Develop Reference

ffmpeg burned-in subtitles render in the wrong font

Trying to burn in subtitles to a video in FFMPEG in GothamProBold font. No matter what I do it keeps reverting to Helvetica. From the console, I see that FFMPEG seems to load the font without error. Then switches over to font provider "coretext"
[Parsed_subtitles_0 # 0x7fed054048c0] Loading font file '/Projects/Fonts/GothaProBol.otf'
[Parsed_subtitles_0 # 0x7fed054048c0] Using font provider coretext
[Parsed_subtitles_0 # 0x7fed054048c0] fontselect: (GothaProBol.otf, 400, 0) -> /System/Library/Fonts/Helvetica.ttc, -1, Helvetica
It seems like it has my font loaded, then loads what is likely a system default of Helvetica instead. My guess is that my chosen font isn't actually loading after all.
FFMPEG command (called from python) is as follows:
ffmpeg_cmd = ["ffmpeg",
"-i", self.source_video_uri,
"-y",
"-c:v", "prores", "-profile:v", "1",
"-c:a", "pcm_s16be",
"-vf", f"subtitles={srt_uri}:fontsdir=/Projects/Fonts:force_style='Fontname=GothaProBol.otf'",
f"{self.source_video_uri}_render.mov"]
subprocess.call(ffmpeg_cmd)
Any ideas?
UPDATE: Found this setting in libass header file "ass.h" - which ffmpeg calls when using the subtitle filter. Don't know how to actually set this variable when ffmpeg calls libass, but here it is. Line 182:
* \brief Default Font provider to load fonts in libass' database
*
* NONE don't use any default font provider for font lookup
* AUTODETECT use the first available font provider
* CORETEXT force a CoreText based font provider (OS X only)
* FONTCONFIG force a Fontconfig based font provider
*
* libass uses the best shaper available by default.
*/
typedef enum {
ASS_FONTPROVIDER_NONE = 0,
ASS_FONTPROVIDER_AUTODETECT = 1,
ASS_FONTPROVIDER_CORETEXT,
ASS_FONTPROVIDER_FONTCONFIG,
ASS_FONTPROVIDER_DIRECTWRITE,
} ASS_DefaultFontProvider;
RE: ANSWER BELOW: For the most part, it seems that if your font is installed in /System/Fonts or /Library/Fonts then CoreText can find it. Though in some cases, the naming conventions can be quite particular and non-intuitive. It also can't seem to find all fonts, necessarily.
For example: Gotham Pro Bold, in the /Library/Fonts folder on my system, file named "GothaProBol.otf" is correctly passed to fontname as: GothamPro-Bold or just Gotham Pro. Gotham Pro Bold, GothamPro, Gotham Pro-Bold, GothaProBol, and GothaProBol.otf do NOT work.
For most fonts it seems the preferred convention is {FontName}-{Style/Weight} as displayed in Mac OS's FontBook, not the filename.
That said, I have a novelty 'Game of Thrones.ttf' font in the same folder as Gotham Pro, and I can't get CoreText to connect to it under any of the above naming conventions.

Do not put the file extension in the font name:
force_style='fontname=GothamPro-Bold'
In my case I got a file called GothamPro-Bold.otf and the output was like this:
[Parsed_subtitles_0 # 0x55c809fd73c0] Shaper: FriBidi 0.19.7 (SIMPLE) HarfBuzz-ng 2.6.4 (COMPLEX)
[Parsed_subtitles_0 # 0x55c809fd73c0] Loading font file './fonts/GothamPro-Bold.otf'
[Parsed_subtitles_0 # 0x55c809fd73c0] Using font provider fontconfig
[Parsed_subtitles_0 # 0x55c809fd73c0] fontselect: (GothamPro-Bold, 400, 0) -> GothamPro-Bold, 0, GothamPro-Bold

I got the custom fonts working in FFMPEG subtitles filter. 🎉
(I'm using a Mac and FFMPEG-PYTHON which is just a wrapper around FFMPEG).
I also have the font files in a folder local to my project.(./fonts) and changing the font file name or using the font name shown in Mac's Font-Book doesn't work.
So here is how I got it working...
Open the font file in Font Forge you can download it here - FontForge.
Click on the Elements tab and then Font Info
You can see the font name on the top
Use the font name exactly as you see it as the FFMPEG force_style args
fontsdir='./fonts',force_style='FontName=HelveticaRoundedLTStd-BdCn,PrimaryColour=0x7FFFD4,Fontsize= 26
Here are my terminal logs showing that it's loading the custom font.
Hope this helps 🚀🚀🚀

