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Could CDRW Disks Replace Videotapes?
Posted by
Cliff
on Wed Oct 23, 2002 04:31 PM
from the an-interesting-thought dept.
from the an-interesting-thought dept.
NewtonsLaw asks: "I'm in the process of building a TiVo-like PC that uses off-the-shelf technology to implement video timeshift, MPEG recording, MP3 recording, etc along with Net-radio functionality. Over the past two months I've effectively replaced VHS video tapes with CDRW disks. Once a program has been captured on the PC in (S)VCD MPEG format, I can either watch it by playing back the recorded file or dump it onto a CDRW and watch it on my DVD player, before blanking the disk and returning it to the 'empty' pile. What I've noticed is that most of the CDRWs I've tried only last about 30-40 rewrites before they start showing significant data dropouts (almost always at the start of a recording). Since disks in (S)VCD format don't carry the same level of error-checking/correction as disks written in regular data format, such dropouts are more noticeable than they would otherwise be (of course the up-side is that you get to store 805MB on a 700MB CDR/RW without overburn).
What I want to know is -- how many rewrites do most people expect from their CDRW media? I seem to recall seeing a figure of a thousand rewrite cycles being touted by some manufacturers. Is this realistic? Thirty rewrites makes a $2.50 RW disk an economic medium for this purpose but it seems a hell of a long way short of 1,000."
"I've tried CDRW disks from several manufacturers and they're being used in a new Sony CDRW drive which seems to function just fine. I've also encountered a slightly shorter lifetime for CDRW media when used for (S)VCD disks and written by a slightly older HP CDR/RW drive.
And before anyone asks 'Why don't you just play directly from the HD?', I should point out that I have to share the TV gear in this house with the rest of the family so it's just easier to burn their stuff to disk and let them use the DVD player than to fight over access to the TiVo-clone."
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I heard around "100" (Score:5, Informative)
Also, what speed are you burning on these CD-RW's at? Maybe you should try lowering the recording speed and seeing if you still get the drop outs.
Re:I heard around "100" (Score:3, Informative)
Off the top of my head - that's a hell of a lot better than VHS, so I'd say the answer's "Yes".
(If you're trying to store 120 minutes of video on a CD-RW, you're going to have to compress it pretty heavily, but on the other hand, you're only competing with VHS quality, so you can probably sacrifice quality for compression.
If I were designing the thing, I'd go with VCD quality - less than 120 minutes per disc, but if your shows are 22, 44, or 66 minutes long (30/60/90 minutes, with the ads cut out), that's a win for the CDRW.
Re:I heard around "100" (Score:5, Informative)
If you get a DVD player that can play out of spec (S)VCDs, this can sort of change. You can up the bitrate of VCDs, and/or make them VBR to increase qulaity. You can also check out the CVD standard, which is 352x480, VBR, mpeg-2. It's a real standard, and it's only a bit off from SVCD. You save a bit ont he bits (giving you a bit more time per disc) and better yet, the valid CVD streams are completely compatible with the DVD spec, meaning if you ever get a DVD burner, the same streams will can be burned as a DVD-Video.
Parent
Re:I heard around "100" (Score:4, Informative)
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CD-RW (Score:3, Insightful)
Re:CD-RW (Score:3, Insightful)
On the other hand...
A lot of CD's fit in the same physical space it would take to store a VHS cassette in. And there are "juke boxes" for audio cd's, a juke box for video CD's (CD/CDRW/DVD etc) sounds more likely than one for VHS cassettes.
Re:CD-RW (Score:3, Interesting)
Re:CD-RW (Score:3, Interesting)
Now before you go around saying that quality is subjective, and I don't know what to look for, I'd like to mention that I work in the video capture and compression industry (coding drivers for various products, including mpeg-2 [en|de]coders). I'm familiar and, generally, fairly sensitised to the various artifacts resulting from DCT and wavelet compression, interlaced video, scaling, etc.
It sounds like you are used to seeing poor quality encodes. There is an art to getting the best quality out of the bandwidth allocated.
