How to use ffmpeg on Android, Kivy, python3, youtube-dl

I am trying to create an app using Kivy 1.11.1 using youtube-dl module in python3. I am using buildozer to create apk from python source code which usage python-for-android to create apk. I have mentioned ffmpeg in buildozer requirements. I can see ffmpeg in pythonforandroid/recipes/. After installing form apk, when I try to print ffmpeg version using the following

merger = youtube_dl.postprocessor.FFmpegMergerPP()
merger._determine_executables()
print(merger.get_versions())

I get this output

{'avprobe': False, 'avconv': False, 'ffmpeg': False, 'ffprobe': False}

which indicate that ffmpeg in not installed in android

this line is included in my buildozer.spec

requirements = python3,kivy,ffmpeg,youtube_dl,kivymd,kivmob,ffpyplayer,ffpyplayer_codecs,ffmpeg-python

except ffmpeg rest all package are installed properly

I am not sure whether this is useful but I saw this in pythonforandroid/recipes/ffmpeg/init.py

def build_arch(self, arch):
        with current_directory(self.get_build_dir(arch.arch)):
            env = arch.get_env()

            flags = ['--disable-everything']

**Goal : ** I want to use ffmpeg in youtube_dl via python3 after installing application from apk created by buildozer.