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• how to specify a seqence of image file to ffmpeg

  5 juillet 2014, par steveh

  i’m trying to encode a sequence of raw rgb image files in ffmpeg

  i have created a list of test files named lmfd001.rgb to lmfd299.rgb (300 total)

  i/m attempting to compress like this

  ffmpeg.exe -s 450x450 -pix_fmt rgb8 -c h264 -i lmfd%03d.rgb out.mp4

  it says

  lmfd%03d.rgb: No such file or directory

  i’m in a cygwin shell. i’m in the .rgb files directory.

  i also tried -i lmfd%03.rgb. i- lmfd001.rgb works but 1 file isn’t much use.

  i’ve googled around and that seems to be the right format. any ideas anyone ?

  i read this
  Warning : ffmpeg command line arguments are position sensitive – make sure you don’t mix up the order. Good rule of thumb to prevent mistakes is to keep the order of

  ffmpeg [input options] -i [input filename] -codec:v [video options] -codec:a [audio options] [output file options] [output filename]

  so i tried that too but didn ;t help

• Why does not work audio element currentTime on ffmpeg encoded mp3 file in Chrome browser

  25 juillet 2013, par Peter

  I have an HTML5 audio element :

  <audio preload="auto">
  
      <source src="./Sound/recording.mp3" type="audio/mpeg">
  
  </source></audio>

  and I need to be able to play last 4 seconds from mp3 recording. My javaScript is :

  audio.currentTime = audio.duration-4;
  
  audio.play();

  Works ok in IE10 and Firefox, but Chrome starts playing from a wrong place. The difference between reported audio.currentTime and actual playback position is about 20s. The recording.mp3 is created with ffmpeg :

  ffmpeg -i recording.wav -ab 32k recording.mp3

  It works, when I strip the ID3v2 header from the recording.mp3 (deleting the first couple bytes in the file before the audio data).

  It also works when I compress to ogg. Can somebody point me to the right direction (ffmpeg switches, audio element attributes or whatever) to get it work also in chrome ?

  Thanks in advance

• Compression of a video with constant background

  28 juin 2017, par Spirou003

  (sorry if my english is bad, I can read it but I don’t write it quite well...)

  I want to compress some videos, which have two particularities :

  • there is a background that covers 90% of the area, during the whole video
  • most of the others elements can be separately described by a picture in move

  My videos are like this one, and don’t have audio. As you can see, almost everything can be described only by using a fixed background, few small images in move, plus a noise. Moreover, this noise will be almost nul and then an entropic coding would be very efficient. I think it will produce tiny files (< 5 Mo) even if the duration is in hours, a result that is very appreciable since I have actually recorded 30h of game (actual size is 3 Go).

  Is there any way to get new video files, that benefit of these informations ? If yes, what are the implication of a such encoding for watching these videos with Windows Media Player, or for usage with ffmpeg ?

  I searched with Google after anything that can help me, but I don’t know which keyword I can use for this, then I didn’t found anything usefull :-(

  Thanks in advance :-)

  PS : another example, the video is accelerated but shows the interesting moves