-SpeedBump
PS: I should concede, though, that the "Legally Blonde" divx that I have probably benefitted from the ability to do multi-pass encoding.
Dead CDRW's (Score:3, Informative)
# of rewrites... (Score:5, Informative)
Personaly I think that to acheve 30 -40 rewrites to a VCD disk with no real loss in quality beats the shit out of a VCR which you only really get 4-5 rewrites out of before you start noticeing quality issues...
Keep up the good work, and keep us informed as to when we can buy the set top version of your system
I download anime fansubs (Score:3, Informative)
No, but they can replace paper tapes: (Score:3, Funny)
| oo
| oo o. o|
| ooo . o |
| ooo . oo|
| ooo
| o . |
| ooo . |
| oo o.ooo|
| ooo . oo|
| ooo
| o. o |
----------
Once will do (Score:3, Insightful)
1 You don't have the time to watch while the program is being broadcast. Save it on the TIVO hard drive and see it later that night or two days after or whatever. Then delete.
2 You have a genuine interest in the program and want to save it for the future. Then save it on a disc, and don't overwrite it.
Tor
Re:Once will do (Score:3, Insightful)
There's many reasons to save something for the medium term.
Why do people insist on trying to convince users that don't need something that they explicitly asked for? And have perfectly legit reasons to request the said item. Fully assess the situation first next time, and then make suggestions.
Re:Once will do (Score:3)
As one of the Men in Black said, "A person can be smart, but people are stupid." Usually you won't have any trouble after explaining why you need it, and they are only trying to save you trouble.
For re-writeable, hard drives are cheaper (Score:4, Insightful)
The one exception I can see to this is if you're using the CD as a data transport mechanism, between your PC in the office with the fast data connection and your DVD player in the living room.
Parent
Perhaps. (Score:5, Insightful)
Why not just use CD-R? (Score:4, Interesting)
Re:Why not just use CD-R? (Score:4, Insightful)
This way, if his family member (who he's burning the shows for) wants a "permanent" archive, he can still reburn to a CDR and put the CDRW back on the blank stack.
What I want to know is which DVD player he's using to view the [S]VCD's. I recently bought a GoVideo DVD+VCR combo for my folks, and out of curiousity, tried burning some SVCD's & VCD's and playing them. I'll have to take GoVideo/SonicBlue at their word that it will play "commercially produced" [S]VCDs, as it sure couldn't play the ones I burned to CDRs.
Parent
Re:Why not just use CD-R? (Score:3, Informative)
Who said anything about quality? :)
For one-off uses like this, generic CD-Rs should be sufficient. I can usually get a 50-pack for $5 or a 100-pack for $8-$10 -- after rebates -- once or twice a month from CompUSA or Circuit City -- the CC 100 packs are frequently even non-generic, such as Fuji.
As far as generics go, I've only had one disk ever fail on me, and that was during the write process.
Fry's CD-Rs on sale. (Score:3, Informative)
Re:$5 for 50?! (Score:3, Informative)
That comes to $5 for 50.
no (Score:4, Insightful)
People don't care about quality! If people cared about quality Microsoft would be out of business, Airlines would have decalred bankupcy years ago, and NO ONE would eat fast food.
Unfortuately people care about how little effort they have to excert to get something done. People don't want to deal with CD-R's because, despite an overall decrease in effort required, short term effects are minimal.
On a side note: CDRs would be a great alternative to video tapes. Tape media sucks
Re:no (Score:3, Interesting)
Can you fit 2 Gigs on a single CD-R? Didn't think so. What I could fit on a CD-R would look like crap on my 51" HDTV set.
As far as the Microsoft comment. The sad thing is, as poor quality as software is these days Microsoft software is higher quality then the competition.
I was thinking about (Score:5, Funny)
Has anyone else done this?
Re:I was thinking about (Score:4, Informative)
Parent
Could CDRW Disks Replace Videotapes? (Score:5, Funny)
Questions answered here. (Score:4, Informative)
Please note there are solutions that require money. How cheap are you going to be?
