[FFmpeg-trac] #9166(undetermined:new): Concat File Referencing UNC Paths from Windows Broken by 4.3.2

[FFmpeg]

#9166: Concat File Referencing UNC Paths from Windows Broken by 4.3.2
--------------------------------------+----------------------------------
             Reporter:  barndawg      |                     Type:  defect
               Status:  new           |                 Priority:  normal
            Component:  undetermined  |                  Version:  4.3.2
             Keywords:  concat        |               Blocked By:
             Blocking:                |  Reproduced by developer:  0
Analyzed by developer:  0             |
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 Summary of the bug:
 I'm running ffmpeg on Windows 10. I have a PowerShell script which
 populates a concat file with a list of UNC paths. That script is broken by
 upgrade to FFmpeg 4.3.2 (and fixed by downgrade back to 4.3.1 with no
 other build changes).

 How to reproduce:
 Create a concat file like the following:
 {{{
 #VideosToConcatenate
 file '\\myserver\archive\file1.mp4'
 file '\\myserver\archive\file2.mp4'
 }}}

 Run the following commands in PowerShell or cmd.exe:

 {{{
 PS> cd \\myserver\archive
 PS> ffmpeg -f concat -safe 0 -i ConcatFile.tmp -codec copy Output.mp4
 ffmpeg version n4.3.2 Copyright (c) 2000-2021 the FFmpeg developers
   built with gcc 9.3-win32 (GCC) 20200320
   configuration: --arch=x86_64 --target-os=mingw32 --cross-
 prefix=x86_64-w64-mingw32- --pkg-config=pkg-config --pkg-config-
 flags=--static --prefix=/home/barndawgie/repos/ffmpeg-cross-compile-
 script/ffmpeg_install --extra-libs='-lstdc++ -lbz2' --extra-cflags
 ='-static-libgcc -static-libstdc++ -static -O3 -s -I/home/barndawgie/repos
 /ffmpeg-cross-compile-script/ffmpeg_install/include' --extra-cxxflags
 ='-static-libgcc -static-libstdc++ -static -O3 -s' --extra-ldflags
 ='-static-libgcc -static-libstdc++ -static -O3 -s -L/home/barndawgie/repos
 /ffmpeg-cross-compile-script/ffmpeg_install/lib' --extra-ldexeflags
 ='-static-libgcc -static-libstdc++ -static -O3 -s' --extra-ldsoflags
 ='-static-libgcc -static-libstdc++ -static -O3 -s' --logfile=./config.log
 --enable-nonfree --enable-gpl --enable-libfdk-aac --enable-libx264
 --enable-libx265 --enable-libxml2 --enable-libopenjpeg --enable-libaom
 --enable-libmp3lame --enable-openssl --enable-libfreetype --enable-
 libfontconfig --enable-libfribidi --enable-libass
   libavutil      56. 51.100 / 56. 51.100
   libavcodec     58. 91.100 / 58. 91.100
   libavformat    58. 45.100 / 58. 45.100
   libavdevice    58. 10.100 / 58. 10.100
   libavfilter     7. 85.100 /  7. 85.100
   libswscale      5.  7.100 /  5.  7.100
   libswresample   3.  7.100 /  3.  7.100
   libpostproc    55.  7.100 / 55.  7.100
 [concat @ 000001cfd3cb36c0] Impossible to open
 'C:\\myserver\archive\file1.mp4'
 C:\Users\BarnD\AppData\Local\Temp\ConcatFile.tmp: No such file or
 directory
 }}}

 Note that some component appears to incorrectly be adding the "C:" to the
 start of the UNC path.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/9166>
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