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• Technically Correct VP8 Encoding

  26 octobre 2010, par Multimedia Mike — VP8

  I know people are anxious to see what happens next with my toy VP8 encoder. First and foremost, I corrected the encoder’s DC prediction. A lot of rules govern that mode and if you don’t have it right, error cascades through the image. Now the encoder and decoder both agree on every fine detail of the bitstream syntax and rendering thereof. It still encodes to a neo-impressionist mosaic piece, but at least I’ve ironed the bugs out of this phase :

  
  
  

  I also made it possible to adjust the quantization levels inside the encoder. This means that I’m finally getting some compression out of the thing, vs. the original approach of hardcoding the minimum quantizers.

• How to play interlaced video, where even lines at top half of picture, and odd lines at bottom half ?

  3 octobre 2012, par Pyih

  I have some device which streams h264 video in following format : top half of picture is even lines of video, and bottom half of picture is odd lines of video. So the question is - how can I play this video in normal visibility, using standart players, ffplay for example.
  I know about "tinterlace:merge" plugin in ffmpeg, but it combines video from two pictures following one by one. So my task is make a correct video from single frame.
  Regards,
  Alexey.

• Building FFMPEG on UBUNTU facing issue while compiling common.mak file

  9 juin 2016, par sumit singh

  I am compiling the ffmpeg library i am facing some issues while compiling this.

  I follow the steps of compilation form here.But i am failed to compile.
  The issues are as below.

  WARNING: /home/sumit/android-ndk-r10e/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86/bin/arm-linux-androideabi-pkg-config not found, library detection may fail.
  
  libavcodec/bsf_list.c is unchanged
  
  libavformat/protocol_list.c is unchanged
  
  common.mak:26: *** unterminated call to function `foreach': missing `)'.  Stop.
  
  common.mak:26: *** unterminated call to function `foreach': missing `)'.  Stop.
  
  common.mak:26: *** unterminated call to function `foreach': missing `)'.  Stop.
  
  sumit@sumit-H81M-S:~/android-ndk-r10e/sources/ffmpeg$ 

  here is my build_android.sh file-

  #!/bin/bash
  
  
  
  NDK=$HOME/android-ndk-r10e
  
  
  
  SYSROOT=$NDK/platforms/android-19/arch-arm/
  
  
  
  TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86
  
  
  
  function build_one
  
  
  
  {
  
  ./configure --prefix=$PREFIX --enable-shared --disable-static --disable-doc --disable-ffmpeg --disable-ffplay --disable-ffprobe --disable-ffserver --disable-avdevice --disable-doc --disable-symver --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- --target-os=linux --arch=arm --enable-cross-compile --sysroot=$SYSROOT --extra-cflags="-Os -fpic $ADDI_CFLAGS" --extra-ldflags="$ADDI_LDFLAGS" 
  
  $ADDITIONAL_CONFIGURE_FLAG
  
  make clean
  
  make
  
  make install
  
  }
  
  
  
  CPU=arm
  
  
  
  PREFIX=$(pwd)/android/$CPU 
  
  
  
  ADDI_CFLAGS="-marm"
  
  
  
  build_one

  common.mak-

  #
  
  # common bits used by all libraries
  
  #
  
  
  
  # first so "all" becomes default target
  
  all: all-yes
  
  
  
  DEFAULT_YASMD=.dbg
  
  
  
  ifeq ($(DBG),1)
  
  YASMD=$(DEFAULT_YASMD)
  
  else
  
  YASMD=
  
  endif
  
  
  
  ifndef SUBDIR
  
  
  
  ifndef V
  
  Q      = @
  
  ECHO   = printf "$(1)\t%s\n" $(2)
  
  BRIEF  = CC CXX OBJCC HOSTCC HOSTLD AS YASM AR LD STRIP CP WINDRES
  
  SILENT = DEPCC DEPHOSTCC DEPAS DEPYASM RANLIB RM
  
  
  
  MSG    = $@
  
  M      = @$(call ECHO,$(TAG),$@);
  
  $(foreach VAR,$(BRIEF), \
  
      $(eval override $(VAR) = @$$(call ECHO,$(VAR),$$(MSG)); $($(VAR))))
  
