What you need to know before touching a video file • Hacker News Board

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

#221

Post by arch1t3cht » Sat, Jan 03, 2026, 11:04 AM UTC

my65thaccount wrote: post #117

rfl890 wrote: post #99

Earlier quoted context omitted.

VLC has always caused problems for me when seeking backwards (graphical glitches). mpv has never caused any issues in this regard.

VLC and mpv literally use the same underlying codec library. (As well as ffmpeg.)

libav{format,codec,...} are just libraries for demuxing and decoding video. There is huge variability in how those libraries are used, let alone how the video is displayed (which needs scaling, color space conversions, tonemapping, subtitle rendering, handling playback timing, etc. etc.). mpv also has its own demuxer for matroska files, since libavformat's is very limited [1].

[1] https://github.com/mpv-player/mpv/wiki/libavformat-mkv-check...

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

#222

Post by arch1t3cht » Sat, Jan 03, 2026, 11:15 AM UTC

netsharc wrote: post #86

The second technical definition in this document is wrong. Great way to put the "the author is opinionated but is clueless" marker right near the top. > Actual video coding formats are formats like H.264 (also known as AVC) or H.265 (also known as HEVC). Sometimes they're also called codecs, short for "encode, decode". Codec is coder/decoder. It's not the format. There's a footnote claiming people mix the 2 terms up…

Thanks for the "encoder/decoder" correction.

But yes, as the other reply says, I am aware of this distinction, and I make a point not to use the word "codec" at any other point in the article. and explain in a lot of detail how much the encoder matters when it comes to encoding in some format. I mention the term to make people aware that it exists.

But, you're right, I will clarify this a bit more.

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

#223

Post by arch1t3cht » Sat, Jan 03, 2026, 11:20 AM UTC

perching_aix wrote: post #38

I've had a lot of misconceptions that I had to contend with over the years myself as well. Maybe this thread is a good opportunity to air the biggest one of those. Additionally, I'll touch on subbing at the end, since the post specifically calls it out. My biggest misconception, bar none, was around what a codec is exactly, and how well specified they are. I'd keep hearing downright mythical sounding claims, such as…

Thanks for bringing this up, since I'm realizing that I did not explicitly spell this out in the post. I'll add a paragraph making this even clearer.

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

#224

Post by embedding-shape » Sat, Jan 03, 2026, 11:23 AM UTC

astrange wrote: post #185

joe_the_user wrote: post #170

Earlier quoted context omitted.

Yeah, as far as I know, to understand video formats, you need to understand encode-decode process, how film/video editor operate normally (keeping in mind film/video editing has levels from $100s to way beyond me), history, how optics and cameras work, etc. Then particular choices and confusions can be understood. This indeed just seems to jump-in in the middle and give a bunch very specific recommendation. I have no…

There are not very many recommendations in this article, but they're good.

Wish I knew which ones were applicable to me, but without any reasoning, these "recommendations" are as good as random tweets with factoids.

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

#225

Post by embedding-shape » Sat, Jan 03, 2026, 11:23 AM UTC

eduction wrote: post #118

embedding-shape wrote: post #9

It seems really weirdly written. It's written with a lot of authority, like saying "Don't use VLC" and "Don't use Y" yet provides no reasoning for those things. Just putting "Trust me, just don't" doesn't suddenly mean I trust the author more, it probably has the opposite effect. Some sections seem to differ based on if the reader knows/doesn't know something, but I thought the article was supposed to be for the latt…

And? It’s a GitHub gist not an oreilly book. Context.

So? This was just a HN comment, not a review of a paper.

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

#226

Post by lelanthran » Sat, Jan 03, 2026, 11:24 AM UTC

Drybones wrote: post #133

jaapz wrote: post #123

Earlier quoted context omitted.

> It is the Firefox of media players. So... the better option?

