Compiling qt project with use of ffmpeg on x64 system - qt

Question

I have a qt project that uses some ffmpeg functionality, that i have compiled previously on windows (x86) and ubuntu. However, its x86 binaries do not work correctly on x64 windows machine. I have tried compiling it but have run into a strange problem.
All ffmpeg functions i use are listed as unresolved exgternals; and the most pecicular thing is, their names all ahve a leading underscore attached to them (so, avformat_close_input -> _avformat_close_input etc). To be sure, i have downloaded latest ffmpeg libraries for x64 machines and run them through a dependency walker - no leading underscores anywhere.
How to fix this problem?
Here is my .pro file:
#-------------------------------------------------
#
# Project created by QtCreator 2013-05-17T10:55:01
#
#-------------------------------------------------
QT += core gui
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = LPR_Demo
TEMPLATE = app
# The application version
VERSION = 1.0
# Define the preprocessor macro to get the application version in our application.
DEFINES += APP_VERSION=\\\"$$VERSION\\\"
SOURCES += main.cpp\
mainwindow.cpp \
imgProcessor.cpp \
qpicturelabel.cpp \
aboutdialog.cpp \
state.cpp \
qt_videoreader.cpp \
roidialog.cpp \
recognitionresult.cpp \
ffmpeg_reader.cpp \
label_videoplayer.cpp
HEADERS += mainwindow.h \
imgProcessor.h \
qpicturelabel.h \
aboutdialog.h \
state.h \
qt_videoreader.h \
roidialog.h \
recognitionresult.h \
global.h \
ffmpeg_reader.h \
label_videoplayer.h
FORMS += mainwindow.ui \
aboutdialog.ui \
roidialog.ui
LPRDIR = $$PWD/LPR
win32: LIBS += -L$$LPRDIR/bin/ -lliblpr
unix:LIBS += -L$$LPRDIR/bin -lLPR
INCLUDEPATH += $$LPRDIR/include
DEPENDPATH += $$LPRDIR/include
INCLUDEPATH += $$PWD/
DEPENDPATH += $$PWD/
#OTHER_FILES += \
# ffmpeg.pri
include(ffmpeg.pri)
#LIBS += -lavformat -lavcodec -lavutil -lswscale
RESOURCES += \
lpr_Res.qrc
win32 {
dlls_to_move.path += $$OUT_PWD/bin
dlls_to_move.files += $$LPRDIR/bin/liblpr.dll
QTDIR=C:/Qt/4.8.4/
CONFIG (debug, debug|release) {
dlls_to_move.files += $$QTDIR/bin/QtCored4.dll \
$$QTDIR/bin/QtGuid4.dll
}
CONFIG (release, debug|release) {
dlls_to_move.files += $$QTDIR/bin/QtCore4.dll \
$$QTDIR/bin/QtGui4.dll
}
img_format.path += $$OUT_PWD/bin/imageformats
CONFIG (debug, debug|release) {
img_format.files += $$QTDIR/plugins/imageformats/qgifd4.dll \
$$QTDIR/plugins/imageformats/qicod4.dll \
$$QTDIR/plugins/imageformats/qjpegd4.dll \
$$QTDIR/plugins/imageformats/qmngd4.dll \
$$QTDIR/plugins/imageformats/qsvgd4.dll \
$$QTDIR/plugins/imageformats/qtgad4.dll \
$$QTDIR/plugins/imageformats/qtiffd4.dll
}
CONFIG (release, debug|release) {
img_format.files += $$QTDIR/plugins/imageformats/qgif4.dll \
$$QTDIR/plugins/imageformats/qico4.dll \
$$QTDIR/plugins/imageformats/qjpeg4.dll \
$$QTDIR/plugins/imageformats/qmng4.dll \
$$QTDIR/plugins/imageformats/qsvg4.dll \
$$QTDIR/plugins/imageformats/qtga4.dll \
$$QTDIR/plugins/imageformats/qtiff4.dll
}
ffmpeg_dll.path += $$OUT_PWD/bin
ffmpeg_dll.files += $$FFMPEG_LIBRARY_PATH/avutil-*.dll \
$$FFMPEG_LIBRARY_PATH/avcodec-*.dll \
$$FFMPEG_LIBRARY_PATH/avformat-*.dll \
$$FFMPEG_LIBRARY_PATH/swscale-*.dll
main_exe.path += $$OUT_PWD/bin
CONFIG (debug, debug|release) {
main_exe.files += $$OUT_PWD/debug/LPR_Demo.exe
}
CONFIG (release, debug|release) {
main_exe.files += $$OUT_PWD/release/LPR_Demo.exe
}
INSTALLS += dlls_to_move img_format ffmpeg_dll main_exe
}
unix {
CONFIG (release, debug|release) {
QMAKE_PRE_LINK += rm LPR_Demo_cmpr LPR_Demo$$escape_expand(\n\t)
QMAKE_POST_LINK += upx -9 -oLPR_Demo_cmpr LPR_Demo$$escape_expand(\n\t)
QMAKE_POST_LINK += cp -v -u LPR_Demo_cmpr $$OUT_PWD/../artifacts/examples/qt_demo/bin/unix
}
}
and here is pri file for ffmpeg:
# Include the configuration file below in the QT .pro file, and modify the path accordingly.
# ##############################################################################
# ##############################################################################
# FFMPEG: START OF CONFIGURATION BELOW ->
# Copy these lines into your own project
# Make sure to set the path variables for:
# 1) ffmpeg_reader,
# 2) FFMPEG include path (i.e. where the directories libavcodec, libavutil, etc. lie),
# 3) the binary FFMPEG libraries (that must be compiled separately).
# Under Linux path 2 and 3 may not need to be set as these are usually in the standard include and lib path.
# Under Windows, path 2 and 3 must be set to the location where you placed the FFMPEG includes and compiled binaries
# Note that the FFMPEG dynamic librairies (i.e. the .dll files) must be in the PATH
# ##############################################################################
# ##############################################################################
# ##############################################################################
# Modify here: set FFMPEG_LIBRARY_PATH and FFMPEG_INCLUDE_PATH
# ##############################################################################
# Set FFMPEG_LIBRARY_PATH to point to the directory containing the FFmpeg import libraries (if needed - typically for Windows), i.e. the dll.a files
win32:FFMPEG_LIBRARY_PATH = $$PWD/ffmpeg/lib
unix: FFMPEG_LIBRARY_PATH = /usr/local/lib
# Set FFMPEG_INCLUDE_PATH to point to the directory containing the FFMPEG includes (if needed - typically for Windows)
win32:FFMPEG_INCLUDE_PATH = $$PWD/ffmpeg/include
unix:FFMPEG_INCLUDE_PATH = /usr/local/include
# ##############################################################################
# Do not modify: FFMPEG default settings
# ##############################################################################
# Set list of required FFmpeg libraries
#unix:LIBS += -L$$FFMPEG_LIBRARY_PATH
unix:LIBS += -lavformat -lavcodec -lavutil -lswscale
# Add the path
win32:LIBS += -L$$FFMPEG_LIBRARY_PATH
win32:LIBS += -lavformat -lavcodec -lavutil -lswscale
INCLUDEPATH += $$FFMPEG_INCLUDE_PATH
# Requied for some C99 defines
DEFINES += __STDC_CONSTANT_MACROS
# ##############################################################################
# FFMPEG: END OF CONFIGURATION
# ##############################################################################