Luma matte transition with multiple clips without blinking/flickering

I’ve seen the luma matte transition tutorial on how to create a transition for a single clip within a track. If I try to add additional clips to the track that have the same start and duration times, I end up with the blinking issue described here.

How do I make my transition work with multiple clips with the exact same start and duration times? The suggestion to prevent the blinking is to create separate tracks, but then my luma matte won’t work with that additional track will it? One simple example I’m trying to create is to watermark a video that appears in the middle of the full video. My workaround has been to offset the additional clips by a small amount of time but that’s not ideal.

Hi @walkthreads,

For luma clips to work only the luma asset and the asset you want to mask need to be on the same track. All your other assets can sit in different tracks with the same timestamps as the clip containing the luma.

Would you be able to share the id of one of the renders that exhibits the blinking behaviour? Then we’ll be able to look up the corresponding JSON and suggest a fix.

48c38f08-4adf-4266-b094-ff8403f55a92 on staging, from 0:10 to 0:17.

This is a totally separate question but also related to the same track, the transition at 0:18 doesn’t behave for the watermark the way I expect it to. It looks like the entire luma asset is being applied to the watermark as a miniature version of the transition. How can I fix that as well?

Luma assets are masks that are applied to everything in the same track independently. If you happen to have a clip in your track with a luma asset in that same track the mask will show on each of the clips in the track.

The way to solve for this is to only have clips in your track that you want affected by the luma asset. In the case of your watermark the solution is to take the clip out of the track and place it on a separate track above the video that you want to place the watermark on.

I’ve sent you a DM with a non-blinking version of your edit, but see below a general example:

{
    "timeline": {
        "soundtrack": {
            "src": "https://shotstack-assets.s3-ap-southeast-2.amazonaws.com/music/unminus/palmtrees.mp3",
            "effect": "fadeOut"
        },
        "fonts": [
            {
                "src": "https://shotstack-assets.s3.amazonaws.com/fonts/Lato-Bold.ttf"
            }
        ],
        "background": "#000000",
        "tracks": [
            {
                "clips": [
                	{
                        "asset": {
                            "type": "luma",
                            "src": "https://shotstack-assets.s3.amazonaws.com/luma-mattes/melts/melting-center.mp4"
                        },
                        "start": 3.6,
                        "length": 2
                    },
                    {
                        "asset": {
                            "type": "video",
                            "src": "https://shotstack-assets.s3-ap-southeast-2.amazonaws.com/footage/table-mountain.mp4"
                        },
                        "start": 0,
                        "length": 5
                    },
                    {
                        "asset": {
                            "type": "html",
                            "html": "<p>This html asset is affected by the luma matte because it sits in the same track",
                            "css": "p { font-size: 48px; color: #ffddd2; font-family: \"Lato Bold\"; margin: 15px; }",
                            "background": "#83c5be",
                            "width": 800,
                            "height": 250
                        },
                        "start": 1,
                        "length": 4.6
                    }
                ]
            },
            {
                "clips": [
                    {
                        "asset": {
                            "type": "html",
                            "html": "<p>This html asset is NOT affected by the luma matte because it sits in a separate track",
                            "css": "p { font-size: 48px; color: #ffddd2; font-family: \"Lato Bold\"; margin: 15px; }",
                            "background": "#83c5be",
                            "width": 800,
                            "height": 250
                        },
                        "start": 5.6,
                        "length": 5
                    }
                ]
            },
            {
                "clips": [
                	{
                        "asset": {
                            "type": "luma",
                            "src": "https://shotstack-assets.s3.amazonaws.com/luma-mattes/melts/melting-center-flipped.mp4"
                        },
                        "start": 7.2,
                        "length": 2
                    },
                    {
                        "asset": {
                            "type": "video",
                            "src": "https://shotstack-assets.s3-ap-southeast-2.amazonaws.com/footage/road.mp4"
                        },
                        "start": 3.6,
                        "length": 5
                    }
                ]
            },
            {
                "clips": [
                    {
                        "asset": {
                            "type": "video",
                            "src": "https://shotstack-assets.s3-ap-southeast-2.amazonaws.com/footage/lake.mp4"
                        },
                        "start": 7.2,
                        "length": 5,
                        "transition": {
                            "out": "fade"
                        }
                    }
                ]
            }
        ]
    },
    "output": {
        "format": "mp4",
        "resolution": "1080"
    }
}