[FFmpeg-devel] [PATCH] doc/examples/muxing: make compatible with C++

Michael Niedermayer michaelni at gmx.at
Sun Apr 13 06:08:47 CEST 2014


On Wed, Mar 19, 2014 at 11:45:08AM +0530, anshul wrote:
> On 03/19/2014 03:44 AM, Michael Niedermayer wrote:
> >On Tue, Mar 18, 2014 at 09:37:01PM +0530, anshul wrote:
> >>On 03/18/2014 04:57 PM, Clément Boesch wrote:
> >>>On Tue, Mar 18, 2014 at 04:12:49PM +0530, anshul wrote:
> >>>>On 03/18/2014 12:28 AM, Stefano Sabatini wrote:
> >>>>>On date Friday 2014-03-14 17:15:23 +0100, Michael Niedermayer encoded:
> >>>>>>On Fri, Mar 14, 2014 at 10:17:16AM +0100, Stefano Sabatini wrote:
> >>>>>>>On date Thursday 2014-03-13 23:10:40 +0100, Clément Boesch encoded:
> >>>>>>>>On Thu, Mar 13, 2014 at 06:03:49PM +0100, Michael Niedermayer wrote:
> >>>>>>>[...]
> >>>>>>>>I don't think supporting examples compilation with g++ is worth the
> >>>>>>>>effort. Actually, I believe it's harmful because people doing C will start
> >>>>>>>>copying naive/broken/c++ patterns (are you going to cast malloc() return
> >>>>>>>>values too?).
> >>>>>>>+1, we decided FFmpeg was C and we shouldn't try to make half-baked
> >>>>>>>attempts at pretending it is C++ or the next looks-almost-like-c
> >>>>>>>thing.
> >>>>>>this patch doesnt change ffmpeg, it changes the examples.
> >>>>>>
> >>>>>>People who want to use ffmpeg from C++ need examples which work in
> >>>>>>C++.
> >>>>>>ive written that patch in response to a question of how to do what
> >>>>>>muxing.c does from C++ as it didnt build even with extern C and the
> >>>>>>error messages truly where not helpfull in figuring out what was
> >>>>>>the cause.
> >>>>>We have this page:
> >>>>>http://trac.ffmpeg.org/wiki/Including%20FFmpeg%20headers%20in%20a%20C%2B%2B%20application
> >>>>>
> >>>>>We could extend the page, probably rename it, add more comments about
> >>>>>using FFmpeg from C++ and link it from the README (which we should
> >>>>>rename DONTREADME so people would actually read it).
> >>>>>
> >>>>>As it is the patch is half baked, because:
> >>>>>
> >>>>>1. it is not written anywhere that examples can be directly converted
> >>>>>to C++ code
> >>>>>2. the preprocessor hack is only adopted in muxing.c, ignoring all the
> >>>>>other C examples.
> >>>>Hi
> >>>>
> >>>>Here is patch attached for cpp examples files.
> >>>>
> >>>>Please report if they fail to compile or do there intended job.
> >>>>
> >>>>
> >>>>Thanks
> >>>>Anshul
> >>>> From 6adc8aaf4da5bb829505f398c0c7d2be8e22081d Mon Sep 17 00:00:00 2001
> >>>>From: Anshul Maheshwari <er.anshul.maheshwari at gmail.com>
> >>>>Date: Tue, 18 Mar 2014 16:07:20 +0530
> >>>>Subject: [PATCH] added examples in cpp
> >>>>
> >>>>---
> >>>>  doc/examples_cpp/Makefile              |  44 ++
> >>>>  doc/examples_cpp/avcodec.cpp           | 659 ++++++++++++++++++++++++++++
> >>>>  doc/examples_cpp/avio_reading.cpp      | 134 ++++++
> >>>>  doc/examples_cpp/demuxing_decoding.cpp | 387 +++++++++++++++++
> >>>>  doc/examples_cpp/filter_audio.cpp      | 364 ++++++++++++++++
> >>>>  doc/examples_cpp/filtering_audio.cpp   | 283 +++++++++++++
> >>>>  doc/examples_cpp/filtering_video.cpp   | 263 ++++++++++++
> >>>>  doc/examples_cpp/metadata.cpp          |  58 +++
> >>>>  doc/examples_cpp/muxing.cpp            | 614 +++++++++++++++++++++++++++
> >>>>  doc/examples_cpp/remuxing.cpp          | 173 ++++++++
> >>>>  doc/examples_cpp/resampling_audio.cpp  | 218 ++++++++++
