partial_serve_flask_3.py

def generate_data_from_response(resp, chunk=2048):
    for data_chunk in resp.iter_content(chunk_size=chunk):
        yield data_chunk


def serve_partial(url, range_header, mime, size=3145728):
    from_bytes, until_bytes = range_header.replace('bytes=', '').split('-')
    if not until_bytes:
        until_bytes = int(from_bytes) + size  # Default size is 3MB
        
    # Make request to YouTube
    headers = {'Range': 'bytes=%s-%s' % (from_bytes, until_bytes)}
    r = requests.get(url, headers=headers, stream=True)

    # Build response
    rv = Response(generate_data_from_response(r), 206, mimetype=mime,
                  direct_passthrough=True)
    rv.headers.add('Content-Range', r.headers.get('Content-Range'))
    rv.headers.add('Content-Length', r.headers['Content-Length'])
    return rv