BIPEDU

my ideas in action

use ffmpeg to edit videos

I want to show here how to produce a video and what are the steps to post-production.

All these are using free and open source software. No need to be expert in computers , only a little bit of courage.

You can use this recipe for homemade videos that you post online, for your vlog/blog or whatever.

I use ffmpeg and Inkscape that are available for Linux and Windows also.

As a general rule, if you have Linux/Unix, then please use the RAM since it is faster (read/write in /tmp folder always for all temporary files).

 

These are the steps :

1= record the video + audio

use a decent camera (preferable HD or 4K) with preferable audio . DSLR is OK also.

If your camera do not have good audio recording from builtin mic, then record the audio separate and clap in front of camera so that you can synchronize video/audio in post-production. Preferably use an external microphone ( ex. lavalier) as close as possible of the sound source. A cheap and good lav mic is Boya BM-M1 (see Amazon)

You can also record with a smartphone but be aware that the sample rate may be 44100 instead of 48000 as camera will record. This may produce audio that is not in sinc with video.

During recording please keep 5-10 seconds of silence , because you may need it later to do some noise reduction (see next step)

2= extract the audio separated and do some processing (if necessary)

Personally I use Audacity ( free and open source) .

I import audio and I do mainly two operations : Noise reduction and Compression. I use default settings from Audacity .. are ok for most cases. In case the audio sample rate is on 44100 then it is preferable to change it to 48000 to match the video.

Save the audio as WAV ( 16bit) in 48000.

3= then replace the video old audio with the new audio (new audio is with noise reduction)

3.1 = strip the audio from the video

ffmpeg -i /tmp/DSC_0009.MOV -an -c:v copy -c:a copy /tmp/p1.mov

3.2 = add new audio to the video

ffmpeg -i /tmp/p1.mov -i /tmp/DSC_0009.wav -vcodec copy -acodec copy /tmp/p2.mov

 

4= cut the video to the correct size

play first the new video and check the quality and note on paper the moments you want to save. For example : from 00:01:12 till 00:25:48 (hh:mm:ss format)

use example : cut from 20 sec till 9min and 36sec :

ffmpeg -i /tmp/p2.mov -vcodec copy -acodec copy -ss 00:00:20 -to 00:09:36 /tmp/p3.mov

5= (optional) add some logo/title/watermark

5.1 = Create the logo

With Inkscape (free and open source) create a image that has the same format as the video. Example if video is HD 1920*1080 then create a page that is 1920*1080. On this place your logo/watermark / artwork and preferable use alpha (transparency) to get more effect. Save the work and export it to PNG and keep the transparency.

5.2 = Overlay the PNG image to the video with ffmpeg

ffmpeg -i /tmp/p3.mov -loop 1 -i /tmp/TitleFile.png -filter_complex “[1:v]fade=in:st=0:d=0.1:alpha=1,fade=out:st=9:d=1:alpha=1[png];[0:v][png]overlay=x=0:enable=’between(t,0,10)'” -b:v 2000k -bufsize 2000k /tmp/p4.mov

Here I overlay the PNG image from second 0 ( st=0) in 0.1sec (d=0.1) and then fadeout starting at second 9 (st=9) for 1 second (d=1). The entire overlay is from seconds 0 to 10 ( see : between(t,0,10) ). Then I also force bitrate to be 2Mb/s (-b:v 2000k -bufsize 2000k) to avoid too much loss of quality. If not the ffmpeg will reduce the bitrate even more and it may be too low.

 

6= (optional) add a static picture at the final with credits/ links/Thanks or other announcements

6.1 = use Inkscape to create a closing image. Same as before, can use transparency (alpha) .

6.2= use ffmpeg to create and concatenate the image at the end of the video:

ffmpeg -i /tmp/p4.mov -loop 1 -framerate 30 -t 5 -i /tmp/Closing.png -f lavfi -t 0.1 -i anullsrc=channel_layout=stereo:sample_rate=48000 -filter_complex “[0:v][0:a][1:v][2:a]concat=n=2:v=1:a=1” -b:v 2000k -bufsize 2000k /tmp/final.mov

options :

framerate=30 : need to match the original framerate of your video ( if you shoot in 60FPS then use 60 here also)

t 5 : generate 5 seconds video that will show your Closing.png image

stereo : add stereo sound if youd video is stereo ( if not you can put mono)

sample_rate=48000 : use the same sample rate as your audio (other option is 44100)

 

7=(optional) post the video online ( Ex: Youtube, Vimeo……etc)

 

 

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