Hao Guan hguandl

Useful Examples of ffmpeg and GNU parallel on the command-line:

Transcoding FLAC music to Opus:

ffmpeg is a highly useful application for converting music and videos. However, audio transcoding is limited to a a single core. If you have a large FLAC archive and you wanted to compress it into the efficient Opus codec, it would take forever with the fastest processor to complete, unless you were to take advantage of all cores in your CPU.

parallel 'ffmpeg -v 0 -i "{}" -c:a libopus -b:a 128k "{.}.opus"' ::: $(find -type f -name '*.flac')

Transcoding Videos to VP9:

#Capture and stream a webcam To capture using the iSight camera on a Mac, or infact any other webcam connected to the Mac, we can use FFmpeg. First get a list of the devices installed.

ffmpeg -f avfoundation -list_devices true -i ""

This will list the aviable video and audio devices.

The below will capture at 30fps and the set video size to a file. ffmpeg -f avfoundation -framerate 30 -video_size 640x480 -i "0:none" out.avi

FFmpeg Minimal Build for RTMP Streaming

This tutorial will work you through steps of configuring an FFmpeg build tailored for RTMP streaming on macOS. At first I think of making it support general live streaming, with additional protocols like HLS, but to keep things simple let's stick with RTMP for now. (Anyway, I do include HLS in the protocol list as well as some related bitstream filters but it's untested.)

Goal

The built FFmpeg executable should

Install Video Dummy Package

sudo apt-get install xserver-xorg-video-dummy

Create Default X Windows Configuration File

Create / Edit xorg.conf file Rename file if already exists for backup

If you have issues with installing numpy related packages on Big sur, these steps helped me: 1- Uninstall pyhon installed with homebrew and use python-installer. This resolves numpy issue. And it's better to install 1.18 or just anything bellow 1.19.

brew uninstall python

And install it from: https://www.python.org/downloads/
Then:

pip install numpy==1.18

	# References:
	# https://cmake.org/cmake/help/latest/command/add_custom_target.html
	# https://samthursfield.wordpress.com/2015/11/21/cmake-dependencies-between-targets-and-files-and-custom-commands/
	# https://gist.github.com/socantre/7ee63133a0a3a08f3990
	# https://stackoverflow.com/questions/24163778/how-to-add-custom-target-that-depends-on-make-install
	# https://stackoverflow.com/questions/30719275/add-custom-command-is-not-generating-a-target
	# https://stackoverflow.com/questions/26024235/how-to-call-a-cmake-function-from-add-custom-target-command
	# https://blog.csdn.net/gubenpeiyuan/article/details/51096777

	cmake_minimum_required(VERSION 3.10)

	class BytesToTexture {
	func texture(bytes: [UInt8], bytesPerRow: Int) -> CGImage {
	let rgbaData = CFDataCreate(nil, bytes, bytes.count)!
	let provider = CGDataProvider(data: rgbaData)!
	let colorSpace = CGColorSpaceCreateDeviceRGB()
	let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.noneSkipLast.rawValue)
	return CGImage(
	width: bytesPerRow / 4,
	height: bytes.count / bytesPerRow,
	bitsPerComponent: 8,

	import Cocoa

	// Say we have a Person model
	enum V1 {
	struct Person: Codable {
	let name: String
	var age: Int
	}
	}

	//
	// ExampleWindowReaderApp.swift
	// Shared
	//
	// Created by Matthaus Woolard on 21/12/2020.
	//

	import SwiftUI

	@main

	tasks.withType<Jar> {
	manifest {
	attributes["Main-Class"] = "com.example.MainKt"
	}
	}