HD to DVD quality drop?

Discussion in 'Blu-ray & DVD Players & Recorders' started by Desk, May 28, 2003.

  1. Desk

    Desk
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    Someone in another forum recently made a troubling suggestion about home DVD recorders with built in hard drives.

    They suggested that archiving material from the hard drive to DVD may result in a loss of quality, as the image has to be reprocessed, and recompressed.

    Can anyone confirm if this is the case, and whether you get a better picture recording directly onto DVD in the first place?

    While I'm on the subject, does anyone know if you lose quality when editing the contents of a DVD-Ram disc onto a DVD-R disc via a PC?

    Many thanks,

    Desk
     
  2. TommyVecetti

    TommyVecetti
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    Unless the HD records the digital stream directly,(like Sky Plus) then yes I'd imagine there would be a quality drop, just like Tivo. But it would be a very small quality drop.
     
  3. RichardA

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    Hi Desk,

    Generally, if you have to decode and then re-code M-PEG files, which is what you would need to do when copying hard-disk to DVD, then there will be a quality loss.

    How visible it would be will depend on the quality of the encoder.

    The problem is that M-PEG compression is not loss-less, even using the best encoders, at the kind of bit rates used in DVD, digital broadcasting and so on.

    If you want to maintain quality use the highest bitrates you can on the HD and the DVD - this will at least minimise any loss.

    Hope this helps, but I'm sure others will be back with real-world observations.
     
  4. Desk

    Desk
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    Just wanted to clarify the scenario I was describing was with a standalone HD/DVD recorder such as the Panasonic DMR-HS2.

    If you record onto the hard drive then there will be an initial drop in quality from the source (albeit minimal).

    If I understand Richard correctly then there will be a further minimal drop in quality when archiving the material from the hard drive to the DVD-R or DVD-RAM, as it has to be re-encoded?

    If this is the case it would suggest that if you know you want to keep something then you would be better recording directly from source to the DVD-R or DVD-RAM and bypassing the machine's hard drive?

    Desk
     
  5. TommyVecetti

    TommyVecetti
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    It's all down to the individual, there is a loss, it's up to you if you feel you can notice it or care enough about it to want to record straight to DVD.

    I have Tivo, record all the programs in 'best' mode and archive from that onto my E30. Sure there may be very minimal loss, but without Tivo, I'd miss everything worth recording so there is no choice.

    Digital TV quality is fairly poor anyway.
     
  6. malcom

    malcom
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    As others have said if you record in XP mode (Highest qty) then copying on to a RAM or DVD-R in SP mode will give you a quality loss which is of no consequence. I use two Panny recorders and do that quite a lot without any decernable change in the picture. Really nothing to worry about in my oppinion.
     
  7. leeb

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    I was of the understanding that you could high speed "dub" from the HS2's (& RD-XS30) HD to DVD-RAM/-R without any further encoding so you'd not lose ANY quality.
     
  8. DaveP

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    You can only do a high speed dub to DVD-RAM, DVD-R can't cope with the high speed. It's only a 1x DVD-R writer.

    Also, as I found out yesterday, you can only do a high speed dub if the source program is an hour or less. If it is more you get a "not enough disk space" message

    Dave
     
  9. kenfowler3966

    kenfowler3966
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    Thats not correct, you can do a high speed dub at any resolution as long as you are not trying to change it. If the source data on the hard drive is in sp mode you can high speed dub as long as the program is less than 2 hours, 4hrs for lp, 6hrs for ep etc.

    The important thing is that you are just transferring the digital data in a high speed dub, with no processing involved
     
  10. DaveP

    DaveP
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    Thanks for pointing that out, I'm still a newbie with the HS2!

    DaveP
     
  11. Cabo 5150

    Cabo 5150
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    I recorded five 45 minute TV episodes on my HS2 hard drive in XP as an experiment, and then dubbed them onto a DVD-R in FR. IMO the loss in quality opposed to my usual technique of using FR direct to the DVD-R week by week was very noticeable. I can only surmise there is some form of recompression going on, I would difinitely advise the direct to disc method. As a side note, hard drive XP to DVD-R XP seems to work with no noticeable loss in quality.
     
  12. SILVERBACK

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    so would you hs2 owners say its worth paying the extra for the hard drive ???? or would you save the cash get a few dvd rams an a few films etc ???
     
