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• How to convert short video clips to TS without sound "gaps" between the segments ?

  10 novembre 2022, par Zvika

  I am trying to convert a sequence of short video files from MP4 to TS using ffmpeg.
I get valid TS files, but when playing them in any HLS player, there is a noticeable short gap in the sound between segment to segment.

  


  If I first stitch all the short video files to a single video file, and convert this file to TS while slicing it to segments, it plays perfectly fine.

  


  To the gory details :
My software creates short video clips that should be concateenated to an output video and streamed as HLS.
Each short clip is an H.264 video file and WAV audio file (I can create other formats if needed).
I then convert each such pair of H.264+WAV to a TS file using ffmpeg :
ffmpeg -y -i seg_0.mp4 -i seg_0.wav -c:a libvo_aacenc -c:v copy -bsf:v h264_mp4toannexb seg_0.ts ffmpeg -y -i seg_1.mp4 -i seg_1.wav -c:a libvo_aacenc -c:v copy -bsf:v h264_mp4toannexb -output_ts_offset 2.01 seg_1.ts ffmpeg -y -i seg_2.mp4 -i seg_2.wav -c:a libvo_aacenc -c:v copy -bsf:v h264_mp4toannexb -output_ts_offset 4.02 seg_2.ts
etc.

  


  and I create an appropriate M3U8 file to play all the short clips as a sequence.
The result is not satisfying, as I have audio gaps between each segment and segment, as you can hear here :
https://rnd3-temp-public.s3.amazonaws.com/HLS_4/out_seg2.m3u8

  


  However, if I concat all the pairs together, and convert the concatenated sequence to TS, while requesting ffmpeg to slice them again to segments, using a command like :
ffmpeg -y -f concat -i mp4_list.txt -f concat -i wav_list.txt -c:a libvo_aacenc -c:v copy -bsf:v h264_mp4toannexb -flags +cgop -g 30 -hls_time 2 out2.m3u8
it plays perfectly OK, as you can hear here :
https://rnd3-temp-public.s3.amazonaws.com/HLS/out2.m3u8

  


  How can I get a clear audio output by still encoding each segment separately ? (It's crucial for my workflow)

  


  Thanks !

  


• FFMPEG to remove audio but keeping background sound

  17 octobre 2022, par Sushil

  I am trying to add voice over to the existing video which has some audio in English and some background sound. I am trying to add other than English audio on top of it and keeping background sound. But when I add new audio it removes all the background sound and when it adds new audio which makes it robotic as original background sound is lost.
When I add new audio by using amix filter, it keeps all sound like English and new language both, and both plays together.

  


  

  1. Is there any way to separate background sound and speaking audio from video separately ?

  


  2. Is it possible to mute or remove audio from only parts of video like offset between time frames ?

  


  


  Command that I am using for add new audio
ffmpeg  -i independance_speech.mp4  -i 01.mp3 -filter_complex "[1]adelay=10000[s1];[s1]amix=inputs=2[a]" -map 0:v  -map "[a]" -c:v copy result.mp4

  


• Start ffmpeg sound recording at system start doesn't work

  3 octobre 2022, par CheatingBoy

  I made a python script to record sound at System boot, but it doesn't work. I've tried using crontab and systemd but it doesn't work. If I start the program manually it works out fine.

  


  #!/bin/python3
import RPi.GPIO as GPIO
import time
import datetime
import subprocess
import os
import signal
GPIO.setmode(GPIO.BCM)
GPIO.setup(24, GPIO.IN)
GPIO.setup(23, GPIO.OUT)
print("Started Sound_Recorder_ULtimate_Control")
p = None
while True:
        time.sleep(0.5)
        if GPIO.input(24) == 1:
            if p is None:
                print("Preparing to recorde")
                today = datetime.datetime.now()
                time1 = "{}.{}.{}_{}:{}:{}".format(today.day , today.month, today.year, today.hour, today.minute, today.second)
                # Aufname starten
                command = "sh -c 'ffmpeg -f pulse -nostdin -i alsa_input.usb-FuZhou_Kingwayinfo_CO._LTD_TONOR_TC30_Audio_Device_20200707-00.mono-fallback /home/pi/sound_recorder/Recordes/'" + time1 + ".mp3"
                print(command)
                #subprocess.Popen(command)
                p = subprocess.Popen(command, stdout=subprocess.PIPE, 
                       shell=True, preexec_fn=os.setsid)
                print("Recording...")
                GPIO.output(23, GPIO.HIGH)
                time.sleep(2)    

            else:
                print("Terminate")
                os.killpg(os.getpgid(p.pid), signal.SIGTERM)
                GPIO.output(23, GPIO.LOW)
                p = None
                time.sleep(2)