DVD Recording Speeds - Explained? - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 20 Old 05-29-2007, 09:36 AM - Thread Starter
Member
 
LeftBackYank's Avatar
 
Join Date: Apr 2007
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
OK, so pehaps this is and should be common knowlege, but I am new to all of this and am having difficulty deciphering on my own the practical implications of discs having various recording speeds.

I'm understanding some of the technical jargon, but I have yet to read anything that has explained, in layman's terms, exactly what the benefit would be of recording on different discs at different speeds.

I'd sure like to hear some plain English on the subject. Thanks.
LeftBackYank is offline  
Sponsored Links
Advertisement
 
post #2 of 20 Old 05-29-2007, 10:12 AM
AVS Special Member
 
Sean Nelson's Avatar
 
Join Date: May 2001
Location: Vancouver BC, Canada
Posts: 3,320
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 18
If you're familiar with VCR recording speeds such as SP, EP, SLP, then the same basic concepts apply. The trade-off is one of capacity vs. quality. When you use higher-quality speeds (XP is the highest quality), the capacity of the disk is limited (1 hour at XP mode) but you get a recording that as close as possible to the original. When you use a lower-quality speed such as LP, you're able to fit more material on the disk (LP = 4 hours for most machines), but it won't look as good.

The degradation you'll see with a lower-quality setting on DVD recorder doesn't look quite the same as what you get with a VCR. Depending on the quality setting and the type of material being recorded (relatively static images vs. lots of action, for example) you might see "softness" (ie, less sharpness), macroblocking (picture breaks up into small squares, especially visible along different-coloured edges in the picture), or posterization (areas of nearly uniform colour break up into colour bands). These artifacts tend to be worse when there's a lot of movement in the picture.

Image quality is a very subjective thing and varies from person to person. Also, the size and accuracy of your TV set has a big role to play in whether you notice image defects. So you're best bet is to make some test recordings of the same material using different recording speeds to see which ones seem acceptable to you. Try to use the same type of material for the test that you typically expect to record (for example, if you plan to record lots of sports then use this as your test material).

One caveat: If you're planning to upgrade your TV set in the near future you may want to choose a higher quality setting than your current TV dictates, otherwise you may find after the upgrade that you're unhappy with your recordings.
Sean Nelson is online now  
post #3 of 20 Old 05-29-2007, 10:50 AM - Thread Starter
Member
 
LeftBackYank's Avatar
 
Join Date: Apr 2007
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Sean Nelson View Post

If you're familiar with VCR recording speeds such as SP, EP, SLP, then the same basic concepts apply. The trade-off is one of capacity vs. quality. When you use higher-quality speeds (XP is the highest quality), the capacity of the disk is limited (1 hour at XP mode) but you get a recording that as close as possible to the original. When you use a lower-quality speed such as LP, you're able to fit more material on the disk (LP = 4 hours for most machines), but it won't look as good.

The degradation you'll see with a lower-quality setting on DVD recorder doesn't look quite the same as what you get with a VCR. Depending on the quality setting and the type of material being recorded (relatively static images vs. lots of action, for example) you might see "softness" (ie, less sharpness), macroblocking (picture breaks up into small squares, especially visible along different-coloured edges in the picture), or posterization (areas of nearly uniform colour break up into colour bands). These artifacts tend to be worse when there's a lot of movement in the picture.

Image quality is a very subjective thing and varies from person to person. Also, the size and accuracy of your TV set has a big role to play in whether you notice image defects. So you're best bet is to make some test recordings of the same material using different recording speeds to see which ones seem acceptable to you. Try to use the same type of material for the test that you typically expect to record (for example, if you plan to record lots of sports then use this as your test material).

One caveat: If you're planning to upgrade your TV set in the near future you may want to choose a higher quality setting than your current TV dictates, otherwise you may find after the upgrade that you're unhappy with your recordings.

OK, good info, but not really what I'm looking for. What I'm interested in is an explanation of the practicalities of the various recording speeds of the MEDIA that is available.

What is the significance of 2x, 2.4x, 4x, 8x, 16x, etc.?
LeftBackYank is offline  
post #4 of 20 Old 05-29-2007, 11:01 AM
Senior Member
 
MorrisonHiker's Avatar
 
Join Date: Dec 2005
Location: Colorado
Posts: 256
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by LeftBackYank View Post

OK, good info, but not really what I'm looking for. What I'm interested in is an explanation of the practicalities of the various recording speeds of the MEDIA that is available.

What is the significance of 2x, 2.4x, 4x, 8x, 16x, etc.?

