Is it possible to convert from webm to mov and keep transparency?

[supercain]

Hi,

I have webm files with transparency. They play well on Firefox and chrome but safari doesnt seem to support webm so I have to convert them to mov. Is it possible to keep the transparency when doing that? I tried with ffmpeg but I coudlnt even convert them

ffmpeg -c:v libvpx-vp9 -i aa1a1.webm -c:v libvpx-vp9 -crf 30 -b:v 0 -pix_fmt yuva420p -metadata:s:v:0 alpha_mode="1" -c:a copy aa1a1.mov

this is the error I get:

[mov @ 0000000000393000] vp9 only supported in MP4.
Could not write header for output file #0 (incorrect codec parameters ?): Invali
d argument
Error initializing output stream 0:0 --

Maybe its the wrong codec?

Thank you.

[cholla]

The error says :

vp9 only supported in MP4

Try changing your output file to .mp4

If that works then see if you can convert that .mp4 to .mov if you need the .mov format.

[supercain]

that one works but the problem is that mp4 wont support transparency.

[cholla]

Using the .mp4 you just created try this:

ffmpeg -i input_file.mp4 -c:v copy -c:a copy -c:s copy -f mov output_file.mov

Note transparency is not something I have worked with.
This means the .mov file created from the .mp4 might not have transparency.
It may even give the vp9 error again.
Worth a try though

[supercain]

That does convert it to mov but the problem is it wont be transparent because the transparency will get lost upon converting to mp4.

[cholla]

I tried both versions of ffmpeg I have & I got the same error as you did in both.
It seems that ffmpeg can only use vp9 to .mp4.
I also read that .mp4 con't have transparency.
There are some howtos that say .mp4 can have transparency.
Several .png files are created & then merged back into a .mp4.
I don't plan to do that but if you want to check it out it might be possible.

[supercain]

I think its just faster to convert from webm to mov directly.

[october262]

That does convert it to mov but the problem is it wont be transparent because the transparency will get lost upon converting to mp4.

try this here - https://www.reddit.com/r/ffmpeg/comments/cyp5vh/encoding_a_webm_as_mov_without_losing_the/

[supercain]

It doesnt work. The first solution gives me this error:

Metadata:
ALPHA_MODE : 1
ENCODER : Lavc59.18.100 libvpx-vp9
DURATION : 00:00:03.390000000
[NULL @ 0000000000477600] Unable to find a suitable output format for 'copy'

whereas the second one gives me the same error I posted previously.
copy: Invalid argument

[october262]

It doesnt work. The first solution gives me this error:

Metadata:
ALPHA_MODE : 1
ENCODER : Lavc59.18.100 libvpx-vp9
DURATION : 00:00:03.390000000
[NULL @ 0000000000477600] Unable to find a suitable output format for 'copy'

whereas the second one gives me the same error I posted previously.
copy: Invalid argument

see here for the 2 errors you are getting - https://superuser.com/questions/1283430/what-is-wrong-with-my-ffmpeg-command

[supercain]

Im not using the -profile option. Sorry to ask but whats the relation?

[cholla]

I found an older version of ffmpeg that I have that works.
I'm attaching a .zip file with it if you want it.

Try this:

ffmpeg -i aa1a1.webm -c:v libvpx-vp9 -crf 30 -b:v 0 -pix_fmt yuv420p -metadata:s:v:0 alpha_mode="1" aa1a1.mov

It will give this warning:

[mov @ 02f63e40] Using MS style video codec tag, the file may be unplayable!

I also had to use yuv420p instead of yuva420p.

It played ok in VLC .
The sample I found & used did not have Audio so I couldn't test if Audio works.

[october262]

Im not using the -profile option. Sorry to ask but whats the relation?

disregard the last post and see if this reddit thread will help - https://www.reddit.com/r/VideoEditing/comments/d66y6f/converting_a_webm_with_alpha_to_...ov_with_alpha/

[supercain]

[QUOTE=october262;2662654
see if this reddit thread will help[/QUOTE]

it does convert it but no transparency is kept. Also, the output file is very big.

[supercain]

I'm attaching a .zip file with it if you want it.

thanks but didt work. The video wont keep transparency and it wont even play on the browser.

[cholla]

thanks but didt work. The video wont keep transparency and it wont even play on the browser.

Sorry I should have tested the .mov file in the browser.
It wouldn't play in FireFox for me either.
I don't have Safari.

I tested in VLC & MPC-HC.

That's all the solutions I have

[supercain]

Can you encode it with hvc1?

[Cornucopia]

Mov file format might be able to "include" a vp9 video stream, but for modern QT formats it is not a legit option, so is no surprise that it might not play. For mov, QT will want to convert to avc, hevc, or prores, or maybe the old "animation" codec. Of those, only prores and animation are commonly created with transparency (alpha channel). And they would be very, or extremely big, respectively.

You could go way round about and create hevc with alpha by following these steps
https://kitcross.net/hevc-web-video-alpha-channel/

Or you could just make everything more easy on yourself by skipping using Safari.


Scott

[supercain]

I would do that because I really hate apple but unfortunately many people use their products so I must make my site responsive for those as well.