## Playing with ffmpeg

...to extrac, manipulate and reassmbly frames 

### Frames extraction
In running the command take note about original video fps
```
ffmpeg -i video.mp4 %05d.png

```

### Video creation from frames
In running the command take note about original video fps
```
ffmpeg -framerate 30 -pattern_type glob -i '*.png' -c:v libx264 -pix_fmt yuv420p paint.mp4

```

### Video warping from  images 
Using CUDA:

```
ffmpeg -y -fflags +genpts -r 30 -hwaccel cuda -hwaccel_output_format cuda -pattern_type glob -i '*.png' -vf "setpts=100*PTS,minterpolate=fps=24:scd=none" -pix_fmt yuv420p  -c:v h264_nvenc "test01.mp4"
```

### Add silent audio track to a video (with no audio tack) 

```
ffmpeg -i "test.mp4" -f lavfi -i anullsrc=cl=stereo:r=48000 -shortest -y "test_silent.mp4"
```
Useful if you want to merge more than one \*.mp4 video and some of these ave no audio track
Make sure that audio rate for the silent track matches the one of file(s) you are going to merge with it


### Crop a video to a well defined size

```
ffmpeg -i test_silent.mp4 -filter:v "crop=512:512:1200:200" -c:a copy te.mp4
```
Crop to size 512x512 starting from 1200,200 where 0,0 is the top left corner

### Concatenation of two videos 
Once you've performed tthe two steps above (same size and a silent audio if needed):

```
ffmpeg -i te.mp4 -i 20231104021840.mp4 -filter_complex "[0:v][0:a][1:v][1:a]concat=n=2:v=1:a=1" -vsync vfr output.mp4
```

### Create a slideshow (video) from images with different timings 

```
ffmpeg -f concat -i input.txt -pix_fmt yuv420p -movflags +faststart intro.mp4
```
in which *input.txt* looks like:
```
file '00.png'
duration 2
file '01.png'
duration 14 
file '02.png'
duration 2
file '03.png'
duration 6 
file '04.png'
duration 2 
file '05.png'
duration 10
file '06.png'
duration 1 
```

### Cut a video in an interval 

```
ffmpeg -ss 00:09:41 -i .\xynthesi_no_titoli.mp4 -t 50 -map 0 -c copy clip02.mp4
```

**t** option is in seconds from the **ss** start timestamp in HH:MM:SS

```
ffmpeg -copyts -ss [start] -i in.mp4 -to [end] -map 0 -c copy out.mp4
```
In this second command we're specifying **start** and **end** with a full timestamp in format HH:MM:SS