Panasonic E80H - High-speed dubbing using less disc space?

[Tony Tower]

So, I've been playing around with various ways to archive off-air TV programs to DVD-R, and, after experimenting and asking advice here, have settled on one of two methods:

(1) Record to HD at XP; remove commercials via playlist or edit function; real-time dub to DVD-R at LP quality.

(2) Record to HD at LP; remove commercials via playlist or edit function; dub to DVD-R via High-Speed dubbing.

Since quality seemed about the same either way, I was using Method #2 for a while. The absence of re-encoding seemed to balance out lower initial acquisition quality. However, when I started seeing some glitches in the edits I didn't like, I went back to Method #1 for a bit. That hasn't totally solved my editing issues, but an oddity came up:

I can fit more shows on a disc with Method #2 than #1.

With Method #1, I can fit five hour-long programs minus commercials (around 43:00 each) with a bit of room to spare. For some reason, Method #2 allows me to get SIX episodes per disc.

Can anyone explain why this would be? Since bother recordings are LP (kinda), why does more fit one way or the other?

Wisdom is appreciated as always.

- Tony Tower

[houtx67]

If you are using LP mode and not FR for the final dub/recording for both methods, I'm at a loss (if the time of each episode is basically the same). I have noticed that when I do high speed dub, the final DVD-R doesn't seem to always peak out at the same bitrate as the original (very close though). I compare the finished product at certain moments with the HD original to measure this. I can't visually tell a quality difference, but I haven't done it with anything above the ~SP level yet. I don't know why it would do this either. If this is true however, then maybe just enough space is recovered on the high speed LP dub to free up the extra minutes you need for the sixth episode.

There are other posters who have used the High Speed mode more than I have (I usually use what you call method #1 on <SP size DVD-R recordings because of personal preference). Perhaps they can share their experiences/theories/explanations.

[houtx67]

Edit.

[houtx67]

Since my last post above, I have experimented more with the high-speed dubbing.

I also experienced Tony Tower's situation when I was able to high speed dub 2:06 Hrs on (1) DVD-R in SP mode whereas straight real-time re-dubbing would have required FR mode. And yes, it finalized fine and plays back fine.

I am inclined to now assume that this is because the high speed dub is possibly not limited to the 4 GB limit the real time recordings on the Panasonic are limited to. I assume this is because high speed dubbing copies the file(s) and does not re-encode.

On the dubbing menu, when in XP, SP, LP, EP, or FR mode, the space on disc and time selected (of programs to be dubbed) shows everything in terms of time (2:00, etc). Whereas in high speed mode, these selections are in terms of file size (4409 mb etc). 4409 mb happens to be the space that shows available on a blank DVD-R in high speed mode, too.

This seems a little more reasonable to me than my earlier theory that the file doesn't contain as much data (bitrate) than the original. I do still notice that the peaks are different between the original and the high speed dub, but I guess that's due to differences in where the bit rate is sampled between (2) physically different sources.

Based on the above (and some experimenting I did with other programs on my HD), it appears that you can't get much more than ~2:06-2:07 on a high speed dub in SP mode. I suppose that maybe this might mean that, on average, you can get 1:03 in XP mode, 4:12 in LP, etc.,. Perhaps Tony Tower can tell us what he experienced in his original post in LP mode.

This is something to consider when you expect your final program size to fall within the above limits. It can reduce your re-dub time from ~ 4 hours in LP mode (for ~ 4hrs of program) to about 51 minutes, plus save HD space if you normally use a higher quality speed for the original when planning to re-dub (which is what I do).

If anyone has comments, or a different experience, please share.

[donpedro]

What if re-encoding needs more bittrate to encode already encoded source ? Just and idea...

[Tony Tower]

Based on the above (and some experimenting I did with other programs on my HD), it appears that you can't get much more than ~2:06-2:07 on a high speed dub in SP mode. I suppose that maybe this might mean that, on average, you can get 1:03 in XP mode, 4:12 in LP, etc.,. Perhaps Tony Tower can tell us what he experienced in his original post in LP mode.

I usually archive 6 hour-long tv shows (minus commercials) per disc at LP, with a bit of room to spare. At 43 minutes each, that's 4 hours, 18 minutes - not including the room to spare.

And as for Don Pedro's re-encoding space concern - my understanding is that High Speed dubs DON'T re-encode, and are a true digital, lossless dub. Perhaps that's hwere the space comes from - a cache of space saved for bitrate variances needed for normal recording that aren't needed for high-speed dubs since the file size is pre-determined.

Make sense?

- Tony[/i]