12 Replies Latest reply: Dec 16, 2013 5:26 PM by dewdude RSS

    Bandwidth required for HD

    OvCollyer Apprentice

      According to the tech specs for both the Slingbox 350 and 500 the minimum bandwidth required for an HD video stream is 2mbps.

       

      Assuming that by 'HD' it is referring to 720p or 1080i - which seems a reasonably assumption to make - my experience after repeated testing of the web player is that you actually need approximately 3.5mbps when in the Best (HD) setting, otherwise the stream will continually stutter due to lack of bandwidth.

       

      I've tested this quite carefully by using QoS at the location of my 350 to limit the upload bandwidth to 2mbps, and only when I allow 3.5mbps+ do I get a smooth stream which doesn't continually choke and thus be unwatchable.

       

      I'd be interested in Sling's comments on this, as I think at the moment the tech specs are misleading.

        • Re: Bandwidth required for HD
          heelphan

          Thanks for that info OvCollyer.  I have an original (red) Pro-HD and have been thinking about upgrading to the 350, but was really interested in the upload speed needed for HD streaming over the internet.  Currently I only have 1mbps upload and am thinking about upgrading my internet speeds.  Of course TimeWarner offers a tier for $10 more a month with 2mbps up and then another $10 for 5mbps up.  So, I guess I will have to pay $20 more a month to get true HD streaming even with a SlingBox 350.  Darned TimeWarner!

          • Re: Bandwidth required for HD
            HT1977 Newbie

            Obviously more B/W  is better, and I have much more available B/W than I need at the house for my SB PROHD.  When I an viewing from outside the house, HD channels show 1.03 to 1.1 Mbps on the B/W meter.

             

            That's when using the client 2.0 and configured with video resolution 1920 x 540, full rate frames/second, the video smoothness bar is far to the right for sharpest picture.

            • Re: Bandwidth required for HD
              dewdude Newbie

              3mbps seems to be where it's at in my expierence for a somewhat usable HD stream. I've been in a few locations where this was about all I was going to get and was able to get a relatively smooth picture; though it had quite a bit of macroblocking distortion. This is based on using the Android tablet app; which doesn't display a full 60hz and may be why it'll work with somewhat lower rate. I'm also wondering if the way you're testing using QoS isn't causing issues. Have you tried dropping the link rate in your WiFi router to 2mbps and see what happens when it's a "physical" network speed limitation and not a packet filtering limitation?

               

              Like stated earlier and pretty obvious; more BW you've got the better. I have a 35mbps uplink; and I've seen my 350 push a good 8 or 9mbps for some HD streams.

                • Re: Bandwidth required for HD
                  OvCollyer Apprentice

                  Yeah 3mbps seems about enough when I use a Mac, where the player doesn't support 50/60 fps. Under windows it's more like 3.5mbps with 50/60 fps.

                   

                  I haven't tried the wifi setting change, but for the Windows web player it's possible via some thirdparty software out there to directly specify to the ActiveX plugin the video bitrate you want to stream at and the plugin then uses this to choose a certain encoding profile. No matter what bitrate I set, it never seems to use a profile that needs less than about 3.5mbps. Eg ask for a bitrate of 1mbps, result = 3.5mbps.....ask for 2mbps, result = 3.5mbps......ask for 4mbps, result = 4mbps.....ask for 5mbps, result = 5mbps, etc.......of course, I'm not sure whether the limit is being set by the plugin or the Slingbox.

                   

                  But this directly backs up my QoS findings.

                   

                  I'd love to know what circumstances you can get an HD picture at 2mbps, according to the tech specs, but if it isn't achievable then that's a pretty blatant bit of misleading information.

                    • Re: Bandwidth required for HD
                      dewdude Newbie

                      I would actually have to argue that doesn't back up your QoS findings at

                      all. If the third party software is  talking to the ActiveX plugin; you

                      don't actually know what it's doing. I mean; it's picking a bitrate

                      profile; that doesn't actually mean it's going to limit the bitrate. So the

                      video encoder is going "well, I'm set for a 1mbps stream but I'm pushing

                      more"; it hasn't been physically constrained to where it would have to

                      change rate. I can pick quality settings in the web app; but since there's

                      still 90mbps of bandwidth available, it's not going to limit itself.

                       

                      I will have to grab my tablet and walk to the corner of my backyard where

                      the wifi signal is weak and see what kind of speeds I'm actually pulling

                      with an HD stream.

                        • Re: Bandwidth required for HD
                          OvCollyer Apprentice

                          Well I suppose the point is that this is a 'manual' bitrate setting which operates outside the usual automated system (think of the manual settings of the legacy desktop player). If I do this over the LAN where there is effectively unlimited bandwidth then it's exactly the same, ie if I ask for 4mbps it gives me just that, and at no point does it 'push for more'. It's very rigid, there is no obvious switching up or down of profiles going on that is evidenced by the bitrate stat, and it attempts to use this video bitrate immediately upon connecting......this contrasts with the auto stream mode which switches up and down the profile according to what bandwidth it thinks is available.

                           

                          This leads me to suspect that either the plugin or Slingbox are coded to use a profile with a bitrate of 3.5mbps minimum for HD.

                          Of course, this is just the Windows web player, maybe the tablet versions support lower quality bitrates while still being HD resolution.

                            • Re: Bandwidth required for HD
                              dewdude Newbie

                              Part of the point I was trying to make...is that maybe 3.5 mbps is the lowest profile supported; so picking something lower than 3.5 results in it using 3.5; where as it might be capable of going lower by viture of variable bitrate encoding.

                               

                              My tablet did produce an HD stream with a reported rate of 2096kbps; although the 2% wifi signal was causing it's own set of issues. When I get around to it later (and everyone is off my access point), I'll enable some low link speeds and see what happens.

                      • Re: Bandwidth required for HD
                        dewdude Newbie

                        The Windows player does not support the Slingbox 350. All I can use are the web players; of which I currently use Chrome. It's a Chrome-native app; so it doesn't use ActiveX.

                          • Re: Bandwidth required for HD
                            OvCollyer Apprentice

                            I  meant the Windows web player, sorry.

                             

                            It would be interesting to see what the Chrome version does and whether that needs 3mbps+ for HD.

                              • Re: Bandwidth required for HD
                                dewdude Newbie

                                Sorry for kicking this up a month later.

                                 

                                Yesterday I was visiting my grandmother to resolve some Windows 8 issues she had; her internet connection is a 3mbps DSL line. After I had the issues resolved; I turned football on using Slingbox in Chrome on my Win7 PC. It reported "Excellent" bandwidth and was streaming in HD at about 2700kbps. It had no problems maintaining that; occasionally dropping to SD because someone was standing in front of the wifi router.

                                 

                                That being said; that's only a 3mbps  downstream limitation; as my home connection is at least 10x that speed on uplink.