[Libav-user] Calling avformat_open_input requires including lzma and that breaks minidlna compiling.

[T J]

I ran into an issue with ffmpeg/libav and I'm not sure if this is a bug or not.Compiling minidlnad, a dlna server daemon that requires ffmpeg, failed consistently on configure testing usability of libavformat. I tried multiple versions of ffmpeg from 2.8.7, 2.8.15, 3.4.2, 4.0.2, including custom compiled and slackware precompiled packages with identical result.
./minidlna-1.2.1/configure:...checking for av_open_input_file in -lavformat... nochecking for avformat_open_input in -lavformat... nochecking for av_open_input_file in -lavformat... nochecking for avformat_open_input in -lavformat... noconfigure: error: Could not find libavformat - part of ffmpeg$
I checked the relevent configure test code that was failing:
cat confdefs.h - <<_ACEOF >conftest.$ac_ext/* end confdefs.h.  */
/* Override any GCC internal prototype to avoid an error.   Use char because int might match the return type of a GCC   builtin and then its argument prototype would still apply.  */#ifdef __cplusplusextern "C"#endifchar avformat_open_input ();intmain (){return avformat_open_input ();  ;  return 0;}_ACEOF
I tried compiling that code snippet to find out the actual gcc error as configure isn't helpful:
$gcc -lavformat test.c/usr/lib/libavcodec.so.57: undefined reference to `lzma_stream_decoder at XZ_5.0'/usr/lib/libavcodec.so.57: undefined reference to `lzma_end at XZ_5.0'/usr/lib/libavcodec.so.57: undefined reference to `lzma_code at XZ_5.0'collect2: error: ld returned 1 exit status
This works:$gcc -lavformat -llzma test.c

So I tried env LIBS="-llzma"   ./minidlna-1.2.1/configureand that worked!

Seems to me if avformat needs lzma it needs to include it itself!! Failing to include it broke minidlna from compiling! I'm not sure if this is a bug or if my install is borked and that's causing the library issue. I'm not fluent in how ldconfig and the like works.I tried rebuilding the ldconfig cache and that didn't fix the problem.
Thanks!
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