I've been trying to solve the same problem all evening, finally figured it out.
OP said that 'Game of Thrones.ttf' didn't work but 'GothaProBol.otf' did.
So I used an online tool to convert my custom font from .ttf to .otf
Then copied my custom font into /Library/Fonts/fontname.otf
Then used the POSTSCRIPT-NAME from Font Book and it worked beautifully :-)
ffmpeg -i input.mp4 -vf "subtitles=subtitle.ass:force_style='Fontname=CUSTOMfontBlack-Regular'" output.mp4

Use matplotlib.pyplot.rcparams with a custom font which is not installed

I'm trying to use a custom ttf font not installed in the system for text element in the matplotlib figure.
with plt.style.context('mplparams.mplstyle'):
plt.plot(np.sin(np.linspace(0, 3 * np.pi)), '-o')
I know I can change the text properties with FontManager but I'm looking for a solution which only involves an external config file.
At the moment I only know that i can change font.sans-serif to a font name, not font path.
Is this possible?

The font to be used has to be known to the Fontmanager, otherwise you cannot get it into the plot. In order to specify a font through rcParams this font must be found in a folder matplotlib would look for it. In case you don't want to install anything, you may copy the .ttf file to the matplotlib font folder. In my case this is
python\Lib\site-packages\matplotlib\mpl-data\fonts
Then you need to clear the font.chache. Find out its path via print(matplotlib.get_cachedir()) and delete the fontList files. (Or make a backup first if you like).
Then run your script which has the rcParam specified
font.sans-serif : <name of font>
or use
plt.rcParams['font.sans-serif'] = "<name of font>"
Also see this question.

Creating a lightweight fallback font with fontforge and fonttools

For a webapp I need a way to prevent that a browser falls back to another font if my web font doesn't include a character. It seems the only way to do this is to add another font to the fontstack which includes "all" possible characters 1.
There are already existing fallback fonts, but those are more debug helpers as they show the codepoint as number, therefore they are much to heavy (>2MB).
The fallback font for my usecase should just show something like a box to signal a missing character.
My idea was to generate a simple font with only one glyph and apply a feature file which will replace all glyphs with this one.
My script for fontforge:
import fontforge
import fontTools.feaLib.builder as feaLibBuilder
from fontTools.ttLib import TTFont
font_name = 'maeh.ttf'
font = fontforge.font()
glyph = font.createChar(33, "theone")
pen = glyph.glyphPen()
pen.moveTo((100,100))
pen.lineTo((100,500))
pen.lineTo((500,500))
pen.lineTo((500,100))
pen.closePath()
for i in range(34, 99):
glyph = font.createChar(i)
glyph.width=10
font.cidConvertTo('Adobe', 'Identity', 0) # doesn't make a difference
font.generate(font_name)
font = TTFont(font_name)
feaLibBuilder.addOpenTypeFeatures(font, 'fallback.fea')
font.save("fea_"+font_name)
My feature file:
languagesystem DFLT dflt;
#all=[\00035-\00039];
##all=[A-Z] this works
feature liga {
sub #all by theone;
} liga;
But the above results in a
KeyError: ('cid00037', 'SingleSubst[0]', 'Lookup[0]', 'LookupList')
with changing numbers for cid00037.
If I use the out commented A-Z from the Feature file it works, so this approach doesn't seem to be completely wrong.
Why can't fonttools find the glyphs if I specify the range in CID notation?
Is there another way to crate a class for the OpenType feature file which includes all glyphs?

While working on the above problem, somebody hinted me to the Adobe NotDef font, which is pretty much what I was looking for. For some reason I wasn't able to convert the .otf of the Adobe NotDef to woff or woff2 with fontforge. Also all the online tools to create the web font files like fontsquirrel failed. To create the woff file I used sfnt2woff from the woff-tools package. For the woff2 file I used https://github.com/google/woff2.

What's the name of this font used in this figure?

I want to use this font in matplotlib plotting, but I can not find out the name. Does anyone know?
This figure is got by IDL plotting on Mac OS (10.9) like:
filename = 'name.eps'
myDevice = !D.NAME
SET_PLOT,'ps'
DEVICE,DECOMPOSED=1,ENCAPSULATED=1,/COLOR,FILENAME=filename
......
DEVICE, /CLOSE
SET_PLOT, myDevice

I'm not a font expert, but this looks a lot to me like the font that was used with pen plotters. Looking around for "pen plotter font", turns up "Hershey Vector Font", which looks quite close.