  13. Rasczak

    Rasczak
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    There will always be some quality loss when re-encoding and the HS2 is no different. However the quality loss is limited to digital artifacts caused by lowering the bitrate/resolution. It is a world apart from the digital-analogue-digital conversion that is used by any other current home use method other than the PC. Here you suffer analogue interference AS WELL AS digital recompression. So yes there is some loss of quality but provided your sensible with the amount you put on a disk then it won't be noticeable even on a high end Home Cinema using a Projector.

    You found the number of artifacts you saw was due to using such a radically different encoding system. XP using a higher resolution and a much high bitrate. By then going to what is, effectively, near the worst recording mode you are slashing the resolution AND the bitrate giving a dire result.

    Encoding nearly four hours of material on a DVD-R is not a good idea at the best of times - if your going to start re-encoding it is even worse. If your archiving this stuff 'forever' then you will kick yourself when you upgrade your TV and find the picture virtually unwatchable!

    By far the best way to use the HS2 is to record everything to the HDD and then copy to DVD-RAM/-R using FR mode for around 90 minutes. This will mean no change to resolution whilst just dropping the bitrate giving only a minimal picture difference to the original. Blown up on a projector this is still minimal.
     
  14. Rasczak

    Rasczak
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    The HS2 (or Toshiba machine coming soon) are the best and most flexibe DVD recorders currently available. If you can afford one you'll find it much more satisfactory solution than a standalone DVD recorder.
     
  15. Cabo 5150

    Cabo 5150
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    I understand your point Rasczak, and I've seen some of your other posts on this subject before. I have to disagree with you though - I find archiving up to 4 hours of material more than satisfactory if I simply record direct to DVD-R using FR. I'm playing back my recordings through the component outputs on my Sony NS900V fed into my Pany Series-4 42" Plasma panel. Yes the artifacting is definitely higher at this bit rate, particularly on wispy smoke etc., but I would still rate the results higher than anything my S-VHS machine could manage - which is more than adequate for me! But as I think you've said before, it's all up to the individual.
     
  16. Rasczak

    Rasczak
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    Fair enough - if your happy with it on a 42" screen then your probably going to be happy with it should you ever upgrade to a projector or anything bigger than 42" :rolleyes: Just thought I'd point it out in case you were using a 28" widescreen set or similar.
     
  17. Cabo 5150

    Cabo 5150
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    Can't quite figure if your being just a tadge sarky or not on the bigger than 42"/upgrading to projector thing, but what the hey - I'm cool about it and still respect your opinions and likely superior knowledge. I'm certain I would notice the artifacting a lot more if I saw it thrown onto a large screen via a projector, but since I've been totally underwelmed by every projector I've ever seen demonstrated, and would certainly never consider buying one as they stand at the moment... I'm more than happy with my pixilated recordings! Peace out and cheers man...
     
  18. Rasczak

    Rasczak
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    I wasn't being sarky at all (although it may have read that way). Picture quality is a very, very subjective thing and if your happy with it then that's brilliant. :smashin:
     
  19. Cabo 5150

    Cabo 5150
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    Cheers dude, it was just the roll eyes:rolleyes: thing, speak to ya on the next thread...
     
  20. TommyVecetti

    TommyVecetti
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    I was thinking about DVD-R recording this evening as I was about to start archiving my S-VHS recordings of Buck Rogers in The 25th Century the series onto DVD-R.

    In the end, I decided to go with LP 4 hour mode which gave a very slightly lower res than the source and some noticable (but not too horrible) artifacting. The reason being, nothing more than I wanted as many eps per disc, since I'd probably only re-watch these once every few years. Yes, blown up it would look less good, but then everything 'now' will look less good in a few years once HD broadcasts and HD DVDs come out. AH well.

    Truth is I probably can live with less than perfect DVD-R recordings, it's only places like these forums that start to make you really fanatical about the quality. :D Sometimes I have to remind myself of the reality. I just want to be able to watch the darn thing.
     
  21. SILVERBACK

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    cheers rasczak for the advice,price really isnt an option neither is the toshiba as i would rather have a smaller hard drive in a panasonic machine than a huge one in a tosh SPIT (long story) lol
     
  22. Rasczak

    Rasczak
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    Others may disagree, and it does depend how you use the machine, but HDD size doesn't matter too much. I only use the HDD to initially record programmes on (in XP), edit and then dub to DVD-R. If I'm unsure if I want to do that I just dub to RAM disk (using the High Speed file transfer mode) until I do want to archive it. Therefore nothing stays on the HDD too long - I record on it until it's full, then format and start refilling it. Therefore 40 or 60GB isn't that important.

    For someone using it as a Timeslip machine I suppose it makes the difference between around 7hrs and 10.5hrs (in XP mode).
     

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