Concatenate mp4 files.

concatenate_mp4.sh

#!/bin/bash


# concatenate second file to end of first file
# first file  1.mp4 duration: 10sec
# second file 2.mp4 duration: 20sec
# output file 1.mp4 duration: 30sec
concatenate_files() 
{
   file1=$1
   file2=$2
   outputFile=$1_out_tmp.mp4
   temp1=$1_temp.ts
   temp2=$2_temp.ts
   

   ffmpeg -y -i $file1 -c copy -bsf:v h264_mp4toannexb -f mpegts  $temp1  
   ffmpeg -y -i $file2 -c copy -bsf:v h264_mp4toannexb -f mpegts  $temp2 
   ffmpeg -f mpegts  -i "concat:$temp1|$temp2"  -c copy -bsf:a aac_adtstoasc  $outputFile 

   #replace outputFile to  first file
   mv $outputFile $file1
   #delete second file and fifos
   rm $2 $temp1 $temp2

}

# get the file name
filename=$(basename "$1")
dirname=$(dirname "$1")

#find the position of suffix,suffix of  stream1_720p_1.mp4 is _1.mp4.  original file stream1_720p.mp4 
position=`echo $filename | grep -b -o -E "_{1}[0-9]+\.mp4$" | awk 'BEGIN {FS=":"}{print $1}'`

echo $position


if [ ! -z $position ] 
then
    echo "matched"
    echo ${filename:0:$position}
    endPosition=`echo $filename | grep -b -o -E "\.mp4$" | awk 'BEGIN {FS=":"}{print $1}'`   
    startPosition=`expr $position + 1` 
    length=`expr $endPosition - $startPosition`
    streamIndex=${filename:$startPosition:$length}
    originalFilename=$dirname/${filename:0:$position}.mp4
    echo "original file name $originalFilename"
    if [ ! -f $originalFilename ]
    then
       echo "Original file($originalFilename) does not exist"
       exit 1 
    fi
    #loop down to 1 to concat files and delete file if it's finished    
     concatenate_files $originalFilename $1
   # for (( i=1; i<=$streamIndex; i++ )) 
   # do
   #    echo  "stream index $i"     
   # done

    
else
    echo "not matched"
    exit 1
fi