subed-record makes it easier to prepare text for subtitles, record a
voiceover, and then compile a video that includes the visuals, audio,
and subtitles specified by the text file.
I’m not sure it works for anyone but me at the moment, so if you run into a problem, it’s probably not you, it’s me. Let me know and/or help me figure it out! =)
Sacha Chua - sacha@sachachua.com - https://github.com/sachac/subed-record
You will need:
- subed is a mode for editing subtitles. It is not yet available as a package, but can get it from https://github.com/rndusr/subed .
- mpv.el plays media files from within Emacs using the MPV command-line tool. mpv.el is available from MELPA, and MPV is available via either your operating system’s package manager or from https://mpv.io/ .
- compile-media puts together the video.
- subed-waveform is optional. You can use it to display the waveform for the current subtitle to help you fine-tune timestamps.
Take a look at the variables in M-x customize-group subed-record.
You can draft your text in an Org Mode file, using file: links to
include images or videos and #+CAPTION: to include captions. You may
want to wrap your lines to be as short as they will be in captions.
Image and video information should be one per line. Here’s an example:
#+CAPTION: Emacs News Highlights - emacsconf.org/2021/talks/news
[[file:images/Screenshot_20211021_002952.png]]
I'm Sacha Chua, and here are
ten Emacs News highlights for 2021.
If you want to follow the links,
check out the wiki page at
https://emacsconf.org/2021/talks/news/ .
- What if I want to include a section of a video or crop an image?
- The current code doesn’t let you specify FFMPEG filters for a specific visual yet, but that’d be a neat addition. In the meantime, you can use your favourite editing tool to put the segment that you want into a file that can be included.
Create a subtitle file (ex: recording.vtt) with the segments you would like to record in one go.
WEBVTT NOTE #+CAPTION: Emacs News Highlights - emacsconf.org/2021/talks/news [[[[file:images/Screenshot_20211021_002952.png]]]] 00:00:00.000 --> 00:00:00.000 I'm Sacha Chua, and here are ten Emacs News highlights for 2021. 00:00:00.000 --> 00:00:00.000 If you want to follow the links, check out the wiki page at https://emacsconf.org/2021/talks/news/ .
If you’re starting with an Org Mode file, you can use
subed-record-org-to-vtt to extract the text from the current Org
subtree. It will keep captions and file links, and it will turn HTTP
links into regular text. It creates a file based on the current
filename, but with a .vtt extension.
Pick an appropriate subed-record-backend, such =’sox= if you have
the command-line sox and rec tools.
Use subed-record to start the recording. It will save the recording
into a file based on the name of the current subtitle file, but ending
with subed-record-extension.
Default keybindings:
| right | accept current segment and continue |
| left | retry current segment |
| up | go back one segment |
| down | go forward one segment |
| RET or q | stop recording |
subed-record overwrites the recording file each time it is called.
If you want to re-record a different segment and splice it into the
rest of your presentation, you can create a new .vtt file and use
subed-record to record into a different audio file. Then you can
include that segment in your original .vtt file with an #+AUDIO:
... specification, like this:
00:00:45.864 --> 00:00:47.644 in his update, so check out his talk. NOTE #+AUDIO: native.ogg #+CAPTION: emacsconf.org/2021/talks/native/ [[ 00:00:00.970 --> 00:00:02.840 file:images/native-comp.png]] Andrea Corallo's giving a talk 00:00:02.840 --> 00:00:04.475 #+AUDIO: native.ogg on native compilation too.
NOTE: subed.el automatically sorts subtitles by timestamp. If you move subtitles around or use this technique to combine different audio files, you may need to disable automatic subed sorting with something like the following code:
(with-eval-after-load 'subed
(remove-hook 'subed-sanitize-functions 'subed-sort))Alternatively, you can start with an already-edited audio file and
then use subed-mode’s commands to create, split, or adjust subtitles
so that they match your audio file.
Load the recording with C-c C-v (subed-mpv-find-video). You may
want to turn off looping with C-c C-l
(subed-toggle-loop-over-current-subtitle).
You can then use the following keyboard shortcuts to divide the subtitles into shorter captions if needed.
