I've searched for this question several times
Many suggested that 'Get both audio and video. And hide video.' and said that 'there is no audio only API'
But it needs more traffic than when only audio is retrieved if I wanted to listen to music via Youtube.
What makes me confused is, an android app called Firetube provides audio only.
Is this just a trick or does Google provides AUDIO ONLY API?
YES YOU CAN
Yes, it is certainly possible, here is an API for that:
While it is against YouTube Terms of Service, it is technically possible to hack your way to the audio-only download link, and that's how the API's above work.
The is how I imagine the SaveDeo API does its magic: Download ONLY audio from a youtube video
This is what the guy at SaveDeo told me:
Youtube has audio only files. Savedeo doesn't do anything beyond providing you with the link. How we're doing this is the reason why are you using savedeo, isn't it.