Ghosts S01e11 Libvpx [2021] -

ffmpeg -i input.mov -c:v libvpx-vp9 \ -tile-columns 2 -row-mt 1 \ -lag-in-frames 16 \ # Reduce from default 25 -auto-alt-ref 1 \ # Keep on, but be careful -arnr-maxframes 3 \ # Reduce temporal filtering -cpu-used 2 \ output.webm Two-pass encoding often masks the bug because the first pass forces the encoder to re-evaluate scene boundaries more strictly.

# Check your version ffmpeg -version | grep libvpx # If it's 1.11 or 1.12, upgrade. If you can’t upgrade (e.g., in a production container), tune around the bug by reducing the temporal dependency depth. ghosts s01e11 libvpx

So next time you see a phantom block haunting your WebM, check your Libvpx version, check your alt-ref frames, and remember: you aren't losing your mind. You’re just wrestling with Season 1, Episode 11. ffmpeg -i input

# Disable alt-ref and limit reference frames ffmpeg -i input.mov -c:v libvpx-vp9 -auto-alt-ref 0 -arnr-maxframes 0 -lag-in-frames 0 output.webm If the ghost disappears, you’ve confirmed it’s an ALTREF or Golden Frame issue. You have three solutions, ranked from "quick fix" to "proper patch." So next time you see a phantom block

The ghosting bug in Libvpx v1.11.0–v1.12.0 is largely fixed in v1.13.0+. The patch (Change-Id: I8a3f7b2e9c4d1a5f6e7b8c9d0e1f2a3b4c5d6e7f) corrects the reference frame buffer reset logic after scene detection.

Ghosts in the Machine: Debugging FFmpeg’s Libvpx Encoder (Season 1, Episode 11)

This wasn't a decoding error. This was the encoder lying to us about its state. In VP9, Libvpx uses a complex reference frame structure. Unlike H.264’s simple "past/future" references, VP9 maintains up to eight reference frames simultaneously: LAST, GOLDEN, ALTREF, and their temporal variants.