Needs to be consumerized.. (Score:4, Interesting)
is it dirt? (Score:4, Insightful)
Ahh...why bother with RW (Score:3, Insightful)
30 to 40 (Score:3, Insightful)
but I am also amazed that you have even actually used any of your discs that much. I would expect that if your using the CDs that much - they'd get scratched up and ruined long before you killed them via to much burning.
I know that all my CDs are treated as a trash commodity that i just toss out when it starts getting bad. or I pre-emptively burn another copy of anything that is getting a lot of use - and throw out the other when its scratched up enough.
How much watching do you do to get 30 or 40 burns on a single RW?
You should use the GNU version of TiVo... (Score:5, Funny)
Re:You should use the GNU version of TiVo... (Score:5, Funny)
You should take a look at the GNU version of TiVo called GnuVo. It's pretty nice except it won't let you watch any shows about capitalism.
You think that's bad, I've got KatzVo. The damn thing only records shows about 9/11, Columbine and Globalism!
GMD
Parent
What about FreeVo? (Score:5, Informative)
Parent
Here is a good resource: (Score:5, Informative)
Still good compared to video tape. (Score:3, Insightful)
CD-RW figures are a BIT optimistic (Score:5, Interesting)
CD-RWs reflect around 25% of the read laser, as opposed to CD-Rs which reflect around 75%, and pressed CDs which reflect close to 100%. When the signal-to-noise ratio is this low, the A/D circuitry has a hard time keeping up even with minor defects- fingerprints and dust are much more deadly on a CD-RW than on a CD-R.
In my experience, the first burn to a virgin CD-RW delivers CD-R-like readability, but once you rewrite it even once, the drive has to work a lot harder. I used to treat my CD-RWs like floppies, carrying them between the lab and my home, playing with them while waiting for an operation to complete, etc. and got maybe 4-5 rewrites on average. I then started keeping them inside jewel cases at all times, exposing them for a few seconds to put into the drive, and immediately got 20+ rewrites out of them.
Also, we were using really bad drives at the lab (some early HP CD-RW burners which often rejected discs) and when we upgraded the machines (to better HP burners, in late 2001) rewritability literally doubled for me to about 40+ rewrites. So the type of drive makes a difference as well IMHO.
perfect (Score:5, Funny)
Sounds like you've reproduced the VHS experience accurately.
Answer (Score:5, Insightful)
Zero. Actually, I find that CDRW are actually CDW. I can write to them, but I never expect to be able to read back from them. I've tried on dozens of CDRW drives, and I've never had luck archiving for a month or more on CDRW. Sure, "most" of the time it works - but it falls far short of my expected success ratios.
I've learned not to trust CDRW. I always use CDR instead.
Tape and discs (Score:3, Interesting)
In the past years since I purchased TiVo, I have never recorded a tape, unless I was lo-teching for an unfortunate friend.
I still think that CD-R's are a more reliable medium, and still, in most cases a faster medium. But if you get right to it, what happens when you recorded a video on a tape, over and over and over. Or watched the same tape over and over and over, the picture quality gets worse and worse.
Phillips is now selling a DVD-RW for such purposes, so It does look like the video tape has one more nail in it's coffin.
To make a TiVo clone would be cool, but to make one that will output to CD's, CDRW's, or DVD's would be great. (But still it's a waste of time to dupe a DVD if you can't get DTS ot Dolby Digital on it...)
Closed captioning data (Score:4, Insightful)
Has anyone noticed... (Score:4, Insightful)
And yes, I've written and pointed this out to my reps. :-)
When companies talk about MTBF, or number of re-writes, or anything like that you have to remember these few rules:
1. They were done under ideal conditions and not your normal, everyday, household conditions.
2. They count every time they were actually able to do whatever. (Like in being able to write to the CDRW disk they will count even partial writes in order to boost their numbers.)
3. They don't care if they make outrageous statements. It takes a very long time to prove them otherwise. (Take the cigarette industry - PLEASE! Look how long it's taken to prove them wrong. [And they are STILL fighting it in the courts.])
