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[[!meta title="Captioning tips"]]
-[[!meta copyright="Copyright © 2021 Sacha Chua"]]
+[[!meta copyright="Copyright © 2021, 2022 Sacha Chua"]]
Captions are great for making videos (especially technical ones!)
easier to understand and search.
-If you see a talk at <https://media.emacsconf.org/2021/protected/> (no
-longer protected now that the conference is done) that you'd like to
-caption, feel free to download it and start working on it with your
-favourite subtitle editor. Let me know what you pick by e-mailing me
-at <sacha@sachachua.com> so that I can update the index and try to
-avoid duplication of work.
+If you see a talk that you'd like to caption, feel free to download it
+and start working on it with your favourite subtitle editor. Let me
+know what you pick by e-mailing me at <sacha@sachachua.com> so that I
+can update the index and try to avoid duplication of work. [Find talks that need captions here](https://emacsconf.org/help_with_main_captions). You can also help by [adding chapter markers to Q&A sessions](https://emacsconf.org/help_with_chapter_markers).
-We've been using <https://github.com/rndusr/subed> to caption things
-as VTT or SRT in Emacs, often starting with autogenerated captions
-from YouTube (the .vtt or .srt file), but you're welcome to make
-captions using your favourite tool.
+You're welcome to work with captions using your favourite tool. We've
+been using <https://github.com/sachac/subed> to caption things as VTT
+or SRT in Emacs, often starting with autogenerated captions from
+OpenAI Whisper (the .vtt).
-We'll be posting VTT files so that they can be included by the HTML5 video
-player (demo: <https://emacsconf.org/2021/talks/news/>), so if you use a
-different tool that produces another format, any format that can be
-converted into that one (like SRT or ASS) is fine. You can e-mail me the
-subtitles when you're done, and then I can merge it into the video.
+We'll be posting VTT files so that they can be included by the HTML5
+video player (demo: <https://emacsconf.org/2021/talks/news/>), so if
+you use a different tool that produces another format, any format that
+can be converted into that one (like SRT or ASS) is fine. `subed` has
+a `subed-convert` command that might be useful for turning WebVTT
+files into tab-separated values (TSV) and back again, if you prefer a
+more concise format.
-# Formatting tips
+You can e-mail me the subtitles when you're done, and then I can merge
+it into the video.
-I generally find it easier to start with the autogenerated captions
+You might find it easier to start with the autogenerated captions
and then refer to any resources provided by the speaker in order to
figure out spelling. Sometimes speakers provide pretty complete
-scripts, which is great, but they also tend to add extra words. I
-tried uploading the scripts to YouTube in order to get YouTube to
-automatically align the text, but then the timing information wasn't
-granular enough for easy splitting, so correcting the autogenerated
-captions myself seemed to be easier. I use some code in my
-[subed configuration](https://sachachua.com/dotemacs/#subed) (see
-`my-subed-fix-common-error` and `my-subed-common-edits`) to help with
-capitalization and commonly misrecognized words.
-
-Please keep captions to one line each so that they can be displayed
-without wrapping, as we plan to broadcast by resizing the video and
-displaying open captions below. Maybe 50 characters max? Since the
-captions are also displayed as text on the talk pages, you can omit
-filler words. We've also been trying to break captions at reasonable
-points (ex: phrases).
+scripts, which is great, but they also tend to add extra words.
+
+# Reflowing the text
+
+First, let's start with reflowing. We like to have one line of
+captions about 60 characters long so that they'll display nicely in
+the stream. If the captions haven't been reflowed yet, you can reflow
+the captions at natural pausing points (ex: phrases) so that they're
+displayed nicely. You don't have to worry too much about getting the
+timestamps precisely.
For example, instead of:
@@ -49,28 +45,100 @@ For example, instead of:
- fun rewrite i did of uh of the bindat
- package
-I would probably edit it to be more like:
+you can edit it to be more like:
- So I'm going to talk today
- about a fun rewrite I did
- of the bindat package.
-# Editing autogenerated captions
-
-If you want to take advantage of the autogenerated captions and the
-word-level timing data from YouTube, you can start with the VTT file
-for the video you want, then use `my-caption-load-word-data` from
-<https://sachachua.com/dotemacs/#word-level> to load the srv2 file
-(also attached), and then use `my-caption-split` to split using the
-word timing data if possible. You can bind this to a keystroke with
-something like `M-x local-set-key M-' my-caption-split`.
+You probably don't need to do this step if you're working with the VTT
+files in the backstage area, since we try to reflow things before
+people edit them, but we thought we'd demonstrate it in case people
+are curious.
+
+We start with the text file that OpenAI Whisper generates. We set my
+`fill-column` to 50 and use `display-fill-column-indicator-mode` to
+give myself a goal column. A little over is fine too. Then we use
+`emacsconf-reflow` from the
+[emacsconf-el](git.emacsconf.org/emacsconf-el/) repository to quickly
+split up the text into captions by looking for where we want to add
+newlines and then typing the word or words. We type in ' to join lines.
+Sometimes, if it splits at the wrong one, we just undo it and edit it
+normally.
+
+It took about 4 minutes to reflow John Wiegley's 5-minute presentation.
+
+<video src="https://media.emacsconf.org/reflowing.webm" controls=""></video>
+
+The next step is to align it with
+[aeneas](https://github.com/readbeyond/aeneas) to get the timestamps
+for each line of text. `subed-align` from the subed package helps with that.
