Adding subtitles to videos

In my ever-growing collection of FFmpeg-related blog posts, I will today show how to add subtitles to videos. These tricks are based on the need to create a captioned version of a video I made to introduce the Workshop on NIME Archiving for the 2022 edition of the International Conference on New Interfaces for Musical Expression (NIME). This is the video I discuss in this blog post: Note that YouTube supports turning on and off the subtitles (CC button)....

June 11, 2022 · 6 min · 1193 words · ARJ

Running a disputation on YouTube

Last week, Ulf Holbrook defended his dissertation at RITMO. I was in charge of streaming the disputation, and here are some reflections on the technical setup and streaming. Zoom Webinars vs YouTube Streaming I have previously written about running a hybrid disputation using a Zoom webinar. We have used variations of that setup also for other events. For example, last year, we ran RPPW as a hybrid conference. There are some benefits of using Zoom, particularly when having many presenters....

May 7, 2022 · 5 min · 958 words · ARJ

Merge multiple MP4 files

I have been doing several long recordings with GoPro cameras recently. The cameras automatically split the recordings into 4GB files, which leaves me with a myriad of files to work with. I have therefore made a script to help with the pre-processing of the files. This is somewhat similar to the script I made to convert MXF files to MP4, but with better handling of the temp file for storing information about the files to merge:...

March 31, 2022 · 1 min · 168 words · ARJ

Edit video rotation metadata in FFmpeg

I am recording a lot of short videos these days for my sound actions project. Sometimes the recordings end up being rotated, which is based on the orientation sensor (probably the gyroscope) of my mobile phone. This rotation is not part of the recorded video data, it is just information written into the header of the MPEG file. That also means that it is possible to change the rotation without recoding the file....

February 12, 2022 · 1 min · 157 words · ARJ

Different 16:9 format resolutions

I often have to convert between different resolutions of videos and images and always forget the pixel dimensions that correspond to a 16:9 format. So here is a cheat-sheet: **2160p: **3840×2160 **1440p: **2560×1440 **1080p: **1920×1080 **720p: **1280×720 540p: 960x540 **480p: **854×480 **360p: **640×360 **240p: **426×240 120p: 213x120 I also came across this complete list of true 16:9 resolution combinations, but the ones above suffice for my usage. Happy converting!

February 3, 2022 · 1 min · 69 words · ARJ

One month of sound actions

One month has passed of the year and my sound action project. I didn’t know how it would develop when I started and have found it both challenging and inspiring. It has also engaged people around me more than I had expected. Each day I upload one new video recording to YouTube and post a link on Twitter. If you want to look at the whole collection, it is probably better to check out this playlist:...

January 31, 2022 · 4 min · 789 words · ARJ

Preparing videos for FutureLearn courses

This week we started up our new online course, Motion Capture: The Art of Studying Human Activity, and we are also rerunning Music Moves: Why Does Music Make You Move? for the seventh time. Most of the material for these courses is premade, but we record a new wrap-up video at the end of each week. This makes it possible to answer questions that have been posed during the week and add some new and relevant material....

January 28, 2022 · 2 min · 376 words · ARJ
Frame differencing image of dancer.

Frame differencing with FFmpeg

I often want to create motion videos, that is, videos that only show what changed between frames. Such videos are nice to look at, and so-called “frame differencing” is also the start point for many computer vision algorithms. We have made several tools for creating motion videos (and more) at the University of Oslo: the standalone VideoAnalysis app (Win/Mac) and the different versions of the Musical Gestures Toolbox. These are all great tools, but sometimes it would be nice also to create motion videos in the terminal using FFmpeg....

January 9, 2022 · 2 min · 246 words · ARJ

Try not to headbang challenge

I recently came across a video of the so-called Try not to headbang challenge, where the idea is to, well, not to headbang while listening to music. This immediately caught my attention. After all, I have been researching music-related micromotion over the last years and have run the Norwegian Championship of Standstill since 2012. Here is an example of Nath & Johnny trying the challenge: https://www.youtube.com/watch?v=-I4CBsDT37I As seen in the video, they are doing ok, although they are far from sitting still....

January 7, 2022 · 1 min · 179 words · ARJ

Pre-processing Garmin VIRB 360 recordings with FFmpeg

I have previously written about how it is possible to “flatten” a Ricoh Theta+ recording using FFmpeg. Now, I have spent some time exploring how to process some recordings from a Garmin VIRB camera. Some hours of recordings The starting point was a bunch of recordings from our recent MusicLab Copenhagen featuring the amazing Danish String Quartet. A team of RITMO researchers went to Copenhagen and captured the quartet in both rehearsal and performance....

December 21, 2021 · 6 min · 1191 words · ARJ