Overlay animated images with transparency over a static background image using ffmpeg?

Question

I'm looking to create a video using a set of png images that have transparency merged with a static background. After doing a lot of digging I seems like it's definitely possible by using the filters library. My initial video making without including the background is: ``` ffmpeg -y -qscale 1 -r 1 -b 9600 -loop -i bg.png -i frame_%d.png -s hd720 testvid.mp4 ``` Using `-vf` I can apply the background as overlay: ``` ffmpeg -y -qscale 1 -r 1 -b 9600 -i frame_%d.png -vf "movie=bg.png [wm];[in][wm] overlay=0:0 [out]" -s hd720 testvid.mp4 ``` However the problem is it's overlaying the background over the input. According libacfilter I can split the input and play with it's content. I'm wondering if I can somehow change the overlay order? Any help greatly appreciated! UPDATE 1: I'm trying to make the following filter work but I'm getting the movie without the background: ``` ffmpeg -y -qscale 1 -r 1 -b 9600 -i frame_%d.png -vf "movie=bg.png [bg]; [in] split [T1], fifo, [bg] overlay=0:0, [T2…

Accepted Answer

The overlay order is controlled by the order of the inputs, from the ffmpeg docs

[...] takes two inputs and one output, the first input is the "main" video on which the second input is overlayed.

You second command thus becomes:

```
ffmpeg -y -loop 1 -qscale 1 -r 1 -b 9600 -i frame_%d.png -vf "movie=bg.png [wm];[wm][in] overlay=0:0" -s hd720 testvid.mp4
```

With the latest versions of ffmpeg the new `-filter_complex` command makes the same process even simpler:

```
ffmpeg -loop 1 -i bg.png -i frame_%d.png -filter_complex overlay -shortest testvid.mp4
```

A complete working example:

The source of our transparent input images (apologies for dancing): Exploded to frames with ImageMagick:

```
convert dancingbanana.gif -define png:color-type=6 over.png
```

(Setting `png:color-type=6` (RGB-Matte) is crucial because ffmpeg doesn't handle indexed transparency correctly.) Inputs are named `over-0.png`, `over-1.png`, `over-2.png`, etc.

Our background image (scaled to banana):

Using `ffmpeg version N-40511-g66337bf` (a git build from yesterday), we do:

```
ffmpeg -loop 1 -i bg.png -r 5 -i over-%d.png -filter_complex overlay -shortest out.avi
```

`-loop` loops the background image input so that we don't just have one frame, crucial! `-r` slows down the dancing banana a bit, optional. `-filter_complex` is a very recently added ffmpeg feature making handling of multiple inputs easier. `-shortest` ends encoding when the shortest input ends, which is necessary as looping the background means that that input will never end.

Using a slightly less cutting-edge build, `ffmpeg version 0.10.2.git-d3d5e84`:

```
ffmpeg -loop 1 -r 5 -i back.png -vf 'movie=over-%d.png [over], [in][over] overlay' -frames:v 8 out.avi
```

`movie` doesn't allow rate setting, so we slow down the background instead which gives the same effect. Because the overlaid movie isn't a proper input, we can't use `-shortest` and instead explicitly set the number of frames to output to how many overlaid input frames we have.

The final result (output as a gif for embedding):

Overlay animated images with transparency over a static background image using ffmpeg?

Solution

Problem