It used to be that if you cut whatever the company said in half you could be close to what the actual figures were. Now it's about a tenth of what they say. Not that all companies are like this. But there are quite a few.
I've already had to ask that same question (Score:3, Informative)
Why are you using CDRW? (Score:4, Insightful)
Why are you using re-writes at all? You can get a spindle of CDR's nowadays for $16.00 CDN on sale. (Must be $10 US?) That's 10 cents a disc, and you get to *keep* them. You are meanwhile spending 2.50 on a CDRW that you say can only be burnt 30 times, or 8.3 cents a burn. Seems to be it just isn't economical at all, when you could be spending pretty much the exact same amount and archiving all yoru movies instead of wiping them.
Re:Hard Drives (Score:5, Funny)
Parent
Re:Hard Drives (Score:5, Insightful)
If it's on a CD in SVCD format then you can take it to nearly any DVD player, stick it in, and watch. That's it.
If you're limited to a computer then you're paying 4-10x the money for the playback device and you can't transport it. Want to record something for someone else, or to take to a friend's house and watch? Too bad. Want to send a recording of an important TV show to family or friends? Nope. Can't do.
Not to mention that labeling a CD as "Junkyard Wars, Season 5, Episode 3" makes it a whole lot easier for a non-techie to deal with than some obscure location on a poorly integrated HTPC.
Parent
Re:Making (S)VCDs under Linux (Score:5, Informative)
Here are my notes about how I made one disc:
I wondered if I got some quality degradation by exporting from MA in motion-JPEG format, rather than keeping it in native DV format, and then encoding to MPEG. Ideally some of the JPEG frames would just directly become keyframes in the MPEG output; but in this case I was scaling too, so that's not possible. Anyway most of the output formats in MainActor for Linux have bugs, and MJPEG happened to work well.
Parent
Re:FYI: SVCD is not MPEG-1! (Score:5, Insightful)
What you say has some merit -- SVCD is certainly streets ahead of VCD in terms of image quality.
However, DivX is not quite the ogre you make it out to be.
For a start, it takes no more CPU to encode DivX format as it does to do a *good* job of multi-pass MPEG encoding.
On a 1.8GHz P4, TMPGenc takes around 6-8 hours to encode a 100 minute movie into an MPEG2 file to SVCD standards using multipass variable-bit-rate encoding.
You can get faster multi-pass MPEG2 encoders but they are *expensive* -- TMPGEnc is free for MPEG1 encoding and costs (from memory) just $49 for the version with MPEG2 capabilities.
By comparison, the same machine usually does a multi-pass DivX encoding in just a fraction that time.
In respect to playback, the DivX codec is quite nice insomuch as it allows some optimizations and post-processing to be performed as the video is played. This means you can create a video file that is able to be played back on a variety of different machines with different CPU-powers -- such that the faster machine will produce a better result but the slower machine will still play without pauses or stuttering.
In the past couple of months I've downloaded and evaluated hundreds of MB of applications, drivers, documentation, etc for all manner of commercial and freeware PVR solutions. These will all be compared on my site shortly.
I'm also about to publish my findings on the Haupaugge PVR card which does hardware-based MPEG1 and MPEG2 encoding -- thus freeing up the PC's CPU and allowing more "headroom". This is important when you're trying to do things such as timeshift or concurrent record/playback.
Linux-based software solutions are also being evaluated but unfortunately (damn it!) there are only two or three that appear to have much merit.
Given Microsoft's agenda to hog-tie all video and audio with DRM I'd really like to come up with a Linux based (and preferably OSS) option that is reliable, functional and ergonomic.
The truth will (eventually) be revealed
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Re:Could you pst a link or something. (Score:4, Informative)
I'm planning to update the site with all my latest findings later this week -- including a review of a Haupaugge tuner/capture card that has onboard hardware MPEG1/MPEG2 encoding.
Linux-based options are also being reviewed as I type this
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