Fatal reading behavior on recent LG drives?

vbimport

#1

This is my first post.

I don’t know if anybody else has noticed this, but I have noticed some recent LG drives seem to be reading garbage data (or blanks) on some movie dvd discs with css encryption. I base this on recently using an internal GH24NSC0 drive, and an external GP50NB40 drive (with a December 2013 manufacturing date).

(For a bit of background).

I’m primarily into collecting/watching movies (and tv shows) on dvd and bluray. I have very little to no interest in the burning capabilities of optical drives.

Over the years I’ve made the mistake of buying too many movie dvds and not watching them immediately. Though once I got around to watching these movie dvd discs, it turned out several had random bad sectors from manufacturing defects. (Deliberate bad sectors due to basketcase drm is an entirely different thing, which I won’t go into here).

These days I found it was easier to just find another dvd copy of the same movie in the local bargain bins, than trying to “salvage” the old defective discs. But with that being said, I’ve kept the defective discs largely to use them as “torture tests” on various dvd drives and players. It turns out not every dvd drive/player is created equally, in regard to reading capabilities. For quite a few of these defective discs, I’ve found that the reading behaviors may be quite different on LiteOn, LG, and Samsung computer dvd drives. (Recent Samsung drives seem to be the smartest at dealing with random bad sectors, which the LiteOn may choke on).

In regard to recent LG drives I’ve tried out, it turns out for several basketcase movie dvd discs I have with random bad sectors, the LG drive just returns junk data where the bad sectors are. On dvddecrypter, the debug logs indicated that the mpeg2 headers are missing from these particular sectors. (On a LiteOn drive reading the same bad sectors, the LiteOn just stops there and repeatedly gives back a read error).

For these same movie discs where I later purchased a second identical copy of the disc, these second copies didn’t have any read errors and had all the proper mpeg2 headers. Dvddecrypter didn’t spit out any error messages when reading these second copies. So my first copies were definitely defective. (These were largely widely released mass market dvd movies, that were available almost everywhere like BestBuy, WalMart, etc …).

In the end, I ended up returning the GH24NSC0 to the store, and purchased a recent ASUS dvd drive instead.


Which drives handle errors well?
Deliberate reading speed limitations for all DVDs with Video?
#2

Doing some googling and noticing the behavior of LG drives I’ve had previously, IIRC LG seemed to have a reputation for “riplocked” dvd drives when it comes to reading movie dvd discs with css encryption.

On one of my previous computers from the mid-2000s, the LG drive was definitely riplocked. (Though I didn’t know about it at the time. I wasn’t really buying any dvds in those days).

More recently, I picked up an ASUS bluray-rom drive (BC-12B1ST) which appears to be a rebadged LG according to blackened2687’s tables. I also recently checked the reading behavior of the dvd section of this BC-12B1ST drive, and it is identical to the reading behavior of the previously mentioned GH24NSC0 and GP50NB40 drives when reading the same defective movie dvd discs. (ie. Returning junk data on bad sectors).

But the big difference between the LG GH24NSC0 and the Asus BC-12B1ST in reading movie dvd discs with css, was that the GH24NSC0 was not riplocked at all. The dvd section of the Asus BC-12B1ST was definitely riplocked. (The bluray section of the BC-12B1ST seems to be fine with no riplock, and it doesn’t appear to have any fatal reading behaviors which have plagued the dvd section).

Does anyone know when LG decided to stop riplocking their computer dvd drives? If I had to guess, it must have been relatively recent. (My BC-12B1ST bluray drive with a riplocked dvd section, has a manufacturing date of September 2014).


#3

[QUOTE=jcroy;2767643]In the end, I ended up returning the GH24NSC0 to the store, and purchased a recent ASUS dvd drive instead.[/QUOTE]

I decided to get this GH24NSC0 drive again, and investigate its dvd reading capabilities further.

I went back to the store and asked whether they still had the exact drive I had returned for a refund a few days ago. But unfortunately they already sold it. (Apparently they sell more than a dozen LG dvd drives every week at this particular computer store). So I just purchased another one this evening.

To turn a vice into a virtue, I’m thinking of using this LG dvd drive (with its fatal shortcomings) as a drive to rip movie dvd discs a second or subsequent times. Since I’ve been buying a lot of movies and tv shows on dvd, I don’t always get around to watching them when I first rip the isos to the computer (with the LiteOn or Samsung drives) to first check whether there are any random bad sectors due to manufacturing defects. Due to a shortage of hard drive space, I end up deleting a lot of isos without ever watching them.

