ffmpeg has a way to extract video images using the following command
ffmpeg -i "video.avi" -vf fps=30 "images/frame_%09d.png" -hide_banner
Is there a way in ffmpeg to extract or cut audios into smaller chunks the same way that is done on the above command but the difference is it will create an audio file not an image file.
I tried the following but it only creates a wav file.
ffmpeg -i "video.avi" -vf fps=30 "images/frame_%09d.wav" -hide_banner
Remove -vf option, you don't need it as you don't need video
Video frames can be assumed as single units, but what you want in audio? Sungle samples. huh? So, you must specify interval
For example:
# ffmpeg -i "video.avi" -f segment -segment_time 3 -c copy "images/frame_%03d.mp3" -hide_banner
Related
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.
I have successfully generated a blue screen to add to an mp3. But, I have always needed to include the length of the clip to match the mp3. When I don't include a timecode it continues to generate footage until I cancel the command.
ffmpeg -f lavfi -i color=blue:s=1920x1080 -i input.mp3 -t 00:02:08 output.mp4
How do I specify that I only want color generated during the length of the mp3 that I am adding?
ffmpeg -i <.jpg> -i <.mp3>
This worked too but I don't want to rely on a jpeg file.
Use -shortest:
ffmpeg -f lavfi -i color=blue:s=1920x1080 -i input.mp3 -shortest output.mp4
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
I currently have a jpeg file which I converted to an flv using the following command:
ffmpeg -r 10 -b 180000 -i test.jpg test.mp4
Now, I want to increase the duration of this .mp4 clip, so the picture stays on the screen for more than a split second. Eventually, I hope to merge a stream of these files to create a slide show out of jpeg files.
Does anyone know how to increase the duration of a clip in ffmpeg?
Looping the input and setting a duration should achieve the effect you want:
ffmpeg -loop_input -i test.jpg -t 10 test.mp4
Doing something like this should work (at least for a single image):
ffmpeg -loop_input -i picture.jpg -r 1 -vcodec flv -b 192k -i Music.mp3 -acodec copy -shortest output.flv
I bet you could get it working with multiple images by adding more inputs though I haven't tested.
(http://forum.videohelp.com/threads/280695-FFMPEG-Loop-input-video)
Does anyone know if it is possible to encode a video using ffmpeg in reverse? (So the resulting video plays in reverse?)
I think I can by generating images for each frame (so a folder of images labelled 1.jpg, 2.jpg etc), then write a script to change the image names, and then re-encode the ivdeo from these files.
Does anyone know of a quicker way?
This is an FLV video.
Thank you
No, it isn't possible using ffmpeg to encode a video in reverse without dumping it to images and then back again. There are a number of guides available online to show you how to do it, notably:
http://ubuntuforums.org/showthread.php?t=1353893
and
https://sites.google.com/site/linuxencoding/ffmpeg-tips
The latter of which follows:
Dump all video frames
$ ffmpeg -i input.mkv -an -qscale 1 %06d.jpg
Dump audio
$ ffmpeg -i input.mkv -vn -ac 2 audio.wav
Reverse audio
$ sox -V audio.wav backwards.wav reverse
Cat video frames in reverse order to FFmpeg as input
$ cat $(ls -r *jpg) | ffmpeg -f image2pipe -vcodec mjpeg -r 25 -i - -i backwards.wav -vcodec libx264 -vpre slow -crf 20 -threads 0 -acodec flac output.mkv
Use mencoder to deinterlace PAL dv and double the frame rate from 25 to 50, then pipe to FFmpeg.
$ mencoder input.dv -of rawvideo -ofps 50 -ovc raw -vf yadif=3,format=i420 -nosound -really-quiet -o - | ffmpeg -vsync 0 -f rawvideo -s 720x576 -r 50 -pix_fmt yuv420p -i - -vcodec libx264 -vpre slow -crf 20 -threads 0 video.mkv
I've created a script for this based on Andrew Stubbs' answer
https://gist.github.com/hfossli/6003302
Can be used like so
./ffmpeg_sox_reverse.sh -i Desktop/input.dv -o test.mp4
New Solution
A much simpler method exists now, simply use the command (adjusting input.mkv and reversed.mkv accordingly):
ffmpeg -i input.mkv -af areverse -vf reverse reversed.mkv
The -af areverse will reverse audio, and -vf reverse will reverse video. The video and audio will be in sync automatically in the output file reversed.mkv, no need to worry about the input frame rate or anything else.
On one video if I only specified the -vf reverse to reverse video (but not audio), the output file didn't play correctly in mkv format but did work if I changed it to mp4 output format (I don't think this use case of reversing video only but not audio is common, but if you do run into this issue you can try changing the output format). On large input videos that exceed the RAM available in your computer, this method may not work and you may need to chop up the input file or use the old solution below.
Old Solution
One issue is the frame rate can vary depending on the video, many answers depend on a specific frame rate (like "-r 25" for 25 frames per second). If the frame rate in the video is different, this will cause the reversed audio and video to go out of sync.
You can of course manually adjust the frame rate each time (you can get the frame rate by running ffmpeg -i video.mkv and look for the number in front of the fps, this is sometimes a decimal number like 23.98). But with some bash code you can easily extract the fps, store it in a variable, and automatically pass it to the programs.
Based on this I've created the following bash script to do that. Simply chmod +x it and run it ./make-reversed-video.sh input.mkv output.mkv. The code is as follows:
#!/bin/bash
#Partially based on https://nhs.io/reverse/, but with some modifications, including automatic extraction of the frame rate.
#Get parameters.
VIDEO_FILE=$1
OUTPUT_FILE=$2
TEMP_FOLDER=$3
echo Using input file: $VIDEO_FILE
echo Using output file: $OUTPUT_FILE
mkdir /tmp/create_reversed_video
#Get frame rate.
FRAME_RATE=$(ffmpeg -i "$VIDEO_FILE" 2>&1 | grep -o -P '[0-9\\. ]+fps' | grep -o -P '[0-9\\.]+')
echo The frame rate is: $FRAME_RATE
#Extract audio from video.
ffmpeg -i "$VIDEO_FILE" -vn -ac 2 /tmp/create_reversed_video/audio.wav
#Reverse the audio.
sox -V /tmp/create_reversed_video/audio.wav /tmp/create_reversed_video/backwards.wav reverse
#Extract each video frame as an image.
ffmpeg -i "$VIDEO_FILE" -an -qscale 1 /tmp/create_reversed_video/%06d.jpg
#Recombine into reversed video.
ls -1 /tmp/create_reversed_video/*.jpg | sort -r | xargs cat | ffmpeg -framerate $FRAME_RATE -f image2pipe -i - -i /tmp/create_reversed_video/backwards.wav "$OUTPUT_FILE"
#Delete temporary files.
rm -rf /tmp/create_reversed_video
I've tested it and it works well on my Ubuntu 18.04 machine on lots of videos (after installing the dependencies like sox). Please let me know if it works on other Linux distributions and versions.