Possibility to use third-party compiled library binaries of ffmpeg (gyan.dev)

[kivisade]

Hi! @asticode! Thank you for providing this excellent library!

I would like to ask for advice regarding possible use of third-party built binaries of ffmpeg (in particular, @GyanD's build of the release 7.0) with your library, instead of building ffmpeg locally.

Background of the question

I am building on Windows. I am not very familiar with building Golang applications requiring C library dependencies, but I was able to set up MinGW-w64 and compile ffmpeg using your instructions provided in README.md and Makefile (although had to face a resolve an issue described here). After that, I was able to build my Golang app using your library and confirm it working for my use case. However, the build process is tedious and time-consuming, and I am not sure that I am knowledgeable enough to make decisions regarding necessary options for ./configure. If possible, I would like to re-use third party builds such as https://www.gyan.dev/ffmpeg/builds/ to avoid the complexity of setting up the build environment and running the build process myself.

After some experimentation, I was also able to build an application using your library and the binary files from @GyanD (ffmpeg-7.0-full_build-shared.7z).

However, the main issue with this approach is that @GyanD's binary distribution does not include pkgconfig files which are necessary to build the Golang app with your library.

I was able to circumvent this problem by taking the lib/pkgconfig files which were generated during the local build, and placing them in the same path lib/pkgconfig under the directory with the extracted ffmpeg-7.0-full_build-shared.7z.

I understand that the problem with this approach is that it is not future-compatible, i.e. when you decide to update the version of ffmpeg supported by your library, new pkgconfig files would need to be generated to be able to use third-party complied binaries.

Question

I'm sorry for a vague question, but I would like to ask if there could be any better solution to allow using your library with vendored binaries?

I would greatly appreciate your advice 🙏

[kivisade]

For reference, I would like to share the Makefiles that I came up with, which support both building ffmpeg from source locally as described in your README.md and Makefile, and using downloaded files from @GyanD's release 7.0.

(I am quoting only relevant parts, omitting some of the variable declarations which are not relevant to subject)

Usage

# Local build
make build-ffmpeg

# Download and prepare built binary files from gyan.dev
make get-gyan.dev-ffmpeg

# Build app with locally build ffmpeg libs
make FFMPEG_VER=n7.0 rebuild

# Build app with ffmpeg libs from gyan.dev
make rebuild

Code

Makefile at root of project

FFMPEG_VER  := gyan.dev-7.0
FFMPEG_ROOT := ffmpeg/$(FFMPEG_VER)

# Environment variables related to building with ffmpeg dependency,
# see https://github.com/asticode/go-astiav?tab=readme-ov-file#install-ffmpeg-from-source
BUILD_ENV_VARS := CGO_ENABLED=1 \
                  CGO_LDFLAGS="-L$$(realpath $(FFMPEG_ROOT)/lib)" \
                  CGO_CFLAGS="-I$$(realpath $(FFMPEG_ROOT)/include)" \
                  PKG_CONFIG_PATH="$$(realpath $(FFMPEG_ROOT)/lib/pkgconfig)"

$(BIN_FILE):
	go mod tidy
	$(BUILD_ENV_VARS) go build -o $(BIN_FILE) $(LDFLAGS) ./cmd/$(COMMAND_NAME)

.PHONY: clean-bin
clean-bin:
	rm -f $(BIN_FILE)

.PHONY: rebuild
rebuild: clean-bin $(BIN_FILE)

.PHONY: build-ffmpeg get-gyan.dev-ffmpeg
build-ffmpeg get-gyan.dev-ffmpeg:
	$(MAKE) -C ffmpeg $@

ffmpeg/Makefile

#==================================================================================
# Option 1: Building from source @ https://github.com/FFmpeg/FFmpeg
#----------------------------------------------------------------------------------

FFMPEG_BUILD_VER         := n7.0
FFMPEG_REPO              := https://github.com/FFmpeg/FFmpeg
FFMPEG_SRC_PATH          := $(FFMPEG_BUILD_VER)/src
FFMPEG_PATCH             := $(shell realpath "patch/ffbuild-library.mak.patch")
FFMPEG_CONFIGURE_OPTIONS := --enable-static --disable-shared