After my LiteOn or Samsung drives have checked that a newly purchased movie dvd disc has no random bad sectors due to manufacturing defects, then I don’t have to check them again. So I can use the LG dvd drive to rip the isos a second or subsequent times, when I finally want to get around to watching the actual movies on the isos.

So far even with heavily scratched dvd discs I’ve checked previously on the LiteOn or Samsung, the LG dvd drive doesn’t appear to produce any junk data. Dvddecrypter can tell whether this LG drive is pumping out garbage data, and it will give a good idea whether there’s any newly appeared bad sectors present (for example, such as from a disc sliding across the floor).

Also I don’t want to prematurely wear out my LiteOn and Samsung dvd drives. My previous LiteOn dvd drive lasted through 4+ years of heavy dvd ripping almost every week (sometimes every day), until it finally died this past summer.

If the LG wears out and dies prematurely, I can always buy another one for less than $20. Hopefully by then, LG would have corrected the fatal reading behavior.

So far it appears that on dvd discs which do not have any bad sectors, the LG is slightly faster than my Samsung and LiteOn drives. (Back in the day, I never would have thought I would ever see an LG drive without any riplock).


#4

What I do like about this LG GH24NSC0 drive, is that the spinning up time is very quick. It goes straight to the max speed (12x for double-layer dvd9 discs, 16x for single-layer dvd5 discs), a lot quicker than on my Samsung and LiteOn drives.

I haven’t set the region yet on this drive, and probably won’t. The brute force cracking done by dvddecrypter is fast too on this LG drive. The few vobs that couldn’t be cracked by brute force (due to a lack of available vulnerable sectors), have so far turned out to be mostly 2 or 3 seconds black screen video segments.


#5

To test whether this fatal LG reading behavior extends to data discs, I tested a particular cdrom disc which I’ve had problems with in the past. It was a pc video game which I found at a garage sale for $1, where the play disc was somewhat scratched up.

Previously, I was only able to extract this particular disc’s entire iso using isopuzzle on my LiteOn drive. It usually took isopuzzle around 12+ loops to eventually properly read all the sectors on this disc.

So I got my Samsung, LiteOn, and this LG GH24NSC0 drive to extract the entire iso of this particular problematic cdrom disc.

As I expected, the LiteOn took over 12+ loops to eventually extract the entire iso.

The Samsung was able to extract the entire iso in in the first read. It didn’t have to loop over again.

The LG GH24NSC0 took 3 loops to eventually extract the entire iso.

To make sure I wasn’t fooling myself completely, I calculated hashes (ie. md5, the sha’s, etc …) on these extracted isos. Not surprisingly, the corresponding respective hashes matched for all three extract iso files.

(I didn’t have time this morning to run a byte for byte comparison between these three extracted isos).


#6

I think I may have found a defective movie dvd disc from my collection, which can give some definitive answers about how “sick” the fatal reading behavior is of this LG GH24NSC0 drive.

The dvd disk in question is a poorly manufactured dvd9 double-layer disc which has no css encryption. For some technical specs from dvddecrypter, this disc has sectors:

LBA: 0 - 4012431

where the first layer covers LBA: 0 - 2065711 and the second layer covers LBA: 2065712 - 4012431.

The bad sectors appear to be around the transition between the two layers. These files of interest in this section are:

VTS_03_0.IFO - (LBA: 1130056 - 1130082)
VTS_03_0.VOB - (LBA: 1130083 - 1130139)
VTS_03_1.VOB - (LBA: 1130140 - 1654341)
VTS_03_2.VOB - (LBA: 1654342 - 2065684)
VTS_03_0.BUP - (LBA: 2065685 - 2065711)

VTS_04_0.IFO - (LBA: 2065712 - 2065748)

On the LG GH24NSC0 drive, it cannot read VTS_04_0.IFO at all. (ie. It is buried under the bad sectors). But the VTS_03 files are readable.

(I later ran isopuzzle on this disc with the LG drive, and it indeed stops in its tracks when it reaches LBA 2065712).

