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fix(quality): scale after videoconvert at exact even WxH

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Live medium-quality stream errored with "negotiation problem" on the
host and rendered a squashed, garbled picture in the viewer. Two causes,
both from inserting videoscale before videoconvert with PAR+range caps:

- videoscale was scaling pipewiresrc's raw output directly. The portal
  source's format/memory (e.g. DMABuf) isn't something software videoscale
  negotiates — the original pipeline always fed pipewiresrc through
  videoconvert first. Move videoscale *after* videoconvert so it operates
  on system-memory NV12/I420.
- `pixel-aspect-ratio=1/1` + a width range over-constrained negotiation
  and risked a non-square-PAR / distorted result. Instead compute an exact
  even WxH from the known source dimensions (Wayland: portal size; X11:
  root/window geometry), preserving aspect, and pin it fully in the caps.
  This is also downscale-only now — a source already at/below the target
  height is left native instead of upscaled. Unknown dims (rare X11
  geometry failure) fall back to the height-only + square-pixel + even
  width-range negotiation.

source_dims threaded through pipeline::spawn from both backends. Smoke
test updated to mirror the new ordering (1920x1080 -> 852x480, videoscale
after videoconvert) and still asserts an even sub-source width.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
Mollusk
2026-05-24 15:25:05 -04:00
parent 7483b9aae8
commit 8044a42f98
4 changed files with 69 additions and 42 deletions
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scripts/smoke-pipeline.sh
+9 -8
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@@ -53,21 +53,22 @@ else
fi
# ── quality-preset downscale check ────────────────────────────────────────
# Mirrors the videoscale element host/pipeline.rs inserts for a non-Source
# preset. A 16:9 source @ 480p wants width 853.3 — the danger case for H.264,
# which needs even dimensions. Asserts videoscale negotiates an even width
# (the pixel-aspect-ratio=1/1 + stepped-even-range caps) and the encoder
# accepts it. Guards the "even-width caveat" the design plan flagged.
# Mirrors the videoscale step host/pipeline.rs inserts for a non-Source preset:
# AFTER videoconvert (scaling system-memory NV12, not the raw source format) and
# pinned to an exact even WxH computed from the source size. A 16:9 source @
# 480p wants width 853.3 -> 852 even. Asserts the negotiated size matches and
# the encoder accepts it. Guards both the "even-width caveat" and the
# negotiation/placement regression that squashed the picture.
SCALED="${TMPDIR:-/tmp}/pixelpass-smoke-scaled-$$.ts"
trap 'rm -f "$OUT" "$SCALED"' EXIT
echo "[smoke] downscale check: 1920x1080 -> height 480 (videoscale, even-width)"
echo "[smoke] downscale check: 1920x1080 -> 852x480 (videoscale after videoconvert)"
gst-launch-1.0 -q \
mpegtsmux name=mux ! queue ! filesink location="$SCALED" \
videotestsrc num-buffers=30 is-live=false \
! video/x-raw,width=1920,height=1080,framerate=30/1 \
! videorate ! video/x-raw,framerate=30/1 \
! videoscale ! "video/x-raw,height=480,pixel-aspect-ratio=1/1,width=[2,8192,2]" \
! videoconvert ! video/x-raw,format=NV12 \
! queue ! videoconvert ! video/x-raw,format=NV12 \
! videoscale ! video/x-raw,format=NV12,width=852,height=480 \
! vah264enc rate-control=cbr bitrate=1000 key-int-max=60 \
! h264parse config-interval=-1 \
! video/x-h264,stream-format=byte-stream,alignment=au ! mux. \