5 Replies Latest reply on Nov 14, 2012 3:15 PM by Gaius Coffey

    Discussion on Android bitrate switching problems in OSMF

    Gaius Coffey Level 2

      Hi,

      I'm prototyping an OSMF for Android app and running into quite a few issues, I'd welcome any suggestions, feedback or workarounds for any of the following issues, or even just some general discussion on developing OSMF for Android!

       

      1. Sound synching: After switching up and down a few times (on a poor and unreliable network...) I frequently find video playback is massively (seconds) out from video display.

       

      2. On lower-spec tablets, bitrate switching provokes display glitches where:

      - Screen flashes green over some or all of the display at intervals

      - Screen jumps every few seconds to display as if the screen was several inches out from where it should be

       

      3. Occasionally, after a bitrate switch, the display freezes entirely and leaves audio running, it never seems to recover...

       

      4. When switching down, I often encounter sound glitches as if somebody was physically dragging a record-player needle across between two records...

       

      Obviously, I can't enable bandrate switching with those issues, so any suggestions to alleviate them are welcome. For example, I've been playing with some of the configs in OSMFSettings, to try to reduce the issues. I've also been experimenting with setting a smaller fullScreenSourceRect and so on.

       

      As I say, this is really a discussion post... I would really welcome any ideas, feedback or suggestions experience and so on about developing OSMF for Android.

       

      Thanks,

      G

        • 1. Re: Discussion on Android bitrate switching problems in OSMF
          Defocalise Level 1

          1. Ensure encoding profile matches Adobe specs. Non variable keyfarmes - make fixed interval.
          2. Ensure you are using baseline encoded assets. Green screen is a sign of the wrong profile. Wrong profile will exibit all the issues you are seeing.

           

          Defo an encoding problem.

          • 2. Re: Discussion on Android bitrate switching problems in OSMF
            Gaius Coffey Level 2

            Thanks, I will check those with the guys who do the encoding and see if it sheds any light anywhere.

            G

            • 3. Re: Discussion on Android bitrate switching problems in OSMF
              Gaius Coffey Level 2

              Hi,

              I had a chat with the encoder guys and it looks like that is already in place - all bitrates use fixed keyframes and standard profiles. Only difference I can see is that the three lower bitrates use "Base" profile where the top bitrate uses "Main" profile as it has so much more data it needs it (apparently) - not sure what is in these profiles, but they are, I think, standard Adobe fare.

               

              I'm wondering whether the different profile for 1024 could be part of the problem? I don't know much about the profiles, but I imagine they should all be the same. Do you know whether there would be a problem using "Main" for all of them?

              G

              • 4. Re: Discussion on Android bitrate switching problems in OSMF
                Defocalise Level 1

                In my 'experience' you should only be using baseline encoded assets if you are producing content for Android devices.

                Main profile seemed to cause problems with our playback so we switched entirely to baseline. Now no problems in that respect.

                I don't think you should be switching from baseline up to main either. Main is a much more complicated profile and it places b frames out of order so it will most likely affect the switching. Get your encoder guys to analyse the packets/metadata and send you a copy. From this it's easy to see any discrepencies.

                I work for a large uk tv company and we stream renditions from 150k to 1200k (with 300, 400, 600, 800 between) - we stream all types of content and in most cases it looks fine from 600 upwards. Their reasoning is invalid.

                 

                We also have experienced issues with FMS 4.5.2 recently where switching doesn't work as it should. We were using a fixed GOP length but with scene detection which meant in some renditions the keyframes were out of sync.

                • 5. Re: Discussion on Android bitrate switching problems in OSMF
                  Gaius Coffey Level 2

                  Thanks, yes, it seems to be running well now I'm sticking with just the baseline assets. I'll chat through with them about the main stuff - also the fixed GOP length, though I'll have to google it first!

                  G