The higher the number, the faster you can record a DVD (assuming you have a compatible DVD burner/recorder).

See the speed chart here
MorrisonHiker is offline  
post #5 of 20 Old 05-29-2007, 11:12 AM - Thread Starter
Member
 
LeftBackYank's Avatar
 
Join Date: Apr 2007
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by MorrisonHiker View Post

The higher the number, the faster you can record a DVD (assuming you have a compatible DVD burner/recorder).

See the speed chart here

OK, now we're getting somewhere. I get that the speeds differ, but what does it mean? What is the effect of recording in faster speeds?

All other things being equal, including recording speed on the recorder, what is the difference in recording on a 4x or 16x disc?
LeftBackYank is offline  
post #6 of 20 Old 05-29-2007, 11:35 AM
Advanced Member
 
ACPewty's Avatar
 
Join Date: Jan 2006
Posts: 889
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Slower burn speeds take up more time to burn, but depending on the burner and media may result in a more reliable DVD. Most recorders will use the fastest speed the media will support, so if you want a slower burn you use slower rated discs.
ACPewty is offline  
post #7 of 20 Old 05-29-2007, 12:04 PM
AVS Special Member
 
Church AV Guy's Avatar
 
Join Date: Dec 2004
Location: High Desert, California
Posts: 4,621
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 51 Post(s)
Liked: 58
Sean answered the question the way I originally read it, as recording quality speeds, where XP is the best quality, and SP, LP and eventually EP6 and EP8 are all lower quality. These are not really recording SPEEDS, they are amounts of compression, and they allow you to decide what quality vs available time you want. The disks have about 4400 Mb of space, so the more you compress the data going onto the disk, the more time you get, but the quality suffers from the compression.

It seems that what you are asking is a write rate limit question. Originally, there was realtime recording, where a two hour movie took two hours to record, and dub. The DVD manufacturers came up with a max I/O rate that I don't know but others here do, where a full disk, 4400 Mb of data (more or less) could be written in one hour and they called that 1x. It didn't matter if the content of that disk was a 1hr XP quality recording, or 8 hours of EP8 quality, the full disk (4400 Mb) took an hour to copy. Then they worked out the bugs, and came up with double the speed, 2x drives. Once the drives came out, the disk manufacturers made media that could reliably be written at 2x speed, so it took half the time to copy a disk. This doubling of I/O rates continued to 4x, 8x, and finally 16x, which we were told might just be the limit due to physics. A few drives are now listed as 18x so that limit might not be a hard limit.

In theory there should be absolutely no difference between a copy made 4x and one made 16x. This merely reflects the I/O rate of the drive and the laser brightness and so on. If you have a drive rated for 16x, but 4x media, the system should always default to the lowest number. In some cases, putting media rated at a high number than the drive, could result in drive damage because the higher media number would attempt to make the drive spin faster than it was designed to do, or maybe make the laster brighter than it was designed for, but those problems have mostly been dealt with by now.

There is a lot of speculation that 16x burns are not as stable as 8x burns, but those claims are yet to be proven. In general these speed ratings are merely a reflection of the more recent technology, and they really have no effect on the finished product, as I think all players would use the same rate to reproduce a 1x burned disk as a 16x burned disk.

One other small point. The higher speed disks start writing at a lower speed a incrementally increase in speed until they reach the highest rating, so a 16x disk is NOT really four times faster then a 4x disk, but it IS faster.

Luke

Evil is charming and beautiful. It makes you doubt yourself. It asks for one small compromise after another until it whittles you down, and it functions best when no one believes in it.-JOA
Church AV Guy is offline  
post #8 of 20 Old 05-29-2007, 12:55 PM
AVS Special Member
 
Sean Nelson's Avatar
 
Join Date: May 2001
Location: Vancouver BC, Canada
Posts: 3,320
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 18
Quote:
Originally Posted by Church AV Guy View Post

One other small point. The higher speed disks start writing at a lower speed a incrementally increase in speed until they reach the highest rating, so a 16x disk is really four times faster then a 4x disk, but it IS faster.

I think cAVg's finger slipped there and he meant to say "a 16x disk is NOT really four times faster then a 4x disk".


To summarize:
  • recording speed (LP, SP, XP) affects disk capacity and quality.
  • write speed (4X, 8X, 16X) affects how long it takes to burn the disk
The two concepts are essentially independent of each other.
Sean Nelson is online now  
post #9 of 20 Old 05-29-2007, 03:03 PM
Senior Member
 
JMas's Avatar
 
Join Date: Dec 2002
Location: Upstate NY
Posts: 342
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Does anybody know the maximum write speed of the Panasonic EH75?