  $(foreach VAR,$(SILENT),$(eval override $(VAR) = @$($(VAR))))
  
  $(eval INSTALL = @$(call ECHO,INSTALL,$$(^:$(SRC_DIR)/%=%)); $(INSTALL))
  
  endif
  
  
  
  ALLFFLIBS = avcodec avdevice avfilter avformat avresample avutil postproc swscale swresample
  
  
  
  # NASM requires -I path terminated with /
  
  IFLAGS     := -I. -I$(SRC_LINK)/
  
  CPPFLAGS   := $(IFLAGS) $(CPPFLAGS)
  
  CFLAGS     += $(ECFLAGS)
  
  CCFLAGS     = $(CPPFLAGS) $(CFLAGS)
  
  OBJCFLAGS  += $(EOBJCFLAGS)
  
  OBJCCFLAGS  = $(CPPFLAGS) $(CFLAGS) $(OBJCFLAGS)
  
  ASFLAGS    := $(CPPFLAGS) $(ASFLAGS)
  
  CXXFLAGS   += $(CPPFLAGS) $(CFLAGS)
  
  YASMFLAGS  += $(IFLAGS:%=%/) -Pconfig.asm
  
  
  
  HOSTCCFLAGS = $(IFLAGS) $(HOSTCPPFLAGS) $(HOSTCFLAGS)
  
  LDFLAGS    := $(ALLFFLIBS:%=$(LD_PATH)lib%) $(LDFLAGS)
  
  
  
  define COMPILE
  
         $(call $(1)DEP,$(1))
  
         $($(1)) $($(1)FLAGS) $($(1)_DEPFLAGS) $($(1)_C) $($(1)_O) $(patsubst $(SRC_PATH)/%,$(SRC_LINK)/%,$<)
  
  endef
  
  
  
  COMPILE_C = $(call COMPILE,CC)
  
  COMPILE_CXX = $(call COMPILE,CXX)
  
  COMPILE_S = $(call COMPILE,AS)
  
  COMPILE_M = $(call COMPILE,OBJCC)
  
  COMPILE_HOSTC = $(call COMPILE,HOSTCC)
  
  
  
  %.o: %.c
  
      $(COMPILE_C)
  
  
  
  %.o: %.cpp
  
      $(COMPILE_CXX)
  
  
  
  %.o: %.m
  
      $(COMPILE_M)
  
  
  
  %.s: %.c
  
      $(CC) $(CCFLAGS) -S -o $@ $<
  
  
  
  %.o: %.S
  
      $(COMPILE_S)
  
  
  
  %_host.o: %.c
  
      $(COMPILE_HOSTC)
  
  
  
  %.o: %.rc
  
      $(WINDRES) $(IFLAGS) --preprocessor "$(DEPWINDRES) -E -xc-header -DRC_INVOKED $(CC_DEPFLAGS)" -o $@ $<
  
  
  
  %.i: %.c
  
      $(CC) $(CCFLAGS) $(CC_E) $<
  
  
  
  %.h.c:
  
      $(Q)echo '#include "$*.h"' >$@
  
  
  
  %.ver: %.v
  
      $(Q)sed 's/$$MAJOR/$($(basename $(@F))_VERSION_MAJOR)/' $^ | sed -e 's/:/:\
  
  /' -e 's/; /;\
  
  /g' > $@
  
  
  
  %.c %.h: TAG = GEN
  
  
  
  # Dummy rule to stop make trying to rebuild removed or renamed headers
  
  %.h:
  
      @:
  
  
  
  # Disable suffix rules.  Most of the builtin rules are suffix rules,
  
  # so this saves some time on slow systems.
  
  .SUFFIXES:
  
  
  
  # Do not delete intermediate files from chains of implicit rules
  
  $(OBJS):
  
  endif
  
  
  
  include $(SRC_PATH)/arch.mak
  
  
  
  OBJS      += $(OBJS-yes)
  
  SLIBOBJS  += $(SLIBOBJS-yes)
  
  FFLIBS    := $($(NAME)_FFLIBS) $(FFLIBS-yes) $(FFLIBS)
  
  TESTPROGS += $(TESTPROGS-yes)
  
  
  
  LDLIBS       = $(FFLIBS:%=%$(BUILDSUF))
  
