I'm using FFMPEG and I want to use a silent track as a template. I want to take two audio streams from a WEBM file and concatenate them together, but the second audio has a delayed start. I want an audio silence between them. How would I do that?
This is what I currently have:
ffmpeg -i W1.webm -itsoffset 10 -i W2.webm -f lavfi -t 600 -i anullsrc=cl=stereo -filter_complex '[0:1][1:1][2:1] amerge=inputs=3' output.webm
Furthermore, I want to end the output at the end of the second audio stream.
No need to use amerge; the concat filter will work.
ffmpeg -i W1.webm -i W2.webm -filter_complex '[1:a]adelay=10s|10s[a1];[0:a][a1]concat=n=2:v=0:a=1' -ac 2 output.webm
Use ffmpeg 4.2 or newer.
Related
I have ubuntu 20.04 and in past days I did this job(merge video and audio) well in terminal and with ffmpeg:
ffmpeg -i input.mp4 -i input2.mp3 -c copy output.mp4
so fast I have recived output.mp4, but now I tried this one and get output without any sound!
I try another ways to merge this ones(also with ffmpeg) but there are no diffrent...
ffmpeg -f concat -safe 0 -i <(for f in ./input*.mp4; do echo "file '$PWD/$f'"; done) -c copy output.mp4
Note -f concat will select a demuxer. This alters the way -i nput files are read.
So instead video-files 'concat expects a txt-file listing the files to concatenate.
However we somehow omit the creation of that text file and use process substitution to generate and pass that list on the fly to demux.
For more details go here:
https://trac.ffmpeg.org/wiki/Concatenate#demuxer
If you want to merge several video files, you can use these command.
merge two video files.
ffmpeg -f concat -i 1.mp4 -1 2.mp4 -codec copy out.mp4
merge multiple video files.
ffmpeg -i 1.mp4 -i 2.mp4 -i 3.mpt -vcodec copy -acodec copy out.mp4
I have a video file without sound and a stereo audio file. Video is several times longer than audio. I'd like to create a background sound which starts from 2 second silence, then trim silence of the audio at both ends and duplicate trimmed audio several times to the end of the video.
I found how to trim audio:
ffmpeg -y -i audio.wav -af silenceremove=start_periods=1:start_threshold=-75dB,areverse,silenceremove=start_periods=1:start_threshold=-75dB,areverse trimmed_audio.wav
And how to create silence:
ffmpeg -y -f lavfi -i anullsrc=channel_layout=stereo:sample_rate=48000:duration=2 silence.wav
How can I duplicate the audio and combine it with the video?
Basic syntax is
ffmpeg -an -i video -stream_loop -1 -i trimmed_audio.wav -af adelay=2000:all=1 -shortest -fflags +shortest -max_interleave_delta 100M out.mp4
Use ffmpeg 4.1 or newer.
Im using this ffmpeg command to convert mp3 to wav:
ffmpeg -i audio.mp3 -acodec libmp3lame -ab 64k -ar 16000 audio.wav
and this command to create waveform from audio.wav:
wav2png --foreground-color=ffb400aa --background-color=2e4562ff -o example4.png papa2.wav
I would love to know, how to run this commands multiple? For example, when conversion from .mp3 to .wav is done, then run the wav2png command.
Thank You!
You have several options here:
Option 1: Use &&
In Bash you can use an and list to concatenate commands. Each command will be executed one after the other. The and list will terminate when a command fails, or when all commands have been successfully executed.
ffmpeg -i audio.mp3 audio.wav && wav2png -o output.png audio.wav
Using -acodec libmp3lame when outputting to WAV makes no sense, so I removed that.
WAV ignores bitrate options, so I removed -ab.
Do you really need to change the audio rate (-ar)? Removed.
Option 2: Pipe from ffmpeg to wav2png
Instead of making a temporary WAV file you can pipe the output from ffmpeg directly to wav2png:
ffmpeg -i audio.mp3 -f wav - | wav2png -o output.png /dev/stdin
Option 3: Just use ffmpeg
Saving the best for last, you can try the showwavespic filter.
ffmpeg -i music.wav -filter_complex showwavespic=s=640x320 showwaves.png
If you want to make a video of the wave form, then try showwaves.
You can see a colored example at Generating a waveform using ffmpeg.
I want to loop same video 4 times and output as video using ffmpeg.
SO I create code like this in ffmpeg.
ffmpeg -loop 4 -i input.mp4 -c copy output.mp4
but when i run it it give the error like this.
Option Loop Not Found.
how to do this withour error. Please Help Me
In recent versions, it's
ffmpeg -stream_loop 4 -i input.mp4 -c copy output.mp4
Due to a bug, the above does not work with MP4s. But if you wrap to a MKV, it works for me.
ffmpeg -i input.mp4 -c copy output.mkv
then,
ffmpeg -stream_loop 4 -i output.mkv -c copy output.mp4
I've found an equivalent work-around with input concatenation for outdated/bugged versions -stream_loop:
ffmpeg -f concat -safe 0 -i "video-source.txt" -f concat -safe 0 -i "audio-source.txt" -c copy -map 0:0 -map 1:0 -fflags +genpts -t 10:00:00.0 /path/to/output.ext
This will loop video and audio independently of each other and force-stop the output at 10 hour mark.
Both text files consist of
file '/path/to/file.ext'
but you must make sure to repeat this line enough times to keep the output satisfied.
For example, if your total video time is less than total audio time then video output will stop earlier than intended and the audio will keep playing until either -t 10H is reached or audio ends prematurely.
With FFmpeg you have the option -t which will set the duration of the output. However I do not see a way to limit the duration of the input. Take this command
ffmpeg -i video.mp4 -c copy -t 60 out.mp4
This simply creates a 60 second clip of the original video. However if I wanted to clip the audio while keeping the full video stream, FFmpeg does not seem to have an option for this.
I have tried simply clipping the audio first, then combining the clipped audio with the video file, but this causes video/audio sync issues for me.
‘-aframes number (output)’
Set the number of audio frames to record. This is an alias for -frames:a.
§ Audio Options
ffmpeg -i video.mp4 -c copy -aframes 100 out.mp4
Use the "-itsoffset" option.
This makes the first 10 seconds mute.
ffmpeg -i video.mp4 -vn -acodec copy -ss 10.0 out_audio.mp4
ffmpeg -itsoffset 10.0 -i out_audio.mp4 -i video.mp4 -vcodec copy -acodec copy out.mp4