I recorded Bury My Heart At Wounded Knee from HBO to the HDD at FR because the movie ran about 2:15. When I copied to a TY Premium 8x DVD-R, it took 13 minutes. On my old E80, it would have taken close to an hour.

John
JMas is offline  
post #10 of 20 Old 05-29-2007, 03:41 PM
Member
 
FLSTFI's Avatar
 
Join Date: Mar 2007
Posts: 97
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
The manual says up to 16X for DVD +/- R
4X for DVD-R DL and +RW
6X for DVD-RW
2.4 for DVD+R DL
and 5X for DVD-RAM
FLSTFI is offline  
post #11 of 20 Old 05-30-2007, 11:46 AM
AVS Special Member
 
Church AV Guy's Avatar
 
Join Date: Dec 2004
Location: High Desert, California
Posts: 4,621
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 51 Post(s)
Liked: 58
Quote:
Originally Posted by Sean Nelson View Post

I think cAVg's finger slipped there and he meant to say "a 16x disk is NOT really four times faster then a 4x disk".


To summarize:
  • recording speed (LP, SP, XP) affects disk capacity and quality.
  • write speed (4X, 8X, 16X) affects how long it takes to burn the disk
The two concepts are essentially independent of each other.

Oops. Right you are, "NOT" four times faster. I have fixed the original post to reflect this correction. Thanks for the peer review.

To summarize, I agree completely. They are independent, mutually exclusive, quantities describing different things about a recording.

Luke

Evil is charming and beautiful. It makes you doubt yourself. It asks for one small compromise after another until it whittles you down, and it functions best when no one believes in it.-JOA
Church AV Guy is offline  
post #12 of 20 Old 05-30-2007, 12:20 PM
Member
 
genem's Avatar
 
Join Date: Aug 2006
Location: Raleigh, NC
Posts: 23
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I've encountered some difficulties lately creating DVDs for my kids to play in our van. They skip and freeze (Sony Accurcore discs and I believe the manufacturer code is CMG). Previous discs burned with my old Sony 4X burner worked fine but I replaced it with a Samsung 18X and the trouble started. The discs play fine in all other players and on four computers in the house but not in the van. I tried various things including changing the compression but all failed. The only thing I felt I had left to try was reburning at 4X and that worked. These were all programs recorded on an Panny ES15, imported to PC, and then burned there after whacking commercials and adding menus. I didn't think the write speed would make any difference but now I'm beginning to wonder.
genem is offline  
post #13 of 20 Old 05-30-2007, 12:35 PM
AVS Special Member
 
Church AV Guy's Avatar
 
Join Date: Dec 2004
Location: High Desert, California
Posts: 4,621
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 51 Post(s)
Liked: 58
As I said, for a long time 16x was considered the architectural limit of what DVDs could be pushed to, mostly because the manufacturers had already been through this with CDs. They had determined the highest speed that could reliably be used was around 48x, which is the same (almost) RPM as 16x on DVDs. High speed camera shots of the disks show that at these angular velocities, the disks no longer stay flat. They start to wrinkle and flutter, making it impossible for the laser to focus on the disk surface. That is at least one reason that some of the people here have stated that they have decided on staying with 8x media, even though they have 16x drives, and 16x media is now readily available.

Luke

Evil is charming and beautiful. It makes you doubt yourself. It asks for one small compromise after another until it whittles you down, and it functions best when no one believes in it.-JOA
Church AV Guy is offline  
post #14 of 20 Old 05-30-2007, 01:02 PM
Newbie
 
the1too's Avatar
 
Join Date: May 2007
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I think EP or LP is technically not more compressed than XP. My understanding on this (from recording with a Panasonic and viewing on a pc) is that recording speed determines resolution or size. All resolutions seem sharp to me---But of course, the low resolution picture is smaller (on a pc). Quality seems to enter into the picture thru zooming a low resolution picture onto a large higher-res screen. I guess that is where the quality of upconversion comes into play.
the1too is offline  
post #15 of 20 Old 05-30-2007, 02:45 PM - Thread Starter
Member
 
LeftBackYank's Avatar
 
Join Date: Apr 2007
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by ACPewty View Post

Slower burn speeds take up more time to burn, but depending on the burner and media may result in a more reliable DVD. Most recorders will use the fastest speed the media will support, so if you want a slower burn you use slower rated discs.

