digital_video_introduction
Av1an
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digital_video_introduction | Av1an | |
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8 | 65 | |
15,080 | 1,338 | |
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7 months ago | 12 days ago | |
Jupyter Notebook | Rust | |
BSD 3-clause "New" or "Revised" License | GNU General Public License v3.0 only |
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digital_video_introduction
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Breakdown of AV1 Video Codec
There's a great introduction to video tech, including codecs, at https://github.com/leandromoreira/digital_video_introduction
- A Hands-On Introduction to Video Codec Technology and FFmpeg
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Topics to cover in a 101 AV class
A couple of AV centric scenarios I'd explore: - Set up two speakers fed with a mono signal, flip the phase on one and have students move around the area. From this introduce constructive and destructive interference and some basic acoustics. - Using an oscilloscope (or just prepped graphics) show a sine wave on an unbalanced line, how this is paired with an inverted copy of itself on a balanced line, and how this works to cancel transmission noise. - With an analogue signal now pictured, introduce analogue to digital conversion and what sample rate and bit depth mean. From this you can also start to introduce why gain staging is important in both pure analogue systems and those where you're bouncing between analogue and digital domains. - Introduce video: colour channels, different ways of representing colour and some (very surface level) compression basics like chroma subsampling. Really good resource for that here. - Introduce base patterns for getting any signals arounds: dedicated circuits (analogue audio, HDMI video, RS-232 control, logic IO) and network based (again for audio, video, and control). Dive intro signal flow, how to read a schematic and where reasoning about each of these modes differs.
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Crestron DMC-D-4K Class Tips/Things to Watch out For
If you want to keep digging from there, get familiar with the compression on NVX, JPEG-XS, and how it behaves. intoPIX are the upstream vendor that do some of the NVX internals and have some great resources on that here: https://www.intopix.com/jpeg-xs. For a guide on all things digital video I also highly recommend https://github.com/leandromoreira/digital_video_introduction.
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[OC] Finally managed to sync the moshing effect to the beat of the music, here's what it looks like on a small test section of a music video
Edit: After finishing writing the comment, I realized that it was more technical than I intended, and assumes that the reader has a basic to medium understanding of video compression. If not, I recommend this writeup/tutorial of digital video, especially the section about frame types.
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Ask HN: How can I learn about video encoding, h.264, ffmpeg, etc.
A good high-level breakdown of H.264: https://sidbala.com/h-264-is-magic/
Associated HN post (although there have been a few): https://news.ycombinator.com/item?id=30710574
More technical: https://github.com/leandromoreira/digital_video_introduction...
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H.264 is magic: a technical walkthrough
For those interested in this topic, I highly recommend the approachable but more extensive technical introduction at https://github.com/leandromoreira/digital_video_introduction
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Help and guidance for a Coding interview for the role of Media Video Engineer (Video Quality)
Go look at this. https://github.com/leandromoreira/digital_video_introduction
Av1an
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Guide to Adopting AV1 Encoding
The hardware encoders are very fast and generally better than x264 (but not by as much as you'd think with the x264 slow preset).
In addition, there are threaded AV1 encoders you may be overlooking, like SVT-AV1. For non-realtime, my favorite is av1an, which also yields better quality than is possible from aomenc: https://github.com/master-of-zen/Av1an
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I have a feeling crunchyroll should be using AV1
I specifically used https://github.com/master-of-zen/Av1an with --target-quality 100 to keep the compression as close to lossless as possible (you could probably shave even more size off if you didn’t use near-lossless compression)
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Automatic choose encode settings?
There's also Av1an as suggested by someone else. It's going to produce more efficient encodes because it uses chunk-based encoding to reach the required VMAF for every single chunk, but this is also slower because every chunk will be re-encoded until the VMAF target is reached. It's also a PITA to compile, has a long list of bugs, and isn't very actively developed. One of the long-standing issues is that frames have a tendency to go missing during splitting, which IME is going to keep happening when the input files aren't standardized. And thus the recommendation is to transcode the input to lossless first, which is just completely unsustainable.
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Building pc for ffmpeg rendering
i'm still trying to figure out if av1an is the breakthrough to using large CPU counts without losing quality. but it's a ridiculously poorly documented program. i haven't gotten it to run effectively yet. https://github.com/master-of-zen/Av1an
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Codecs for the 4K Era: HEVC, AV1, VVC and Beyond
I don't know about VVC, but I've never seen a recommendation of preset 0 for SVT-AV1. The docs say "presets 1-3 represent extremely high efficiency, for use when encode time is not important and quality/size of the resulting video file is critical". It seems like 0 is the equivalent placebo preset. But if you want AV1 with coding efficiency over all else, IIRC the typical approach is to use av1an to detect scene transitions and farm out parallel encodes with aomenc.
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Automating av1 encoding?
That might be because it doesn't work.
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VMAF is confusing me
Have you seen Av1an? It's supposed to encode to a target VMAF.
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Trying to use av1an without success
Are you using the current version, 0.4.0, from https://github.com/master-of-zen/Av1an/releases
- Av1an - Cross-platform command-line AV1 encoding framework written in Rust
- Av1an: Cross-platform command-line AV1 encoding framework written in Rust
What are some alternatives?
PHP-FFmpeg-video-streaming - 📼 Package media content for online streaming(DASH and HLS) using FFmpeg
HandBrake - HandBrake's main development repository
VVCEasy - VVCEasy is that you don't have to compile or/and coding to encode VVC (known as Versatile Video Codec). Simple. Easy. Encode. Decode
SVT-AV1
SVT-AV1 - Welcome to the GitHub repo for the SVT-AV1! This repo is set to read-only for archiving purposes. Please join us at https://gitlab.com/AOMediaCodec/SVT-AV1. We look forward to seeing you there
FastFlix - FastFlix is a free GUI for HEVC and AV1 encoding, GIF/WebP/AVIF creation, and more!
NotEnoughAV1Encodes - GUI for AV1 (aomenc, rav1e & svt-av1)
SwiftFFmpeg - A Swift wrapper for the FFmpeg API
FFmpeg-Builds
Ant-Media-Server - Ant Media Server is a live streaming engine software that provides adaptive, ultra low latency streaming by using WebRTC technology with ~0.5 seconds latency. Ant Media Server is auto-scalable and it can run on-premise or on-cloud.
ab-av1 - AV1 re-encoding using ffmpeg, svt-av1 & vmaf.