Export only annotation, not composite of frame+annotation

[David_Humphreys]

Hey there,

I am just looking into the feasibility of exporting annotations dawn in rv, however, just the annotation over alpha, and not a composite of the frame+annotation.

Is this possible through file>export>annotatedframes. Or would we require a more custom solution?

[alexaz]

Hey David,

Unfortunately it’s not easy but it’s certainly possible. We don’t support exporting annotations over alpha, and I’m not quite sure why. I’ll put in a feature request to add that support.

Meanwhile, if you’re not averse to scripting, you can build a package that will do it for you.

Here’s the spec for it:

1. You’ll need to use a movieproc as a blank placeholder in the background of your annotations. You can use commands.setSourceMedia command to achieve that. Here’s a rough example:

from rv import commands, extra_commands
frame = commands.frameStart()
source = commands.sourcesAtFrame(commands.frame())[0]
commands.setSourceMedia(source, [“solid,red=0,green=0,blue=0,alpha=0,start=1,end=10.movieproc”])

2. You can get the annotated frames number via commands.markedFrames().Then you can take a look at export_utils.exportMarkedFrames under RV_INSTALL_PATH/PlugIns/Mu/export_utils.mu to see how RV exports the annotations.

3. RV exports annotations in a flattened format, which won’t maintain your alpha channel and will render annotations with black background instead of alpha composite. This isn’t entirely useful, so you’ll need to write your own exporter. This can be part of the same plugin as your annotations. We already have an exporter example here, if you export annotations as pngs that should be suitable though:

Export H264 Package for RV

Export H264 Package - RV Developer Example Series [h264_exporter] In this example, we expose how to create your own Export menu that will use internal events to process RVIO commands within RV. This could be useful if you want to create your own export options that RV doesn’t support or if you’d like to know how to use RVIO from within RV without having to explicitly subprocess the rvio command. One of the benefits of calling RVIO this way is that you’re utilizing the internal RV export utils,…

If you don’t know how to get started with our packages, you can read our post here:

How do I write my first package in RV?

RV can be nearly infinitely customizable but it can be difficult finding documentation for where to begin developing your own plugins. There are a couple of things that you should know. RV offers a couple of ways to write plugins: Mu, Python, PySide and GLSL. The best way to start with RV scripting is to use Python. Unfortunately, Python is not native to RV and most of “Python” commands that you will find in RV are bindings on top of Mu. However, this means that you can use nearly all command…

A couple of gotchas:

• You’ll need to specify the start and end frame for the movieproc that matches your media length, otherwise movieproc will replace the length and chop off your annotated frames. This means that you’ll need to cycle through all of your sources to see which one has the longest frame range, or you can be lazy and set end to something really long like 10000.
• You may want to replace the media back to what it was after you’re done exporting.

Hope this helps!

Thanks,
Alexa

[David_Humphreys]

Thank you so much Alexa,

This is great. I’ll certainly be reading through this info over the holidays

Cheers!

–Dave

[David_Humphreys]

Hey Again, checking in here

I’ve been going over the code examples and docs, and it looks like RVIO is the command that does the exporting that needs modification.

It is mentioned in the user manual that RVIO utilitzes ffmpeg. Does anyone know if RVIO accepts any/all commands that ffmpeg uses? or is it limited to the commands /+ args listed in the docs?

RVIO commands list

Thanks

–Dave

[alexaz]

Hey David,

What are you looking to add to your command?

RVIO isn’t exactly 1:1 with ffmpeg, but it’s pretty flexible.

If you’re feeling adventurous, you can also pre-pend your ffmpeg executable in your plugin and subprocess it. It’s not exactly pretty but you’d get your own ffmpeg in RV

Thanks,
Alexa