🛠️ Edit videos in terminal

Anthony — Mon, 10 Apr 2023 09:47:49 +0000

I have been making some videos using AI and I couldn't resist editing it with an awesome CLI tool ffmpeg.
Here are some of my favorite ffmpeg commands for quick video editing.

Overlay audio over a video, lowering the original volume by 80%

#!/bin/bash
video="$1"
audio="$2"
ffmpeg \
    -i "$video" \
    -i "$audio" \
    -filter_complex \
    "[1:a]apad[A];[0:a]volume=0.20,[A]amerge[out]" \
    -c:v copy -map 0:v -map [out] -y \
    "processed_${video:0:10}.mp4"

Make a video from a single image

#!/bin/bash
image="$1"
audio="$2"
length="$3" #Hh:Mm:Ss
ffmpeg \
    -r 0.01 -loop 1 -i "$image" \
    -i "$audio" -c:v libx264 \
    -tune stillimage -preset ultrafast \
    -ss 00:00:00 -t "$length" \
    -c:a aac -b:a 96k -pix_fmt yuv420p \
    -shortest out.mp4 -y

Concat multiple videos (listed in a file) into one

#!/bin/bash
ffmpeg \
  -f concat -safe 0 \
  -i mylist.txt -c copy output.mp4

$ cat mylist.txt
 file '/path/to/file1'
 file '/path/to/file2'
 file '/path/to/file3'

Split a video given a timestamp

#!/bin/bash
video="$1"
timestamp="$2" # Hh:Mm:Ss

ffmpeg -i "$video" -to "$timestamp" -c copy first.mp4
ffmpeg -i "$video" -ss "$timestamp" -c copy second.mp4

Trim beginning of the video (Removing ads, intros)

#!/bin/bash
video="$1"
time="$2"
ffmpeg \
    -i "$video" -vcodec copy \
    -c:a copy -map 0 -ss "$time" \ 
        "trimmed_${video:0:10}.mp4"

🪐 Why useState returns an array in React?

Anthony — Sun, 19 Mar 2023 06:39:38 +0000

I have always wondered why does React useState returns an array instead of an object.

const [count, setCount] = useState(0);

This assigns the current state value to the count variable, and the update function to the setCount variable. This syntax is concise and easy to read, making it a popular choice for managing state in React.

If useState were to return an object instead of an array, you would need to use property destructuring to access the state value and update function. This can be more verbose, as you would need to provide an explicit property name for each value:

const {state: count, setState: setCount} = useState(0);

If useState returns an Object the destructring assignment wouldn't be that convenient, because you'd have to implicitly rename the object fields. And if don't rename the object fields, then we would only be able to use only one useState in a component.

This syntax is less convenient than array destructuring, as you need to rename the properties of the returned object to avoid naming conflicts. If you don't rename the properties, you would only be able to use one useState call in a component.

Overall, using an array to return the state value and update function is a simple and effective way to manage state in React. While returning an object would be possible, it would require more verbose syntax and would be less convenient for most use cases. By returning an array, React makes it easy to use useState to manage state in your functional components.

DEV Community: Anthony

🛠️ Edit videos in terminal

🪐 Why useState returns an array in React?