I am using a Samsung DVD-R155 recorder. I just combed through the manual and there is no mention of its own burning speed.

I'm recording on three formats: -R, -R(DL), -RW

So far 16x -Rs look pretty good in SP and LP from both SD and HD content. 2x -RWs don't look so good at EP (more experimenting to come). And I probably won't use anything but XP for the DL discs as those will be for movies.

What media speeds should I be using or avoiding?
LeftBackYank is offline  
post #16 of 20 Old 05-30-2007, 03:45 PM
AVS Special Member
 
Sean Nelson's Avatar
 
Join Date: May 2001
Location: Vancouver BC, Canada
Posts: 3,320
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 18
Quote:
Originally Posted by the1too View Post

I think EP or LP is technically not more compressed than XP.

I guess it depends on what you mean by "compression". If you're saying that LP isn't more compressed because the picture size is smaller to begin with, then (assuming the math works out) that might be a way to view it. But on some machines (Panasonic, for example) the picture at LP mode is the same size (720 x 480) as at XP mode. Since you can get four hours at LP mode vs. one hour at XP mode, there's obviously a lot more compression going on.
Sean Nelson is online now  
post #17 of 20 Old 05-30-2007, 03:55 PM
AVS Special Member
 
vferrari's Avatar
 
Join Date: May 2002
Location: Wash DC Metro Area
Posts: 3,693
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by LeftBackYank View Post

I am using a Samsung DVD-R155 recorder. I just combed through the manual and there is no mention of its own burning speed.

I'm recording on three formats: -R, -R(DL), -RW

So far 16x -Rs look pretty good in SP and LP from both SD and HD content. 2x -RWs don't look so good at EP (more experimenting to come). And I probably won't use anything but XP for the DL discs as those will be for movies.

What media speeds should I be using or avoiding?


Since you are recording in real time to the DVD's it really doesn't matter because you are actually recording at 1X speed (in XP mode) or less. Speed rating only really matters when high speed dubbing (i.e., non-real-time, data transfer) from a DVD recorder with a built-in hard drive to the DVD media (i.e., it determines how quickly the high speed dub will occur). Real time recording via the line inputs cannot be any faster than 1X speed if you are recording in XP mode (1-hour mode) and will be less than 1X speed in any other mode. Since higher speed rated media provides no advantage during real time recording, I would personally ignore speed rating and go with what is generally conisidered good quality media brands such as Taiyo Yuden - look for online deals.

BTW the quality differences you are noting have nothing to do with the type (-R/-RW) or speed rating (16x/2x) of the media you are using and have EVERYTHING to do with the quality modes you have selected (SP should look better than LP which should in turn look better than EP modes since each of these modes are using successively lower bitrates. You should see practically no difference in quality for a given mode (e.g, SP) whether its recorded to a 2X -RW or 16X DVD-R given the same source material. Poor quality media will result in more uncorrectable bit errors on a recording which will manifest itself in playback artifacts or an unreadible/unplayable disc in the worst case.

The Future ain't what it used to be...
vferrari is offline  
post #18 of 20 Old 05-30-2007, 03:56 PM
AVS Special Member
 
Sean Nelson's Avatar
 
Join Date: May 2001
Location: Vancouver BC, Canada
Posts: 3,320
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 18
Quote:
Originally Posted by LeftBackYank View Post

What media speeds should I be using or avoiding?

Let's review:
  • Recording speed (XP, SP, LP, etc) affects disk capacity and picture quality.
  • Burn speed (4X, 8X, 16X) affects the amount of time it takes to burn a disk.
You aren't going to see any difference in picture quality when you play back a disc burned at 4X, 8X or 16X. The only reason the burn speed will make a difference is if the burn quality is so bad that the player can't correct all the errors as it plays back the disc.

Burn quality is different than picture quality. Picture quality is what you see when you're watching the disc play. Burn quality refers to how accurately the 1's and 0's are written to the disc. Fortunately since DVDs include ECC (error correction codes), even disks with lots of badly written 1's and 0's still play back perfectly. It's only when the errors get too frequent that the player may start to stutter.

The downside is that you can have a disk that's poorly burned that plays perfectly. The disc may be right on the edge of being unreadable, but the ECC codes heroically do their job. The problem is that if there's any slight degradation of the disc at this point you're going to loose your data. The only way to tell if a disc is burned well or not is to use a computer equipped with a DVD drive and software that reports the raw error rates.

