Sur d’autres sites (15141)

• fftools/cmdutils : tighten condition for media type stream specifiers

  8 août 2024, par Anton Khirnov

  fftools/cmdutils : tighten condition for media type stream specifiers
  Require the character indicating media type to be followed by a
  
  non-alphanumeric character (or end of string).
  Needed by future syntax extensions.
  

  • [DH] fftools/cmdutils.c

• Seeking while Transcoding videos from Windows Media Player

  3 juillet 2015, par prakharsingh95

  I am using Windows Media Player’s default DLNA server and the streaming is great.

  However, when I try to stream AC3 to VLC for iOS, on iPad Air 2, it converts it to a large number of available formats :
  

  If I try AVC_MP4_BL_L31_HD_AAC, this provides the untranscoded media, which I can stream and SEEK. However, AC3 is not playable.

  However, AVC_MP4_MP_HD_720p_AAC is transcoded by Windows Media Player on the fly, but is NOT SEEKABLE.

  How do I add support for seeking transcoded media from Windows Media Player ?

  I can convert using ffmpeg, but I would prefer the above solution.

• 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.