Why does recording use 3% CPU and playback uses 23%?

[fpdave]

I have a hauppauge HVR-1300 on my relatively low powered server PC and it only uses about 3% of CPU whilst recording.

Playing on my desktop (livetv) uses about 23% or so of the CPU.

on the desktop:
Radeon X1650 Series, 3GB RAM, 2.2Ghz AMD Winxp Pro

I'm using PVRX2 and playing back on a 2nd LCD monitor and I'm finally really happy with the quality.

Playback config is:
video renderer:VMR9 Custom
MPEG-2 playback: vid:MPEG Video decoder, audio:Nero, audiorenderer:realtek ac97

Is this CPU usage about right or can I reduce it somehow?

[Dava]

Hi,

I believe it is that the capture card is doing the encoding work and just send a stream to the drive, whereas the viewing PC has to decode the stream using the processor for the software decoder.

[sub]

Those CPU numbers are fairly normal.

Recording is a relatively easy task. It usually just involves writing data to disk as it is received from the capture card.

Playback is much more complex, and requires the machine to do a lot of work (buffer management, decoding frames, displaying them on the screen etc).

[fpdave]

I always thought that compression (at recording time) was always much harder work that de-compression.

Its a shame that playback cant be hardware accelerated also, in fact with a good graphics card this should be built in surely?

[stustunz]

the encoding is been done by the tuner card if analog (otherwise you would see it at 30-50% aswell when recording)
if digital its just putiing the stream in bits back together

the video is hardware accelerated well can be if its not then you will see the same thing happening
if you look at your decoder properties you should get the option under advanced for you r video decoder
since you are using mpeg decoder you may not get this choice
if using nvidia or power dvd you can turn it on