FFmpeg : How to create rotating 3D (haas) effect in mp3 using ffmpeg? - audio

I want to add a rotating 3d effect (Haas effect) in mp3. I mean that the audio will seem to change its directions from left to right and vice versa periodically (as shown below) when listened through the headphone. For this, I searched on the Internet and tried to achieve it in the following ways:
Firstly, I thought, if I change the audio of the left and right channel periodically (like when the right channel has full volume (100%), left channel has low volume (20%) and vice versa) then I can achieve it, but it's not like 3D.
Secondly, when I researched more than found that it is done by creating a delay between the two channels. I found that I can create a delay of 0.0 to 0.8 milliseconds according to requirement.
To do this, I use the following commands in FFmpeg :
Step 1: Splitting Audio Channels :
ffmpeg -i D:\ffmpeg\Down.mp3 -map_channel 0.0.0 D:\ffmpeg\L.mp3 -map_channel 0.0.1 D:\ffmpeg\R.mp3
Stem 2: Splitting Left channel into parts :
Note: We will only change the speed of Left channel so we split left
channel into 4 seconds parts.
ffmpeg -i D:\ffmpeg\L.mp3 -f segment -segment_time 4 D:\ffmpeg\Split\%03d.mp3
Step 3: Changing the tempo of each part
Now We change the tempo (speed) of each part so it may feel like the sound
is moving from left to right and vice versa
ffmpeg -y -i D:\ffmpeg\Split\000.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\000.mp3
ffmpeg -y -i D:\ffmpeg\Split\001.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\001.mp3
ffmpeg -y -i D:\ffmpeg\Split\002.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\002.mp3
ffmpeg -y -i D:\ffmpeg\Split\003.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\003.mp3
ffmpeg -y -i D:\ffmpeg\Split\004.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\004.mp3
ffmpeg -y -i D:\ffmpeg\Split\005.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\005.mp3
ffmpeg -y -i D:\ffmpeg\Split\006.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\006.mp3
ffmpeg -y -i D:\ffmpeg\Split\007.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\007.mp3
ffmpeg -y -i D:\ffmpeg\Split\008.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\008.mp3
ffmpeg -y -i D:\ffmpeg\Split\009.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\009.mp3
ffmpeg -y -i D:\ffmpeg\Split\010.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\010.mp3
ffmpeg -y -i D:\ffmpeg\Split\011.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\011.mp3
ffmpeg -y -i D:\ffmpeg\Split\012.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\012.mp3
ffmpeg -y -i D:\ffmpeg\Split\013.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\013.mp3
ffmpeg -y -i D:\ffmpeg\Split\014.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\014.mp3
ffmpeg -y -i D:\ffmpeg\Split\015.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\015.mp3
ffmpeg -y -i D:\ffmpeg\Split\016.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\016.mp3
ffmpeg -y -i D:\ffmpeg\Split\017.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\017.mp3
ffmpeg -y -i D:\ffmpeg\Split\018.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\018.mp3
ffmpeg -y -i D:\ffmpeg\Split\019.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\019.mp3
ffmpeg -y -i D:\ffmpeg\Split\020.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\020.mp3
ffmpeg -y -i D:\ffmpeg\Split\021.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\021.mp3
ffmpeg -y -i D:\ffmpeg\Split\022.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\022.mp3
ffmpeg -y -i D:\ffmpeg\Split\023.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\023.mp3
ffmpeg -y -i D:\ffmpeg\Split\024.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\024.mp3
ffmpeg -y -i D:\ffmpeg\Split\025.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\025.mp3
ffmpeg -y -i D:\ffmpeg\Split\026.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\026.mp3
ffmpeg -y -i D:\ffmpeg\Split\027.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\027.mp3
ffmpeg -y -i D:\ffmpeg\Split\028.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\028.mp3
ffmpeg -y -i D:\ffmpeg\Split\029.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\029.mp3
ffmpeg -y -i D:\ffmpeg\Split\030.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\030.mp3
ffmpeg -y -i D:\ffmpeg\Split\031.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\031.mp3
ffmpeg -y -i D:\ffmpeg\Split\032.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\032.mp3
ffmpeg -y -i D:\ffmpeg\Split\033.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\033.mp3
ffmpeg -y -i D:\ffmpeg\Split\034.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\034.mp3
ffmpeg -y -i D:\ffmpeg\Split\035.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\035.mp3
ffmpeg -y -i D:\ffmpeg\Split\036.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\036.mp3
ffmpeg -y -i D:\ffmpeg\Split\037.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\037.mp3
ffmpeg -y -i D:\ffmpeg\Split\038.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\038.mp3
ffmpeg -y -i D:\ffmpeg\Split\039.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\039.mp3
ffmpeg -y -i D:\ffmpeg\Split\040.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\040.mp3
ffmpeg -y -i D:\ffmpeg\Split\041.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\041.mp3
ffmpeg -y -i D:\ffmpeg\Split\042.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\042.mp3
ffmpeg -y -i D:\ffmpeg\Split\043.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\043.mp3
ffmpeg -y -i D:\ffmpeg\Split\044.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\044.mp3
ffmpeg -y -i D:\ffmpeg\Split\045.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\045.mp3
ffmpeg -y -i D:\ffmpeg\Split\046.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\046.mp3
ffmpeg -y -i D:\ffmpeg\Split\047.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\047.mp3
ffmpeg -y -i D:\ffmpeg\Split\048.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\048.mp3
ffmpeg -y -i D:\ffmpeg\Split\049.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\049.mp3
ffmpeg -y -i D:\ffmpeg\Split\050.mp3 -af atempo=0.9992 D:\ffmpeg\Modi\050.mp3
ffmpeg -y -i D:\ffmpeg\Split\051.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\051.mp3
ffmpeg -y -i D:\ffmpeg\Split\052.mp3 -af atempo=1.0008 D:\ffmpeg\Modi\052.mp3
ffmpeg -y -i D:\ffmpeg\Split\053.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\053.mp3
ffmpeg -y -i D:\ffmpeg\Split\054.mp3 -af atempo=1.0000 D:\ffmpeg\Modi\054.mp3
Here I used 1.0000 for normal speed
and 1.0008 for increased speed
and 0.9992 for decreased speed
Spet 4: Merging small pieces of audio
ffmpeg -f concat -safe 0 -i D:\ffmpeg\f.txt -c copy D:\ffmpeg\output.mp3
where f.txt contains :
file 'D:\ffmpeg\Modi\000.mp3'
file 'D:\ffmpeg\Modi\001.mp3'
file 'D:\ffmpeg\Modi\002.mp3'
file 'D:\ffmpeg\Modi\003.mp3'
file 'D:\ffmpeg\Modi\004.mp3'
file 'D:\ffmpeg\Modi\005.mp3'
file 'D:\ffmpeg\Modi\006.mp3'
file 'D:\ffmpeg\Modi\007.mp3'
file 'D:\ffmpeg\Modi\008.mp3'
file 'D:\ffmpeg\Modi\009.mp3'
file 'D:\ffmpeg\Modi\010.mp3'
file 'D:\ffmpeg\Modi\011.mp3'
file 'D:\ffmpeg\Modi\012.mp3'
file 'D:\ffmpeg\Modi\013.mp3'
file 'D:\ffmpeg\Modi\014.mp3'
file 'D:\ffmpeg\Modi\015.mp3'
file 'D:\ffmpeg\Modi\016.mp3'
file 'D:\ffmpeg\Modi\017.mp3'
file 'D:\ffmpeg\Modi\018.mp3'
file 'D:\ffmpeg\Modi\019.mp3'
file 'D:\ffmpeg\Modi\020.mp3'
file 'D:\ffmpeg\Modi\021.mp3'
file 'D:\ffmpeg\Modi\022.mp3'
file 'D:\ffmpeg\Modi\023.mp3'
file 'D:\ffmpeg\Modi\024.mp3'
Step 5: The last operation is combining the both channels :
ffmpeg -i D:\ffmpeg\L.mp3 -i D:\ffmpeg\output.mp3 -filter_complex [0:a][1:a]amerge=inputs=2[aout] -map [aout] D:\ffmpeg\LRM.mp3
But even then the result is very poor. It looks like FFmpeg combines audio in Step 4 took a delay after each audio.
I think there may be some bug in my solution. I don't think that I can change tempo like this in audio without splitting the audio(Let me know if I am wrong).
Does anyone have a different solution to achieve this?
Please help me in this. Thanks in advance...

