overlay filter with simple PNG adds black fringe

Question

Trying a simple overlay example, getting nasty black fringes:

fmpeg -y -i b.png -i a.png -filter_complex "[0:v]format=rgba[a];
    [1:v]format=rgba[b];
    [a][b]overlay,format=rgba"  normal.png

Expected over Result zoomed in 😱

Open a ticket at trac.ffmpeg.org. Run your command with -v verbose added and capture log. Share full command and log there.. — Gyan, Mar 10, 2020 at 8:27
Workaround: ffmpeg -y -i b.png -i a.png -filter_complex "[0:v]format=rgba[a]; [1:v]format=rgba[b]; [a][b]overlay=format=auto" normal.png — llogan, Mar 10, 2020 at 17:35

llogan · Accepted Answer · 2020-03-10 20:52:39Z

2

Default pixel format for overlay filter is yuv420p. Use the format option in overlay to set it as auto or rgb.

ffmpeg -y -i b.png -i a.png -filter_complex "[0:v]format=rgba[a]; [1:v]format=rgba[b]; [a][b]overlay=format=auto" normal.png

answered Mar 10, 2020 at 20:52

llogan

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