The font is indeed a Hershey vector font: Hershey Simplex Light. This user on Github has the font definition files (otf) that you can copy/clone into your system and set as the default fonts in your matplotlibrc. Not all the characters are included, but you can use fontforge to open the otf and/or sfd files and merge/copy/create missing glyphs.

(updated in 2022)
I think this font is a kind of vector font belonging to the Hershey family.
Here is a set of TTF fonts that are based on the Hershey font https://github.com/yangcht/Hershey_font_TTF.
You can download them and load them when you make plots.

Matplotlib PDF export uses wrong font

I want to generate high-quality diagrams for a presentation. I’m using Python’s matplotlib to generate the graphics. Unfortunately, the PDF export seems to ignore my font settings.
I tried setting the font both by passing a FontProperties object to the text drawing functions and by setting the option globally. For the record, here is a MWE to reproduce the problem:
import scipy
import matplotlib
matplotlib.use('cairo')
import matplotlib.pylab as pylab
import matplotlib.font_manager as fm
data = scipy.arange(5)
for font in ['Helvetica', 'Gill Sans']:
fig = pylab.figure()
ax = fig.add_subplot(111)
ax.bar(data, data)
ax.set_xticks(data)
ax.set_xticklabels(data, fontproperties = fm.FontProperties(family = font))
pylab.savefig('foo-%s.pdf' % font)
In both cases, the produced output is identical and uses Helvetica (and yes, I do have both fonts installed).
Just to be sure, the following doesn’t help either:
matplotlib.rc('font', family = 'Gill Sans')
Finally, if I replace the backend, instead using the native viewer:
matplotlib.use('MacOSX')
I do get the correct font displayed – but only in the viewer GUI. The PDF output is once again wrong.
To be sure – I can set other fonts – but only other classes of font families: I can set serif fonts or fantasy or monospace. But all sans-serif fonts seem to default to Helvetica.

Basically, #Jouni’s is the right answer but since I still had some trouble getting it to work, here’s my final solution:
#!/usr/bin/env python2.6
import scipy
import matplotlib
matplotlib.use('cairo')
import matplotlib.pylab as pylab
import matplotlib.font_manager as fm
font = fm.FontProperties(
family = 'Gill Sans', fname = '/Library/Fonts/GillSans.ttc')
data = scipy.arange(5)
fig = pylab.figure()
ax = fig.add_subplot(111)
ax.bar(data, data)
ax.set_yticklabels(ax.get_yticks(), fontproperties = font)
ax.set_xticklabels(ax.get_xticks(), fontproperties = font)
pylab.savefig('foo.pdf')
Notice that the font has to be set explicitly using the fontproperties key. Apparently, there’s no rc setting for the fname property (at least I didn’t find it).
Giving a family key in the instantiation of font isn’t strictly necessary here, it will be ignored by the PDF backend.
This code works with the cairo backend only. Using MacOSX won’t work.

The "family" argument and the corresponding rc parameter are not meant to specify the name of the font can actually be used this way. There's an (arguably baroque) CSS-like font selection system that helps the same script work on different computers, selecting the closest font available. The usually recommended way to use e.g. Gill Sans is to add it to the front of the value of the rc parameter font.sans-serif (see sample rc file), and then set font.family to sans-serif.
This can be annoying if the font manager decides for some obscure reason that Gill Sans is not the closest match to your specification. A way to bypass the font selection logic is to use FontProperties(fname='/path/to/font.ttf') (docstring).
In your case, I suspect that the MacOSX backend uses fonts via the operating system's mechanisms and so automatically supports all kinds of fonts, but the pdf backend has its own font support code that doesn't support your version of Gill Sans.

This is an addition to the answers above if you came here for a non-cairo backend.
The pdf-backend of matplotlib does not yet support true type font collections (saved as .ttc files). See this issue.
The currently suggested workaround is to extract the font-of-interest from a .ttc file and save it as a .ttf file. And then use that font in the way described by Konrad Rudolph.
You can use the python-package fonttools to achieve this:
font = TTFont("/System/Library/Fonts/Helvetica.ttc", fontNumber=0)
font.save("Helvetica-regular.ttf")
As far as I can see, it is not possible to make this setting "global" by passing the path to this new .ttf file to the rc. If you are really desperate, you could try to extract all fonts from a .ttc into separate .ttf files, uninstall the .ttc and install the ttfs separately. To have the extracted font side-by-side with the original font from the .ttc, you need to change the font name with tools like FontForge. I haven't tested this, though.

Check if you are rendering the text with LaTeX, i.e., if text.usetex is set to True. Because LaTeX rendering only supports a few fonts, it largely ignores/overwrites your other fonts settings. This might be the cause.