> >>>>  doc/examples_cpp/scaling_video.cpp     | 143 +++++++
> >>>>  doc/examples_cpp/transcode_aac.cpp     | 754 +++++++++++++++++++++++++++++++++
> >>>>  doc/examples_cpp/transcoding.cpp       | 602 ++++++++++++++++++++++++++
> >>>>  14 files changed, 4696 insertions(+)
> >>>>  create mode 100644 doc/examples_cpp/Makefile
> >>>>  create mode 100644 doc/examples_cpp/avcodec.cpp
> >>>>  create mode 100644 doc/examples_cpp/avio_reading.cpp
> >>>>  create mode 100644 doc/examples_cpp/demuxing_decoding.cpp
> >>>>  create mode 100644 doc/examples_cpp/filter_audio.cpp
> >>>>  create mode 100644 doc/examples_cpp/filtering_audio.cpp
> >>>>  create mode 100644 doc/examples_cpp/filtering_video.cpp
> >>>>  create mode 100644 doc/examples_cpp/metadata.cpp
> >>>>  create mode 100644 doc/examples_cpp/muxing.cpp
> >>>>  create mode 100644 doc/examples_cpp/remuxing.cpp
> >>>>  create mode 100644 doc/examples_cpp/resampling_audio.cpp
> >>>>  create mode 100644 doc/examples_cpp/scaling_video.cpp
> >>>>  create mode 100644 doc/examples_cpp/transcode_aac.cpp
> >>>>  create mode 100644 doc/examples_cpp/transcoding.cpp
> >>>>
> >>>This lacks the integration with our build system. It sounds like this is
> >>>going to be a hell to maintain...
> >>>
> >>>[...]
> >>>
> >>>
> >>>
> >>>_______________________________________________
> >>>ffmpeg-devel mailing list
> >>>ffmpeg-devel at ffmpeg.org
> >>>http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >>I have added integration with build system.
> >>
> >>Thanks
> >>Anshul Maheshwari
> >>  Makefile                               |    7
> >>  doc/Makefile                           |   10
> >>  doc/examples_cpp/Makefile              |   44 +
> >>  doc/examples_cpp/README                |   23 +
> >>  doc/examples_cpp/avcodec.cpp           |  659 ++++++++++++++++++++++++++++
> >>  doc/examples_cpp/avio_reading.cpp      |  134 +++++
> >>  doc/examples_cpp/demuxing_decoding.cpp |  387 ++++++++++++++++
> >>  doc/examples_cpp/filter_audio.cpp      |  365 +++++++++++++++
> >>  doc/examples_cpp/filtering_audio.cpp   |  283 ++++++++++++
> >>  doc/examples_cpp/filtering_video.cpp   |  263 +++++++++++
> >>  doc/examples_cpp/metadata.cpp          |   58 ++
> >>  doc/examples_cpp/muxing.cpp            |  614 ++++++++++++++++++++++++++
> >>  doc/examples_cpp/remuxing.cpp          |  173 +++++++
> >>  doc/examples_cpp/resampling_audio.cpp  |  218 +++++++++
> >>  doc/examples_cpp/scaling_video.cpp     |  143 ++++++
> >>  doc/examples_cpp/transcode_aac.cpp     |  754 +++++++++++++++++++++++++++++++++
> >>  doc/examples_cpp/transcoding.cpp       |  602 ++++++++++++++++++++++++++
> >>  17 files changed, 4734 insertions(+), 3 deletions(-)
> >>7c6a83b9b007df59913920f5c0084f5af16cf1d0  0001-added-CPlusPlus-examples.patch
> >> From a98dc136a7f66ef29be0b1bca6bf9eaa9a01e9cd Mon Sep 17 00:00:00 2001
> >>From: Anshul Maheshwari <er.anshul.maheshwari at gmail.com>
> >>Date: Tue, 18 Mar 2014 21:32:08 +0530
> >>Subject: [PATCH] added CPlusPlus examples
> >>
> >>---
> >>  Makefile                               |   7 +-
> >>  doc/Makefile                           |  10 +-
> >>  doc/examples_cpp/Makefile              |  44 ++
> >>  doc/examples_cpp/README                |  23 +
> >>  doc/examples_cpp/avcodec.cpp           | 659 ++++++++++++++++++++++++++++
> >>  doc/examples_cpp/avio_reading.cpp      | 134 ++++++