  FFEXTRALIBS := $(LDLIBS:%=$(LD_LIB)) $(EXTRALIBS)
  
  
  
  OBJS      := $(sort $(OBJS:%=$(SUBDIR)%))
  
  SLIBOBJS  := $(sort $(SLIBOBJS:%=$(SUBDIR)%))
  
  TESTOBJS  := $(TESTOBJS:%=$(SUBDIR)%) $(TESTPROGS:%=$(SUBDIR)%-test.o)
  
  TESTPROGS := $(TESTPROGS:%=$(SUBDIR)%-test$(EXESUF))
  
  HOSTOBJS  := $(HOSTPROGS:%=$(SUBDIR)%.o)
  
  HOSTPROGS := $(HOSTPROGS:%=$(SUBDIR)%$(HOSTEXESUF))
  
  TOOLS     += $(TOOLS-yes)
  
  TOOLOBJS  := $(TOOLS:%=tools/%.o)
  
  TOOLS     := $(TOOLS:%=tools/%$(EXESUF))
  
  HEADERS   += $(HEADERS-yes)
  
  
  
  PATH_LIBNAME = $(foreach NAME,$(1),lib$(NAME)/$($(2)LIBNAME))
  
  DEP_LIBS := $(foreach lib,$(FFLIBS),$(call PATH_LIBNAME,$(lib),$(CONFIG_SHARED:yes=S)))
  
  STATIC_DEP_LIBS := $(foreach lib,$(FFLIBS),$(call PATH_LIBNAME,$(lib)))
  
  
  
  SRC_DIR    := $(SRC_PATH)/lib$(NAME)
  
  ALLHEADERS := $(subst $(SRC_DIR)/,$(SUBDIR),$(wildcard $(SRC_DIR)/*.h $(SRC_DIR)/$(ARCH)/*.h))
  
  SKIPHEADERS += $(ARCH_HEADERS:%=$(ARCH)/%) $(SKIPHEADERS-)
  
  SKIPHEADERS := $(SKIPHEADERS:%=$(SUBDIR)%)
  
  HOBJS        = $(filter-out $(SKIPHEADERS:.h=.h.o),$(ALLHEADERS:.h=.h.o))
  
  checkheaders: $(HOBJS)
  
  .SECONDARY:   $(HOBJS:.o=.c)
  
  
  
  alltools: $(TOOLS)
  
  
  
  $(HOSTOBJS): %.o: %.c
  
      $(COMPILE_HOSTC)
  
  
  
  $(HOSTPROGS): %$(HOSTEXESUF): %.o
  
      $(HOSTLD) $(HOSTLDFLAGS) $(HOSTLD_O) $^ $(HOSTLIBS)
  
  
  
  $(OBJS):     | $(sort $(dir $(OBJS)))
  
  $(HOBJS):    | $(sort $(dir $(HOBJS)))
  
  $(HOSTOBJS): | $(sort $(dir $(HOSTOBJS)))
  
  $(SLIBOBJS): | $(sort $(dir $(SLIBOBJS)))
  
  $(TESTOBJS): | $(sort $(dir $(TESTOBJS)))
  
  $(TOOLOBJS): | tools
  
  
  
  OBJDIRS := $(OBJDIRS) $(dir $(OBJS) $(HOBJS) $(HOSTOBJS) $(SLIBOBJS) $(TESTOBJS))
  
  
  
  CLEANSUFFIXES     = *.d *.o *~ *.h.c *.map *.ver *.ver-sol2 *.ho *.gcno *.gcda *$(DEFAULT_YASMD).asm
  
  DISTCLEANSUFFIXES = *.pc
  
  LIBSUFFIXES       = *.a *.lib *.so *.so.* *.dylib *.dll *.def *.dll.a
  
  
  
  define RULES
  
  clean::
  
      $(RM) $(HOSTPROGS)
  
      $(RM) $(TOOLS)
  
  endef
  
  
  
  $(eval $(RULES))
  
  
  
  -include $(wildcard $(OBJS:.o=.d) $(HOSTOBJS:.o=.d) $(TESTOBJS:.o=.d) $(HOBJS:.o=.d) $(SLIBOBJS:.o=.d)) $(OBJS:.o=$(DEFAULT_YASMD).d)