RGBA video overlay on existing multicam project

johnebaker wrote on 6/4/2017, 2:37 AM

Hi

. . . . it's provided alpha being applied. How do I do that? . . . .

Movie Edit Pro (MEP) does not support embedded Alpha channels in video.

To achieve the effect you need to create the Alpha channel as a separate monochrome video to create a mask.

Import the mask as well as the overlay video and apply the Chromakey, Alpha effect to the mask in MEP.

HTH

John EB

Hackemesser wrote on 6/4/2017, 2:51 AM

Are you sure it does not support it? After adding the clip to a separate channel I found now that the transparent parts of that overlay video are transparent in the result video. Just... A transparency fade in slope in it causes flickering in the result. not sure yet if Blender is at fault with that, or Magix.

Scenestealer wrote on 6/4/2017, 9:45 PM

Hi John

It definitely supports uncompressed 32bit RGBA .AVI's ie. RGB 24bit + 8bit Alpha and probably other compressed codecs as well.

Hackemesser wrote on 6/5/2017, 12:06 AM

Yes that is what I produced, 32bit RGBA in HUFFYUV encoding in AVI container. I had it with a black background that gets transparent in the end and the preview in MEPP shows that effect, but not clean, some frames go almost intransparent, then some very transparent and so. I am not sure if the flaw is in the alpha of the raw input or in the processing in MEPP. I need a tool that can play me the four channels of the clip separately, frame by frame. Any suggestions?

johnebaker wrote on 6/5/2017, 1:35 AM

Hi

@ Scenestealer

. . . . It definitely supports uncompressed 32bit RGBA .AVI's ie. RGB 24bit + 8bit Alpha and probably other compressed codecs as well. . . .

Do you know when this feature was introduced? I have had no luck with MOV files that have an alpha channel, and I can find no mention of support for video alpha channel in the manual or online.

@ Hackemesser

. . . . I had it with a black background that gets transparent in the end and the preview in MEPP shows that effect, but not clean, some frames go almost intransparent, then some very transparent . . .

Is the RGBA video variable or constant framerate ?

John EB

Hackemesser wrote on 6/5/2017, 3:05 PM

As far as I know you can not change the frame rate in a video (never heard of that), the bitrate may be variable. I produced it with 1080p25 like the targeted video.

Scenestealer wrote on 6/5/2017, 4:37 PM

@Hackemesser

A little confused here about what you are doing?

If I place that on top of the video it shows me an overlap and there i can choose a fade - but actually I want the overlay to be on top of the underlying video and it's provided alpha being applied. How do I do that?

If you want to overlay the RGBA object over another video object then you should be placing the Alpha on the track below the background object. It sounds like you are placing the 2 objects on the same track which is creating one long crossfade which of course will go from fully transparent to untransparent or vica versa.

I would suggest you spend some time with the PDF manual or some of the tutorials available and learn the basics of how MEP works.

John EB is referring to streaming video that has been captured where the frame rate is varied depending on the bandwidth available due to the internet connection strength. I doubt your file would have this problem.

@johnebaker

That ability to import alpha .avi's without needing to apply chromakey or an Alpha mask has been in MEP for as long as I can remember. It's been a long while since I experimented with compressed codecs so can not remember if I was successful, but I know I couldn't get RGBA .MOV's to work.

Peter

johnebaker wrote on 6/5/2017, 5:06 PM

Hi

. . . . the frame rate is varied depending on the bandwidth available due to the internet connection strength . . .

It is not just Internet video that is variable frame rate, mobile phones, some cameras, and screen capture programs also use variable frame rate - this was the issue in another topic yesterday.

@Hackenmesser

Think of track 1 as the background, track 2 = layer 2 on top and so on.

@Peter

. . . . That ability to import alpha .avi's . . . . has been in MEP for as long as I can remember . . . .

Well all I can say is thank you, this enlightenment makes my custom masks / transitions a lot easier to make.

I have just tested this in MEP 17 Plus HD with an RGBA AVI I created this morning and it sure does work, .

John EB

Hackemesser wrote on 6/5/2017, 5:39 PM

@Hackemesser

A little confused here about what you are doing?

If I place that on top of the video it shows me an overlap and there i can choose a fade - but actually I want the overlay to be on top of the underlying video and it's provided alpha being applied. How do I do that?

If you want to overlay the RGBA object over another video object then you should be placing the Alpha on the track below the background object. It sounds like you are placing the 2 objects on the same track which is creating one long crossfade which of course will go from fully transparent to untransparent or vica versa.

I am actually having that on a track for overlays. Track 1&2 is the master (multicam-sync), 2,3,4 are camera tracks (muted, hidden), 5 is my FX track.

