LinuxQuestions.org - [SOLVED] bash: How can executing an external command confuse a while (read lines from file) loop?

Hi,

I have a set of corrupted .mp4 videos and I wrote a bash script to fix them using ffmpeg. Fortunately, only the container is corrupted, and the streams are OK. While fixing, I would like to add titles that are read from a .m3u playlist.

The script reads the .m3u file line by line, ignores empty lines and the leading #EXTM3U, and then it depends on the line content:
If the line contains "EXTINF:", the title is extracted from that line, remembered, and used for the next line that contains a file name. With that information, ffmpeg is executed. No one alters the input .m3u file.

The problem is:
After the first time ffmpeg is really executed, the lines read from the .m3u are incomplete, trimmed or whatever. If I comment out the line executing ffmpeg, the file is parsed as expected.

This is a shortened version of the .m3u playlist:

Code:

#EXTM3U



#EXTINF:2886,01 Premiere

01_Premiere.mp4



#EXTINF:2913,02 Das Leben soll nicht enden

02_Das_Leben_soll_nicht_enden.mp4



#EXTINF:2813,03 Gefährlicher Besucher an Bord

03_Gefaehrlicher_Besucher_an_Bord.mp4

I have verified that it only has unix/Linux file endings (LF).

And this is the script (whith ffmpeg commented out):

Code:

#!/bin/bash



delimiter() {

  echo "================================================================================"

}



INPUTFILE=$1

TARGETDIR=$2



if [ "$INPUTFILE" == "" -o "$TARGETDIR" == "" ]

then

  echo "Input-File and/or target-dir missing."

  exit 1

fi



CURRENT_TITLE=



while read INPUT_LINE

do

  if [ "$INPUT_LINE" == "" -o "$INPUT_LINE" == "#EXTM3U" ]

  then

    continue

  fi



  delimiter

  echo "LINE=\"$INPUT_LINE\""



  if [[ $INPUT_LINE =~ EXTINF: ]]

  then

    CURRENT_TITLE="`echo "$INPUT_LINE" | sed -e 's/.*#EXTINF:[0-9]*,//;'`"

    echo "TITLE=$CURRENT_TITLE"

  else

    if [ -f "$INPUT_LINE" ]

    then

      if [ "$CURRENT_TITLE" != "" ]

      then

        OUTPUTFILE="${TARGETDIR}/${INPUT_LINE##*/}"

        echo "$INPUT_LINE -> $CURRENT_TITLE"

#        ffmpeg -i "$INPUT_LINE" -loglevel quiet -c copy -metadata title="$CURRENT_TITLE" "$OUTPUTFILE"

      else

        echo "ERROR: no current title for file \"$INPUT_LINE\"."

        exit 1

      fi

    else

      echo "ERROR: line \"$INPUT_LINE\" is neither title nor file."

      exit 1

    fi

    CURRENT_TITLE=

  fi

done < <(cat "$INPUTFILE")

As you see, it has some diagnostic echo's.

This is the expected output that I only can achieve with ffmpeg commented out:

Code:

================================================================================

LINE="#EXTINF:2886,01 Premiere"

TITLE=01 Premiere

================================================================================

LINE="01_Premiere.mp4"

01_Premiere.mp4 -> 01 Premiere

================================================================================

LINE="#EXTINF:2913,02 Das Leben soll nicht enden"

TITLE=02 Das Leben soll nicht enden

================================================================================

LINE="02_Das_Leben_soll_nicht_enden.mp4"

02_Das_Leben_soll_nicht_enden.mp4 -> 02 Das Leben soll nicht enden

================================================================================

LINE="#EXTINF:2813,03 Gefährlicher Besucher an Bord"

TITLE=03 Gefährlicher Besucher an Bord

================================================================================

LINE="03_Gefaehrlicher_Besucher_an_Bord.mp4"

03_Gefaehrlicher_Besucher_an_Bord.mp4 -> 03 Gefährlicher Besucher an Bord

But with the ffmpeg line being active, it looks like this:

Code:

================================================================================

LINE="#EXTINF:2886,01 Premiere"

TITLE=01 Premiere

================================================================================

LINE="01_Premiere.mp4"

01_Premiere.mp4 -> 01 Premiere

================================================================================

LINE="oll nicht enden"

ERROR: line "oll nicht enden" is neither title nor file.

So, the line

Code:

#EXTINF:2913,02 Das Leben soll nicht enden

is trimmed to

Code:

oll nicht enden

and therefore not recognized as #EXTINF.

What did I miss ?

Regards,
Markus