Re: [Alsa-user] Making video from Audacity?

[Alan C. <ala...@gm...>]

No fancy stuff: https://sourceforge.net/projects/audiogram-c/  Written
in C, needs turbojpeg with the dev stuff and ffmpeg.  I might try to
figure out libmad and make it work with mp3 files, right now it does
wav only.  Looks like the VU meter part of Audacity with a cursor line
moving across.

On 9/25/20, Stuart Longland <st...@lo...> wrote:
> On 26/9/20 7:35 am, Alan Corey wrote:
>> What I had in mind was to make Audacity have a hook to call an
>> external program each time it updates the screen.   Then call
>> something like xwd from the hook and put the frames together later.
>> No sound that way though, you'd have to mix in the audio file that
>> Audacity is playing/displaying. xwd can do screen dumps of a specific
>> window id, which Audacity would have access to since it owns it.
>
> Yeah, the best place to ask about that would be the Audacity lists
> themselves.  My understanding is that Audacity does not use ALSA
> directly: it uses `portaudio` which can use ALSA as a back-end (among
> others).  So the audio interface is already abstracted.  AFAIK
> `portaudio` communicates with ALSA via a thread which would then be
> communicating progress information back to the main thread running their
> UI (`wxWidgets`-based).
>
> Doing a `fork()` then `exec()` could be quite expensive at the sort of
> rates they may be repainting the screen at.  This is quite a niché
> application too… which is why "some assembly" may be required.
>
> The question then is, how often is this being done?
>
> If it's a once-off, use `ffmpeg` with carefully positioned windows and
> be done with it.  Otherwise, it might be worth exploring solutions like
> `gstreamer`'s visualisation plug-ins to achieve what you're after.
>
> https://xkcd.com/1205/
> --
> Stuart Longland (aka Redhatter, VK4MSL)
>
> I haven't lost my mind...
>   ...it's backed up on a tape somewhere.
>


-- 
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Education is contagious.