Sur d’autres sites (4329)

• Extracting media duration in R

  27 septembre 2015, par Jason French

  I’m investigating the fastest way to extract film duration in R using ffprobe and the data.table package.

  Setup Example Source Media

  wget https://ia801403.us.archive.org/13/items/AboutBan1935/AboutBan1935_512kb.mp4
  
  mv AboutBan1935_512kb.mp4 one.mp4
  
  for file in two.mp4 three.mp4 four.mp4 five.mp4 ; do cp one.mp4 "$file" ; done

  Various Approaches

  library(data.table)
  
  library(parallel)
  
  
  
  # Get locations
  
  executables <- Sys.which(c('ffprobe', 'ffmpeg'))
  
  
  
  # Duration Function
  
  get_duration_parallel <- function(files){
  
    mclapply(X = files, FUN = function(file){
  
      ffprobe_duration <- paste(executables['ffprobe'],
  
                                " -v quiet -print_format compact=print_section=0:nokey=1:escape=csv -show_entries format=duration ",
  
                                '"', file, '"', sep = "")
  
  
  
      file_duration <- as.numeric(system(command = ffprobe_duration, intern = TRUE))
  
      return(file_duration)
  
    }, mc.cores = detectCores())
  
  }
  
  
  
  get_duration <- function(files){
  
    sapply(X = files, FUN = function(file){
  
      ffprobe_duration <- paste(executables['ffprobe'],
  
                                " -v quiet -print_format compact=print_section=0:nokey=1:escape=csv -show_entries format=duration ",
  
                                '"', file, '"', sep = "")
  
  
  
      file_duration <- as.numeric(system(command = ffprobe_duration, intern = TRUE))
  
      return(file_duration)
  
    })
  
  }
  
  
  
  # Example table
  
  dt <- data.table(Path = list.files(path = ".", pattern = "*.mp4$"))
  
  
  
  
  
  system.time(
  
    dt[, Seconds := get_duration_parallel(Path)]
  
  )
  
  # 9.667 seconds    
  
  
  
  system.time(
  
    dt[, Seconds := get_duration(Path)]
  
  )
  
  # 0.078 seconds

  Am I missing any obvious speed-ups ? Scanning a 500-file archive for ffprobe stats takes 5 minutes in testing.

• how do i modify this ffmpeg build script for minimal binary size output

  13 janvier 2015, par Brian

  I’m trying to build the ffmpeg binaries for android on 3 chipsets. The output file size is too large to include in the project around 15mb.

  https://github.com/falnatsheh/ffmpeg-android is the github project repo

  the .sh build script for ffmpeg is like this

  #!/bin/bash
  
  
  
  . abi_settings.sh $1 $2 $3
  
  
  
  pushd ffmpeg
  
  
  
  case $1 in
  
    armeabi-v7a | armeabi-v7a-neon)
  
      CPU='cortex-a8'
  
    ;;
  
    x86)
  
      CPU='i686'
  
    ;;
  
  esac
  
  
  
  make clean
  
  
  
  ./configure \
  
  --target-os="$TARGET_OS" \
  
  --cross-prefix="$CROSS_PREFIX" \
  
  --arch="$NDK_ABI" \
  
  --cpu="$CPU" \
  
  --enable-runtime-cpudetect \
  
  --sysroot="$NDK_SYSROOT" \
  
  --enable-pic \
  
  --enable-libx264 \
  
  --enable-pthreads \
  
  --disable-debug \
  
  --disable-ffserver \
  
  --enable-version3 \
  
  --enable-hardcoded-tables \
  
  --disable-ffplay \
  
  --disable-ffprobe \
  
  --enable-gpl \
  
  --enable-yasm \
  
  --disable-doc \
  
  --disable-shared \
  
  --enable-static \
  
  --pkg-config="${2}/ffmpeg-pkg-config" \
  
  --prefix="${2}/build/${1}" \
  
  --extra-cflags="-I${TOOLCHAIN_PREFIX}/include $CFLAGS" \
  
  --extra-ldflags="-L${TOOLCHAIN_PREFIX}/lib $LDFLAGS" \
  
  --extra-libs="-lm" \
  
  --extra-cxxflags="$CXX_FLAGS" || exit 1
  
  
  
  make -j${NUMBER_OF_CORES} && make install || exit 1
  
  
  
  popd

  I tried adding —disable-everything as the first line in configure but then the compiler complains that I didnt set a target-os even though its the next line

  In the app I only use ffmpeg to take input mp4 videos and transpose and rotate them
  here are the two commands

  -y -i %s -vf transpose=%d -tune film -metadata:s:v rotate=0 -c:v libx264 -preset ultrafast -crf 27 -c:a copy -bsf:a aac_adtstoasc %s

  where %s is a file path

  and then concat files

  -y -i concat:%s -preset ultrafast -crf 27 -c:v copy -c:a copy -bsf:a aac_adtstoasc %s

  If someone can help me with the build script that would be awesome

• libavutil : introduce AVFilmGrainParams side data

  12 novembre 2020, par Lynne

  libavutil : introduce AVFilmGrainParams side data
  This patch introduces a new frame side data type AVFilmGrainParams for use
  
  with video codecs which support it.
  It can save a lot of memory used for duplicate processed reference frames and
  
  reduce copies when applying film grain during presentation.
  

  • [DH] doc/APIchanges
  • [DH] libavutil/Makefile
  • [DH] libavutil/film_grain_params.c
  • [DH] libavutil/film_grain_params.h
  • [DH] libavutil/frame.c
  • [DH] libavutil/frame.h
  • [DH] libavutil/version.h