[mythtv-users] Frame by frame rewind problems

[Nick Rout]

On Wed, Dec 14, 2011 at 1:34 AM, Brian J. Murrell <brian at interlinx.bc.ca> wrote:
> On 11-12-12 09:51 PM, Nick Rout wrote:
>>
>> That makes sense, in that the system needs to process the keyframe in
>> order to understand the next frames - which are essentially only a
>> flash mathematical diff between the previous frame and the current
>> frame.
>
> Right.  But processing keyframes should not necessarily mean displaying
> them.  That sounds a bit like a bug to me.  Even if back-stepping needed
> to back up to a keyframe to calculate the frame you back-stepped to, it
> should not actually do any display until the back-stepped frame has been
> calculated.
>
> But an even better way to handle this would be to simply always buffer
> the last few displayed frames up to the last keyframe so that
> back-stepping didn't require backing up to a keyframe and calculating
> the back-stepped frame.  Of course, at every keyframe, the buffer is
> thrown away and built again until the next keyframe (he says without
> really giving any thought to how much memory that could possibly consume
> :-) ).

Particularly when decoding is being done on the GPU. I don't think the
decoded frames ever exist in system RAM.