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• How to configure FFMPEG to generate position independent code on IOS

  8 juillet 2013, par madadi

  I am developing an app on iOS which makes use of FFMPEG for video decoding. I want to get 'position independent code' of FFMPEG working on my app. --enable-pic option in the FFMPEG configuration generates position independent code only if I set --disable-asm. I concluded this when I ran the otool on my app(otool -hv 'appname'). Below are the details :

  If I set --enable-pic alone, below is the output with otool :

  magic     cputype  cpusubtype  caps  filetype  ncmds  sizeofcmds  flags
  
  MH_MAGIC  ARM      V7          0x00  EXECUTE   29     3724        NOUNDEFS DYLDLINK TWOLEVEL WEAK_DEFINES BINDS_TO_WEAK

  If I set --enable-pic and --disable-asm below is the output with otool,

  magic     cputype  cpusubtype  caps  filetype  ncmds  sizeofcmds  flags
  
  MH_MAGIC  ARM      V7          0x00  EXECUTE   51     5520        NOUNDEFS DYLDLINK TWOLEVEL WEAK_DEFINES BINDS_TO_WEAK **PIE** 

  Below are my configuration settings for FFMPEG(build-ffmpeg-ios.sh) :

  if [  `uname` =  "Darwin" ]; then
  
    SEDCMD="sed -i '' "
  
  else
  
    SEDCMD="sed -i "
  
  fi
  
  
  
  
  
  make clean
  
  ./configure \
  
      --prefix=$PREFIX \
  
      --enable-version3 \
  
      --enable-static \
  
      --disable-shared \
  
      --disable-doc \
  
      --disable-ffmpeg \
  
      --disable-ffplay \
  
      --disable-ffprobe \
  
      --disable-ffserver \
  
      --disable-avdevice \
  
      --disable-avfilter \
  
      --disable-postproc \
  
      --enable-small \
  
      --cross-prefix="$DEVROOT/usr/bin/" \
  
      --enable-cross-compile \
  
      --target-os=darwin \
  
      --arch=$ARCH \
  
      --cpu=$CPU \
  
      --cc="$CC" \
  
      --as="$AS" \
  
      --extra-cflags="$CFLAGS" \
  
      --extra-ldflags="$CFLAGS" \
  
      --disable-symver \
  
      --disable-debug \
  
      --disable-indevs \
  
      --disable-encoders \
  
      --disable-bsfs \
  
      --enable-pic \
  
      --disable-filters \
  
      $CONFIGURE_FLAGS || exit 1;
  
  $SEDCMD 's/HAVE_INLINE_ASM 1/HAVE_INLINE_ASM 0/g' config.h
  
  make install || exit 1;

  And below is the make file I use(iOS.mk) :

  FFMPEG_LIBS := libavcodec.a libavformat.a libavutil.a libswscale.a
  
  
  
  IOS_ARMV7_FFMPEG_LIB := $(addprefix build/ios/armv7/lib/, $(FFMPEG_LIBS))
  
  
  
  IOS_UNI_FFMPEG_LIB := $(addprefix build/ios/universal/lib/, $(FFMPEG_LIBS))
  
  
  
  
  
  
  
  IPHONE_SDK_VERSION := "5.0"
  
  IPHONE_DEPLOY_SDK := "3.2"
  
  
  
  ALL_IOS_LIBS := $(IOS_UNI_FFMPEG_LIB) 
  
  
  
  build/ios/universal/lib/%.a : build/ios/armv7/lib/%.a
  
      mkdir -p build/ios/universal/lib
  
      lipo -create -output $@ $^
  
  
  
  
  
  
  
  $(IOS_ARMV7_FFMPEG_LIB): 
  
      export PREFIX="`$(ABSPATH) build/ios/armv7`" && \
  
      export ARCH="arm" && \
  
      export CPU="cortex-a8" && \
  
      export IOS_BASE_SDK="$(IPHONE_SDK_VERSION)" && \
  
      export IOS_DEPLOY_TGT="$(IPHONE_DEPLOY_SDK)" && \
  
      export CONFIGURE_FLAGS="--enable-neon" && \
  
      export PATH="`$(ABSPATH) venders`:$$PATH" && \
  
      cd venders/ffmpeg && bash ../iphone-compile.sh arm7 ../build-ffmpeg-ios.sh

  Can someone please help me with getting the FFMPEG up and running with both 'pic' and assembly optimization enabled. Without assembly optimizastion, FFMPEG would not be helpful to me as the video decoding is extremely slow.

• lavc/hevcdec : move the check for multiple frames in a packet

  3 juin 2024, par Anton Khirnov

  lavc/hevcdec : move the check for multiple frames in a packet
  Do not do it in hls_slice_header(), which is the wrong place for it.
  
  Avoids special magic return value of 1 in that function. The comment
  
  mentioning potential corrupted state is no longer relevant, as
  
  hls_slice_header() modifies no state beyond SliceHeader, which will only
  
  get used for a valid frame.
  

  • [DH] libavcodec/hevc/hevcdec.c

• Have ffplay output current time in millisecond resolution

  21 août 2020, par 12.yakir

  What are the arguments for ffplay to output the duration/time-stamp of the current frame in millisecond resolution (dumping it to stderr or stdout, not embedding or overlaying it into the video) ?

  


  Right now playing a video (and pausing it) will look like this :

  


  ~$ ffplay -i video.mp4 -hide_banner -loglevel 8 -stats
   2.09 A-V: -0.004 fd=   6 aq=   31KB vq=   84KB sq=    0B f=0/0


  


  Note that the current time, 2.09, is in "centi-seconds" (one hundredth of a second), not millisecond (one thousandeth of a second).

  


  Ideally, it would output only the current time in millisecond resolution :

  


  ~$ ffplay -i video.mp4 -hide_banner -loglevel 8 -stats <enter magic="magic" arguments="arguments" here="here">&#xA;   2.093&#xA;</enter>