> >>  doc/examples_cpp/demuxing_decoding.cpp | 387 +++++++++++++++++
> >>  doc/examples_cpp/filter_audio.cpp      | 365 ++++++++++++++++
> >>  doc/examples_cpp/filtering_audio.cpp   | 283 +++++++++++++
> >>  doc/examples_cpp/filtering_video.cpp   | 263 ++++++++++++
> >>  doc/examples_cpp/metadata.cpp          |  58 +++
> >>  doc/examples_cpp/muxing.cpp            | 614 +++++++++++++++++++++++++++
> >>  doc/examples_cpp/remuxing.cpp          | 173 ++++++++
> >>  doc/examples_cpp/resampling_audio.cpp  | 218 ++++++++++
> >>  doc/examples_cpp/scaling_video.cpp     | 143 +++++++
> >>  doc/examples_cpp/transcode_aac.cpp     | 754 +++++++++++++++++++++++++++++++++
> >>  doc/examples_cpp/transcoding.cpp       | 602 ++++++++++++++++++++++++++
> >>  17 files changed, 4734 insertions(+), 3 deletions(-)
> >>  create mode 100644 doc/examples_cpp/Makefile
> >>  create mode 100644 doc/examples_cpp/README
> >>  create mode 100644 doc/examples_cpp/avcodec.cpp
> >>  create mode 100644 doc/examples_cpp/avio_reading.cpp
> >>  create mode 100644 doc/examples_cpp/demuxing_decoding.cpp
> >>  create mode 100644 doc/examples_cpp/filter_audio.cpp
> >>  create mode 100644 doc/examples_cpp/filtering_audio.cpp
> >>  create mode 100644 doc/examples_cpp/filtering_video.cpp
> >>  create mode 100644 doc/examples_cpp/metadata.cpp
> >>  create mode 100644 doc/examples_cpp/muxing.cpp
> >>  create mode 100644 doc/examples_cpp/remuxing.cpp
> >>  create mode 100644 doc/examples_cpp/resampling_audio.cpp
> >>  create mode 100644 doc/examples_cpp/scaling_video.cpp
> >>  create mode 100644 doc/examples_cpp/transcode_aac.cpp
> >>  create mode 100644 doc/examples_cpp/transcoding.cpp
> >>
> >>diff --git a/Makefile b/Makefile
> >>index f497f57..ca68bb5 100644
> >>--- a/Makefile
> >>+++ b/Makefile
> >>@@ -47,6 +47,7 @@ FFLIBS := avutil
> >>  DATA_FILES := $(wildcard $(SRC_PATH)/presets/*.ffpreset) $(SRC_PATH)/doc/ffprobe.xsd
> >>  EXAMPLES_FILES := $(wildcard $(SRC_PATH)/doc/examples/*.c) $(SRC_PATH)/doc/examples/Makefile $(SRC_PATH)/doc/examples/README
> >>+CPP_EXAMPLES_FILES := $(wildcard $(SRC_PATH)/doc/examples_cpp/*.cpp) $(SRC_PATH)/doc/examples_cpp/Makefile $(SRC_PATH)/doc/examples_cpp/README
> >>  SKIPHEADERS = cmdutils_common_opts.h compat/w32pthreads.h
> >>@@ -146,10 +147,12 @@ install-progs: install-progs-yes $(AVPROGS)
> >>  	$(Q)mkdir -p "$(BINDIR)"
> >>  	$(INSTALL) -c -m 755 $(INSTPROGS) "$(BINDIR)"
> >>-install-data: $(DATA_FILES) $(EXAMPLES_FILES)
> >>+install-data: $(DATA_FILES) $(EXAMPLES_FILES) $(CPP_EXAMPLES_FILES)
> >>  	$(Q)mkdir -p "$(DATADIR)/examples"
> >>+	$(Q)mkdir -p "$(DATADIR)/examples_cpp"
> >>  	$(INSTALL) -m 644 $(DATA_FILES) "$(DATADIR)"
> >>  	$(INSTALL) -m 644 $(EXAMPLES_FILES) "$(DATADIR)/examples"
> >>+	$(INSTALL) -m 644 $(CPP_EXAMPLES_FILES) "$(DATADIR)/examples_cpp"
> >>  uninstall: uninstall-libs uninstall-headers uninstall-progs uninstall-data
> >>@@ -173,7 +176,7 @@ distclean::
> >>  config:
> >>  	$(SRC_PATH)/configure $(value FFMPEG_CONFIGURATION)
> >>-check: all alltools examples testprogs fate
> >>+check: all alltools examples examples_cpp testprogs fate
> >>  include $(SRC_PATH)/tests/Makefile
> >>diff --git a/doc/Makefile b/doc/Makefile
> >>index 10f03cc..eddd6b4 100644
> >>--- a/doc/Makefile
> >>+++ b/doc/Makefile
> >>@@ -56,6 +56,8 @@ ALL_DOC_EXAMPLES   := $(ALL_DOC_EXAMPLES_LIST:%=doc/examples/%$(PROGSSUF)$(EXESU
> >>  ALL_DOC_EXAMPLES_G := $(ALL_DOC_EXAMPLES_LIST:%=doc/examples/%$(PROGSSUF)_g$(EXESUF))
