Showing stream video

SGaist

Because VLC is the Swiss Army Knife of vidéo decoding and supports a larger palette of codecs than most OSs provide out of the box.

BrMisha

@SGaist I would't like to use VLC but you have convinced me)))
Tomorrow i will try to build VLC for windows

SGaist

There's likely already a prebuilt package.

See also VLC-Qt

BrMisha

@SGaist is VLC-Qt still actuality now? Last commit was in 2016 year and based on VLC 2.2.4

SGaist

It does not mean it does not work anymore. I'd say it's worth a try.

BrMisha

Unfortunately, VLC doesn't provide prebuilt packages for my compiler (MinGW32-64 7.3.0).
After googling i decided to try ffmpeg. I build it following this manual https://ffmpeg.org/platform.html#Native-Windows-compilation-using-MinGW-or-MinGW_002dw64 , then add libs to *pro file:

LIBS += -LF:/FFmpeg/tempinstall/usr/local/lib/ -llibavcodec.dll -llibavformat.dll
INCLUDEPATH += F:/FFmpeg/tempinstall/usr/local/include
DEPENDPATH += F:/FFmpeg/tempinstall/usr/local/include

and i called avformat_open_input(some args). But got error^

c:/qt/qt5.14.1/tools/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/8.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: main.o: in function `qMain(int, char**)':
D:\projects_test\qt\PlayerVideo\build-PlayerVideo-Desktop-Debug/../PlayerVideo/main.cpp:58: undefined reference to `avformat_open_input(AVFormatContext**, char const*, AVInputFormat*, AVDictionary**)'

So, i'm searching my mistake... I compared compiler versions between msys2 and qt, booth have GNU Make 4.2.1, but msys2 has gcc 8.3.0 and qt has 7.3.0.
That is problem?

SGaist

It's "-lavcodec"

BrMisha

@SGaist no, it isn't helpfull((

SGaist

Did you fix all libraries name ?

BrMisha

@SGaist this part of .pro

LIBS += -LF:/Musor/FFmpeg_linbuild/ffmpeg/lib/ -lavformat

INCLUDEPATH += F:/Musor/FFmpeg_linbuild/ffmpeg/include
DEPENDPATH += F:/Musor/FFmpeg_linbuild/ffmpeg/include

In code i'm calling only avformat_license(), which locates in avformat

SGaist

Do you have ffmpeg built for the same architecture as your Qt version ?

BrMisha

@SGaist yes, booth is x64

BrMisha

Men, I really don't understand what is happening.
I installed msys2, and some packages for that, then i copied *c:\Qt\Qt5.14.2\Tools\mingw730_64* to *c:\msys64\mingw64*.
Then built libav (it is "small" version of FFmpeg) and got this files:

build\usr\local\bin\avcodec.lib
build\usr\local\bin\avcodec-58.dll
build\usr\local\bin\avconv.exe
build\usr\local\bin\avdevice.lib
build\usr\local\bin\avdevice-57.dll
build\usr\local\bin\avfilter.lib
build\usr\local\bin\avfilter-7.dll
build\usr\local\bin\avformat.lib
build\usr\local\bin\avformat-58.dll
build\usr\local\bin\avprobe.exe
build\usr\local\bin\avresample.lib
build\usr\local\bin\avresample-4.dll
build\usr\local\bin\avutil.lib
build\usr\local\bin\avutil-56.dll
build\usr\local\bin\swscale.lib
build\usr\local\bin\swscale-5.dll

build\usr\local\include\libavcodec\	<< here is *.h
build\usr\local\include\libavdevice\	<< here is *.h
build\usr\local\include\libavfilter\	<< here is *.h
build\usr\local\include\libavformat\	<< here is *.h
build\usr\local\include\libavresample\	<< here is *.h
build\usr\local\include\libavutil\	<< here is *.h
build\usr\local\include\libswscale\	<< here is *.h

build\usr\local\lib\pkgconfig\
build\usr\local\lib\avcodec-58.def
build\usr\local\lib\avdevice-57.def
build\usr\local\lib\avfilter-7.def
build\usr\local\lib\avformat-58.def
build\usr\local\lib\avresample-4.def
build\usr\local\lib\avutil-56.def
build\usr\local\lib\libavcodec.dll.a
build\usr\local\lib\libavdevice.dll.a
build\usr\local\lib\libavfilter.dll.a
build\usr\local\lib\libavformat.dll.a
build\usr\local\lib\libavresample.dll.a
build\usr\local\lib\libavutil.dll.a
build\usr\local\lib\libswscale.dll.a
build\usr\local\lib\swscale-5.def

*c:\Qt\Qt5.14.2\Tools\mingw730_64* was added to PATH. When I start, for example, avconv.exe, it works ok, so definitely libav was built with true mingw (which uses qt).
Next, i added to *.pro (using "Add library...") this:

win32: LIBS += -LF:/Musor/libav/build/usr/local/lib/ -llibavformat.dll
INCLUDEPATH += F:/Musor/libav/build/usr/local/include
DEPENDPATH += F:/Musor/libav/build/usr/local/include

main.c:

