FFMPEG from Zero to Hero • Hacker News Board

Re: FFMPEG from Zero to Hero

#11

Post by herpderperator » Sat, Mar 06, 2021, 11:28 PM UTC

Confiks wrote: post #2

Might have come in handy while I was struggling to type out ffmpeg -i part0.mp4 -i part1.mp4 -filter_complex "[1:v]scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2[v1]; [0:v] [0:a] [v1] [1:a] concat=n=2:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" out.mp4 to concatenate two videos with different sizes today. My relation with it is almost identical to my relation with any bash scripting m…

It's true, and I feel the same, but to give it some credit: wouldn't that apply to anything you don't use regularly? Programming languages or even regular languages. You have to use it or lose it.

Re: FFMPEG from Zero to Hero

#12

Post by IncRnd » Sat, Mar 06, 2021, 11:30 PM UTC

hardwaregeek wrote: post #4

If this book does what it claims to do, it should probably cost more (pls raise the price after I buy it). I strongly believe that inside ffmpeg may be the secret to the cosmos, the universe and life itself

Well, there is at least a poster image of the cosmos.

Re: FFMPEG from Zero to Hero

#13

Post by amelius » Sat, Mar 06, 2021, 11:32 PM UTC

Confiks wrote: post #2

Might have come in handy while I was struggling to type out ffmpeg -i part0.mp4 -i part1.mp4 -filter_complex "[1:v]scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2[v1]; [0:v] [0:a] [v1] [1:a] concat=n=2:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" out.mp4 to concatenate two videos with different sizes today. My relation with it is almost identical to my relation with any bash scripting m…

I just grep through my bash history ;)

Re: FFMPEG from Zero to Hero

#14

Post by sergiotapia » Sat, Mar 06, 2021, 11:38 PM UTC

Is FFMPEG globally unique in being extremely powerful, ubiquitous and totally incomprehensible? It's a real treasure and gift to humanity.

Re: FFMPEG from Zero to Hero

#15

Post by merb » Sat, Mar 06, 2021, 11:40 PM UTC

the_only_law wrote: post #10

ffmpeg is really useful, but isn't doing some of these things on a CPU really inefficient? I know there are some offloads for Nvidia GPU’s for some video stuff, but I was under the impression that they used Nvidia’s proprietary libraries that have limited codec support.

it's always a tradeoff between speed and quality. and most of the time cpu offers more quality while hardware encoders are faster, this is mostly because gpu encoders have a different use case than cpu encoders.

Re: FFMPEG from Zero to Hero

#16

Post by aneutron » Sat, Mar 06, 2021, 11:42 PM UTC

hprotagonist wrote: post #8

abnry wrote: post #3

I feel like someone should teach a course on how to use the grouping of command line applications: convert (image magick), pdftk, pandoc, and ffmpeg. Lots of power to be had in mastering them.

type command. roll face on keyboard. hit enter. repeat until results look good!

So machine learning

Re: FFMPEG from Zero to Hero

#17

Post by e-clinton » Sat, Mar 06, 2021, 11:42 PM UTC

Just what I need! Wish you offered a print as well, but this will do

Re: FFMPEG from Zero to Hero

#18

Post by Liru » Sat, Mar 06, 2021, 11:42 PM UTC

sergiotapia wrote: post #14

Is FFMPEG globally unique in being extremely powerful, ubiquitous and totally incomprehensible? It's a real treasure and gift to humanity.

Perl edges it out, but only barely.

Re: FFMPEG from Zero to Hero

#19

Post by varenc » Sat, Mar 06, 2021, 11:46 PM UTC

the_only_law wrote: post #10

ffmpeg is really useful, but isn't doing some of these things on a CPU really inefficient? I know there are some offloads for Nvidia GPU’s for some video stuff, but I was under the impression that they used Nvidia’s proprietary libraries that have limited codec support.

ffmpeg supports various hardware decoders/encoders: https://trac.ffmpeg.org/wiki/HWAccelIntro

I use the h264_videotoolbox hardware encoder on macOS all the time! But in my experience, CPU based encoding is always better and offers more fine tune control. It's just slow. And there's all sorts of filters and transformations that aren't possible in hardware.

FFmpeg's Nvidia hardware support seems pretty good too. There's an official support doc on using ffmpeg: https://docs.nvidia.com/video-technologies/video-codec-sdk/f...

Re: FFMPEG from Zero to Hero

#20

Post by astrange » Sat, Mar 06, 2021, 11:51 PM UTC

whateveracct wrote: post #9

Confiks wrote: post #2

Might have come in handy while I was struggling to type out ffmpeg -i part0.mp4 -i part1.mp4 -filter_complex "[1:v]scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2[v1]; [0:v] [0:a] [v1] [1:a] concat=n=2:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" out.mp4 to concatenate two videos with different sizes today. My relation with it is almost identical to my relation with any bash scripting m…

Feels like a nice & typed Haskell eDSL on top of ffmpeg would be helpful.

It would be hard to be expressive enough considering there’s a lot of exceptions where things don’t really quite work.

eg copying without conversion between different formats isn’t really possible when it looks like it should be, because there’s a lot of incorrect handling of timestamps both in libavformat and in files themselves.