[vdr] Re: Softdevice + EPIA-M / Sound resampling

[Henrik Johansson <henjo@ieee.org>]

Colin Paton wrote:

> Playing back with sound + MPEG decoding but no video display (but call to
> 'Flip') = ~17% CPU
> Playing back with blit added (get video display) = ~78% CPU
> Playing back with FB sync but no blit = ~46% CPU
> Playing back with blit + FB sync = ~98% CPU
>
> Without sync and blit audio sounds OK.
>
> My next task is to try and track down why sync and blit are using lots of
> CPU. I suspect there's a busy loop in there somewhere.
>  
Sounds likely.

> I figured it would probably be suitable just to be simple and drop or add a
> frame in order to maintain sync between the broadcast timestamps and the
> video clock. I go with the assumption that the difference between the two
> shouldn't be too much, therefore the odd frame slip won't be noticeable.
> Obviously setting the clock exactly is the correct way to do it - but I
> suspect would be quite involved, especially as I don't have datasheets for
> the chip.
>
>
>  
With most framebuffer devices you could set the videomode (not vesafb) 
through ioctls so with viafb I think this could be done. Maybe there
is a wrapper in DirectFB to do this too.
BTW, what is the vertical frequency of the mode you're using when 
testing? If it's not matched as close as possible to the frame rate in 
the stream
you would defenately run in to trouble with the VBL  syncing.

Regards

Henrik



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