[HELP] Looking for video editing help

[fagustree]

In discussing features for viewtopic.php?f=25&t=22191 with pseudonym, I ran into an interesting dilemma. I wanted to use a video beatmeter that had a transparent background to overlay it on a video (the feature is to allow for beatmeters to be hot-swapped by the author).

I want to try to overlay a transparent background video file on top of another video element.
From my research, the only codecs that seem to do this are VP8/9 (webm). Can any of you encode a sample vid with transparent background for me to test out? Pseudonym said that he was having trouble with the tool he used (vegas)

[high_octane]

You probably already know this, but for performance and space reasons, the beat meter video should be the dimensions of the beat meter graphics themselves, plus the width of the underlying video. For my productions, they are about 1920x30 (for a 1080p video). The codec that I prefer to use is FFV1, which can be found in FFmpeg. That codec supports lossless compression and alpha channel.

Now, what exactly is going to be the use case of this? If this video is to be played back in a web browser, then FFV1 is off the table. Is this overlay going to be performed in real-time? If so, then FFV1 might be too intense, performance-wise. If this is just as a means to store video beat meters separately from the video with actual content, then FFV1 is fine, though the files themselves would end up being quite large.

Another possible option would involve color-keying. With that method, you would be able to use whichever codec you want. All that you'd have to do is assign the background to a certain color, which would then be keyed-out in a video editor (green screen effect).

So, all you need is a video with a transparent background? I can do that. I'll make it 5 seconds long, 1080p, and encode it with FFV1. Is that okay?

Here's the link:
https://mega.nz/#!Cg8QiCQL!B_BXfRIsQkch ... o-WAhm7cO4

[fagustree]

Yep, I'm aware. Thank you for the video, but it needs to play in the webbrowser.
also, if you can get any old beatmeater and loop it for about a minute to test sync, that would be perfect. <3

Thank you so much for the help

[fagustree]

The goal, as you said, is to greenscreen the beatmeter :)

[high_octane]

Okay, here's a 1 minute clip of a beat meter with a transparent background, constant stream of quarter notes, at 120 BPM. For synchronization purposes, the FPS is 30000/1001 (29.97), and the first beat is hit at exactly 00:00:04.071. Audio is provided, as well.

https://mega.nz/#!uo8lFQZJ!-u1rN-O4eOPt ... mWxHDpggpU

The graphics are the same ones I used for CH French Riviera. Also, I encoded this in FFV1, but I figure that you can re-encode it to what suits your needs, as it is currently in a lossless format.

Also, the width of this video is 1920 / 2, because the beats disappear once they reach the "center", which is technically the left edge of the screen in this video.

[fagustree]

hmm... i'm getting audio but no video in the video element in the browser....

:(

[high_octane]

It might have something to do with the pixel format. I'm not all that familiar with the constraints of web browsers in terms of what they do and don't support. Did you re-encode the video to VP9, or something similar? For VP9 with alpha channel, the pixel format is yuva420p.

I just converted it to VP9/Opus (webm), and it played back correctly on Firefox:
https://mega.nz/#!Tgc0jY5Z!P9soQRNqNsnz ... jrRqKktXJU

Here's what I did to convert it (you might not need to explicitly specify the pixel format):

Code: Select all

ffmpeg -i "$input" -c:v libvpx-vp9 -pix_fmt yuva420p -c:a libopus "$output"

I didn't play around with any specific encoding settings (like bitrate), although you probably would want to if preserving high quality is important to you.

[fagustree]

IT WORKS!!!! and whats more, it works really well....

I'd like to get this demo ready for pseudonym... but im having issues trying to turn this alpha channel on a video he gave me.
I have handbrake but im not sure how to turn the black here to alpha.

Thank you SO MUCH for your help

[fagustree]

I have been trying to get this to work for a long time... the videos i was able to render have an alpha channel in quicktime (mov)

But when I try to convert them with ffmpeg, they are black screen instead...

