Support range requests

[MarcelloTheArcane]

At the moment, if I try to seek to a position with an HTML audio element, it restarts the audio.

Could HTTP range requests be supported, so that I can seek to places in music?

[MarcelloTheArcane]

Some handy docs:
https://developer.mozilla.org/en-US/docs/Web/HTTP/Range_requests

1. Add the Accept-Ranges: bytes header to media requests
2. Return Content-Range: 0-/<total> header by default, with a 200 status
3. If a Range header is present on the request, return the appropriate ranges with a 206 status and Content-Range: <start>-<end>/<total> header.

It should be possible to set up round about here in the code, I'm not too sure how to implement it.

gmusicproxy/GMusicProxy

Lines 285 to 293 in 47eb52e

	mp3 = opener.open(url)
	logger.debug('tag size: %s byte', tagsSize)
	logger.debug('content estimated size: %s byte', songSize)
	if mp3.info().get('Content-Length'):
	songSize = int(mp3.info().get('Content-Length'))
	logger.debug('content size from HTTP headers: %s byte', songSize)
	self._send_headers(200, 'audio/mpeg', 'inline; filename=%s.mp3' % id.strip(), ((tagsSize if not do_shoutcast else 0) + songSize) if (songSize > 0)
	else None, downloadBlockSize if do_shoutcast else None, self._icy_name(tags.album, tags.artist, tags.title) if config['shoutcast_metadata'] else None)

[jdwoody]

We could make this work, I've noticed this issue from time to time when navigating in volumio and/or mpd. The get_song method can use some clean up and I'm focusing on the YT music migration, but will work this in as time allows.

[MarcelloTheArcane]

@jdwoody Are updates pretty much on hold till we have the YT music integration?

[jdwoody]

No, updates are not on hold. I'll be cutting releases. I was looking at moving to Flask for serving content, which provides easier route configuration, Swagger docs, etc. I'm not sure how involved this will be. If you can provide some documentation/code that would start play at a certain offset, I will try to work it in.

[MarcelloTheArcane]

I'm not that confident coding with Python, so this is something I've found - not sure if you can make something of it: https://gist.github.com/lizhiwei/7885108