Unable to embed font while using ebook-convert cli

[kaldan]

I am trying to embed a font while converting a html file to .epub. For that, I am using this command:
font_family = "Monlam Uni Ouchan2"
f'ebook-convert {out_html_fn} {out_epub_fn} --extra-css=./template.css --embed-font-family="{font_family}" '

i am getting this:
Flattening CSS and remapping font sizes...
Embedding font: Monlam Uni OuChan2
Property: Unknown Property name. [1:48: panose-1]
Source base font size is 15.00000pt

My output epub is showing expected font while i opened it in calibre ebook reader. But when i open it in my ipad using ibook, it is not showing the expected font. please help me!!

[kovidgoyal]

You likely will have to add some iBooks specific code to the epub to get embedded fonts to work. Cant remember what it is off the top off my head, but ask in the iBookssub-forum or google ibooks font embedding.

[kaldan]

I have searched regarding your ibook specific code. I referred to this post
https://ebooks.stackexchange.com/que...w-up-in-ibooks
But still it is not working.. Can you please help me

[DNSB]

If your ebook is epub3, to enable embedded fonts for iBooks, you will need to add <meta property="ibooks:specified-fonts">true</meta> in the metadata section of the content.opf file. The com.apple.ibooks.display-options.xml file is not needed.

<?xml version="1.0" encoding="utf-8"?>
<package version="3.0" unique-identifier="BookId" xmlns="http://www.idpf.org/2007/opf">
  <metadata xmlns:dc="http://purl.org/dc/elements/1.1/">
    <dc:identifier id="BookId">urn:uuid:c6753a11-b049-4b2d-99e5-445b301adab5</dc:identifier>
    <dc:language>en</dc:language>
    <dc:title>[Main title here]</dc:title>
    <meta property="dcterms:modified">2021-04-27T08:47:09Z</meta>
    <meta property="ibooks:specified-fonts">true</meta>
  </metadata>
  <manifest>
    <item id="Section0001.xhtml" href="Text/Section0001.xhtml" media-type="application/xhtml+xml"/>
    <item id="sgc-nav.css" href="Styles/sgc-nav.css" media-type="text/css"/>
    <item id="nav.xhtml" href="Text/nav.xhtml" media-type="application/xhtml+xml" properties="nav"/>
  </manifest>
  <spine>
    <itemref idref="Section0001.xhtml"/>
    <itemref idref="nav.xhtml" linear="no"/>
  </spine>
</package>

You can check the Apple Books Asset Guide 5.2.12 for more information (or a cure for insomnia ).