#include <libavformat/avformat.h>
int main(int argc, char *argv[]) {
	avformat_license();
	return 0;
}

After compilation i got:

C:/Qt/Qt5.14.2/Tools/mingw730_64/bin/mingw32-make -f Makefile.Debug
mingw32-make[1]: Entering directory 'D:/projects_test/qt/qt_test/build-qt_test-Desktop_Qt_5_14_2_MinGW_64_bit-Debug'
g++ -c -fno-keep-inline-dllexport -g -std=gnu++11 -Wall -Wextra -Wextra -fexceptions -mthreads -DUNICODE -D_UNICODE -DWIN32 -DMINGW_HAS_SECURE_API=1 -DQT_DEPRECATED_WARNINGS -DQT_QML_DEBUG -DQT_SERIALPORT_LIB -DQT_CORE_LIB -I..\qt_test -I. -IF:\Musor\libav\build\usr\local\include -IC:\Qt\Qt5.14.2\5.14.2\mingw73_64\include -IC:\Qt\Qt5.14.2\5.14.2\mingw73_64\include\QtSerialPort -IC:\Qt\Qt5.14.2\5.14.2\mingw73_64\include\QtCore -Idebug -IC:\Qt\Qt5.14.2\5.14.2\mingw73_64\mkspecs\win32-g++  -o debug\main.o ..\qt_test\main.cpp
..\qt_test\main.cpp: In function 'int main(int, char**)':
..\qt_test\main.cpp:4:14: warning: unused parameter 'argc' [-Wunused-parameter]
 int main(int argc, char *argv[])
              ^~~~
..\qt_test\main.cpp:4:31: warning: unused parameter 'argv' [-Wunused-parameter]
 int main(int argc, char *argv[])
                               ^
g++ -Wl,-subsystem,console -mthreads -o debug\qt_test.exe debug/main.o  -LF:\Musor\libav\build\usr\local\lib F:\Musor\libav\build\usr\local\lib\libavformat.dll.a C:\Qt\Qt5.14.2\5.14.2\mingw73_64\lib\libQt5SerialPort.a C:\Qt\Qt5.14.2\5.14.2\mingw73_64\lib\libQt5Core.a   
debug/main.o: In function `main':
D:\projects_test\qt\qt_test\build-qt_test-Desktop_Qt_5_14_2_MinGW_64_bit-Debug/../qt_test/main.cpp:6: undefined reference to `avformat_license()'
collect2.exe: error: ld returned 1 exit status
mingw32-make[1]: *** [Makefile.Debug:68: debug/qt_test.exe] Error 1
mingw32-make: *** [Makefile:45: debug] Error 2
mingw32-make[1]: Leaving directory 'D:/projects_test/qt/qt_test/build-qt_test-Desktop_Qt_5_14_2_MinGW_64_bit-Debug'
18:45:50: The process "C:\Qt\Qt5.14.2\Tools\mingw730_64\bin\mingw32-make.exe" exited with code 2.
Error while building/deploying project qt_test (kit: Desktop Qt 5.14.2 MinGW 64-bit)
When executing step "Make"

Whyyyyyyy?????
I have tried to change -llibavformat.dll to -lavformat, "-lavformat.dll" and "-lavformat" but i'm stil getting this error.

SGaist

Might be silly but try linking to all the ffmpeg libraries, just in case.

Pablo J. Rogina

@BrMisha said in Showing stream video:

build\usr\local\bin\avformat.lib
build\usr\local\bin\avformat-58.dll

not sure if that's the issue, but you're showing libraries built in build\usr\local\bin but you're using build\usr\local\lib in your .pro file:

win32: LIBS += -LF:/Musor/libav/build/usr/local/lib/ -llibavformat.dll

In addition, and not sure since it's a long time I don't use libraries in Windows, also keep in mind that you have different names between the .lib and .dll files (avformat.lib vs. avformat-58.dll)

BrMisha

@SGaist said in Showing stream video:

Might be silly but try linking to all the ffmpeg libraries, just in case.

I tried to add this LIBS += -llibavcodec.dll -llibavdevice.dll -llibavfilter.dll -llibavformat.dll -llibavresample.dll -llibavutil.dll -llibswscale.dll but i'm still getting errors.
By the way, if in cpp i'm adding

extern "C" {
	#include <libavformat/avformat.h>
}

then compils but falls in runtime on calling avformat_license()

BrMisha

@Pablo-J-Rogina "bin" contains *.exe and *dll. Libraries locates in "lib" folder

SGaist

Because you are likely missing the path to the folder where the dlls are in the PATH environment variable.

You can do that in the Run part of the Project panel.

BrMisha

But i did set *\libav\build\usr\local\bin\ to PATH before)))

BrMisha

Men, i have done it)))
So, we need to add bin to PATH, in .pro LIBS += -L/libav/build/usr/local/lib/ -llibavformat.dll.
I think, in a past it doesn't work because i didn't restart qt qreator after adding to PATH