Can Recorded Video B Btter Than Original Source?

[jmsrickland]

Hi,

Here is an example of my question.

I have a Panasonic DVD recorder that has 'Flexible Record' feature.

If I copy from a VHS tape that has a 90 minute program and it was recorded in SP mode and I set the Flex record time to 90 minutes and copy from tape to disc will the recorded output on DVD be better than the original video source?

[noki]

will the recorded output on DVD be better than the original video source?

totally subjective.
I know that people feel you cannot improve upon the source but that is not entirely true. for example Ive transferred HI-8 tapes to DVDR via a settop recorder and I think the DVDR looks "BETTER" than the tape. WHY? the dvdr has a softer look that I think is better than the somewhat grainy original.

[nwo]

Hi,

Here is an example of my question.

I have a Panasonic DVD recorder that has 'Flexible Record' feature.

If I copy from a VHS tape that has a 90 minute program and it was recorded in SP mode and I set the Flex record time to 90 minutes and copy from tape to disc will the recorded output on DVD be better than the original video source?

No, northing can be better then the original source.

[greymalkin]

unless you use some image processing hardware or software the image will at best be close to the original. The media alone isn't going to make the video look any better.

[davideck]

MPEG 2 compression constitutes image processing hardware/software.

The timebase correction, noise reduction and compression techniques incorporated into a DVD Recorder (or PC capture setup) will alter the image. The challenge is to not overdo it. Whether or not it looks "better" is subjective like noki stated.

[greymalkin]

By hardware/software image processing I was referring to things that would enhance the video such as brightness/contrast/sharpness/stabilization/etc. I was relying on context to connect those dots.

[edDV]

Hi,
...
will the recorded output on DVD be better than the original video source?

In theory any dubbing you do will degrade "quality" but you can work the filtering tradeoffs to make the degraded result look better to you.

[jmsrickland]

OK, all makes sense except for one thing.

If I copy a 90 minute tape (or TV or whatever) to a DVD recorder then sinse it is less than 2 hours then the choise recording mode would be SP, right?

Now if 'Flex Record' takes a 90 minute show and records it the finished recording will consume the entire DVD disc but 90 minutes recorded in SP will take approx 3/4 of the DVD disc space. This tells me that Flex Record is using a compression ratio that spreads the 90 minutes over a 2 hour disc space. So, if the copied recording cannot be better that the original input source then I question the purpose of Flex Record. If I record the 90 minutes in SP and use 3/4 of the disc space and then record it again using Flex Record using 100% of the disc space would the results be the same? If so, then I do not see the purpose of Flex Record.

[jmsrickland]

Oh, here's something else. I was in a retail store the other day looking at various DVD recorders. I am not sure of the brand name but I think it was also a Panasonic but a different model than the one I have; the one in the store was a Combi, and as I was reading the stuff that it did I noticed a statement on the info card that said something like this:

Records from VHS to DVD internally with equal and in most cases better quality [than the source].

So, if you all say you cannot get better than the original input and I believe that to be so then it looks like the advertizment for this DVD recorder is a false statement.

[trhouse]

It is not the mpeg compression algorithms that change. It is the bitrate. For example, most recorders can record in XP, SP, and LP modes. The difference is that ( these are just round numbers ) the bitrate for XP is about 10 Mbs, SP about 5 Mbs, and LP about 2.5 Mbs. The higher the bitrate the more the capture will retain the detail from the original.

Flex mode just allows you to go between the standard modes. Your example of a 90 minute capture would use a bitrate between XP and SP of about 7.5 Mbs.

[edit] Regarding your second comment. It depends on what you mean by better. Most people are thinking in terms of noise, color, detail, etc. but most recorders have other features that do improve on the original. Some have a form of TBC ( time base corrector ) or frame synchronizer. Others like the Panasonics have input processing that can correct a rolling VHS tape.

I have done this test with the ES10, ES30V, and ES35V. They can take a VHS tape that rolls vertically and has some horizontal jitter and remove both. With the combos, I have them set up so that I can switch the TV between VCR and dvd output. The VCR output can roll vertically seven times but the dvd side only shows a semi-transparent bar that moves slowly up the screen but the rolling and horizontal jitter are completely absent.

[Nelson37]

My God, a false statement in advertising!! Alert the media!! Call out the National Guard!!

As stated, difference in quality is totally and completely subjective. To amplify on that, it is very easy to see a video product, particularly one which you have put some effort into, and say "That looks great! Not possible to be any better!" Until you see it done better, then you try to duplicate that, and then the cycle repeats itself.

[greymalkin]

You have chosen wisely to not believe the advertisement.

I understand how this would be confusing. The bitrate in and of itself doesn't determine whether or not the image quality of the finished product is "better or worse". More like "a little worse or alot worse". Let's assume for just a moment that no processing is done to the video stream (OTHER than MPEG2 compression).

The video is most likely travelling to your DVD-recorder via RCA cables. Just travelling down these cables causes the video to degrade somewhat. Then the DVD-Recorder encodes the video as MPEG2. This process also causes some degrading of the quality. The higher the bitrate the dvd recorder chooses, the closer to the original the end product will look.

However! The bitrate is only part of the equation. The quality of your source will also determine how good the end product looks. A smooth, clean video encoded at a bitrate of 6500kbps might look closer to the original than a jittery, grainy video at 10000kbps. MPEG encoding works by using reference frames, then noting the changes between them. If there is very little change between these frames, less bitrate is required to adequately reproduce them. If the video is very noisy or full of motion, it requires much more bitrate to reproduce.

So do you benefit by using the flex mode? The answer is: depends on your source.
Usually as a general rule, you want to use the max bitrate allowed for the duration of the program you want to record. Sounds like that is what the flex recording is doing.

[jmsrickland]

It's all becoming quite clear now. I sure wish I had that DVD recorder that corrects or helps correct the rolls on the tape because I sure have alot of tapes with minor rolls. The model I have is the DMRES25S. I don't think it changes anything. Those model numbers look like Panasonic ones. Maybe I will check into on of them and give it a try.

[trhouse]

The ES25 is the similar to the combo ES35V I have. The combo does correct some but not all tapes. The other models are now obselete.