# ffmpeg build instructions based on https://github.com/asticode/go-astiav/blob/master/Makefile
.PHONY: build-ffmpeg
build-ffmpeg:
	rm -rf $(FFMPEG_SRC_PATH)
	mkdir -p $(FFMPEG_SRC_PATH)
	git clone --branch $(FFMPEG_BUILD_VER) --single-branch --depth 1 $(FFMPEG_REPO) $(FFMPEG_SRC_PATH)
ifneq "" "$(FFMPEG_PATCH)"
	cd $(FFMPEG_SRC_PATH) && git apply $(FFMPEG_PATCH)
endif
	cd $(FFMPEG_SRC_PATH) && ./configure --prefix=.. $(FFMPEG_CONFIGURE_OPTIONS)
	cd $(FFMPEG_SRC_PATH) && make
	cd $(FFMPEG_SRC_PATH) && make install
	rm -rf $(FFMPEG_SRC_PATH)

#==================================================================================
# Option 2: Downloading from https://github.com/GyanD/codexffmpeg/releases/tag/7.0
#----------------------------------------------------------------------------------

FFMPEG_GYAND_VER   := 7.0
FFMPEG_GYAND_ROOT  := gyan.dev-$(FFMPEG_GYAND_VER)
GYAN_DEV_DIST_FILE := ffmpeg-$(FFMPEG_GYAND_VER)-full_build-shared.7z
GYAN_DEV_DIST_URL  := https://github.com/GyanD/codexffmpeg/releases/download/$(FFMPEG_GYAND_VER)/$(GYAN_DEV_DIST_FILE)

.PHONY: get-gyan.dev-ffmpeg
get-gyan.dev-ffmpeg:
	rm -rf $(FFMPEG_GYAND_ROOT)
	mkdir -p $(FFMPEG_GYAND_ROOT)
	wget -q -P $(FFMPEG_GYAND_ROOT) $(GYAN_DEV_DIST_URL)
	cd $(FFMPEG_GYAND_ROOT) && bsdtar --strip-components=1 -xf $(GYAN_DEV_DIST_FILE)
	rm $(FFMPEG_GYAND_ROOT)/$(GYAN_DEV_DIST_FILE)
	cp -r pkgconfig $(FFMPEG_GYAND_ROOT)/lib/

ffmpeg/patch/ffbuild-library.mak.patch

diff --git a/ffbuild/library.mak b/ffbuild/library.mak
index 793e9d41fa..1104819e4a 100644
--- a/ffbuild/library.mak
+++ b/ffbuild/library.mak
@@ -35,7 +35,9 @@ OBJS += $(SHLIBOBJS)
 endif
 $(SUBDIR)$(LIBNAME): $(OBJS) $(STLIBOBJS)
 	$(RM) $@
-	$(AR) $(ARFLAGS) $(AR_O) $^
+	$(file >objs.txt,$^)
+	cat objs.txt
+	$(AR) $(ARFLAGS) $(AR_O) @objs.txt
 	$(RANLIB) $@
 
 install-headers: install-lib$(NAME)-headers install-lib$(NAME)-pkgconfig

Directory ffmpeg/pkgconfig

Contains *.pc files generated by local build under ffmpeg/n7.0/lib/pkgconfig when running make build-ffmpeg.

[asticode]

Thing is, from go-astiav's standpoint, using pkgconfig is the best way since it removes all the complexity of gathering all proper CFLAGS and LDFLAGS for ffmpeg depending on the OS.

Therefore unfortunately I don't see another option for you than providing the pkgconfig files 🤔 Apart from creating an issue in gyan.dev's repo to get pkgconfig files in the releases.

Also, if you build manually ffmpeg to get the pkgconfig files, why use the gyan.dev release? 🤔

[GyanD]

I'll consider including pc files with the next release. However, the prefix will need to be adjusted by the user.

@asticode The rationale for a vendor build may be the third-party libraries linked. My full build referred to here has 80 external libs.