[mythtv-users] HDMI capture card with linux drivers

[Raymond Wagner]

On 4/16/2010 02:15, Douglas Peale wrote:
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> Raymond Wagner wrote:
>    
>> On 4/16/2010 01:24, Douglas Peale wrote:
>>      
>>> Your computer could do nothing else but write the disk, so there is no
>>> possibility of encoding while recording.
>>>
>>>        
>> Why not?  Obviously the BlackMagic Windows software already performs
>> this impossible task of encoding to MJPEG on the fly.
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>>      
> Unless they are using a raid system, they are not writing the
> uncompressed file directly to disk.
>    

Correct, their software compressed to MJPEG for storage in real time.  
Your original claim was that the CPU would be so busy trying to write to 
the disk, that it would not have the power to compress the feed to 
something smaller.  That is false.

> Are you sure they are doing this in software? I'm not aware of any
> software that can handle HD compression in real time on a PC. Unless of
> course you don't care about the quality.
>    

'HD compression' is an absolutely meaningless term if you don't specify 
the codec in use.  Huffyuv is extremely fast, such that the author's 
400MHz Celeron was able to compress DVD video (480p30) in real time.  
Any Core2 or Athlon64 should be able to handle 1080i60 in real time.  
MJPEG is almost as fast, if a bit lossy and so less suited for video 
editing.