+
+<video src="https://media.emacsconf.org/alignment.webm" controls=""></video>
+
+# Edit the VTT to fix misrecognized words
+
+The next step is to edit these subtitles. VTT files are plain text, so
+you can edit them with regular `text-mode` if you want to. If you're
+editing subtitles within Emacs,
+[subed](https://github.com/sachac/subed) can conveniently synchronize
+video playback with subtitle editing, which makes it easier to figure
+out technical words. subed tries to load the video based on the
+filename, but if it can't find it, you can use `C-c C-v`
+(`subed-mpv-find-media`) to play a file or `C-c C-u` to play a URL.
+
+Look for misrecognized words and edit them. We also like to change
+things to follow Emacs keybinding conventions. We sometimes spell out
+acronyms on first use or add extra information in brackets. The
+captions will be used in a transcript as well, so you can add
+punctuation, remove filler words, and try to make it read better.
+
+Sometimes you may want to tweak how the captions are split. You can
+use `M-j` (`subed-jump-to-current-subtitle`) to jump to the caption if
+I'm not already on it, listen for the right spot, and maybe use
+`M-SPC` to toggle playback. Use `M-.` (`subed-split-subtitle`) to
+split a caption at the current MPV playing position and `M-m`
+(`subed-merge-with-next`) to merge a subtitle with the next one. Times
+don't need to be very precise. If you don't understand a word or
+phrase, add two question marks (`[??]`) and move on. We'll ask the
+speakers to review the subtitles and can sort that out then.
+
+If there are multiple speakers, indicate switches between speakers
+with a `[speaker-name]:` tag.
+
+<video src="https://media.emacsconf.org/editing.webm" controls=""></video>
+
+Once you've gotten the hang of things, it might take between 1x to 4x
+the video time to edit captions.
+
+# Playing your subtitles together with the video
+
+To load a specific subtitle file in MPV, use the `--sub-file=` or
+`--sub-files=` command-line argument.
+
+If you're using subed, the video should autoplay if it's named the
+same as your subtitle file. If not, you can use `C-c C-v`
+(`subed-mpv-play-from-file`) to load the video file. You can toggle
+looping over the current subtitle with `C-c C-l`
+(`subed-toggle-loop-over-current-subtitle`), synchronizing player to
+point with `C-c ,` (`subed-toggle-sync-player-to-point`), and
+synchronizing point to player with `C-c .`
+(`subed-toggle-sync-point-to-player`).
+
+# Using word-level timing data
+
+If there is a `.srv2` file with word-level timing data, you can load
+it with `subed-word-data-load-from-file` from `subed-word-data.el` in
+the subed package. You can then split with the usual `M-.`
+(`subed-split-subtitle`), and it should use word-level timestamps when
+available.
# Starting from a script
-Some talks don't have autogenerated captions because YouTube didn't
-produce any. Whenever the speaker has provided a script, you can use
-that as a starting point. I generally start by making a VTT file with
-one subtitle spanning the whole video, like this:
+Some talks don't have autogenerated captions, or you may prefer to
+start from scratch. Whenever the speaker has provided a script, you
+can use that as a starting point. One way is to start by making a VTT
+file with one subtitle spanning the whole video, like this:
```text
WEBVTT
@@ -79,18 +147,20 @@ WEBVTT
If the speaker provided a script, I usually put the script under this heading.
```
-I move to the point to a good stopping point for a phrase, toggle
-playing with `M-SPC`, and then `M-.` (`subed-split-subtitle`) when the
-player reaches that point. If it's too fast, I use `M-j` to repeat the
-current subtitle.
+If you're using subed, you can move to the point to a good stopping
+point for a phrase, toggle playing with `M-SPC`, and then `M-.`
+(`subed-split-subtitle`) when the player reaches that point. If it's
+too fast, use `M-j` to repeat the current subtitle.
# Starting from scratch
-Sometimes there are no autogenerated captions and there's no script.
-Then I guess we just have to type it by hand.
+You can send us a text file with just the text transcript in it and
+not worry about the timestamps. We can figure out the timing using
+[aeneas for forced alignment](https://www.readbeyond.it/aeneas/).
-I generally start by making a VTT file with
-one subtitle spanning the whole video, like this:
+If you want to try timing as you go, you might find it easier to start
+by making a VTT file with one subtitle spanning the whole video, like
+this:
```text
WEBVTT
@@ -98,10 +168,34 @@ WEBVTT
00:00:00.000 -> 00:39:07.000
```
-Then I start playback and type, using `M-.` (`subed-split-subtitle`)
-to split after I've typed a reasonable length for a subtitle. If it's
-too fast, I use `M-j` to repeat the current subtitle.
+Then start playback and type, using `M-.` (`subed-split-subtitle`) to
+split after a reasonable length for a subtitle. If it's too fast, use
+`M-j` to repeat the current subtitle.
+
+# Chapter markers
+
+In addition to the captions, you may also want to add chapter markers.
+An easy way to do that is to add a =NOTE Chapter heading= before the
+subtitle that starts the chapter. For example:
+
+```text
+...
+00:05:13.880 --> 00:05:20.119
+So yeah, like that's currently the problem.
+
+NOTE Embeddings
+
+00:05:20.120 --> 00:05:23.399
+So I want to talk about embeddings.
+...
+```
+
+We can then extract those with
+`emacsconf-subed-make-chapter-file-based-on-comments`.
+
+For an example of how chapter markers allow people to quickly navigate
+videos, see <https://emacsconf.org/2021/talks/bindat/> .
-Please let me know if you need any help!
+Please let us know if you need any help!
Sacha <sacha@sachachua.com>