MPEG captures w/AIW 9800 smaller than AIW 7500?

  • Thread starter Thread starter Fountainhead
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Fountainhead

I previously used an AIW 7500 to capture shows via the TV tuner and burn
to DVD. I had 3 custom MPEG-2 capture settings for 1 Hr, 2 Hr, 3 Hr,
depending on how much I needed to fit on a single DVD. The settings were
all basically the same (352 x 480) with the bitrate set differently for
each. I just built a new PC around the AIW 9800. I re-created the exact
custom settings on the 9800, but I notice that the resulting MPEG files
are smaller than they were on the 7500. For example, 1 Hr of MPEG
recorded on my 1 Hr setting produces an MPEG of ~2900MB, compared to
approx 4000MB on the 7500.

Not that this is a bad thing, but it makes me wonder if I'm overlooking
something. Or is the MPEG encoding on the 9800 more efficient somehow?
 
I previously used an AIW 7500 to capture shows via the TV tuner and burn
to DVD. I had 3 custom MPEG-2 capture settings for 1 Hr, 2 Hr, 3 Hr,
depending on how much I needed to fit on a single DVD. The settings were
all basically the same (352 x 480) with the bitrate set differently for
each. I just built a new PC around the AIW 9800. I re-created the exact
custom settings on the 9800, but I notice that the resulting MPEG files
are smaller than they were on the 7500. For example, 1 Hr of MPEG
recorded on my 1 Hr setting produces an MPEG of ~2900MB, compared to
approx 4000MB on the 7500.

Not that this is a bad thing, but it makes me wonder if I'm overlooking
something. Or is the MPEG encoding on the 9800 more efficient somehow?
Click to expand...

It's possible that you have enabled "Video Soap" with the newer version of
MMC you are now using with the AIW 9800. Video Soap allows you to clean up
the picture you are capturing. It's helpful especially when you don't have
a crystal-clear source. So, with less noise in your picture, the resulting
MPEG file will be smaller in size.

-lyj
 
Fountainhead skriblede:
Not that this is a bad thing, but it makes me wonder if I'm
overlooking something. Or is the MPEG encoding on the 9800 more
efficient somehow?
Click to expand...

Are you using the same version of the capture software (MMC)?

The encoding takes place in software - not hardware.

David
 
Fountainhead skriblede:


Are you using the same version of the capture software (MMC)?

The encoding takes place in software - not hardware.

David
Click to expand...

I was using 8.5 with the 7500, and 8.7 with the 9800. In response to the
other poster, I am using the same Video Soap settings as before. One
thing thing that *is* different is that the 9800 has "hardware assisted*
MPEG encoding, and the 7500 does not. I don't know if that has anythig
to do with it or not.
 
Fountainhead skriblede:
I was using 8.5 with the 7500, and 8.7 with the 9800. In response to
the other poster, I am using the same Video Soap settings as before.
One thing thing that *is* different is that the 9800 has "hardware
assisted* MPEG encoding, and the 7500 does not. I don't know if that
has anythig to do with it or not.
Click to expand...

To my knowledge the hardware assist only works in decoding, i.e. when you
play a file. But it could be the newer version of mmc - at least the
capture driver changed with MMC 8.6. But the videosoap - was it even
available on the 7500? Videosoap is a hardware feature on the series 9xxx i
think.

David
Click to expand...
 
To my knowledge the hardware assist only works in decoding, i.e. when you
play a file. But it could be the newer version of mmc - at least the
capture driver changed with MMC 8.6. But the videosoap - was it even
available on the 7500? Videosoap is a hardware feature on the series 9xxx i
think.

David
Click to expand...

Video Soap showed up in MMC 8.1. I was using 8.5 with the 7500. You
*can* use video soap with the 7500 with MMC 8.x. I was able to get the
later MMC's as I have a 9700 Pro in another PC, so I had the proper
original CD's for verification, etc. And ATI says that the AIW 9800 has
"hardware assisted encoding", which I take to mean that real-time MPEG
encoding is at least partially processed via the card itself. The 7500
definitely has no hardware assist.
 
Fountainhead skriblede:
Video Soap showed up in MMC 8.1. I was using 8.5 with the 7500. You
*can* use video soap with the 7500 with MMC 8.x. I was able to get the
later MMC's as I have a 9700 Pro in another PC, so I had the proper
original CD's for verification, etc.
Click to expand...

Ah. Well I read up a bit and it seems that videosoap uses the graphics
chip's pixel shader to calculate its filtering as well as using the cpu.
Perhaps this explains it. The video soap can use the R350's pixel shader
but I believe the 7500 (dunno chip name) has no pixel shader capabilities
and is thus not able to utilize video soap to its fullest?

I read anout VS here:
http://www.anandtech.com/video/showdoc.html?i=1740&p=3
And ATI says that the AIW 9800
has "hardware assisted encoding", which I take to mean that real-time
MPEG encoding is at least partially processed via the card itself.
Click to expand...

True - I remembered wrongly from another discussion where someone claimed
the card did hardware encoding. It does assist in encoding.
The 7500 definitely has no hardware assist.
Click to expand...

Agreed.

David
 
Ah. Well I read up a bit and it seems that videosoap uses the graphics
chip's pixel shader to calculate its filtering as well as using the cpu.
Perhaps this explains it. The video soap can use the R350's pixel shader
but I believe the 7500 (dunno chip name) has no pixel shader capabilities
and is thus not able to utilize video soap to its fullest?

I read anout VS here:
http://www.anandtech.com/video/showdoc.html?i=1740&p=3
Click to expand...

Interesting link, thanks. I'll post my findings here (AIW 9800 vs AIW
7500) in case anyone pulls this up via google at some later date. I
created a DVD containing clips made with each of my custom settings (1,
2 and 3 hr) and I can say that the quality of each of these is noticably
better than what I got from the AIW 7500 with the same settings. The 3
Hr setting in particular was FAR better than before.

For the record, here are my settings using MMC 8.7:

MPEG-2 at 352x480
Encode Interlaced
48,000 KHz Stereo
P Frames 4
B Frames 2
Do not check 3:2 pulldown
Check the little box for Closed Group of Pictures
1 Hr - 8.5 MBit
2 Hr - 4.42 MBit
3 Hr - 2.93 MBit
(These are set up to record approx 3.9 GB in the alloted time)
Motion Estimation 100%
Audio Encoding 224Kbit
Video Soap - Comb Filter #1 - 70%

These all record with no dropped frames. One thing that I find
interesting is that TV captures made at 352x480 actually look better
than those recorded at 720x480, with all other settings the same. I
would have thought the 720x480 would produce a better video image, but
it doesn't. I wonder why?
 
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