Re: [Audacity-devel] Add support for importing/exporting SRT subtitles as labels

[Robert H. <aar...@gm...>]

On 14/10/2019, Pokechu22 <pok...@gm...> wrote:
> For me at least, I implemented this so that I could caption an audio file
> <https://commons.wikimedia.org/wiki/File:Eisenhower_farewell_address.ogg>.
> Captioning a video file would definitely also work, but that adds a bit of
> complexity regarding positions on screen (which both SubRip and WebVTT
> support to various degrees).  I don't think it's super important for the
> average user (since I don't think many people use labels as is) but I think
> people who have a use for it would benefit greatly.
>
> Barring that, one thing I did not address with SubRip is that it supports
> multiple lines in captions, which is not supported by labels in audacity.
> Beyond just editing, the current text format would not work with multiple
> lines on a single label.  With the current PR I just flattened it into one
> line when importing, but more advanced labels would allow for it.
>
> Code-wise, I would like some advice on how to improve the timestamp
> parsing, since it's rather messy.
>
> Regarding Karaoke: it probably failed to record since it's not rendered
> using the GPU.  An external screen recorder (e.g. OBS
> <https://obsproject.com/>) probably would work.  It probably also would be
> possible to render a video using FFmpeg since I believe you can pipe raw
> video to it and it can encode it, but I don't know enough about that to
> implement it.
>
> Regarding images: I don't think any subtitle format supports those, since
> it would not be machine readable.  It looks like WebVVT might support
> it through
> CSS <https://w3c.github.io/webvtt/#obtaining-css-boxes>, but it would be
> pretty messy.  I'm not entirely sure how it'd be used, either.
The images would constitute the video stream.  It is fairly simple to
use FFMPEG to combine images and audio. However, it would be even
simpler by using a label track to place those images exactly.
Ffmpeg allows also to integrate a subtitle stream, thus you could use
a second label track to feed in this information.
Alternatively, the labels could be rendered in order to produce lyrics
videos. It would be advantageous if Audacity could render the Karaoke
window content directly as you wouldn't have the frame rate issues due
to slow computers.
My view point is that we have now more or less track abstraction that
would allow to introduce types that are derived from the label track
type.
It is also thinkable that you use the track dropdown menu of a label
track to check the radio button "Subtitles" or "Lyrics" or "Playlist"
which would inform Audacity what to do on export.
Anyway, just a little fancy of mine.
It is a good start Poke if you just implement the SRT export option.
Robert

> --Poke
>
> On Mon, Oct 14, 2019 at 12:00 PM Robert Hänggi <aar...@gm...>
> wrote:
>
>> I'm 100 % for it.
>> While we're at video:
>> I've tried to make a lyrics video from Audacity by screen capturing
>> the Karaoke  window (with the XBox game bar, Windows+G) but it didn't
>> work for my graphics card.
>> A native way to do it would be great.
>> It would also be nice to be able to import still images into a label
>> and let Audacity export that.
>> Looking forward to your suggestions/PRs.
>> Robert
>>
>> On 14/10/2019, James Crook <cr...@in...> wrote:
>> > We're not doing too well on staying on top of pull requests.
>> > We have 26 open and 338 closed.
>> >
>> > Ideally we'd have one person responsible for ensuring every pull
>> > request
>> > got an answer and most of the time have no open pull requests.
>> >
>> > I suspect nothing happened there because no one here had worked with
>> > sub
>> > rip format, so noone had an idea of how important (or not) it was.
>> > I don't think support for WebVTT is essential to progressing/accepting
>> > srt support.  I do think if we intend WebVTT, it would be wise to plan
>> > an update to labels.
>> >
>> > --James.
>> >
>> >
>> > On 14/10/2019 18:49, Jonatã Bolzan wrote:
>> >> Hi
>> >>
>> >> I see no discussion about this PR:
>> >> https://github.com/audacity/audacity/pull/170
>> >>
>> >> What do you think? I think this is interesting as Audacity can be used
>> >> for
>> >> video-related projects. In the future, I would be interested in
>> extending
>> >> support for WebVTT if this is something you are interested in.
>> >>
>> >> Thanks for considering.
>> >> --
>> >> Jonatã Bolzan Loss
>> >>
>> >>
>> >>
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>> >
>>
>>
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