Bit Rates

Discussion in 'Blu-ray & DVD Players & Recorders' started by AVFan7667, Feb 16, 2005.

  1. AVFan7667

    AVFan7667
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    I use my XS32 to record from my Telewest Digital Cable to HDD and archive if required.

    I tend to use a bit rate of 4.6 most of the time unless I know it's not something I will want to keep and then I use 2.2.

    Just curious as to what the highest bit rate I could use which would be useful. What is the highest bit rate that Telewest Digital is likely to transmit in? Seems pointless recording in a rate higher than this.
     
  2. redsox_mark

    redsox_mark
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    I see your logic, but it doesn’t quite work that way. Whatever bit rate Telewest uses, using a higher rate on the recorder will more accurately capture that.

    Say for example if Telewest used a fairly low bit rate of 4.0. (Just an example). If you set the XS32 to 4.0, you’d be making a fairly low quality copy of fairly low quality input… so what you get will be worse than the original. While if you record at 9.2, what you get will be indistinguishable from the input. The key here is what you are recording is an analog recording – it is not like you are re-encoding.

    But if the input quality isn’t that high, 9.2 would be overkill… and maybe recording at 6.0 would be indistinguishable from the original.

    Really you need to experiment and see where you can notice the difference. 4.6 on the XS32 is pretty good. From Freeview at least (I don’t have Telewest), I can tell the difference between 4.6 and a higher rate like 6.0. Much harder to tell between 6.0 and 9.2. But it depends on your eyes and your screen.

    Mark
     
  3. AVFan7667

    AVFan7667
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    Thanks for that. It does makes more sense that way.
     
  4. tobyjuggler

    tobyjuggler
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    Anything I'm going to delete after watching I record at 5.0. If I think I might keep a recording I record it at 9.2, then re-encode to a minimum of 6.0 if I'm going to burn to disc. If a drop to below 6.0 were necessary to fit a recording or set of recordings onto one disc then I spread it/them out over two or more discs. Since a rate of 9.2 appears to be indistinguishable from the original I don't see any harm in re-encoding to a lower resolution if necessary to get it to fit on a disc, as long as I don't go below the 6.0 mark for the re-encoding. There are one or two other drawbacks, like the need to re-chapter and re-encoding is carried out ion real time, but I find this acceptable at the moment.

    All a matter of personal taste though.
     
  5. AVFan7667

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    If I'm recording a movie or something like that which I want to keep, I set the bit rate in advance to one which will fill the disc with the specific recording.

    I try and avoid having to do rate-conversion wherever possible as it's time consuming (being real-time).

    I have recorded (and on rare occasions rate-converted) stuff I wasn't that bothered about but wanted to keep just in case down to 2.2 (and lower on one occasion) to cram a lot on a single disc and in all honesty, you could tell it was lower quality but it wasn't so bad that it was unwatchable.

    Like I said though, I record everything in 4.6 unless I specifically want to make it fill/fit a disc and then I try and set the bit-rate in advance.

    Like you say though, it's each to their own. Some people will hate anything lowerthan full-quality, others will be happy with 2.2 for everything.
     

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