You want the apulsator filter or the eponymous Haas filter.
ffmpeg -i D:\ffmpeg\Down.mp3 -af apulsator=hz=0.125 out.mp3
This will rotate the audio from left to right and back in 8 seconds (1/0.125).

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I'm facing a big misunderstanding with bash.
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process is logged to the file.
But executing
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Thanks anybody for trying to help me! :)

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2) stream the video to a udp address:
ffmpeg -re -i test.mp4 -c copy -f flv udp://127.0.0.1:48550
I am trying to combine both these instructions into one command line instruction, using &&, as suggested in the answer to a previous question of mine:
ffmpeg -r 60 -f image2 -s 1920x1080 -i rotated-pano_frame%05d_color_corrected_gradblend.jpg -vcodec libx264 -crf 25 -pix_fmt yuv420p test.mp4 \
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Currently, using ffmpeg, I am using two commands on my Terminal to:
1) create a video from a bunch of images:
ffmpeg -r 60 -f image2 -s 1920x1080 -i rotated-pano_frame%05d_color_corrected_gradblend.jpg -vcodec libx264 -crf 25 -pix_fmt yuv420p test.mp4
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Need to concat audio files and add background music in a single command.
Right now I use the following commands to do so,
To concat:
ffmpeg -i 1.mp4 -i 2.mp4 -i 3.mp4 -i 4.mp4 -i 5.mp4 -i 6.mp4 -i 7.mp4 -i 8.mp4 -i 9.mp4 -i 10.mp4 -filter_complex '[0:0][1:0]concat=n=10:v=0:a=1[out]' -map '[out]' -strict -2 -y 10_final.mp4
To add background music:
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But his process is a quite time-consuming process as every time the file read/write happening to the output.
Is there a way I can merge these two above commands to a single so that the command should be optimized.
Use
ffmpeg -i 1.mp4 -i 2.mp4 -i 3.mp4 -i 4.mp4 -i 5.mp4
-i 6.mp4 -i 7.mp4 -i 8.mp4 -i 9.mp4 -i 10.mp4
-i music.mp4
-filter_complex '[0:0][1:0]...[9:0]concat=n=10:v=0:a=1,volume=1dB[a0];
[10]volume=0.5dB[a1];[a0][a1]amerge[a]'
-map '[a]' -strict -2 -y 10_with_music.mp4

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