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Filter_text Documentation
This filter allows you to render arbitrary text into the video stream
It uses libfreetype2 to render the font so it can handle all fonts
libfreetype can handle.
You need libfreetype2 installed and enabled during configure time to
make use of this filter.
PARAMETERS
As usual, the default setting should get you going, still there a tons
of options to play with.
* 'string' text to print [date]
This is probably the most important option you want to change. It is
the text which will be rendered into the video. If the string is not
specified, the filter will render the current time and date.
* 'dpi' dots-per-inch resolution [96]
The dots-per-inch resolution of the rendered letters.
* 'points' point size of font in 1/64 [25]
The point size of the rendered letters.
* 'font' full path to font file [/usr/X11R6/.../arial.ttf]
Specifies which font file to use. You must supply the full path to the
file. Default is /usr/X11R6/lib/X11/fonts/TrueType/arial.ttf
* 'fade' Fade in and/or fade out [0=off, 1=slow, 10=fast]
turns on a smooth fadein and fadeout. As higher the argument is, the
faster the text will be blended. If you specify a range for the filter
to apply, the fadein will start at the beginning of the range and
fadeout will be finished at the end of the range. See below for an
ascii art.
* 'notransparent' disable transparency
Default is to enable transparency. Sometimes the text is unreadable
especially on bright background so you may wish to disable it. The
text will be drawn in a black box.
* 'pos' Position (0-width x 0-height) [0x0]
Position of the text (in pixels) The "origin" of the text is the
upper left corner of the bounding box.
* 'posdef' Position (0=None, 1=TopL 2=TopR 3=BotL 4=BotR 5=Cent 6=BotCent) [0]
Predefined Position.
1: Top Left
2: Top Right
3: Bottom Left
4: Bottom Right
5: Center
6: Center Bottom
* 'range' apply filter to [start-end]/step frames [0-oo/1]
defines a frame range in which the image should appear in the
video
'range' together with 'fade'
Say you want the text to be visible from frame 50 until frame 250
and you also want a slow fade (e.g. 2). The number of frames the fade
will take is 100/2 = 50 frames, so
0 50 100 150 200 250
|---------|----------|-----------|----------|----------|------> Frames
fadein full fadeout invisible
start visible start
EXAMPLES
* The above example with the fade:
$ transcode [...] -J text=string="Hello World":fade=2:range=50-250
* Place the text in the center of the image
$ transcode [...] -J text=string="Hello World":posdef=5
* Make the text to appear larger in the center
$ transcode [...] -J text=string="Hello World":posdef=5:points=30
* No transparency, fast fadein/out, range and center at bottom
-J text=string="Hello World":posdef=6:notransparent:fade=7:range=50-250
LIMITATIONS
* The text is always white and does not look very good on bright
background probably because of antialiasing artifacts.
* The filter does not handle linebreaks. If the text is too long to be
displayed on one line, the output will look garbled.
(C) 2003 Tilmann Bitterberg <transcode@tibit.org>
Tue Apr 29 14:57:38 CEST 2003
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