How is the drawtext filter used in FFmpeg?
This is a very useful application of the drawtext filter and is used in demonstrating low-latency applications or visual quality testing so that one knows precisely what the timestamps/timecodes are at each time. This uses the timestamp and pts options to display time in hour:min:sec format using the hms format specifier.
How do you center text in FFmpeg video?
If you look at the image above, you’ll see that it starts at the center of the video and extends towards the right. If you want to center the text itself, then you can subtract the height and width of the rendered text when telling drawtext where to render the text. Here’s how.
How to enable default font fallback in FFmpeg?
As per the documentation, you need the following options as well if you want to, enable default font fallback and the font option you need to configure FFmpeg with –enable-libfontconfig. enable the text_shaping option, you need to configure FFmpeg with –enable-libfribidi. The complete list of options for drawtext filter can be accessed here.
How to change the Y position in FFmpeg?
You start off by telling by FFmpeg that the y-position is h – 80*t so that everytime the value of time increases, the value of h – 80*t* decreases, and the text is displayed higher. Makes sense? Tip: change 80 to 100 or 120 and see the effect on the scrolling speed.
How does the overlay filter in FFmpeg work?
The overlay filter takes in input the first unchanged output of the split filter (which was labelled as [main] ), and overlay on its lower half the output generated by the crop,vflip filterchain. Some filters take in input a list of parameters: they are specified after the filter name and an equal sign, and are separated from each other by a colon.
Where do I find the escaping procedure in FFmpeg?
See (ffmpeg-utils)the “Quoting and escaping” section in the ffmpeg-utils (1) manual for more information about the employed escaping procedure. A first level escaping affects the content of each filter option value, which may contain the special character : used to separate values, or one of the escaping characters \\’ .
How to draw box and scale its size with ffmpeg?
Maybe the expression for out_w:’if (gte (t*20,600),600,t*20)’ or for out_h:’20’ is self-referencing. Now, if I set the width to a fixed value, it runs, but then there’s the problem that the overlay contains the whole video itself as it is the input of the drawbox filter.
When to use out or in in FFmpeg?
In a filter description, if the input label of the first filter is not specified, “in” is assumed; if the output label of the last filter is not specified, “out” is assumed. In a complete filterchain all the unlabelled filter input and output pads must be connected.