Amazon Prime sucked on my Xoom. Over at the Motorola Xoom Forum, a very knowledgeable poster (gmanapps) posted the following explanation for the Xoom issues:
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Prior to ICS, flash had support for each individual CPU/GPU combo with specific video acceleration code for each type of CPU/GPU (OMAP, Snapdragon, Tegra, etc) which meant that flash could totally take advantage of the hardware.
When adobe ported flash to ICS they used the new ICS API. Under ICS all devices are only required to support the lowest encoding profile, but may support the higher bitrate encoding profiles.
Adobe decided that since only the lower bitrate profile was guaranteed to work with hardware acceleration accross all ICS device, to only send the lower bit rate profiles through the ICS hardware accelerated API. Everything else is done as software decoding inside of flash. So while the Xoom hardware is capable of accelerating/decoding the higher bitrate encoded data, flash no longer sends it to the GPU for decoding and tries to do it in software which is slow.
Amazon's content is encoded in one of 4 different mpeg encoding profiles. One of the profiles goes through hardware acceleration and works fine. But higher bitrate data profiles get stuck getting decoded in flash's software decoder and looks horrible.
Adobe could have provided a configuration option, test or other method to allow individuals to enable decoding of the other profiles in hardware....or at least try it and see if it worked on their device. On many devices it would work. But they chose not to go that route.
So unless you are running a high end quad core device, with a small screen, the software decoding of much of higher resolution flash content is going to be painful to watch.
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Out of curiousity I just tried it with Dolphin on my Galaxy S3 phone - HD video of Downton Abbey looked beautiful and had no synch issues at all. But a very small picture ...
Dave