How can I stream only the sound of a video from YouTube? [closed]

Question

I would like to stream only sound from youtube. I need this for IOS but others can be ok. I have searched on stackoverflow but I couldn't find. Because I don't want to use another software, I want to directly stream only sound of youtube video by code. Also It should work on background.

Answer 1

Flashgot (for Firefox) has a way to download only the audio of a Youtube video. It exposes links to the audio that looks like this:

https://r3---sn-p5qlsu7d.googlevideo.com/videoplayback?id=887ce37c617a3225&itag=141&source=youtube&requiressl=yes&gcr=ca&ratebypass=yes&mime=audio%2Fmp4&gir=yes&clen=4012348&lmt=1409362978343745&dur=125.828&signature=0A00B9B16BB6EF3192DF33EEF9B2AB67F66F501F.0B649D407144B914A7CC7BE00E795B5BD1B9D932&upn=VFAbXgDGSU8&key=cms1&fexp=900718%2C924231%2C924637%2C927622%2C930809%2C931354%2C932404%2C9405454%2C941004%2C943917%2C945066%2C947209%2C947218%2C948124%2C952302%2C952605%2C952901%2C955301%2C957103%2C957105%2C957201&sver=3&ip=24.235.37.181&ipbits=0&expire=1419930614&sparams=clen,dur,expire,gcr,gir,id,ip,ipbits,itag,lmt,mime,mm,ms,mv,ratebypass,requiressl,source&cmbypass=yes&req_id=3eb2c618c54ca3ee&redirect_counter=2&cms_redirect=yes&mm=26&ms=tsu&mt=1419909012&mv=m

OK, so that is a very big link. This is the same link dissected into pieces:

https://r3---sn-p5qlsu7d.googlevideo.com/videoplayback?id=887ce37c617a3225
&itag=141
&source=youtube
&requiressl=yes
&gcr=ca
&ratebypass=yes
&mime=audio/mp4 #Here's where audio only is specified.
&gir=yes
&clen=4012348
&lmt=1409362978343745
&dur=125.828
&signature=0A00B9B16BB6EF3192DF33EEF9B2AB67F66F501F.0B649D407144B914A7CC7BE00E795B5BD1B9D932
&upn=VFAbXgDGSU8
&key=cms1
&fexp=900718,924231,924637,927622,930809,931354,932404,9405454,941004,943917,945066,947209,947218,948124,952302,952605,952901,955301,957103,957105,957201
&sver=3
&ip=24.235.37.181 #Oh, look. My IP address.
&ipbits=0
&expire=1419930614
&sparams=clen,dur,expire,gcr,gir,id,ip,ipbits,itag,lmt,mime,mm,ms,mv,ratebypass,requiressl,source
&cmbypass=yes
&req_id=3eb2c618c54ca3ee
&redirect_counter=2
&cms_redirect=yes
&mm=26
&ms=tsu
&mt=1419909012
&mv=m

Very interesting. This enables Flashgot to download only the audio and skip the video, thus saving bandwidth. I'm missing details, like how Flashgot created this link, but if Flashgot has a way to do it, it stands to reason that other HTTP clients could do it too.

Answer 2

According to the Youtube API blog post, the only options you have of playing youtube on iOS is to link to the video (and have the internal YouTube app play the video), or link from a UIWebView and play from there. Audio-only playback is not supported.