Merge multiple audio files along with silence using ffmpeg.

ffmpeg_audio_merged.py

import subprocess
import json


def main():
    jsonfilename = 'source_list.json'

    with open(jsonfilename) as f:
        data = json.load(f)
        inFiles = data["read_info"]["files"]
        outFile = data["write_info"]["file"]
        ffmpeg_args = data["ffmpeg_args"]

    # prepare the ffmpeg_args
    for i in range(len(inFiles) + 1):
        replace_str = '%' + str(i) + '%'
        if replace_str in ffmpeg_args:
            ffmpeg_args = ffmpeg_args.replace(replace_str, inFiles[i - 1])

    # replace the output file name
    if '%OUTFILE%' in ffmpeg_args:
        ffmpeg_args = ffmpeg_args.replace('%OUTFILE%', outFile)

    # print(ffmpeg_args)
    # subprocess.check_output(cmd, shell=True) 
    subprocess.call('ffmpeg ' + ffmpeg_args, shell=True)


main()

source_list.json

{
	"read_info": {"bucket":"lentil2-dev",
		 "files": [
		 "audio1.aac",
		 "audio2.aac",
		 "audio3.aac"
		 ]
	 },
	"write_info": {
		"bucket":"lentil2-dev",
		"file":"merged_audio"
        },

	"ffmpeg_args": "-f lavfi -t 0.731 -i anullsrc=channel_layout=mono:sample_rate=48000 -i %1% -f lavfi -t 7.949 -i anullsrc=channel_layout=mono:sample_rate=48000 -i %2% -f lavfi -t 13.049 -i anullsrc=channel_layout=mono:sample_rate=48000 -i %3% -filter_complex concat=n=6:v=0:a=1[audio] -map [audio] -y -t 120.207 %OUTFILE%.mp4"
}