The fatal reading behavior of this LG drive shows up when I get dvddecrypter to read VTS_03_2.VOB - (LBA: 1654342 - 2065684). I read VTS_03_2.VOB five different times, where the error messages indicated junk data being read in different batches of sectors. No two times did the exact same sectors coincide with junk data. It was as if the LG was pumping out garbage data on the fly if it couldn’t immediately read an mpeg2 data sector properly. Calculating md5 hashes on these five different copies of VTS_03_2.VOB I made, showed that they were indeed different.

(Using my LiteOn and Samsung drives to copy VTS_03_2.VOB with dvddecrypter, there were no error messages about garbage data sectors. Hashes on these LiteOn and Samsung rips of VTS_03_2.VOB showed that they were the same files).

I then got dvddecrypter to copy the VTS_03_0.IFO and VTS_03_0.BUP files ten times with the LG drive. A few times the LG drive stuttered for a few seconds when attempting to read the VTS_03_0.BUP file. Calculating hashes for all these copies of VTS_03_0.IFO and VTS_03_0.BUP, showed that they were indeed all the same. (As they should be). I even looked at each of these ifo and bup files on a text editor, just too see whether they showed the same pattern of ascii characters, for which they did.

These anecdotal observations suggests that the fatal reading behavior of the LG GH24NSC0 drive, appears to be primarily affecting sectors which correspond to mpeg2 packets (ie. vob files). Non-mpeg2 sectors might possibly not be affected by this fatal reading behavior.

I don’t know how exactly this LG GH24NSC0 drive distinguishes between mpeg2 and non-mpeg2 sectors, especially in the case of unreadable bad sectors. If I had to guess, there might be a table somewhere on a dvd disc which tells you which sector ranges are mpeg2 and which ones are not ?


#7

(Continuation of previous post, with further analysis).

The random bad sectors due to manufacturing defects which plagues this particular dvd disc, mainly affects VTS_04_0.IFO, VTS_04_0.VOB, and VTS_04_1.VOB which are on the disc’s second layer with lba ranges of:

VTS_03_0.BUP - (LBA: 2065685 - 2065711)

VTS_04_0.IFO - (LBA: 2065712 - 2065748)
VTS_04_0.VOB - (LBA: 2065749 - 2065805)
VTS_04_1.VOB - (LBA: 2065806 - 2590007)

VTS_04_2.VOB - (LBA: 2590008 - 3114209)
VTS_04_3.VOB - (LBA: 3114210 - 3638411)
VTS_04_4.VOB - (LBA: 3638412 - 3826578)
VTS_04_0.BUP - (LBA: 3826579 - 3826615)

Using my LiteOn iHAS124 drive with dvddecrypter, it can fully read VTS_04_0.IFO and VTS_04_0.VOB. But the LiteOn encounters a read error when attempting to extract VTS_04_1.VOB, which it gets stuck in the middle of.

Using my Samsung SH224FB drive with dvddecrypter, it can full read all of VTS_04_0.IFO, VTS_04_0.VOB, and VTS_04_1.VOB without any read errors. Though the drive slowed down when it was reading VTS_04_1.VOB.

I got the LiteOn and Samsung drives to copy VTS_04_0.IFO and VTS_04_0.BUP several times, where the respective hashes on these copies were the same. The respective hashes calculated on VTS_04_0.VOB also corresponded.

In the case of the LG GH24NSC0 drive, it was not able able to rip VTS_04_0.IFO, VTS_04_0.VOB, and VTS_04_1.VOB, where dvddecrypter got stuck. For these three files, the LG didn’t spew out any garbage data sectors from its fatal reading behavior.

The few partial sectors that the LG + dvddecrypter was able to successfully read from the attempts at reading VTS_04_0.VOB and VTS_04_1.VOB before getting stuck, appeared to have the correct mpeg2 pack headers (0x000001BA). From a casual inspection of these partial vob files (using isobuster), the first few dozen or so sectors appear to be identical to the corresponding sectors of the same files extracted by the Samsung.


#8

As to the actual data content of these garbage sectors being spewed out by the LG’s fatal reading behavior, so far I have noticed there’s two varieties.

The first variety of garbage sector, had all zeros in the entire sector. (ie. Blanks). Nothing ambiguous here.

The second variety of garbage sector, appeared to be largely random data. I was not able to figure out if it corresponded to anything meaningful.

Of the samples of these non-zero garbage random data sectors I have looked at, none of them had the mpeg2 pack header 0x000001BA sequence of bytes anywhere among the randomness. So most likely these garbage sectors do not contain any obvious “misaligned” mpeg2 data.


