[Chimera-users] Creating movies with alpha channel / transparent background

[Tom Goddard]

Hi Martin,

  It is possible that some Chimera movie encode command format option will put the transparency channel into the movie -- it all depends on what ffmpeg does and what those formats support.  I don't know what ffmpeg supports nor what formats support transparency -- you could try to look that up online, or you could simply try each of the Chimera formats and see if it produces a movie with transparency.  Chimera simply hands the sequence of PNG images to ffmpeg (which is bundled with Chimera, ffmpeg version 2.1).  From what I saw in ffmpeg docs there is not a special include transparency option -- it is simply a matter of having a transparency channel in the images and having ffmpeg support for the specific output format.

	https://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/movie.html#encode-options

  Tom


> On Oct 28, 2019, at 2:04 PM, Martin Textor <martin_textor at gmx.de> wrote:
> 
> Hi Tom,
> 
> thank you. I'm aware that Chimera can output a series of images with a transparent background, I have done this already (using png). As this is possible, and the "movie encode" command supports, besides other formats, .avi and .mov, both of which definitely support an alpha channel, I had hoped there might be some option for "movie encode" that's just not described in the documentation which allows obtaining a video with transparent background and spares me from having to use a third-party tool. 
> 
> With regards to Elaine's reply, I want to use the video overlaid to another one, so a static background image is not an option in this specific case, but thanks for the suggestion.
> 
> Best,
> Martin
> 
> Am Mo., 28. Okt. 2019 um 20:05 Uhr schrieb Tom Goddard <goddard at sonic.net <mailto:goddard at sonic.net>>:
> Hi Martin,
> 
>   You can have Chimera save a series of transparent background images using the movie command, for example,
> 
> 	set bgtransp
> 	movie record dir ~/Desktop/test format png ; turn y 1 90 ; wait 90 ; movie stop
> 
> Then you would need to encode the PNG images in ~/Desktop/test into a movie using some encoding program.  I doubt the Chimera "movie encode" command supports any video format that can handle transparent background.  Chimera uses ffmpeg to encode movies and apparently ffmpeg can encode some video formats with transparency, for example, as described here the motion PNG format in .mov can handle transparency
> 
> 	https://stackoverflow.com/questions/644684/turn-image-sequence-into-video-with-transparency <https://stackoverflow.com/questions/644684/turn-image-sequence-into-video-with-transparency>
> 
>   Tom
> 
> 
> 
> 
>> On Oct 28, 2019, at 10:06 AM, Martin Textor wrote:
>> 
>> Hello,
>> 
>> I was wondering if it is possible to create movies with a transparent background? I know that it's possible to create images with a transparent background and that the video formats supported by Chimera to encode movies include avi and mov, both of which support an alpha channel as far as I know.
>> 
>> Kind regards,
>> Martin Textor
>> 
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> 
> 
> -- 
> Martin Textor
> 20 Elmer Mews,
> Leatherhead, Surrey,
> KT22 9DN, UK
> 
> Fon:  +49(0)178 3993650 <>
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