Bruce,
Here's more examples in a more methodical format.
From the Quality Screen on a Series 2 Tivo.

I recorded four 5-minute sections of the same program using the Record by Time & Channel
option. Each 5-minute section had a different quality setting as per the above screen.
After using Tivo Transfer to get the recordings on to my Mac I used Tivo Decoder to get
to the MPEG videos encapsulated in the .Tivo files, then using the application MediaInfo
I got the resulting movie and file sizes . . .




So we see 3 different file sizes and 4 different bitrates with each step-down about 25% until
the last step which seems about 40%.
Plus the ability of only one stream to catch the closed captioning information, strange.
Best 33MB/min 544x480
High 24.4MB/min 480x480
Medium 19.3MB/min 352x480
Basic 12MB/min 352x480
So I ran the collection of .Tivo files through Toast 10 video converter. I had to peruse the
manual to figure out how to export without burning, push the red button, huh, that's an
interface inconsistency. So with .Tivo files, no options are available, just Standard. Okay,
here it goes.
It took 12 minutes and 31 seconds to convert the .Tivo files to iPod playable MPEG4/H.264
video files.
After reading your post about your set-up:
"My mac - powerbook g4 15" ; 1.5 GHz PowerPC G4; 1.25 GB DDR SDRAM"
"My Tivo - Series 3HD"
I converted the file captured at Best Quality which would work out to about 3.96 GB for a
two hour program. (165MB * (120/5min))=3.96GB With Toast 10 it took 4 minutes and 20
seconds, which would come to about 52 minutes to encode an hour of video. That is on a
MacBook Intel Core 2 Duo 2.2GHz and 4GB RAM.
So I tried out the video with VisualHub with the settings from the video converted by
Toast 10, 480x360 900Kbps 29.97 fps, 128Kbps, 48KHz, stereo and it took 5 min 8 sec on
the Mac with the above specs.
Then I tried the same Best Quality file on an iMac G5 1.8GHz and 2GB RAM in VisualHub
with the same settings above and it took 39 min 37 sec, or what would be just short of 8
hours to encode an hour of video. I remember encoding video for DVD on that G5 and taking
several days to finish, because I would pause it during the day and resume it overnight.
So the answer to your questions is that you don't have enough ponies in your Mac to get the
job done in a timely fashion.
I'm surprised that your G4 PowerBook is keeping up with a G5 with what looks like
similar file sizes, anyway it looks like there might be a new Mac or an Elgato Turbo H264 in
your future.
Elgato Online StoreThe Turbo seems to be on sale 2009/07/20 at the Elgato online store. BTW the Turbo.264 HD
will not work on your G4, it requires an Intel Mac.
Hope this helped.
Cheers!