[fagustree]

I got an option with ffmpeg to color screen the video, so that's working good enough for a demo... would be nice to have detailed instructions for doing this from the ground up so the alpha channel looks better. I'll have to let authors who are interested in this feature manage that.

[digitalparkinglot]

Hey,

I have been using Beatmeter generator for quite a while with great results. I also wanted a transparent background and realized I could render the video with an odd color assigned for background (like bright green) and then in my editing software, I'm using Adobe Premiere Pro, I apply an "Ultra Key filter" to the clip and eyedropper the background color of the beatmeter clip. This is the definition of green screening. Like magic it becomes transparent. Super easy, no weird codecs and small file sizes.

I hope this helps!

-digitalparkinglot

[3xTripleXXX]

Hey,

I have been using Beatmeter generator for quite a while with great results. I also wanted a transparent background and realized I could render the video with an odd color assigned for background (like bright green) and then in my editing software, I'm using Adobe Premiere Pro, I apply an "Ultra Key filter" to the clip and eyedropper the background color of the beatmeter clip. This is the definition of green screening. Like magic it becomes transparent. Super easy, no weird codecs and small file sizes.

I hope this helps!

-digitalparkinglot

If you're looking for a transparent background on your beatmeter, that's built right into Beatmeter Generator. If you set a custom color (for anything), there's an opacity option that you can just slide down to 0. No need to greenscreen or anything.

[high_octane]

I'm not sure if fagustree is looking for a solution in a video editor. I believe he's looking for a way to overlay a smaller beat meter video with a transparent background on top of a larger video with sexy content, within a web browser.

Or maybe that's not the case and I'm mistaken, I don't really know.

I have been trying to get this to work for a long time... the videos i was able to render have an alpha channel in quicktime (mov)

But when I try to convert them with ffmpeg, they are black screen instead...

If you have ffprobe, the output from that could help me figure out what's going wrong. Also when I play the webm video in mpv, the alpha is completely broken for some reason (probably a bug), but it works as expected in Firefox.

I got an option with ffmpeg to color screen the video, so that's working good enough for a demo... would be nice to have detailed instructions for doing this from the ground up so the alpha channel looks better. I'll have to let authors who are interested in this feature manage that.

Detailed instructions for what? Color-keying in FFmpeg? Sorry, I'm confused ... I feel like I'm not seeing the whole picture. If you could provide a synopsis of how all of this is going to work, I'd appreciate it, and I'd be able to voice my thoughts on it better.

[fagustree]

I'm not sure if fagustree is looking for a solution in a video editor. I believe he's looking for a way to overlay a smaller beat meter video with a transparent background on top of a larger video with sexy content, within a web browser.

correct

If you have ffprobe, the output from that could help me figure out what's going wrong. Also when I play the webm video in mpv, the alpha is completely broken for some reason (probably a bug), but it works as expected in Firefox.

This is probably my fault. I was using a beta of davinci resolve which lacked vp8 output. so i was making a quicktime file and using ffmpeg to convert it. On one of those steps something was borked. I gave up.
I found ffmpeg had a color filter and I used that to set the original mp4 with black background to transparent. It worked great for a demo, but obviously lacked quality around the edges of the meter... this is good for now.

Detailed instructions for what? Color-keying in FFmpeg? Sorry, I'm confused ... I feel like I'm not seeing the whole picture. If you could provide a synopsis of how all of this is going to work, I'd appreciate it, and I'd be able to voice my thoughts on it better.

I'll need to let authors know the best way to export the bm video segments (with alpha) with some guidance, and maybe for a few programs when/if people end up liking this. From talking with Pseudonym, it seems he uses vegas and is in a similar boat to me. So I'll need to figure out how to get him to make a suitable intermediate format and use ffmpeg to get a webm or something.

[high_octane]

Food for thought, but if at any point in the future you need a beatmeter that can be modified at run time, using these pre-rendered video files will no longer be suitable.

In that case, it might make more sense to use a list of timestamps corresponding to individual beats. Granted, this is much more resource intensive, but it offers much more flexibility in return.