The overlay I produced is 250 frames - 10 seconds at 25p framerate. it is opaque up to frame 200 and then parts of it become transparent towards frame 250. I play back and forth framewise in MEPP on the timeline and see that my gradient transparency slope in the video becomes jumpy in the preview, also the animation seems to be jumpy.

And what is most weird is, that yesterday night I had one moment where it was doing as intended while skipping manually as well as in playback. Maybe there is a bug in the app interpreting AVI/H.264/HUFFYUV frames?

Scenestealer wrote on 6/5/2017, 5:44 PM

Thanks John, I am aware there are other sources of variable frame rate video, I was not trying to put words in your mouth.I should have used the words "e.g.".

I believe Blender would not have an ability to (inadvertently) create variable frame rates.

johnebaker wrote on 6/6/2017, 3:59 AM

Hi Peter

My comment re other sources of variable frame rate video was not aimed at you directly - however the thanks for the enlightenment was.

Thanks again

John EB

Hackemesser wrote on 6/7/2017, 1:00 AM

I really wonder now if MEPP has an issue with the file format or size. I created a caption on blender and exported it in same format (1920x1080p25, AVI, H.264, HUFFYUV -> 32bit RGBA) and after pulling it on its track in the preview frames of that overlay are appearing mixed up. It is hard to explain, but VLC plays the clip nicely, so it is not a faulty video. Mixed up means the frames do not appear in original order, neither in play nor in frame by frame.

Scenestealer wrote on 6/7/2017, 1:18 AM

Have you tried exporting it from Blender uncompressed?

I am still unclear about the fading you had in your original question. Could you post a screen shot of the section of your timeline that shows the clips?

Peter

Hackemesser wrote on 6/7/2017, 3:35 AM

how much more uncompressed than huffyuv can it be? The AVI container has 757MB for roughly 15 seconds, and 7zip churns it down to 18MB.

Screenshot 1: caption over master vid

Screenshot 2, master muted, caption only

and here the caption file: https://www.dropbox.com/s/yyqz8858kohnqyl/Nicole%20Foss%20Caption0000-0355.7z?dl=0

Cheers,

Kai

Hackemesser wrote on 6/7/2017, 3:51 AM

For the first clip two more screen shots,

First Overlay on master, chosen a semi-transparent frame:

.

Same frame, overlay muted - notice the preview being brighter:

as you can see, transparency/alpha is not the problem - just in playback and export the overlay frames get mixed up.

johnebaker wrote on 6/7/2017, 4:16 AM

Hi

The huffyuv codec is no longer developed and the last official release was in 2002. There is another release (2.2) from Dec 2003 - ie 14 years ago and is known to cause some issues on some systems.

I suspect the issue you are using is due to the huffyuv codec you are using not being compatible with modern software and Windows 10.

Do you have the option to use Basic Windows bitmap format codec with Raw RGB ?

John EB

Hackemesser wrote on 6/7/2017, 4:40 AM

There are three codecs in blender that support RGBA, that is PNG, QT and HuffYuv. I know PNG and Huffyuv to be lossless, but I does MEPP support PNG? is QT lossless?

Scenestealer wrote on 6/7/2017, 7:03 AM

how much more uncompressed than huffyuv can it be?

Some probably. Codec = Compressor / Decompressor so if you are using a Codec then some compression is being applied. Try "None" in your last SShot.

Hackemesser wrote on 6/7/2017, 3:13 PM

'None' does not support RGBA :(

Hackemesser wrote on 6/7/2017, 4:26 PM

Just found that H.264 output has a lossless setting, and it supports RGBA, so I am rendering it now and report results then.

Scenestealer wrote on 6/8/2017, 1:15 AM

I have tried some old tests with compressed files and none of them will reveal the Alpha channel in MEP. Uncompressed AVI 32bit is the only video format that works on my systems. A TGA image sequence works and might be a solution for you seeing it is only a lower third graphic.

Hackemesser wrote on 6/8/2017, 1:32 AM

My H.264 experiment today failed - blender did not export alpha despite of setting the options to be RGBA and including transparency. So how do I import an image sequence as frame-by-frame into MEPP?

Scenestealer wrote on 6/8/2017, 1:46 AM

Just save them into a folder on your HDD and then drag that folder onto the time from the media pool. Depending on what you have set for an Image import length in Program settings (the default is 7 seconds) you will need to select all the imported frames on the timeline track then Rt click >Change photo length>1frame. You could try a PNG sequence also.

Hackemesser wrote on 6/8/2017, 4:07 PM

Thanks,I'll try that now. How does MEPP react to the situation if frames are added or changed on the folder imported? Just for the case that I re-render or extend a scene in blender? I know that MEPP write-locks video files when involved in a sequence (even after removing them from the sequence, until app is closed)