yondon ~
1) It's up to the vendor to decide if they wish to continue maintaining any specific codec. MainConcept doesn't feel it's important to their future. They're probably simply putting their development dollars into something else. That said, there are some vendors who have h.264 encoders that support the 980 and are designed to leverage it, for example (I have not used this codec nor am I recommending it, just an example):
High performance CUDA H264 Codec
2) Yes, encoding as in "compressing" the final video. Not "application" performance. That's why I said "the applications also need to make use of the SDK themselves". And this is what most of us actually want. We want fast previews, accelerated filters, etc. At the moment, Adobe does not utilize Maxwell CUDA for any of that. Keep in mind, this generation of CUDA was designed with "general purpose" computing power in mind. That is fairly brand new. Previously there was a very limited way to utilize GPU power. GPUs are great at graphics but they are not a "general purpose" processor like a "CPU" is. Therefore there was limited interest in spending time trying to utilize the small amount of the GPU that was usable for application performance. Maxwell can be utilized much more like a CPU core now, so we hope vendors will start to use the cores for "application" performance.
Just keep in mind, what I mean by "encoding" is exporting and compressing the final video. "Application" performance is how the application is utilizing the GPU to speed up editing, previews, filters, 3D, lighting, pixelshading, etc.
3) My guess would be if you have a gigantic PNG sequence your hard drive is your bottleneck. It simply can't keep up with reading a huge amount of small files. You'd do yourself a big favor encoding those into a real video so you can utilize your GPU decoders for playback. If you need transparency then you can use something lossless but encoded like Quicktime Animation Millions+ (RGBA). Open up your resource monitor during PNG playback and while you see your CPU bored at 10% you'll probably see your HD at max.
Right now the 900 series cards are testing fine with the MPE engine and acceleration. I have not seen any limitation including effects. So I am not sure where people are running into problems. AE acceleration is ray tracer and on the way outs. Dont expect Nvidia to maintain the version AE left at in the drivers and I would be surprised if any new cards work with it since Adobe is done updating it. Very few use it at this point and C4D with Octane is far better especially for the GPU acceleration.
Eric
ADK