Redefined ffmpeg's av_err2str macro to be c++ friendly (shadps4-emu#815)

* Fixed compiler error for av_err2string by redefining in c++ friendly way

* removed link from comment, putting in PR

* fixed formatting

* Minor fix: enable qt gui to find PKG files with lowercase extension .pkg

* Added missing dependencies and instructions for enabling QT for linux builds

documents/building-linux.md

@@ -9,7 +9,7 @@ SPDX-License-Identifier: GPL-2.0-or-later
 
 #### Debian & Ubuntu
 ```
-sudo apt-get install build-essential libasound2-dev libpulse-dev libopenal-dev zlib1g-dev libedit-dev libvulkan-dev libudev-dev git libevdev-dev libsdl2-2.0 libsdl2-dev libjack-dev libsndio-dev
+sudo apt-get install build-essential libasound2-dev libpulse-dev libopenal-dev zlib1g-dev libedit-dev libvulkan-dev libudev-dev git libevdev-dev libsdl2-2.0 libsdl2-dev libjack-dev libsndio-dev qt6-base-dev qt6-tools-dev
 ```
 
 #### Fedora
@@ -34,9 +34,9 @@ git clone --recursive https://github.com/shadps4-emu/shadPS4.git
 cd shadPS4
 ```
 
-Generate the build directory in the shadPS4 directory:
+Generate the build directory in the shadPS4 directory. To enable the QT GUI, pass the ```-DENABLE_QT_GUI=ON``` flag:
 ```
-cmake -S . -B build/
+cmake -S . -B build/ -DENABLE_QT_GUI=ON
 ```
 
 Enter the directory:
@@ -49,8 +49,11 @@ Use make to build the project:
 cmake --build . --parallel$(nproc)
 ```
 
-Now run the emulator:
-
+Now run the emulator. If QT is enabled:
+```
+./shadps4
+```
+Otherwise, specify the path to your PKG's boot file:
 ```
 ./shadps4 /"PATH"/"TO"/"GAME"/"FOLDER"/eboot.bin
 ```

src/core/libraries/avplayer/avplayer_source.cpp

@@ -20,6 +20,17 @@ extern "C" {
 #include <libswscale/swscale.h>
 }
 
+// The av_err2str macro in libavutil/error.h does not play nice with C++
+#ifdef av_err2str
+#undef av_err2str
+#include <string>
+av_always_inline std::string av_err2string(int errnum) {
+    char errbuf[AV_ERROR_MAX_STRING_SIZE];
+    return av_make_error_string(errbuf, AV_ERROR_MAX_STRING_SIZE, errnum);
+}
+#define av_err2str(err) av_err2string(err).c_str()
+#endif // av_err2str
+
 namespace Libraries::AvPlayer {
 
 using namespace Kernel;

src/qt_gui/main_window.cpp

@@ -577,7 +577,7 @@ void MainWindow::SaveWindowState() const {
 void MainWindow::InstallPkg() {
     QFileDialog dialog;
     dialog.setFileMode(QFileDialog::ExistingFiles);
-    dialog.setNameFilter(tr("PKG File (*.PKG)"));
+    dialog.setNameFilter(tr("PKG File (*.PKG *.pkg)"));
     if (dialog.exec()) {
         QStringList fileNames = dialog.selectedFiles();
         int nPkg = fileNames.size();
@@ -949,4 +949,4 @@ void MainWindow::OnLanguageChanged(const std::string& locale) {
     Config::setEmulatorLanguage(locale);
 
     LoadTranslation();
-}
+}