M-j | subed-mpv-jump-to-current-subtitle |
M-SPC | subed-mpv-toggle-pause |
M-. | subed-split-subtitle |
You can adjust the timestamps by manually typing in new values or by using the following keyboard shortcuts:
M-[ | subed-decrease-start-time |
M-] | subed-increase-start-time |
M-{ | subed-decrease-stop-time |
M-} | subed-increase-stop-time= |
It can be easier to determine the starting and stopping timestamps from the waveform instead of trying to pause at the right moment. subed-waveform allows you to see the waveform for the current subtitle, play samples at different positions, and set the start or stop times.
To test whether the audio flows together, mark a region and use
M-x subed-record-compile-try-flow. You may want to bind this to a
convenient shortcut with something like the following:
(with-eval-after-load 'subed-record
(define-key subed-mode-map
(kbd "C-c C-c")
#'subed-record-compile-try-flow))This exports the audio segments in the region to a new file specified
by subed-record-compile-output-filename (default: output.webm),
overwriting existing files. After processing, it will play it in a
separate MPV process. You can stop playing with M-x mpv-kill.
You can test the visuals as well. M-x
subed-record-compile-test-visuals compiles all the images, animated
GIFs, and videos from the subtitle file into the output file specified
by subed-record-compile-output-filename (default: output.webm)
with a duration of 1 second per visual.
To tweak the display, consider customizing the following variables:
subed-record-compile-description-heightsubed-record-compile-caption-heightsubed-record-compile-output-video-widthsubed-record-compile-output-video-heightsubed-record-compile-description-drawtext-filter-params
Clear the region or select the whole buffer, then run M-x
subed-record-compile-video. This will compile the video, audio, and
subtitles into the output file specified by
subed-record-compile-output-filename (default: output.webm).
Audio segments will be concatenated, one after the other. Visuals (specified by file: links) will be stretched or squeezed to fit the time until the next visual is specified. Visual information will be removed from the subtitles, and the resulting subtitles will accompany the audio segments.
You can specify multiple output files with the #+OUTPUT: keyword, like this:
WEBVTT NOTE [[file:/home/sacha/proj/emacsconf/assets/in-between/journalism.png]] #+OUTPUT: journalism.webm 00:00:04.794 --> 00:00:07.559 The next talk is called "Emacs journalism 00:00:07.560 --> 00:00:09.879 (or everything's a nail if you hit it with Emacs)", 00:00:09.880 --> 00:00:10.800 by Alfred Zanini. 00:00:11.393 --> 00:00:14.026 They will answer questions via BigBlueButton. 00:00:14.027 --> 00:00:16.744 You can join using the URL from the talk page 00:00:16.745 --> 00:00:20.394 or ask questions through Etherpad or IRC. NOTE [[file:/home/sacha/proj/emacsconf/assets/in-between/school.png]] #+OUTPUT: school.webm 00:00:27.526 --> 00:00:30.606 The next talk is called "Back to school with Emacs". 00:00:33.860 --> 00:00:36.251 Daniel Rosel demonstrates Lectorg, 00:00:36.332 --> 00:00:39.881 a package that he wrote to make note taking faster and simpler. 00:00:39.882 --> 00:00:44.319 Afterwards, he will handle questions over IRC.
#+AUDIO:- specify the audio file
#+OUTPUT:- everything until the next output comment goes into the specified file.
#+CAPTION:- text that will be displayed at the top
#+SKIP- skip the following subtitle
[[file:...]]- include that image or video
subed-record timestamps might overlap if you use multiple audio sources. You may want something like this at the end of your file:
NOTE Local Variables: subed-enforce-time-boundaries: nil End:
If you like to move sections around, you’ll also want to (remove-hook
'subed-sanitize-functions 'subed-sort).
While testing, it can be useful to add ~”-r”~ ~”1”~ to compile-media-ffmpeg-arguments. It makes a video with one frame per second, which is choppy but still handy for checking the flow.
If you’re compiling or trying part of a video and you’re midway between visuals, the previous visual won’t be included. To work around this, start with a caption that has a file link for the visual.
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