fourier-debian: Path A — ffmpeg into /opt/fourier prefix (no more KDE cascade) #36
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marfrit (Markus Fritsche)
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Reference: marfrit/marfrit-packages#36
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Problem
On trixie hosts (e.g. higgs),
apt install ffmpeg-v4l2-request-fourier libva-v4l2-request-fourierwould trigger removal of ~50 packages including kde-plasma-desktop, vlc, dolphin, sddm-theme-breeze, nextcloud-desktop, plasma-* etc. Root cause: the ffmpeg-v4l2-request-fourier .deb declaredConflicts: libavcodec61, libavformat61, ...because the design intent was 'drop-in replacement for stock ffmpeg'. But the package actually ships FFmpeg 8.1 (libavcodec.so.62), while stock trixie is FFmpeg 7.1 (libavcodec.so.61) — different SONAMEs, NOT ABI-compatible. Even if apt hadn't cascaded the removal, ldd of every libavcodec61-linked binary would have failed.Arch dodges this because rolling-Arch stock ffmpeg is also already on .so.62. Debian trixie is stable.
Fix (Path A)
Private prefix
/opt/fourier. Live alongside the stock ffmpeg, only fourier-aware consumers reach in.--prefix=/opt/fourier, libs at/opt/fourier/lib, bins at/opt/fourier/bin-Wl,-rpath,/opt/fourier/libfor self-sufficient/opt/fourier/bin/ffmpeg/etc/ld.so.conf.d/fourier.confadds/opt/fourier/libto ld cache via postinst → dlopen-by-SONAME consumers (firefox, daedalus) findlibavcodec.so.62automatically without any LD_LIBRARY_PATH wrapper./usr/bin/ffmpeg-fourier+/usr/bin/ffprobe-fourier.Depends: ffmpeg-v4l2-request-fourier (>= 2:8.1+rfourier)instead of stockffmpeg (>= 7.1). The binary was built against libavcodec.so.62 on the CI runner; at runtime it MUST get .so.62 from the fourier pkg.NOT touched
v4l2_request_drv_video.soat/usr/lib/<triplet>/dri/which stock libva dlopens by file pattern. Path A would break the lookup unless every consumer launcher setsLIBVA_DRIVERS_PATH=/opt/fourier/lib/dri(which someone always forgets). Driver-file name is unique, no conflict. STAY at /usr/lib.Depends:already bound to fourier ffmpeg. Binary is linked againstlibavcodec.so.62from the CI runner; at runtime on higgs it'll find /opt/fourier/lib/libavcodec.so.62 via ld.so cache. No recipe change needed.Test plan
apt install ffmpeg-v4l2-request-fourier libva-v4l2-request-fourieron higgs trixie no longer prompts to remove kde-plasma-desktop et al/opt/fourier/bin/ffmpeg -versionworksldconfig -p | grep libavcodec.so.62returns/opt/fourier/lib/...Stock Debian trixie ships FFmpeg 7.1 (libavcodec.so.61), our fork ships FFmpeg 8.1 (libavcodec.so.62) — different SONAMEs, NOT a drop-in for trixie's libavcodec61-consuming desktop. Previous Conflicts: libavcodec61, libavformat61, ... triggered apt to remove ~50 packages (kde-plasma-desktop, vlc, dolphin, ...) when a user just wanted ffmpeg-v4l2-request-fourier installed alongside. This commit: 1. ffmpeg-v4l2-request-fourier (pkgrel=2): - --prefix=/opt/fourier (instead of /usr) - --extra-ldexeflags / --extra-ldsoflags: -Wl,-rpath,/opt/fourier/lib so /opt/fourier/bin/ffmpeg finds its own libs without external help - Ship /etc/ld.so.conf.d/fourier.conf with /opt/fourier/lib + ldconfig in postinst/postrm. dlopen-by-SONAME consumers (firefox, daedalus) find libavcodec.so.62 via ld.so cache without LD_LIBRARY_PATH. - Drop ALL Conflicts/Replaces/Provides for libav* / libpostproc / libsw* — no SONAME clash with stock libavcodec61, no reason to evict anything. - /usr/bin/ffmpeg-fourier + ffprobe-fourier convenience symlinks. 2. daedalus-v4l2 (pkgrel=2): - Depends: ffmpeg-v4l2-request-fourier (>= 2:8.1+rfourier) instead of stock 'ffmpeg (>= 7.1)'. The daedalus binary was linked against libavcodec.so.62 at build time (CI runner had marfrit/ffmpeg-v4l2-request-fourier installed); at runtime it needs the .so.62 that only the fourier pkg provides. Not touched: - libva-v4l2-request-fourier: ships only v4l2_request_drv_video.so at /usr/lib/<triplet>/dri/ which libva dlopens by file pattern. Path A would break the lookup unless every consumer launcher sets LIBVA_DRIVERS_PATH. Driver name is unique; no conflict. STAY. - mpv-fourier: Depends already correctly bound to fourier ffmpeg. Will receive libavcodec.so.62 via the ld.so.cache mechanism above without recipe changes.