Thai characters not rendering correctly until both libass and harfbuzz are enabled

[foxtailmega]

I had some rendering issue of subtitle when i tried to hardcode thai srt subtitle on video. For single tone in thai, it renders correctly but with double tone thai characters, which should be either two characters above or below, doesn't render correctly.

I asked this question to ffmpeg-user mailing list, and there, i figured out that other people had same issue and libass along with harfbuzz needs to be enabled in ffmpeg in order to render the text correctly. Now libass is available in flutter-ffmpeg but harfbuzz needs to be enabled too. Please help.

[foxtailmega]

i see fribidi as default shaper and not harfbuzz. fribidi works for simple languages, but as soon as languages become complex like thai, arabic, chinese, indian languages, then it doesn't render the text correctly. Please help in enabling harfbuzz in flutter-ffmpeg

[tanersener]

This issue has to be analysed in the parent project, mobile-ffmpeg. I know that harfbuzz is disabled there but not sure if it is possible to enable it.

[foxtailmega]

so is there any way to enable harfbuzz complex shaper in mobile-ffmpeg ? Because currently its rendering it incorrect with fribidi simple shaper. Its very much needed now.

[tanersener]

You can try to build mobile-ffmpeg yourself by enabling it here.

[foxtailmega]

sure, let me try to build it myself and i will reply here how it goes.

[foxtailmega]

I tried building parent project mobile-ffmpeg by changing some parameters Here in this line android-freetype.sh. I changed it to --with-harfbuzz \

Also i changed here in this line android-libass.sh. I changed it to --enable-harfbuzz \

Now before making these changes, it used to build fully without any issues. But after making these changes, build fails at fontconfig

fox@foxy:~/Desktop/expanded/mobile-ffmpeg$ ./android.sh --lts --disable-arm-v7a-neon --disable-arm64-v8a --disable-x86 --disable-x86-64 --full

Building mobile-ffmpeg LTS library for Android

Architectures: arm-v7a
Libraries: android-zlib, android-media-codec, fontconfig, freetype, fribidi, gmp, gnutls, lame, libass, libiconv, libtheora, libvorbis, libvpx, libwebp, libxml2, opencore-amr, shine, speex, wavpack, kvazaar, libilbc, opus, snappy, soxr, libaom, chromaprint, twolame, sdl, tesseract, openh264

Building arm-v7a platform on API level 16

fribidi: ok
gmp: ok
libiconv: ok
libvpx: ok
libxml2: ok
opencore-amr: ok
shine: ok
speex: ok
wavpack: ok
kvazaar: ok
libilbc: ok
opus: ok
snappy: ok
soxr: ok
libaom: ok
chromaprint: ok
sdl: ok
openh264: ok
giflib: ok
jpeg: ok
libogg: ok
libpng: ok
libuuid: ok
nettle: ok
tiff: ok
expat: ok
libsndfile: ok
freetype: ok
gnutls: ok
lame: ok
libvorbis: ok
libwebp: ok
twolame: ok
leptonica: ok
fontconfig: failed

HERE IS THE COMPLETE build.log build.log

I did install libharfbuzz-dev

[tanersener]

There is a misunderstanding there.

For example, to enable support for libwebp, mobile-ffmpeg builds libwebp as you can see from the output. It does not install libwebp using brew/apt/yum install libwebp-dev. Installing libharfbuzz in that way will never work.

[foxtailmega]

Well which of the below suggested step should i follow to enable harfbuzz library in ffmpeg ?

====================== suggestion 1============================ -> okay so first should i add harfbuzz library just like other library has been added to src folder -> and then in build directory i should make android-harfbuzz.sh and add all flags and config parameters there just like other libraries -> and then in android.sh i should declare that library and also change the parameters in android-libass.sh(--enable-harfbuzz ) and android-freetype.sh(--with-harfbuzz ) -> and run it so it builds using android-ndk ?

or

====================== suggestion 2============================ should i just change the parameters in android-libass.sh(--enable-harfbuzz \) and android-freetype.sh(--with-harfbuzz \) and just let it build ?

[tanersener]

1)

[foxtailmega]

i did build harfbuzz but because there is a circle dependency between harfbuzz and freetype, so -> i first build freetype normally without harfbuzz and then -> i build harfbuzz with freetype and fontconfig, and it builds successfully, But next i need to build again freetype with that previously built harfbuzz so as to incorporate harfbuzz into freetype, thats what is not working currently, and until harfbuzz support is not there in freetype, no use of enabling libass with harfbuzz support.

I need to sort out that circle dependency though.

Still i would like to test the generated aar android archive.

How do i test that mobile-ffmpeg.aar in flutter ? How do i add that to flutter ?

[tanersener]

clone flutter_ffmpeg, remove existing mobile-ffmpeg dependency from build.gradle file and add the dependency for your new .aar file.