Video export: keep encoded segments on failure, fall back to cuts, report ffmpeg exit status - #194
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With -loglevel error a process killed from outside (e.g. OOM) writes nothing, so the UI showed a bare 'ffmpeg failed:'. Include the exit status in the error and log the full command and stderr. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01QkwxQ29m5Zfq3XfaEjDyeZ
… if the crossfade stitch fails A render that died at the stitch threw away every encoded segment, and a retry (a new job) re-encoded all of them. Segments are now filed in a content-keyed cache (hard links, pruned after 48h, discarded on success), so a retry - even with a different transition - only encodes what changed. The crossfade (xfade) stitch holds every segment open at once and is what gets OOM-killed on a small host. If it fails, join with straight cuts and warn rather than failing a render whose encoding is finished. Also fixes the run() failure test added earlier, which had a class-scope bug. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01QkwxQ29m5Zfq3XfaEjDyeZ
davior
marked this pull request as ready for review
September 30, 2026 11:29
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Problem
A video export failed with a bare
ffmpeg failed:. Host logs showed the kernel OOM-killedffmpegduring the crossfade (xfade) stitch (Circle transition) — the one step that holds every segment open at once — after all segments had already been encoded. Because the scratch dir is always removed and a retry is a new job, every segment was thrown away and had to be re-encoded.Changes
ffmpeg.run(): the error now includes the exit status (killed by signal 9 (most likely out of memory)), and the full argv + stderr are logged. Previously-loglevel error+ a signal kill produced an empty message.video/shot_cache.py(new): encoded segments are filed under a fingerprint of the exact ffmpeg command plus input content (not the job id or whole options), as hard links. A retry — even with a different transition — reuses unchanged segments. Entries are discarded on success and pruned after 48h.renderer.py: uses the cache per shot (replaying the "rendered without motion" warning on reuse); if the xfade stitch fails, it falls back to a plain cut join with a warning and rebuilds chapters/subtitles for the un-overlapped timeline.Tests
tests/test_video_shot_cache.py– fingerprinting, hit/miss, plain-fallback marker, cleanup, prune.tests/test_video_render_resume.py– drives realrender()with a faked ffmpeg: crossfade fallback, failed render keeps segments and retry reuses them, segment-affecting changes miss the cache.tests/test_video_ffmpeg.py– exit-status message.Not verified against a real ffmpeg (none in the dev sandbox). Cache/fallback behaviour is covered with a fake; worth one real export on the server.
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https://claude.ai/code/session_01QkwxQ29m5Zfq3XfaEjDyeZ
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