I have two videos from two GoPro cameras. Both videos are rendered via ffmpeg side-by-side into a single video (left and right) and the audio is currently combined/mixed into two channels (stereo). I can hear both camera audio channels at the same time.
Two channels stereo:
ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex "[0:v][1:v]hstack=inputs=2[v]; [0:a][1:a]amerge[a]" -map "[v]" -map "[a]" -ac 2 side-by-side.mp4
audio from both videos mixed into a single file with 2 channels - mediainfo
Now I want to switch between the two audio channels (cam1 or cam2) while I'm playing the side-by-side video.
My first try: With four channels (without -ac 2 parameter):
ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex "[0:v][1:v]hstack=inputs=2[v]; [0:a][1:a]amerge[a]" -map "[v]" -map "[a]" side-by-side.mp4
audio from both videos mixed into a single file with 4 channels - mediainfo
But the most video players can't easily select the channels 1+2 or 3+4 while playing.
So I tried two languages:
ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex "[0:v][1:v]hstack=inputs=2[v]; [0:a][1:a]amerge[a]" -map "[v]" -map "[a]" -metadata:s:a:0 language=ger -metadata:s:a:1 language=eng side-by-side.mp4
audio from both videos mixed into a single file with 4 channels with languages - mediainfo
But that's wrong. I can only see german with 4 channels. How can I put channels 1+2 into german and channels 3+4 into english? Afterwards I should be able to use the multi language feature from most video players to switch the audio between cameras.
Thank you,
Miriam
This worked for me
ffmpeg -i Video1.mp4 -i Video2.mp4 -filter_complex "[0:v][1:v]hstack=inputs=2[v]" -map [v] -map 0:a:0 -map 1:a:0 -metadata:s:a:0 language=ger -metadata:s:a:1 language=eng output.mp4
With this you should be able to switch between the audios
Related
I explored google and StackOverflow for how to add background music to the video and many of them suggested to use
ffmpeg -i input.mp4 -i audio.mp3 -shortest output.mp4
I have been trying to achieve this but it just does not work. When I try to add map like
ffmpeg -i "input.mp4" -i bg.mp3 -map 0:v:0 -map 1:a:0 oo.mp4
The video sound is replaced by the bg.mp3
And if I try -map 0 -map 1:a:0 or not provide map, the audio is not added at all.
How do I add the background music? I don't also get any error.
-map is a selector; select a type of stream from an input "file". To merge two audio streams, you need an audio filter:
ffmpeg -i input.mp4 -i audio.mp3 -lavfi "[0:a][1:a]amerge[out]" -map 0:v -map [out]:a -shortest output.mp4
-lavfi: Same as -filter_complex, because you have two inputs
[0:a][1:a] take audio stream from the first and second inputs
-map 0:v select the video stream from the first input without processing
-map [out]:a select the audio stream from the filtergraph (processed)
The shortest option in the amerge filter is set by default.
If you have problems, you might want to check also the amix filter, the audio codecs of your files, and the volume filter to adjust the volume of the inputs in the filtergraph.
Additional references:
https://ffmpeg.org/ffmpeg-filters.html#amerge
https://ffmpeg.org/ffmpeg-filters.html#amix
https://ffmpeg.org/ffmpeg-filters.html#volume
If the video length is longer than music you can add "-stream_loop -1" to repeat music until end of video
ffmpeg -i video_with_audio.mkv -stream_loop -1 -i background_music.mp3 -lavfi "[0:a][1:a]amerge[out]" -map 0:v -map [out]:a -shortest video_with_audio_and_background_music.mkv
If you want increase or decrease the volume, follow this command:
ffmpeg -i video_with_audio.mkv -stream_loop -1 -i background_music.mp3 -lavfi "[1:a]volume=0.2,apad[A];[0:a][A]amerge[out]" -map 0:v -map [out]:a -shortest video_with_audio_and_background_music.mkv
I would like to append 2 seconds of silence to an existing video using ffmpeg.
I would like to keep the last frame displayed while the 2 seconds of video playsback not a black screen.
Thank you.
