent development for me to realize that the various encoder options and presets are specific to the encoder, not the format (and now, that the same is true for lossless formats too).

for video there is another constraint - time

hardware encoders (like the ones in GPUs) typically work realtime-ish, so they do minimal exploration of encoding space

you also have the one-pass/two-pass thing which is key for unlocking high quality compression

Re: What you need to know before touching a video file

#104

Post by wafflemaker »

Jabrov wrote: post #6

What's wrong with VLC?

In the olden times of not working/playing movies (00's) and being a clueless tech support for ppl even more clueless about them computers,

The vlc was how you could get any movie to work (instead of messing with all these codecs, which apparently, in lieu to another comment in this thread, aren't really codecs).

Re: What you need to know before touching a video file

#105

Post by perching_aix »

weinzierl wrote: post #57

The article talks about image comparisons but does not say what the best way to extract an image is. If I want the best possible quality image at a precisely specified time, what would I do? Can I increase quality if I have some leeway regarding the time (to use the closest keyframe)? Is there a way to "undo" motion blur and get a sharp picture?

You'll need to settle on a decoder. I personally just use my video player for this, mpc-hc.

In mpc-hc, you can framestep using CTRL+LeftArrow (steps a frame backward) or CTRL+RightArrow (steps a frame forward). This lets you select the frame you want to capture. You do not need to be on a keyframe. These keybinds are configurable and may be different on the latest version.

Then in the File menu, there's an export image option. It directly exports the frame you're currently on, to disk. Make sure to use a lossless format for comparisons (e.g. PNG).

I'm aware this can be done in other players - like mpv - as well, although there I believe no keybinds are set up for this by default, and the default export format is JPEG.

Re: What you need to know before touching a video file

#106

Post by mmcclure »

Shameless plug for anyone that wants to go deeper on specific video topics: I've been organizing a conference for video devs for 11 years now and there's a wealth of info in the recordings. A talk from the most recent one on hacking a Sega Genesis to stream video might not seem that practical, but there were some fascinating bits on compression (or, rather, not being able to use actual compression). https://www.youtube.com/watch?v=GZdxdpw-3nI

If folks want to get involved, there's also a chat community that's pretty active: https://video-dev.org.

Re: What you need to know before touching a video file

#107

Post by LiamPowell »

ffsm8 wrote: post #66
Etheryte wrote: post #17

Earlier quoted context omitted.

Exactly, very hard to take the rest of it seriously after the VLC bit. VLC has literally never left me hanging, across I don't know how many decades. It's gonna take more than a trust me bro to challenge that.

You're talking about VLC for video playback, TFA is taking about video editing. VLC ignores a lot for it's outstanding video playback support, which is great if you want the playback too just work... But that's the player perspective, not the editing/encoding

While VLC is excellent at playing every format under the sun, it's not good at playing all those formats correctly. Off the top of my head:

- Transfer functions are just generally a mess but are close enough that most people don't notice they're wrong. Changing the render engine option will often change how the video looks.

- Some DV profiles cause videos to turn purple or green.

- h.264 left and right crops are both applied as left crops that are summed together which completely breaks many videos. They could just ignore this metadata but from what I've heard their attitude is that a broken implementation is better than no implementation.

Re: What you need to know before touching a video file

#108

Post by gruez »

ryandrake wrote: post #81
BitsAndObjects wrote: post #35

Earlier quoted context omitted.

Follow-up comment: I love how the author’s one brief take-down shot at VLC is currently the dominant criticism in the HN comments (inc. mine). 10,000+ words and the entire lot is being questioned because of one dubious throwaway comment about VLC. A lesson to learn in that. Lol

There was an article[1] yesterday where a single poor word choice derailed much of the comment section with rat-holing and nitpicking until the author revised the article. HN's gotta HN. 1: https://news.ycombinator.com/item?id=46413256

If you're talking about the use of the word "hover", I think that was quite justified, given that it was a critical element of the claim, and the poor wording made it neigh impossible to reproduce the author's claim.

Re: What you need to know before touching a video file

#109

Post by echelon »

unloader6118 wrote: post #95
echelon wrote: post #80

Earlier quoted context omitted.

That advice is not universal, and without context it's simply wrong. You wouldn't upscale a classic film in this way, but there are plenty of low-resolution shots that benefit. Especially with VGA resolution renders and modern AI workflows. Just looking at the Topaz marketing, you can see a lot of places where it indeed does work. And 20-year industry professionals are using it today for their day jobs. If you want t…

In any case, blindly apply upscaling is just wrong .. You apply it to where it is needed. Not every scene need the same treatment.

The article simply says "Trust me, just don't."

Re: What you need to know before touching a video file

#110

Post by eviks »

ffsm8 wrote: post #66
Etheryte wrote: post #17

Earlier quoted context omitted.

Exactly, very hard to take the rest of it seriously after the VLC bit. VLC has literally never left me hanging, across I don't know how many decades. It's gonna take more than a trust me bro to challenge that.

You're talking about VLC for video playback, TFA is taking about video editing. VLC ignores a lot for it's outstanding video playback support, which is great if you want the playback too just work... But that's the player perspective, not the editing/encoding

what are you talking about? Of course it's only about playback just like the other 2 alternatives

> single best media player out there ... VLC is not recommended.

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