#9

Combing through the dvddecrypter logs of my LG drive’s fatal reading behavior, the garbage data frequently show up in blocks of 16 consecutive sectors (or less) which coincide approximately with the dvd’s error correction (ECC) blocks of 16 consecutive sectors.

IIRC, the dvd’s error correction codes are handled in blocks of 16 consecutive sectors. (ie. lba 0-15 is the first ECC block, lba 16-31 is the second ECC block, lba 32-47 is the third ECC block, etc …). It would make sense for a dvd player/drive to process 16 consecutive sectors at a time, to handle the error correction appropriately.

(This is purely speculation on my part).

The simplest reading algorithm that I can think of offhand for the LG’s fatal reading behavior of mpeg2 dvd sectors, would be to read the first four bytes of each of the 16 consecutive sectors of a particular ECC block. If the first four bytes of a sector is 0x000001BA, then that particular sector is an mpeg2 sector, and is flagged as mpeg2.

If any of the 16 sectors are not flagged as mpeg2, and the error correction has failed, then the same 16 sectors are read again. (The already flagged list of known mpeg2 sectors is kept as a running tally). This repeated reading of the same 16 sectors is done until all 16 sectors are flagged as mpeg2.

If all 16 sectors are flagged as mpeg2 and the error correction is still failing, then the LG drive just returns the good sectors of the latest read, while the still-erroroneous sectors are returned as garbage data of zeros.


#10

I can not be of assistance, but I find your monologue interesting. I do not know how to ‘smoke out’ the real CD-Freaks to respond to you, but I will say this; if there ever were anyone, you have deserved their attention by your very persistence. :flower:


#11

[QUOTE=Xercus;2767898]I can not be of assistance, but I find your monologue interesting. I do not know how to ‘smoke out’ the real CD-Freaks to respond to you, but I will say this; if there ever were anyone, you have deserved their attention by your very persistence. :flower:[/QUOTE]

Thanks for compliment. :slight_smile:

At this point, there probably isn’t much more I can figure out about the fatal reading behavior of this LG drive. I’m more or less done for the time being.


#12

[QUOTE=jcroy;2767644][B][U]Does anyone know when LG decided to stop riplocking their computer dvd drives?[/U][/B] If I had to guess, it must have been relatively recent. (My BC-12B1ST bluray drive with a riplocked dvd section, has a manufacturing date of September 2014).[/QUOTE]

(To answer my own question).

I came across some documents via googling, which appear to be some test results of various LG GH24NS models of internal dvd drives from over the past five years or so.

If these “test” results are reliable, then it appears the riplock was removed starting with the LG GH24NSB0 model released sometime in mid-2013.

  • GH24NS70
  • GH24NS90
  • GH24NS95
  • GH24NSB0
  • GH24NSD0

#13

[QUOTE=jcroy;2767919]

  • GH24NS90

[/QUOTE]

Errr … wrong link ^. (I can’t edit my previous post).

The correct link for the GH24NS90 test results is:


#14

The only semi-plausible reason I can think of offhand for designing a dvd drive with this type of fatal reading behavior of mpeg2 sectors, would be if this particular drive was originally designed to be used in a standalone dvd player (or recorder).

(This is excluding human-related issues like engineer/designer incompetence, stupidity, sabotage, etc …).

On a standalone dvd player, garbage sectors with zeros would probably show up as pixelation on the screen. If there are long enough sequences of consecutive sectors which are unreadable/zeros, then it would probably show up as skipping.


#15

Never ascribe something to deliberately malicious intent when it is far more easily explained by lack of competence, or in this case, simply not caring if it works. DVD drives have become commodity products, and are basically seen as obsolete. For those few who still need one, it is easier toss the malfunctioning drive and replace it.

I’m one of the old time CDFreaks guys, but unfortunately for you, I’m the video person, not a drive or optical format expert. All I can add is that optical drives vary on their reading capabilities, not only from brand to brand, model to model, but individual drives with the very same hardware and firmware can vary considerably in their reading and writing abilities. Call it one of the hazards of modern manufacturing with very little quality control applied to such low profit items.

If you find a drive that is a good reader, hang onto it. LG drives are not inherently bad at reading discs. My GGW-H20L Blu-ray drive is one of the best I’ve seen, much better than my best writers, a Pioneer 207MBK Blu-ray drive, and my Optiarc 7200S.