Use the tpad and apad filters:
ffmpeg -i input.mp4 -filter_complex "[0:v]tpad=stop_mode=clone:stop_duration=2[v];[0:a]apad=pad_dur=2[a]" -map "[v]" -map "[a]" output.mp4
A faster, but less compatible method is to stream copy the video and use the apad filter if your player and output container format supports dissimilar stream durations:
ffmpeg -i input.mp4 -filter_complex "[0:a]apad=pad_dur=2[a]" -map 0:v -map "[a]" -c:v copy output.mp4
If in doubt use the first command.
I have 4 audio streams in my video file. They are from 4 microphones placed at 4 different people speaking. I want to transcode to a preview file that can be listened to on headphones where everybody's voice can be heard.
I have seen the -ac 2 option, but I can't tell if this will merge all the audio streams or just select the 1st two. I've also seen the amerge filter, but the docs say this will produce 4 audio channels in the output file. So I'm wondering how headphones will deal with the additional 2 channels
You have several options. This assumes each individual audio stream in in.mp4 is mono.
Mono
Using the amerge filter and -ac 1:
ffmpeg -i in.mp4 -filter_complex "[0:a]amerge=inputs=4[a]" -ac 1 -map 0:v -map "[a]" -c:v copy out.mp4
With amix:
ffmpeg -i in.mp4 -filter_complex "[0:a]amix=inputs=4[a]" -map 0:v -map "[a]" -c:v copy out.mp4
Stereo
With amerge and -ac 2:
ffmpeg -i in.mp4 -filter_complex "[0:a]amerge=inputs=4[a]" -ac 2 -map 0:v -map "[a]" -c:v copy out.mp4
Manually mixed stereo
Using amerge and pan with custom downmix:
Channel 0 will be 100% in FL
Channel 1 will be 75% in FL & 25% in FR
Channel 2 will be 25% in FL & 75% in FR
Channel 3 will be 100% in FR
ffmpeg -i in.mp4 -filter_complex "[0:a]amerge=inputs=4,pan=stereo|FL<c0+0.75*c1+0.25*c2|FR<0.25*c1+0.75*c2+c3[a]" -map 0:v -map "[a]" -c:v copy out.mp4
Try the amerge audio filter, used to solve this similar question: How do I use ffmpeg to merge all audio streams (in a video file) into one audio channel?
amix should even better should fit your purpose.
I am attempting to use ffmpeg for a number of files.
The actual number of audio streams (there is usually one channel per stream) per file isn't known until I'm using ffmpeg.
The desired outcome is to somehow have ffmpeg get the count of audio channel, use the number in the command line to amerge those into one single audio channel.
The goal is to create a preview version of the original video file for use in a simple HTML5 page.
Is this possible in just one call to ffmpeg?
(Also, apologies as some parts of this problem I'm still learning about)
Edit:
Dumas stackoverflow asker here.
Yes, I've been trying multiple combinations of ffmpeg args.
To answer the other question, we have video files that have multiple streams, usually with single channels.
I'll post some cmdline examples shortly.
This cmdline example kind of does what I want; there are 8 streams, and I'm able to combine all audio into one. THe issue is having to know the number before running ffmpeg:
ffmpeg -i EXAMPLE.MOV -filter_complex "[0:v]scale=-2:720,format=yuv420p[v];[0:a]amerge=inputs=8[a]" -map "[v]" -map "[a]" -c:v libx264 -crf 23 -preset medium -c:a libmp3lame -ar 44100 -ac 2 OUTPUT.mov
You can use ffprobe to find the number of audio streams and use the output as a variable in your ffmpeg command. Bash example using wc to count the audio streams listed by ffprobe:
ffmpeg -i input.mov -filter_complex "[0:v]scale=-2:720,format=yuv420p[v];[0:a]amerge=inputs=$(ffprobe -loglevel error -select_streams a -show_entries stream=codec_type -of csv=p=0 input.mov | wc -l)[a]" -map "[v]" -map "[a]" -c:v libx264 -crf 23 -preset medium -c:a libmp3lame -ar 44100 -ac 2 output.mov
The following command should do the same thing as llogan's answer but doesn't recompress the video track and requires you to identify how many audio tracks should be merged together.
If you want to know how many audio streams are present, try:
ffprobe originalfile.mov 2>&1 | grep 'Stream #'
Once you have identified how many audio streams should be merged, use that number in the amerge=inputs=2 parameter here. This command will merge the streams into one and recompress the audio using aac compression.
ffmpeg -i originalfile.mov -c:v copy -c:a aac -b:a 160k -ac 2 -filter_complex amerge=inputs=2 output.mp4
I have a project that requires merging of a video file with another audio file. The expected out put is an video file that will have both the audio from actual video and the merged audio file. The length of the output video file will be same to the size of the actual video file.
