- Took video with iPhone.
- Copy video to MacBook using AirDrop.
- Edit video sequence, change speed, transition. Subtitling in iMovie sucks, so I only do the video transitions here, which is what it does best. Cropping and rearranging snippets of videos is very intuitive.
- Export video using
File -> Share -> File - Use Aegisub to create a subtitle file. I’ve known this program since a long time ago and it’s amazing that it still works with Mac OS Catalina. The audio spectrum display is amazing as well. It’s really stable. I’m very impressed.
- The audio has a noise, so I need to edit the audio. We can use ffmpeg to extract just the audio from the video, use m4a, saving it with aac extension will cause the audio to have incorrect length. I specified the bitrate and sampling frequency.
ffmpeg -i video.mp4 -vn -b:a 102k -ar 48000 -acodec copy video.m4a - Open in Audacity (To open m4a files, make sure to download and install the ffmpeg library from Audacity guide, it requires a specific version and it says it won’t get conflict with ffmpeg installed using brew), check the high pitch frequency using
Anaylze -> Plot Spectrum - Select All (Cmd + A), Apply
Effect -> Low Pass Filterwith desired frequency and 48db for Roll-off to remove the high pitched noise - Replace old video’s audio with the edited audio without reencoding the video (Really fast!)
ffmpeg -i video.mp4 -i audio.m4a -c:v copy -map 0:v:0 -map 1:a:0 new_video.mp4 - Hard code the subtitle into the video. Open Handbrake, load the video. In the Subtitles tab, at the dropdown for Tracks, click
Add External Subtitles Track...and select the previously created subtitle (works with Aegisub’s .ass file) - Start encoding!