#16

LG has always designed their drives to read a disc even if other drives fail. You’d have to go back about 6 to 8 years to when they used other chipsets to see if the behavior was the exact same, but I wouldn’t be surprised if this is how LG has always done their error correction/failure-proof reading. Those older drives only error out on a true fatal condition, indicating that there’s no way to grab any semblance of your data.


#17

[QUOTE=Albert;2767931]LG has always designed their drives to read a disc even if other drives fail. You’d have to go back about 6 to 8 years to when they used other chipsets to see if the behavior was the exact same, but I wouldn’t be surprised if this is how LG has always done their error correction/failure-proof reading. Those older drives only error out on a [I]true[/I] fatal condition, indicating that there’s no way to grab any semblance of your data.[/QUOTE]

I have an older LG drive which dates back to a manufacturing date in the mid 2000s.

I have a few defective dvd discs which I used this older LG drive to read using isopuzzle. This older LG did not spew out any garbage sectors, unlike my more recent LG GH24NSC0 has been doing.

In fact I knew exactly the behavior of these particular defective dvd discs on various older drives I had. So when I ran the LG GH24NSC0 on these same defective dvd discs, the behavior was completely different.

This is the main reason reason why I made a post on this particular topic. :slight_smile:

(ie. I was wondering if anybody else has noticed this type of behavior on LG drives of different vintages).


#18

[QUOTE=Kerry56;2767928]LG drives are not inherently bad at reading discs.[/QUOTE]

At the present time, I am estimating that this LG GH24NSC0 drive is only really spewing out garbage sectors for discs which were really poorly manufactured to begin with.

Today I ran my LG GH24NSC0 through several dozen really scratched up dvd discs from my collection. These particular scratched up discs were mostly discs I found at library book sales, thrift shops, garage sales, etc … which I picked up for around 50 cents a pop (or less). They were mostly mass market movie titles released by the big major movie companies (ie. Warner, Disney/Buena Vista, Universal, Fox, Paramount, Sony, etc …). Many of these discs appear to be former library copies, or former rental copies.

Much to my surprise, none of these particular heavily scratched up discs spewed out any garbage sectors when ripped on the LG GH24NSC0 with dvddecrypter.

Tomorrow I’m going to go through my collection of dvd discs released by bottom-feeder movie companies like Mill Creek, Echo Bridge, etc … and see how many of them trigger this fatal reading behavior on my LG GH24NSC0 drive.


#19

Here’s some very interesting behavior, which appears to be very definitive on the LG GH24NSC0 drive.

Using dvddecrypter, I ran several Sony dvd discs from 2006 which had “deliberate bad sectors” type drm. On all my previous dvd drives, these 2006 Sony discs would give back a repeated read error whenever they encountered such “deliberate bad sectors”.

Typically these “deliberate bad sectors” would appear in the same VTS as the actual feature movie, in the cells before and after the video content of the feature film. IIRC, the commands in the *.ifo file would tell a standalone dvd player to skip over the cells which contained these “deliberate bad sectors”. (The cells after the movie was finished, were also never played by a standalone dvd player).

On my LG GH24NSC0 drive using dvddecrypter to rip these particular 2006 Sony dvds, it would actually read through the “deliberate bad sectors” and return garbage sectors just right before the feature film video content. (They were in large blocks of several 180+ consecutive garbage sectors, in cells which were never played on a standalone dvd player).

Though the “deliberate bad sectors” which were in cells after the feature film was finished, dvddecrypter got stuck at these sectors and repeatedly gave back a read error.


#20

(Continuation from previous post).

I tried ripping some Lionsgate dvd discs from 2013-2015 which had “deliberate bad sectors” drm, using dvddecrypter.

For the most part when ripping the VTS which had the feature film, the behavior of the LG GH24NSC0 is almost identical to how it ripped my Sony 2006 discs which had “deliberate bad sectors” drm.

I also examined the behavior of my LG GH24NSC0 drive + dvddecrypter on some Paramount released dvd discs from 2009-2014 which had “deliberate bad sectors” drm. For some of these Paramount dvd discs, the ripping behavior was also almost identical to the above mentioned Sony and Lionsgate dvd discs.

For a few of these Paramount dvd discs when I ran them through isopuzzle on my LG GH24NSC0 drive, it turned out isopuzzle was able to extract the entire iso in one shot. (ie. It didn’t have to loop again). Like a hot knife cutting through butter.

This never happened on my LiteOn and Samsung drives.