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• Bash - Get time difference from ffmpeg

  2 octobre 2017, par arjuncc

  I am building an an application using ffmpeg. In which I need to subtract start time of two files(there are only two files as input). following is my code.

  #!/bin/bash
  
  mkvarray=()
  
  mkvarray_name=()
  
  for video_name in *.mkv; do
  
  output=$(ffprobe -v error -show_entries format=start_time -of default=noprint_wrappers=1:nokey=1 "$video_name")
  
  mkvarray+=($output)
  
  mkvarray_name+=("$video_name")
  
  done 
  
  
  
  arraylength=${#mkvarray[@]}
  
  for (( i=0; i<${arraylength}; i++ ));
  
  do
  
    echo ${mkvarray_name[$i-1]} "------>  " ${mkvarray[$i-1]}
  
  done
  
  
  
  max_number=0
  
  if [[ ${mkvarray[0]} < ${mkvarray[1]} ]]; then
  
    echo "first-------------"
  
  
  
    max_number = ${mkvarray[0]} - ${mkvarray[1]}
  
    echo "first " $max_number
  
  else
  
     echo "second-------------"
  
     max_number = ${mkvarray[0]} - ${mkvarray[1]}
  
     echo "second " $max_number
  
  fi
  
  
  
  echo $max_number

  OUTPUT

  $ ./ffmpeg_updated.bash RTda01986c816052106c00f417387a83ff.mkv ------>
  2.040000 cc.mkv ------> 2.040000 RT4bafb05e1b36885c75d7d67a16f5e3b2.mkv ------> 4.086000
  first------------- ./ffmpeg_updated.bash : line 24 : max_number : command
  not found first 0 0

  from this I understood that, floating point arithmetic is not possible. So Is there any suggestion to proceed from this. I am pretty much new to bash. Or is there any alternative way to get things done in ffmpeg ?

• 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