Is there a single line FFMPEG command to achieve this using copy and -map parameters ?
The video form I will be using is either flv or mp4
And the audio file format will be mp3
There can be achieved without using map also.
ffmpeg -i video.mp4 -i audio.mp3 output.mp4
In case you want the output.mp4 to stop as soon as one of the input stops (audio/video)
then use
-shortest
For example: ffmpeg -i video.mp4 -i audio.mp3 -shortest output.mp4
This will make sure that the output stops as and when any one of the inputs is completed.
Since you have asked that you want to do it with map. this is how you do it:
ffmpeg -i video.mp4 -i audio.mp3 -map 0:0 -map 1:0 -shortest output.mp4
Now, since you want to retain the audio of the video file, consider you want to merge audio.mp3 and video.mp4. These are the steps:
Extract audio from the video.mp4
ffmpeg -i video.mp4 1.mp3
Merge both audio.mp3 and 1.mp3
ffmpeg -i audio.mp3 -i 1.mp3 -filter_complex amerge -c:a libmp3lame -q:a 4 audiofinal.mp3
Remove the audio from video.mp4 (this step is not required. but just to do it properly)
ffmpeg -i video.mp4 -an videofinal.mp4
Now merge audiofinal.mp3 and videofinal.mp4
ffmpeg -i videofinal.mp4 -i audiofinal.mp3 -shortest final.mp4
note: in the latest version of ffmpeg it will only prompt you to use '-strict -2' in case it does then use this:
ffmpeg -i videofinal.mp4 -i audiofinal.mp3 -shortest -strict -2 final.mp4
hope this helps.
You can not do that using one cmd.
1. Get the audio from video file, the audio file name is a.mp3
ffmpeg.exe -i video.mp4 a.mp3
2. Merge two audio files(audio.mp3+a.mp3=audiofinal.mp3)
ffmpeg.exe -i audio.mp3 -i a.mp3 -filter_complex amerge -c:a libmp3lame -q:a 4 audiofinal.mp3
3. Merge video file and audio file(video.mp4+audiofinal.mp3=output.mp4)
ffmpeg.exe -i video.mp4 -i audiofinal.mp3 -map 0:v -map 1:a -c copy -y output.mp4
I don't think extracting the audio from the video is necessary. We can just use -filter_complex amix to merge both audios:
ffmpeg -i videowithaudio.mp4 -i audiotooverlay.mp3 -filter_complex amix -map 0:v -map 0:a -map 1:a -shortest videowithbothaudios.mp4
-filter_complex amix overlays the audio from the first input file on top of audio in the second input file.
-map 0:v video stream of the first input file.
-map 0:a audio stream of the first input file.
-map 1:a audio stream of the second input file.
-shortest the length of the output is the length of the shortest input
Use case:
add music to your background
you rendered a video, but muted some part of it, so you don't want to render it again(coz it's too long), instead you render only audio track(fast) and wanna merge it with original video.
Assuming
you have your video with you speech (or just audio track, whatever)
your music_file is not loud. Otherwise, you will not hear yourself D:
Steps:
1) Extract audio from the video
ffmpeg -i test.mp4 1.mp3
test.mp4 - your file
2) Merge both audio.mp3 and 1.mp3
ffmpeg -i audio.mp3 -i 1.mp3 -filter_complex amerge -c:a libmp3lame -q:a 4 audiofinal.mp3
audiofinal.mp3 - audio with music
3) Delete audio from original
ffmpeg -i example.mkv -c copy -an example-nosound.mkv
example-nosound.mkv - your video without audio
4) Merge with proper audio
ffmpeg -i audiofinal.mp3 -i example-nosound.wmv -c:v copy -vcodec copy final.wmv
final.wmv - your perfect video.
This is very easy with FFmpeg:
ffmpeg -i vid.mp4 -i audio.mp3 -codec:a libmp3lame -ar 44100 -ab 64k -ac 1 -q:v 1 -pix_fmt yuv420p -map 0:0 -map 1:0
First remove the sound from video if you are not able to merge video and audio by using this command:
ffmpeg -i video.mp4 -an videofinal.mp4