The burn speed (4X, 8X, 16X, etc) does affect the burn quality, but it's not a simple relationship. It depends on the media, the drive firmware, the mode in which the disc is burned, etc. Discs burned at a given speed that give good results for me may not give good results for you. The only real way to be sure that a particular combination is giving you good burns is to test the results in a computer.
Sean Nelson is online now  
post #19 of 20 Old 05-31-2007, 06:33 AM
Newbie
 
the1too's Avatar
 
Join Date: May 2007
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
The great picture quality of EP seems to have dupped me into the resolution-only theory. There may be high compression between XP and LP, but I'm not sure about this when comparing EP. Since XP has about 4 times more resolution by area than EP, but 6 or 8 times more capacity---then EP8 seems to have only a compression factor of 2 (8/4) which is no worse than SP. LP may have a lot of compression but this does not appear to be the case with EP.
the1too is offline  
post #20 of 20 Old 05-31-2007, 08:48 AM
AVS Special Member
 
vferrari's Avatar
 
Join Date: May 2002
Location: Wash DC Metro Area
Posts: 3,693
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by the1too View Post

The great picture quality of EP seems to have dupped me into the resolution-only theory. There may be high compression between XP and LP, but I'm not sure about this when comparing EP. Since XP has about 4 times more resolution by area than EP, but 6 or 8 times more capacity---then EP8 seems to have only a compression factor of 2 (8/4) which is no worse than SP. LP may have a lot of compression but this does not appear to be the case with EP.

You are throwing around some terminology (e.g., high compression/resolution by area/compression factor) in a manner that confuses me and may be causing some confusion on your end.

Let's start with the basics again - the following applies specifically to Panny recorders but can also be generally applied to other manufacturers

All Panny recorders use Variable Bit Rate mpeg2 recording and record DIGITAL audio in either uncompressed PCM (user selectable for XP mode only) or compressed constant bitrate Dolby Digital 2.0 aka AC3. COMPRESSION is DIRECTLY related to BITRATE as follows.

XP mode is 1-Hour Mode with an avg bitrate of about 8+ Mbit/sec. This is the LEAST COMPRESSED quality mode available (i.e., highest bitrate available). Resolution on the latest Pannys for this mode is 720x480 (Full D1) and used to be 704x480 for pre-2006 Panny recorders.

SP mode is 2-Hour Mode with an avg bitrate of about 4+ Mbit/sec. This is the SECOND LEAST COMPRESSED quality mode available. Resolution for this mode on the latest Pannys is 720x480 (Full D1) and used to be 704x480 for pre-2006 Panny recorders (i.e., same as XP).

LP mode is 4-Hour Mode with an avg bitrate of about 2+ Mbit/sec. This is the SECOND MOST COMPRESSED quality mode available. Resolution for this mode on the latest Pannys is 720x480 (Full D1) and used to be 704x480 for pre-2006 Panny recorders (i.e., same as XP and SP). On Pre-2005 Pannys the resolution of this mode was 352x480.

EP mode is 6/8-Hour mode with an avg bitrate of about 1+/1.5 (8/6-hr mode) and is the MOST COMPRESSED mode (i.e., lowest bitrate available) and is recorded at a resolution of 352x240. The higher 8 hour mode is achieved by lowering the constant bitrate of the AC3 digital audio stream which allows Panny to not have to lower the EP video bitrate all the way to half of the LP mode bitrate.

Higher compression (i.e., lower bitrate) allows more minutes of video content to be squeezed onto a fixed disc capacity such as a standard DVD.

The quality modes are DIRECTLY related by their proportionate bitrates only. The fixed resolutions for the various modes only determine how many bits are available per pixel to render the image. For a given FIXED BITRATE a lower (by half) resolution such as going from 704x480 to 352x480 DOUBLES the number of bits available per pixel. Trading off resolution for bitrate is a way encoders can compensate for lower bitrates to mitigate digital artifacts such as macroblocking that typically occur as COMPRESSION INCREASES with DECREASING BITRATE. This is a game of diminishing returns as there is some point wherein you cannot continue to decrease resolution to compensate for the lowering bitrate. The image becomes too blurry and cannot mitigate the high compression artifacts. AFAIC - this occurs well before you get to EP mode (i.e., I personally consider EP mode unwatchable). The above paragraph is somewhat of an oversimplification for the purpose of illustrating key points such as the relationship between COMPRESSION, BITRATE, and RESOLUTION. Other factors such as noise suppression, encoder algorithm, and quality of the source material all cause variations to some degree.

Hope this helps to clarify things and doesn't just add to the confusion.

The Future ain't what it used to be...
vferrari is offline  
Reply DVD Recorders (Standard Def)

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off