Bug: 2.4.1 and ffmpeg7.1 need issue

[Pro-pra]

Observed Behavior

On build stage this error:

decklink_producer.cpp:641:52: error: 'AVFilterLink' {aka 'struct AVFilterLink'} has no member named 'min_samples'
  641 |                     audio_filter_.sink->inputs[0]->min_samples = audio_cadence_[0];

Expected behaviour

In ffmpeg7 min_samples i see in libavfilter/filters.h but it is not installed by default
https://github.com/FFmpeg/FFmpeg/blob/a5f0daf8433899d7d644523156ad1078301543f8/libavfilter/filters.h#L153

Ok, i patch ffmpeg7 and install libavfilter/filters.h

Also patch casparcg-server:

--- a/modules/decklink/producer/decklink_producer.cpp	2024-10-08 23:45:44.000000000 +0900
+++ b/modules/decklink/producer/decklink_producer.cpp	2024-11-16 10:57:32.174492429 +0900
@@ -51,7 +51,7 @@
 #endif
 extern "C" {
 #include <libavcodec/avcodec.h>
-#include <libavfilter/avfilter.h>
+#include <libavfilter/filters.h>
 #include <libavfilter/buffersink.h>
 #include <libavfilter/buffersrc.h>
 #include <libavformat/avformat.h>

And this not help me :(( AVFilterLink not have min_samples
https://github.com/FFmpeg/FFmpeg/blob/a5f0daf8433899d7d644523156ad1078301543f8/libavfilter/avfilter.h#L578

Steps to reproduce

build with ffmpeg7

Environment

gcc-14
ffmpeg-7.1

[Julusian]

What distro are you compiling on? (trying the same will be the easiest way for me to try it)

The newest ffmpeg I have tried is 7 in ubuntu 24.04 and that is happy.

[Pro-pra]

I use Rosa 13 linux for build.

Now check version 2.4.2 - build fail. My compile options:

cd /var/lib/notamock/rpmbuild/BUILD/server-2.4.2-stable/src/build/modules/decklink && /usr/bin/g++ -DBOOST_ALL_DYN_LINK -DBOOST_LOCALE_HIDE_AUTO_PTR -DBOOST_NO_SWPRINTF -DDIAG_FONT_PATH=\"LiberationMono-Regular.ttf\" -DGLEW_NO_GLU -DNDEBUG -DSFML_STATIC -DTBB_USE_CAPTURED_EXCEPTION=1 -DUNICODE -D_UNICODE -D__NO_INLINE__ -Ddecklink_EXPORTS -I/var/lib/notamock/rpmbuild/BUILD/server-2.4.2-stable/src/build/generated -I/var/lib/notamock/rpmbuild/BUILD/server-2.4.2-stable/src/modules/decklink/.. -I/var/lib/notamock/rpmbuild/BUILD/server-2.4.2-stable/src/modules/decklink/../.. -O2 -fomit-frame-pointer -gdwarf-4 -Wstrict-aliasing=2 -pipe -Wformat -Werror=format-security -D_FORTIFY_SOURCE=2 -fPIC -fstack-protector-strong --param=ssp-buffer-size=4 -m64 -mtune=generic -fno-strict-aliasing -O3 -DNDEBUG -fPIC -O3 -msse3 -mssse3 -msse4.1 -fnon-call-exceptions -Wno-deprecated-declarations -Wno-write-strings -Wno-multichar -Wno-cpp -Werror -Wno-terminate -Winvalid-pch -include /var/lib/notamock/rpmbuild/BUILD/server-2.4.2-stable/src/build/modules/decklink/CMakeFiles/decklink.dir/cmake_pch.hxx -MD -MT modules/decklink/CMakeFiles/decklink.dir/producer/decklink_producer.cpp.o -MF CMakeFiles/decklink.dir/producer/decklink_producer.cpp.o.d -o CMakeFiles/decklink.dir/producer/decklink_producer.cpp.o -c /var/lib/notamock/rpmbuild/BUILD/server-2.4.2-stable/src/modules/decklink/producer/decklink_producer.cpp
/var/lib/notamock/rpmbuild/BUILD/server-2.4.2-stable/src/modules/decklink/producer/decklink_producer.cpp: In member function 'virtual HRESULT caspar::decklink::decklink_producer::VideoInputFrameArrived(IDeckLinkVideoInputFrame*, IDeckLinkAudioInputPacket*)':
/var/lib/notamock/rpmbuild/BUILD/server-2.4.2-stable/src/modules/decklink/producer/decklink_producer.cpp:640:52: error: 'AVFilterLink' {aka 'struct AVFilterLink'} has no member named 'min_samples'
  640 |                     audio_filter_.sink->inputs[0]->min_samples = audio_cadence_[0];

[Pro-pra]

This commit in ffmpeg make build casparcg-server failed:
FFmpeg/FFmpeg@99ee7a9#diff-4a686e1241a6e9bc014aee81bb55e652e021a10256ef06ba734e03d97835195eR1225

[Pro-pra]

may be need not use min_samples, libavfilter/filters.h is not installed by default

[Julusian]

It might be enough to simply comment out the offending line, but I don't know what the side effects of that would be.

It appears that property is an internal property of ffmpeg and we shouldn't be touching it, and they moved it so that we can no longer access it.

Looking at the ffmpeg source, it looks like av_buffersink_set_frame_size would have the same effect, so is probably the correct way to do this.

Before making this change myself, I want to test it with some 59.94 content/channels to make sure it at least appears to work, I wouldn't be surprised if isn't as simple as it looks like it might be.