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October 2025

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Re: [Cin] [Libav-user] Dynamic_input filters and avfilter_pad_get_type
by Andrew Randrianasulu 19 Nov '25

19 Nov '25

On Sat, May 10, 2025 at 9:05 AM Paul B Mahol <onemda(a)gmail.com> wrote: > > > > On Fri, May 9, 2025 at 11:38 PM Andrew Randrianasulu <randrianasulu(a)gmail.com> wrote: >> >> I was looking at why our application (cinelerra-gg) crashed at trying to use libplacebo >> >> I found that libplacebo defines itself >> >> https://ffmpeg.org/doxygen/7.0/vf__libplacebo_8c.html >> >> as >> >> .flags = AVFILTER_FLAG_HWDEVICE | AVFILTER_FLAG_DYNAMIC_INPUTS, >> >> so only output pad is defined, as far as I can see: >> >> static const AVFilterPad libplacebo_outputs[] = { >> { >> .name = "default", >> .type = AVMEDIA_TYPE_VIDEO, >> .config_props = &libplacebo_config_output, >> }, >> }; >> >> >> >> then when our code calls >> >> avfilter_pad_get_type() > > > You need to call it only after filtergraph have been configured, not before because in such cases number of output pads may be 0 before configuration. > In any case you need to check current number of input pads and output pads for each filter before trying to access them. > Thanks. Attached patch makes this crash go away, just 32-bit cingg can't cope with 4k frames filtering en-masse :) Andrea, can you test attached patch + this opts file put alongside test 4k HDR video decodable by hardware? > >> >> >> it promptly crashes. >> >> BC_Signals::dump_stack >> cin() [0x8b2c9e2] >> linux-gate.so.1(__kernel_rt_sigreturn+0) [0xf7fb8590] >> cin(avfilter_pad_get_type+0x14) [0x99266a4] >> cin(_ZN13FFVideoStream13create_filterEPKc+0xbc) [0x865669c] >> cin(_ZN6FFMPEG12open_decoderEv+0x80f) [0x865732f] >> cin(_ZN10FileFFMPEG9check_sigEP5Asset+0x81) [0x8670071] >> cin(_ZN4File5probeEv+0x376) [0x867cd86] >> cin(_ZN4File9open_fileEP11PreferencesP5Assetii+0x378) [0x867d628] >> cin(_ZN7MWindow14load_filenamesEP9ArrayListIPcEiii+0x250) [0x87301f0] >> cin(_ZN17CommandLineThread3runEv+0x53) [0x86e2cd3] >> cin(_ZN6Thread10entrypointEPv+0x41) [0x8b70c11] >> /lib/libpthread.so.0(+0x7328) [0xf7df9328] >> /lib/libc.so.6(clone+0x66) [0xf0373f06] >> >> >> >> We still hope to get libplacebo's tonemapping + vulkan hevc decoding going, so any pointers how to talk to those dynamic_input filters will be useful. Even swscale is dynamic_input in ffmpeg 7.1+, so I (we) really hope to keep it working, too. >> >> Code: >> >> https://git.cinelerra-gg.org/git/?p=goodguy/cinelerra.git;a=blob;f=cinelerr… >> >> >> >> _______________________________________________ >> Libav-user mailing list >> Libav-user(a)ffmpeg.org >> https://ffmpeg.org/mailman/listinfo/libav-user >> >> To unsubscribe, visit link above, or email >> libav-user-request(a)ffmpeg.org with subject "unsubscribe". > > _______________________________________________ > Libav-user mailing list > Libav-user(a)ffmpeg.org > https://ffmpeg.org/mailman/listinfo/libav-user > > To unsubscribe, visit link above, or email > libav-user-request(a)ffmpeg.org with subject "unsubscribe".

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