Hi, On 24/11/17 15:40, James Cowgill wrote: > Control: severity -1 grave > Control: retitle -1 libavutil55: ABI broken by "add vector_dmac_scalar()" > Control: forwarded -1 https://trac.ffmpeg.org/ticket/6861 > Control: tag -1 - moreinfo > Control: found -1 7:3.4-1 > > On 24/11/17 14:46, Carl Eugen Hoyos wrote: >> Hi! >> >> I created FFmpeg ticket #6861, thank you for the report! >> https://trac.ffmpeg.org/ticket/6861 > > That is not a nice bug. > > I'll have to think about the best way to handle this. I guess we will > have to revert the ABI breaking commit, identify the packages which are > broken (including ffmpeg itself like in this bug), add some Breaks for > them, and finally binNMU them. Alternatively we could force an ABI > transition and rebuild everything, but I'm not sure if I want to do > that (especially since we'll have to do another in a few months anyway).
On closer inspection (and reading the upstream bug), the ABI break occurs in the private float_dsp.h header and the only consumers are libavcodec and libavfilter. This makes things much easier than I originally thought since the breakage is internal to ffmpeg. I think this can be fixed by keeping the new ABI and use package dependencies to enforce that it's used only with 3.4. We need to ensure 3.4 libavcodec/libavfilter uses 3.4 libavutil, but this is already guaranteed through the existing symbols system. We then need to prevent 3.4 libavutil from being used with pre-3.4 libavcodec/libavfilter by adding this to libavutil55: Breaks: libavcodec57 (<< 7:3.4), libavcodec-extra57 (<< 7:3.4), libavfilter6 (<< 7:3.4), libavfilter-extra6 (<< 7:3.4) I think that will fix the bug. Can anyone see anything I've missed? Thanks, James
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