fix(viewer): aspect-fit, gapless looping, and 30fps cap for pi1/2/3 video#3004
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…ideo Fixes the issue #2987 regressions on the Qt5 linuxfb boards by moving playback from a bash gst-launch relaunch loop into a small in-process GStreamer helper (anthias_viewer/gst_fbdev_player.py): - Portrait/4:3 videos no longer stretch to the framebuffer: a CAPS-event pad probe reads the decoder's native dims + PAR and pins aspect-fit caps (pixel-aspect-ratio=1/1) on the capsfilter, so the bcm2835 ISP scales aspect-correct and fbdevsink centers the frame. The previous fb-sized forced caps parked the distortion in a PAR that fbdevsink ignores (reproduced on-device: 1080x1920 -> 3840x2160 par 81/256). - Clips no longer freeze/cut at loop boundaries: playbin about-to-finish re-queues the same URI for a gapless loop instead of rebuilding the whole pipeline per iteration (0.4-1.7 s per loop measured on a Pi 4, several seconds on a Pi 3, all eaten out of the fixed slot duration). Flush-seek on EOS and NULL->PLAYING restart remain as fallbacks. - 50/60 fps sources drop to an even 30 fps cadence up front (videorate drop-only) instead of juddering on irregular late-frame drops; the decode->ISP->memcpy chain sustains ~40 fps at 1080p on a Pi 3. - The framebuffer is zeroed at startup so letterbox borders are black rather than remnants of the previous asset. - The helper runs by path (not -m) so the package __init__ (Django settings, redis, D-Bus) never imports in the child; validated e2e on the armhf image: negotiation, rotation, looping, SIGTERM exit 0. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Pull request overview
This PR improves Raspberry Pi 1/2/3 (Qt5 linuxfb) video playback by moving the GStreamer looping/playback logic from an external bash + gst-launch respawn loop into an in-process Python helper, enabling aspect-correct “fit” scaling, gapless looping, and a 30fps output cap to reduce judder.
Changes:
- Replace
gst-launchrespawn looping with a dedicatedgst_fbdev_player.pyhelper process that manages aplaybinpipeline and looping behavior in-process. - Add unit tests for the helper’s pure functions (aspect-fit math, caps building, argv parsing, framebuffer clear).
- Update existing media player tests and documentation to reflect the new execution model and playback behavior.
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
| tests/test_media_player.py | Updates command-building and spawn tests to validate invoking the helper with CLI flags instead of gst-launch. |
| tests/test_gst_fbdev_player.py | Adds unit tests for helper utilities (fit-dim math, caps strings, sink description, fb clearing). |
| src/anthias_viewer/media_player.py | Switches Pi1/2/3 video playback to spawn the helper by path with explicit CLI parameters. |
| src/anthias_viewer/gst_fbdev_player.py | New helper implementing gapless looping, aspect-fit caps pinning, 30fps cap, and framebuffer clearing. |
| docs/board-enablement.md | Documents the new helper-based playback path and rationale (aspect-fit, looping, 30fps cap). |
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- Correct the module docstring: the helper is executed by file path, not -m (the package __init__ must not import in the child) - Fail fast with a clear log line when the GStreamer python bindings are missing instead of crashing with a traceback - Clear the framebuffer in scanline-sized chunks so a 4K console doesn't peak a ~33 MB allocation on a 512 MB board Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Integrated testbed run surfaced a wholesale-failure mode the relaunch loop also had: a broken audio branch killed the video with it. Two real-world triggers: the ALSA card is absent (HDMI audio disabled in config.txt -> no vc4hdmi), and an undecodable audio codec (AC3 - a52dec lives in plugins-ugly, not shipped). Retry once with GST_PLAY_FLAG_AUDIO cleared on both the synchronous start failure (alsasink can't reach READY) and the first async pipeline error; a genuine video error recurs on the retry and still exits non-zero. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Integrated testbed run surfaced a divergence the sysfs read hides: sysfs virtual_size reports xres_virtual/yres_virtual, which can be larger than the scanned-out mode (panning / double-buffer configs — observed live: visible 1920x1080, virtual 3840x2160). fbdevsink centers/crops against varinfo.xres/yres, so scaling to the virtual size paints mostly off-screen. Query the same ioctl fbdevsink uses; keep the sysfs read (and the 1080p default) as fallbacks for hosts without fb access. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Clearing GST_PLAY_FLAG_AUDIO is not sufficient: an element set on the audio-sink property remains a playsink child and is still state-synced with the pipeline, so a failing alsasink failed the retry too (observed live on the testbed). Replace it with a fakesink when degrading to silent video. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The integrated testbed run showed two things the previous in-place retry missed: - a playbin whose sink activation failed does not reliably restart after NULL: the video-only retry failed instantly on the reused element with no further GStreamer error; - alsasink opens the PCM on NULL->READY, so a missing card is detectable synchronously before it can poison playbin's whole sink activation. So: pre-flight the device with a standalone alsasink and only wire the audio branch when it opens; on any pipeline error with audio enabled (e.g. an undecodable AC3 track mid-preroll), tear down and rebuild a fresh video-only playbin instead of restarting the errored one. Genuine video errors recur on the rebuilt pipeline and still exit non-zero. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Issues Fixed
Part of #2987 (the Pi 3 symptoms: stretched portrait videos, clips freezing and getting cut off at the start/end, jerky 50/60 fps playback).
Description
Moves Qt5-linuxfb (pi1/2/3) video playback from the
bash+gst-launchrelaunch loop into a small in-process GStreamer helper (anthias_viewer/gst_fbdev_player.py):pixel-aspect-ratio=1/1) on a capsfilter, so the bcm2835 ISP scales aspect-correct andfbdevsinkcenters the frame. The old fb-sized forced caps madev4l2convertfill the screen and park the distortion in a PAR thatfbdevsinkignores.about-to-finishre-queues the same URI for a gapless loop instead of rebuilding the pipeline each iteration (measured 0.4–1.7 s per loop on a Pi 4, more on a Pi 3 — all eaten out of the fixed slot duration while the last frame sat frozen). Flush-seek-on-EOS and a fresh rebuild remain as fallbacks.videorate drop-only=true max-rate=30drops 50/60 fps sources to an even half-cadence before the ISP + framebuffer blit (the chain sustains ~40 fps at 1080p on a Pi 3).FBIOGET_VSCREENINFOioctl (xres/yres— the fieldsfbdevsinkcenters against) instead of sysfsvirtual_size, which can be larger than the scanned-out mode.-m) so the package__init__never imports in the child.No image changes needed:
python3-gi+gir1.2-gstreamer-1.0already ship in the pi1/2/3 viewer image.Validation
Component level (shipped armhf
latest-pi3image on the Pi 4 testbed, binaries run natively): caps negotiation incl. 90° rotation, gapless looping across clip boundaries, SIGTERM → exit 0. Reproduced the original stretch (1080x1920 → 3840x2160 par 81/256) with the shipped pipeline first.Integrated stack (full viewer container —
asset_loop → view_video → helper spawn— from this branch on the Pi 4 testbed, armhf, faked device-tree model; webview stubbed with a D-Bus shim due to host-specific 32-bit QtWebEngine instability that does not occur on real Pi 3 silicon):1080x1920 → 608x1080negotiated AND verified at the pixel level — framebuffer rows read[656px black][608px content][656px black]. ✅state: RUNNING; an AC3 track (no decoder shipped) is skipped gracefully, video continues. ✅Outstanding on real Pi 3 hardware (Pi 3B+ reachable, currently headless — no
/dev/fb0without a display): the fbdev paint path, the literalvc4hdmicard open, and VideoCore IV decode rates. Will be run as soon as a display/dummy is attached; the audio pre-flight + VPU decode probes run there next regardless.Checklist
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