> >>  PROGS              += $(DOC_EXAMPLES)
> >>+DOC_EXAMPLES_CPP_DIR := doc/examples_cpp/
> >>+
> >>  all-$(CONFIG_DOC): doc
> >>  doc: documentation
> >>@@ -65,6 +67,9 @@ documentation: $(DOCS)
> >>  examples: $(DOC_EXAMPLES)
> >>+examples_cpp:
> >>+	make -C $(DOC_EXAMPLES_CPP_DIR)
> >this will not work on BSD as its called gmake there
> >
> >
> >
> >>+
> >>  TEXIDEP = perl $(SRC_PATH)/doc/texidep.pl $(SRC_PATH) $< $@ >$(@:%=%.d)
> >>  doc/%.txt: TAG = TXT
> >>@@ -158,7 +163,10 @@ examplesclean:
> >>  	$(RM) $(ALL_DOC_EXAMPLES) $(ALL_DOC_EXAMPLES_G)
> >>  	$(RM) $(CLEANSUFFIXES:%=doc/examples/%)
> >>-docclean: examplesclean
> >>+examples_cpp_clean:
> >>+	make -C $(DOC_EXAMPLES_CPP_DIR) clean
> >>+
> >>+docclean: examplesclean examples_cpp_clean
> >>  	$(RM) $(CLEANSUFFIXES:%=doc/%)
> >>  	$(RM) $(TXTPAGES) doc/*.html doc/*.pod doc/*.1 doc/*.3 doc/avoptions_*.texi
> >>  	$(RM) -r doc/doxy/html
> >>diff --git a/doc/examples_cpp/Makefile b/doc/examples_cpp/Makefile
> >>new file mode 100644
> >>index 0000000..fc5ce9f
> >>--- /dev/null
> >>+++ b/doc/examples_cpp/Makefile
> >>@@ -0,0 +1,44 @@
> >>+
> >>+CC=g++
> >its not guranteed the c++ compiler is called g++ nor is it guranteed
> >that one is there at all
> >
> >
> >also if you want to maintain this code, please add yourself to
> >the MAINTAINERs file
> >
> >[...]
> >
> >
> >
> >_______________________________________________
> >ffmpeg-devel mailing list
> >ffmpeg-devel at ffmpeg.org
> >http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> Done the suggested changes

running a make distclean with this patch applied
produces:
Package libavdevice was not found in the pkg-config search path.
Perhaps you should add the directory containing `libavdevice.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libavdevice' found
Package libswresample was not found in the pkg-config search path.
Perhaps you should add the directory containing `libswresample.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libswresample' found
Package libavdevice was not found in the pkg-config search path.
Perhaps you should add the directory containing `libavdevice.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libavdevice' found
Package libswresample was not found in the pkg-config search path.
Perhaps you should add the directory containing `libswresample.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libswresample' found

[...]
>  
> diff --git a/doc/Makefile b/doc/Makefile
> index 44049c4..5c1371a 100644
> --- a/doc/Makefile
> +++ b/doc/Makefile
> @@ -36,6 +36,13 @@ DOCS-$(CONFIG_MANPAGES)  += $(MANPAGES)
>  DOCS-$(CONFIG_TXTPAGES)  += $(TXTPAGES)
>  DOCS = $(DOCS-yes)
>  
> +EXAMPLE_CPP_MAKE=make
> +EXAMPLE_CPP_MAKE_VERSION := $(shell $(EXAMPLE_CPP_MAKE) --version 2> /dev/null )
> +ifndef EXAMPLE_CPP_MAKE_VERSION
> +EXAMPLE_CPP_MAKE=gmake
> +EXAMPLE_CPP_MAKE_VERSION := $(shell $(EXAMPLE_CPP_MAKE) --version 2> /dev/null )
> +endif

that looks really wrong
a Makefile should not need to test for how the make application is
called


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The real ebay dictionary, page 1
"Used only once"    - "Some unspecified defect prevented a second use"
"In good condition" - "Can be repaird by experienced expert"
"As is" - "You wouldnt want it even if you were payed for it, if you knew ..."
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