IDK where you have been for the last decade, but Firefox has not been the better option since Chromium was made Disliking Google Chrome proper is one thing, but Chromium is superior in every way. Rendering, features, speed, memory management

> Chromium is superior in every way. Rendering, features, speed, memory management

Being faster, prettier and using less memory[1] is pointless if the browser won't let me block all ads.

I mean, it's like comparing a turd sandwich made with expensive exotic bread, and a cheese sandwich made with cheap grocery store break.

Sure, the one has great exotic bread, but I don't want the turd it comes with.

So, yeah, it actually doesn't matter how much prettier, faster or smaller web pages are with Chrome, at least FF lets me (currently) block almost anything.

---------------------------------------

[1] Chrome beats out FF in exactly one of those, and it's not the memory or speed. Turns out ads take up a lot of RAM, and slow down pages considerably.

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

#227

Post by liampulles » Sat, Jan 03, 2026, 12:29 PM UTC

I remember using Gordian Knot to create avi files from my DVDs back when XviD was the pragmatic method for encoding videos, and the whole goal was to get movies under 700mb so that you could write them to a CD. Avisynth and community filters were largely geared towards undoing all sorts of crap done to an image because artifacts that were relatively unnoticeable on a general CRT television were quite apparent on a computer monitor, as well as to then prepare the video to look good once it has been highly compressed with XviD or DivX.

These days I'm much more inclined to try and transparently encode the source material, tag it appropriately in the media container, and let the player adjust the image on the fly. Though I admit, I still spend hours playing around with Vapoursynth filter settings and AV1 parameters to try and get a good quality/compression ratio.

I have to say that the biggest improvement to the experience of watching my videos was when I got an OLED TV. Even some garbage VHS rip can look interesting when the night sky has been adjusted to true black.

Given the increasing abilities of TVs and processing abilities and feature sets of players, I'm not much persuaded to upgrade my DVD collection to Blu-Ray. Though I admit some of that is that I enjoy the challenge of getting a good video file out of my DVDs.

I partially disagree with the use of ASS subtitles. For a lot of traditional movies, using SRT files is sensible because more players support it, and because it's often sensible to give the player the option of how to render the text (because the viewing environment informs what is e.g. the appropriate font size).

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

#228

Post by liampulles » Sat, Jan 03, 2026, 12:37 PM UTC

socalgal2 wrote: post #188

Tangential but, at least for me, I find lots of video creators making 2-3 gig videos for no noticable difference in quality for me re-encoding them to 1/4th the size or less. My impression is, their audience equates file size with quality so the bigger the file the more "value" they got from the creator. This is frustrating because bigger files means hitting transfer limits, slower to download, slower to copy, taking…

Do youngins even know why AVI files are under 700mb? I think obsessions over quality/compression are the concern of us aging hobbyist encoders.

Unless one lives in a country where the internet is slow and/or hard drives are expensive, I think the audience does not care.

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

#229

Post by liampulles » Sat, Jan 03, 2026, 12:45 PM UTC

zzo38computer wrote: post #119

Sometimes I would want to convert from MPEG-TS H.264 to DVD video format, or other conversions, so there are reasons to do so. However, once I had got desynchronized audio, and I don't know if that is because of the original source, because of the conversion, or because some segments have not been recorded. (Also, it could not retain the EIA-608 captions, but that seems to be a limitation with FFmpeg, rather than som…

Did you use a decent piece of DVD authoring software? Here are some options: https://www.videohelp.com/software/sections/authoring-dvd

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

#230

Post by liampulles » Sat, Jan 03, 2026, 12:56 PM UTC

jdprgm wrote: post #151

Just writing off AI upscaling completely is bs. It's not some magic bullet to use on every video and there is a learning curve on how to apply but there are absolutely scenarios where you can get shockingly good results. I think a lot of people make judgements on it based on super small sample sizes. On a separate note also not mentioned llm's are really good at generating ffmpeg commands. Just discuss with chatGPT y…

AI upscaling can also be done during playback, to the benefit of lower file sizes, but at the cost of higher processor utilisation. So it is a trade-off.