Sur d’autres sites (9185)

• 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.

• live-streaming media with

  8 février 2012, par Thanh Hoang

  My live-streaming system streams media in following step :

  1. Server loads source (from a file, webcam,...)
  2. Server decodes this source by using ffmpeg to get audio and video stream in raw format
  3. Server encodes audio and video to aac and libx264 and then stores them with [AVPacket] (http://ffmpeg.org/doxygen/0.6/avpacket_8c.html)
  4. Then server transmits these packets to client
  5. Client receive these packets, then calculates pts and dts and then display them using libsdl. (following this [tutorial] (http://dranger.com/ffmpeg/tutorial01.html).

  And now, I want to change in client. I want when client receive audio and video packets, It will stream them under http stream, rtp stream or somethings like those to a player such as windows media player, flash player.... Anyone can helps me ? Thanks a lot. :)

• FFmpeg .jpg images to .mp4 incompatible with Windows Media Player

  8 janvier 2020, par willspill

  I have a series of 10 images with which I am trying to form an animation. I have used the following code below in the command line :

  ffmpeg -f image2 -i plot-%03d.jpg -r 5 -pix_fmt yuv420p -vcodec mpeg4 output.mp4

  This creates a .mp4 file with a seemingly valid file size, however, when trying to open with Windows Media Player gives the following error :

  Windows Media Player cannot play the file. The Player might not support the file type or might not support the codec that was used to compress the file.

  I have tried many solutions from previous threads but have found no solution. I have checked that my version of windows media player is compatible with mp4, avi, wmv etc. and have tried all of these outputs also. Any ideas of the issue ?

  The full code :

  M:Example\Frames_plot-001_jpg>ffmpeg -f image2 -i plot-%03
  
  ix_fmt yuv420p -vcodec mpeg4 output.mp4
  
  FFmpeg version SVN-r11200, Copyright (c) 2000-2007 Fabrice Bellard,
  
    configuration: --enable-memalign-hack
  
    libavutil version: 49.5.0
  
    libavcodec version: 51.48.0
  
    libavformat version: 52.1.0
  
    built on Dec 11 2007 14:33:27, gcc: 3.4.5 (mingw special)
  
  Input #0, image2, from 'plot-%03d.jpg':
  
    Duration: 00:00:00.4, start: 0.000000, bitrate: N/A
  
      Stream #0.0: Video: mjpeg, yuvj420p, 4167x4167 [PAR 120:120 DAR
  
  tb(r)
  
  Output #0, mp4, to 'output.mp4':
  
      Stream #0.0: Video: mpeg4, yuv420p, 4167x4167 [PAR 1:1 DAR 1:1]
  
   kb/s,  5.00 tb(c)
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Press [q] to stop encoding
  
  Compiler did not align stack variables. Libavcodec has been miscomp
  
  and may be very slow or crash. This is not a bug in libavcodec,
  
  but in the compiler. You may try recompiling using gcc >= 4.2.
  
  Do not report crashes to FFmpeg developers.
  
  frame=    3 fps=  3 q=4.0 Lsize=     917kB time=0.6 bitrate=12522.6
  
  video:916kB audio:0kB global headers:0kB muxing overhead 0.072455%