Title: Remixing a 90-minute video using ffmpeg: Linear perspective and other techniques
Introduction
In this article, we will discuss how to remix a 90-minute video using ffmpeg, a powerful open-source tool for handling multimedia files. We will cover techniques such as linear perspective, speed control, and audio adjustments.
Linear Perspective
Linear perspective is a technique used to create the illusion of depth in a two-dimensional image. In video editing, this technique can be used to make objects appear closer or farther away, giving a more realistic feel to the video.
To achieve linear perspective using ffmpeg, we can use the scale and unsharp_mask filters. Here's an example command:
ffmpeg -i input.mp4 -vf "scale=w=trunc(oh*a/2)*2:h=trunc(ow*a/2)*2,unsharp_mask=5:5:0.8,setdar=1" -c:v libx264 -crf 23 -preset slow -c:a aac -b:a 192k output.mp4
In this command, scale resizes the video while maintaining the aspect ratio. unsharp_mask sharpens the edges of objects, giving the illusion of depth. setdar sets the display aspect ratio to 16:9.
Speed Control
Speed control is another important technique in video editing. With ffmpeg, we can change the playback speed of a video without changing the pitch of the audio.
To change the playback speed, we can use the setpts filter. Here's an example command:
ffmpeg -i input.mp4 -vf "setpts=N/180000" -c:v libx264 -crf 23 -preset slow -c:a aac -b:a 192k output_slow.mp4
In this command, setpts=N/180000 sets the playback speed to N times slower. Adjust the value of N to speed up or slow down the video.
Audio Adjustments
In addition to speed control, we can also adjust the volume, normalize the audio, and add fade-ins and fade-outs.
To adjust the volume, we can use the volume filter. Here's an example command:
ffmpeg -i input.mp4 -vf "volume=0.5" -c:v libx264 -crf 23 -preset slow -c:a aac -b:a 192k output_quiet.mp4
In this command, volume=0.5 sets the volume to 50% of its original value.
To normalize the audio, we can use the loudnorm filter. Here's an example command:
ffmpeg -i input.mp4 -vf "loudnorm=I=-16:T=0:L=16:print_levels=1" -c:v libx264 -crf 23 -preset slow -c:a aac -b:a 192k output_normalized.mp4
In this command, loudnorm normalizes the audio to a target loudness of -16 LUFS.
Conclusion
In this article, we discussed how to remix a 90-minute video using ffmpeg. We covered techniques such as linear perspective, speed control, and audio adjustments. With these techniques, you can create professional-quality videos from your raw footage.