Error after embedding fonts

[MerlinMama]

I'm not sure when this error started happening, because generally, I run Check Book before I embed fonts.

I first noticed in mid-June that after embedding fonts, if I run Check Book, I get this error message. It has happened consistently since I noticed. As the embedding and generation of the content.opf is performed by Calibre (to my knowledge) I'm not sure where, or if, I can fix this. It also happens for ALL fonts I try to embed (I have about 4 that I have used for years)

The file fonts/Dion.otf has its MIME type specified as font/otf in the OPF file. The recommended MIME type for files with the extension "otf" is application/vnd.ms-opentype. You should change either the file extension or the MIME type in the OPF.

It’s a quick fix, I just hit the "Try to correct all...” link and it's fine, but I'd like to know if there's something I need to do to not have this step.

I'm running Calibre 5.44 on Windows 11 and all my plugins are up to date.

[DNSB]

The file fonts/Dion.otf has its MIME type specified as font/otf in the OPF file. The recommended MIME type for files with the extension "otf" is application/vnd.ms-opentype. You should change either the file extension or the MIME type in the OPF.

Both of those formats are correct for epub3 though the font/xxxxx form is the preferred form. If you are using epub2, the vendor specific form application/vnd.ms-opentype is the correct choice. However most renderers don't seem to care.

[MerlinMama]

OK...So there's no way to avoid that extra step when I get the message (I realize now it's a 'warning' and not an 'error')? It does seem to affect how the text with that font appears on my Kobo, as that is why I noticed it in the first place.

[Foozle]

Normally if you import a font, it automatically adds the mimetype for you. Not sure why you would get that message if it's properly imported. Without knowing your process, it's hard to say why it happens. However, to answer the question, there's no way to avoid it if it finds that it should be changed to the proper mimetype.

[kovidgoyal]

@MerlinMama: What version of EPUB is this? I tried the following steps with an EPUB 3.0 file:

1) Click File->New file
2) Click import resource
3) Choose an OTF font file
4) Click OK
5) Open content.opf and find the newly created entry for the font
6) The media-type is application/vnd.ms-opentype as expected

[MerlinMama]

I'm not sure about ePub2 or ePub3, probably both?

I've had these fonts installed since at least 2017 -- just as I was about to hit send I realized that while I've been using them for years I had to reinstall them when I got my new computer in February. I think I only started having trouble in early to mid-June, but could be wrong.

I don't import them each time, should I be? I usually just embed and then subset the fonts once I'm ready to sent to my Kobo. I also tried without subsetting them and it doesn't change anything.

I'll have to get an older book that already has them embedded from before February and see if I get that message

[JSWolf]

Originally Posted by MerlinMama

I'm not sure about ePub2 or ePub3, probably both?

I've had these fonts installed since at least 2017 -- just as I was about to hit send I realized that while I've been using them for years I had to reinstall them when I got my new computer in February. I think I only started having trouble in early to mid-June, but could be wrong.

I don't import them each time, should I be? I usually just embed and then subset the fonts once I'm ready to sent to my Kobo. I also tried without subsetting them and it doesn't change anything.

I'll have to get an older book that already has them embedded from before February and see if I get that message

Is there a reason to embed when you can just side load the fonts to your Kobo and not have to embed to use the font?

[MerlinMama]

Because these are not the overall font. I use one for letters, one for transitions (eg. Later that Day), and one for Newspaper articles. If I don't embed, even if they are on my Kobo, they do not show. If I don't have any of these instances, I don't embed.

So if the book is in, for example, New Times Roman, and that's all there is, I don't embed. If there's a letter, I have just that show as Segoe Print. A newspaper article, Kirsty. Even if I have all the Fonts on my Kobo, everything shows up only in Times New Roman.

I've never been able to get it to work without embedding, on any of my Kobo devices.

[JSWolf]

Originally Posted by MerlinMama

Because these are not the overall font. I use one for letters, one for transitions (eg. Later that Day), and one for Newspaper articles. If I don't embed, even if they are on my Kobo, they do not show. If I don't have any of these instances, I don't embed.

So if the book is in, for example, New Times Roman, and that's all there is, I don't embed. If there's a letter, I have just that show as Segoe Print. A newspaper article, Kirsty. Even if I have all the Fonts on my Kobo, everything shows up only in Times New Roman.

I've never been able to get it to work without embedding, on any of my Kobo devices.

There used to be a way to access side loaded fonts in CSS as though they were embedded without actually having to embed.

I'm not 100% sure if this will work on the 4.33 firmware.

@font-face {
font-family: monospace;
font-style: normal;
font-weight: normal;
src: url("res:///fonts/normal/Dark Courier");
}
@font-face {
font-family: monospace;
font-style: normal;
font-weight: bold;
src: url("res:///fonts/bold/Dark Courier");
}
@font-face {
font-family: monospace;
font-style: italic;
font-weight: normal;
src: url("res:///fonts/italic/Dark Courier");
}
@font-face {
font-family: monospace;
font-style: italic;
font-weight: bold;
src: url("res:///fonts/bolditalic/Dark Courier");
}

[kovidgoyal]

Ah you use embed, this should take care of it: https://github.com/kovidgoyal/calibr...ba5532f364a086

[icallaci]

Thank you for this, Kovid. I have the same issue and this will make things easier.

[MerlinMama]

Thank you