ffmpeg: Improved fix for checking if const AVCodec* is necessary

CMakeLists.txt

@@ -116,6 +116,7 @@ if(NOT IOS)
 	list(APPEND CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake/sdl)
 endif()
 
+include(CheckCXXSourceCompiles)
 include(GNUInstallDirs)
 
 add_definitions(-DASSETS_DIR="${CMAKE_INSTALL_FULL_DATADIR}/ppsspp/assets/")
@@ -953,6 +954,23 @@ if(USE_FFMPEG)
 	endif()
 
 	find_package(FFmpeg REQUIRED avcodec avformat avutil swresample swscale)
+	# Check if we need to use avcodec_(alloc|free)_frame instead of av_frame_(alloc|free)
+	# Check if we need to use const AVCodec
+	set(CMAKE_REQUIRED_LIBRARIES avcodec;avformat)
+	set(CMAKE_REQUIRED_FLAGS "-pedantic -Wall -Werror -Wno-unused-variable")
+	check_cxx_source_compiles("extern \"C\" {
+		#include <libavcodec/avcodec.h>
+		#include <libavformat/avformat.h>
+		}
+		static AVCodecContext *s_codec_context = NULL;
+		int main() {
+			const AVCodec *codec = avcodec_find_encoder(s_codec_context->codec_id);
+			return 0;
+		}
+		" HAVE_LIBAVCODEC_CONST_AVCODEC FAIL_REGEX "invalid conversion")
+
+	# Check if we need to use avcodec_alloc_context3 instead of stream->codec
+	# Check if we need to use av_frame_get_buffer instead of avcodec_default_get_buffer
 endif(USE_FFMPEG)
 
 find_package(ZLIB)
@@ -2024,6 +2042,7 @@ add_library(${CoreLibName} ${CoreLinkType}
 	Core/ELF/PrxDecrypter.h
 	Core/ELF/ParamSFO.cpp
 	Core/ELF/ParamSFO.h
+	Core/FFMPEGCompat.h
 	Core/FileSystems/tlzrc.cpp
 	Core/FileSystems/BlobFileSystem.cpp
 	Core/FileSystems/BlobFileSystem.h
@@ -2358,6 +2377,9 @@ target_compile_features(${CoreLibName} PUBLIC cxx_std_17)
 
 if(FFmpeg_FOUND)
 	target_compile_definitions(${CoreLibName} PRIVATE USE_FFMPEG=1)
+	if (HAVE_LIBAVCODEC_CONST_AVCODEC)
+		target_compile_definitions(${CoreLibName} PRIVATE HAVE_LIBAVCODEC_CONST_AVCODEC=1)
+	endif()
 	set_target_properties(${CoreLibName} PROPERTIES NO_SYSTEM_FROM_IMPORTED true)
 	target_include_directories(${CoreLibName} BEFORE PUBLIC ${FFmpeg_INCLUDE_avcodec})
 	target_link_libraries(${CoreLibName}

Core/AVIDump.cpp

@@ -45,9 +45,7 @@ extern "C" {
 #define av_frame_free avcodec_free_frame
 #endif
 
-#if LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(59, 16, 100)
+#include "FFMPEGCompat.h"
-#define AVCodec const AVCodec
-#endif
 
 static AVFormatContext *s_format_context = nullptr;
 static AVCodecContext *s_codec_context = nullptr;

Core/FFMPEGCompat.h

@@ -0,0 +1,8 @@
+#ifndef FFMPEG_COMPAT_H
+#define FFMPEG_COMPAT_H
+
+#ifdef HAVE_LIBAVCODEC_CONST_AVCODEC
+#define AVCodec const AVCodec
+#endif
+
+#endif // FFMPEG_COMPAT_H

Core/HLE/sceAtrac.cpp

@@ -129,10 +129,7 @@ extern "C" {
 #include "libavcodec/avcodec.h"
 #include "libavutil/version.h"
 }
-
+#include "Core/FFMPEGCompat.h"
-#if LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(59, 16, 100)
-#define AVCodec const AVCodec
-#endif
 
 #endif // USE_FFMPEG
 

Core/HLE/sceMpeg.cpp

@@ -113,9 +113,7 @@ extern "C" {
 #include "libswscale/swscale.h"
 #include "libavcodec/avcodec.h"
 }
-#if LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(59, 16, 100)
+#include "Core/FFMPEGCompat.h"
-#define AVCodec const AVCodec
-#endif
 static AVPixelFormat pmp_want_pix_fmt;
 
 #endif

Core/HW/MediaEngine.cpp

@@ -56,9 +56,7 @@ extern "C" {
 
 #ifdef USE_FFMPEG
 
-#if LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(59, 16, 100)
+#include "Core/FFMPEGCompat.h"
-#define AVCodec const AVCodec
-#endif
 
 static AVPixelFormat getSwsFormat(int pspFormat)
 {

Core/HW/SimpleAudioDec.cpp

@@ -33,6 +33,7 @@ extern "C" {
 #include "libavutil/samplefmt.h"
 #include "libavcodec/avcodec.h"
 }
+#include "Core/FFMPEGCompat.h"
 
 #endif  // USE_FFMPEG
 

Core/HW/SimpleAudioDec.h

@@ -33,10 +33,6 @@ extern "C" {
 #include "libavutil/version.h"
 };
 
-#if LIBAVFORMAT_VERSION_INT >= AV_VERSION_INT(59, 16, 100)
-#define AVCodec const AVCodec
-#endif
-
 #endif
 
 // Wraps FFMPEG for audio decoding in a nice interface.
@@ -90,6 +86,9 @@ private:
 	int wanted_resample_freq; // wanted resampling rate/frequency
 
 	AVFrame *frame_;
+#if HAVE_LIBAVCODEC_CONST_AVCODEC // USE_FFMPEG is implied
+	const
+#endif
 	AVCodec *codec_;
 	AVCodecContext  *codecCtx_;
 	SwrContext      *swrCtx_;