[MPlayer-dev-eng] [PATCH] blue back tv feature (automute with no signal)

[Loren Merritt]

On Fri, 25 May 2007, Vladimir Voroshilov wrote:

>> WTF is the point of that priv->blank_frame? It only needs a lot of code
>> and thrashes the caches even more than just calling fill_blank_frame
>> directly. If fill_blank_frame is significantly slower fix it.
>> Or if you want it to be really faster use EXPORT type image, then you
>> won't have to do any memcpy or memset or whatever at all except once.
>
> I thought one memcpy (assuming that video frame size will not be
> frequently changed)
> will be a bit faster. Fixed to fill_blank_frame_call. I didnt
> undestand what did you mean by "EXPORT type image". Could you explain
> this for me ?

memcpy takes twice as much memory bandwidth as memset, since it has to 
read and then write the data. Or 1.5 times if neither uses write-combining 
and the destination has to be loaded into cache too.
There may be a little cpu overhead in the uyvy and yuy2 cases, but if 
memory writes aren't the limiting factor then you've implemented it 
inefficiently.

--Loren Merritt