#2526: ffmpeg on windows crashes when using Avisynth 2.5.8
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Reporter: Zarxrax | Owner:
Type: defect | Status: new
Priority: important | Component:
Version: unspecified | undetermined
Keywords: regression | Resolution:
Blocking: | Blocked By:
Analyzed by developer: 0 | Reproduced by developer: 0
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Comment (by qyot27):
It does affect 4.7.x as well, as part of that discussion Zarxrax linked to
originally dealt with builds that were compiled with 4.7.2. It was
exactly the same sort of error in DllMain, and only affected AviSynth
2.5.8.
For that matter, I can also confirm that MSVC builds exhibit this problem
with 2.5.8 (while 2.6 works fine) as well. I'd compiled an MSVC test
build for that discussion, and can reproduce it with said same build
(which, granted, is from April 21st, but the gdb output of that MSVC build
is exactly the same as the backtrace from the current build I posted
above).
Unless I'm way off (totally possible here), the crash seems to be
occurring *within* avisynth.dll, due to how libavformat is trying to load
it. The DllMain errors would seem to point to this. My best guess is that
AviSynth 2.6 adds protection meant to avoid this problem, and it doesn't
show up on Linux/OSX because dlopen doesn't have the same limitations as
LoadLibrary, or because AvxSynth (which is based on AviSynth 2.5.8)
backported any necessary changes concerning this issue from 2.6.
One distinct difference between libavformat/avisynth.c and x264's
input/avs.c is that in x264's case the struct containing the
AVSC_DECLARE_FUNC definitions (func) is nested inside the struct for the
environment (avs_hnd_t), whereas in libavformat, AviSynthLibrary and
AviSynthContext are separate from each other.
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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2526#comment:6>
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