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• Should libavcodec handle non-packed/non-byte-aligned mp3 packets ?

  27 août 2015, par Rhythmic Fistman

  I’m transcoding shoutcast streams using libavcodec and I noticed that during the day I get a few 10s’ of packets that it cannot decode without some help :

  1. Leading zero bytes before a packet sync word, e.g. 0x0000fffa

  2. non-byte aligned syncword, e.g 0x82a0fffa

  In the first case I have to toss out the zero bytes and in the second I have to shift the data up by an odd number of nibbles.

  I don’t have a watertight knowledge of the mp3 spec (is there one ?), but my impression was that the packet format was a bit oriented, not byte, so both types of packets look right to me.

  So who is in the wrong here ?

  Is it libavcodec for not parsing valid packets ?

  Or the stream encoder for producing non-standard packets ?

• ffmpeg I want to combine the three command in one command

  12 janvier 2019, par Abdulwahed AbuAbed

  hello I’m new here I want to marge many command in one, like add subtitle file , image (watermark) and write word in top right in video .
  without effecting video Quality and size , and if it possible make it fast like a single command .

  ffmpeg -i input.mkv -vf subtitles=subtitle.srt -sn out.mkv  
  
  ffmpeg -i input.mkv -vf "movie=image.png [watermark]; [in][watermark] overlay=10:10 [out]" out.mkv  
  
  ffmpeg -i input.mkv -vf drawtext=text='Hallo':x=10:y=H-th-10:fontfile=/path/to/font.ttf:fontsize=12:fontcolor=white:shadowcolor=black:shadowx=5:shadowy=5" out.mkv

• subprocess.Popen crashes when run in background

  17 mars 2016, par user2810298

  In a program I’m working with right now, I try to check for the version of FFMPEG that is installed on the users machine. This works perfectly fine by using subprocess.Popen when run in the foreground OR when run in a detached screen.

  However, when you run it in the background without screen (e.g. COMMAND &> /dev/null &) this process crashes the program. (see below) I’ve seen some people having similar issues on the web, but I still can’t seem to fix this...

  I’ve Any ideas ?

  version_ffmpeg = subprocess.Popen(["ffmpeg","-version"],stdout=subprocess.PIPE,stderr=None)
  
  
  
  f_out = version_ffmpeg.communicate()
  
  (then...)
  
  if f_out --> 3rd word contains --> etc.