What does DVDShrink reduce?

[moviebuff2]

Hi everyone:

Would someone please tell me what DVDShrink reduces when it shrinks the size of a video?

I have 2 homemade DVDs, recorded at SP. Each DVD is approximately 1.5 hour long. I used DVDShrink to put the 2 DVDs on one single-layer DVD.

The calculated compression rate was approximately 84% (shown by DVDShrink).

I was worried that the video quality of the combined DVD will suffer greatly. But to my surprise, when I watched the DVD on a 20-inch TV monitor (not a plasma or flat screen TV), the picture looked just fine.

I checked the video stream infos of both the original and the shrunk DVD. Both streams showed the same video bit rate of 4.38 MB, the same chroma 4:2:0, the same VBV buffer rate of 224 KB.

How can I find out what was taken out of the original DVD by DVDShrink in the re-encoding process?

Thanks

[politiken]

DVD Shrink is a transcoder not a re-encoder :: DVD Shrink only changes the color of the pixels and
thus saves space (adjacent pixels with almost same color is changed to have the same color)

Always use (enable) Backup DVD/Quality settings/Perform deep analysis...

regards Pol

[lordsmurf]

20-inch monitor hides flaws. It probably does look like crap, just harder to see that small.

Transcoders do not change colors or pixels. It alters the math of the encoding equation, which results in data being thrown out. The outcome of this is blocks more noise in the video. If the video is very high quality and clean with excessive bitrate (many DVD releases), then it can work up to a point. If the source is homemade (already noisy), then you can easily make it look bad, even by a slight alteration. Some DVD releases are noisy and lack bitrate (Pokemon and Married With Children come to mind), and look like crap shrunk/transcoded.

It is as effective as reducing the bitrate, but not the same.

The best way to "shrink" video is to fully re-encode it (full, true decode and re-encode). Better yet is to just split it do discs, use larger media, or just leave it alone.

[moviebuff2]

Thanks.

I did use "analysis" before "backup". I also chose optimal settings such as "maximum sharpness", provided by DVDShrink.

The original videos were recorded in SP by my Philips DVD Recorder. The video bit rate is 4.38 MB.

These video are my homemade DVDs of my 2 piano recitals. I burnt the unshrunk combined video (5.5 GB in size) onto a double-layer disc; but the disc paused for a very brief moment going from layer 1 to layer 2 during playback. The brief pause happened right in the middle of a Chopin's waltz.

That's why I want to shrink the video to fit on a single layer disc.

I only have a 20-inch TV monitor. I will have to test view the DVD on someone else's plasma or flat screen TV.

I just wonder if there are any tools to quantify the differences (video & audio) between the original and the shrunk DVDs.

[guns1inger]

The bitrate is already low. Shrinking them will only make them worse. Try HCEnc, as it is pretty good at low bitrates.

[fritzi93]

Would someone please tell me what DVDShrink reduces when it shrinks the size of a video?

Maybe more than you want to know:

http://forum.doom9.org/showthread.php?&threadid=63587

[manono]

I just wonder if there are any tools to quantify the differences (video & audio) between the original and the shrunk DVDs.

The audio stays the same. The video average bitrate goes down and the average quant goes up. Bitrate Viewer can show you the before and after.

[moviebuff2]

I thought the video bitrate would go down, too.

But I used VideoRedo to open 2 vob files (an orginal and a shrunk), the program provided me exactly the same video bitrate for both vob files. That's what surprised me.

I don't have Bitrate Viewer yet. But I will try to get it to see what the program will show.

Thank you for all your replies.

[thecoalman]

I just wonder if there are any tools to quantify the differences (video & audio) between the original and the shrunk DVDs.

http://www.compression.ru/video/quality_measure/video_measurement_tool_en.html

[lordsmurf]

These video are my homemade DVDs of my 2 piano recitals. I burnt the unshrunk combined video (5.5 GB in size) onto a double-layer disc; but the disc paused for a very brief moment going from layer 1 to layer 2 during playback. The brief pause happened right in the middle of a Chopin's waltz. .

How was it burned, and on what media?

Re-author with a chapter mark where you'd like the layer break (somewhere between songs). Use the PgcEdit/ImgBurn authoring method for DL, and select your chapter mark for the layer break.

Use Verbatim DVD+R DL, and ONLY Verbatim DVD+R DL media.

[noki]

"...I also chose optimal settings such as "maximum sharpness", provided by DVDShrink. ..

I believe if you want the highest quality video after the shrink process you need to go the OPPOSITE direction. the maximum smoothness, not sharpness selection would allow DVD Shrink to analyze every frame of the video (which is why it might takes hours and hours) to determine how to apply it's algorithm to give the best video quality (usually reserved for videos that need high compression to fit on a single layer disc).

good luck.

[moviebuff2]

I used Memorex DL discs and Nero 6 to burn the original uncompressed DVD (5.5GB).

The DVD was authored with TMPGEnc. Chapter marks were made at the end of each piano piece.

But Nero seems not to pay attention to the chapter mark when it goes from layer 1 to layer 2. Maybe there is a feature in Nero that tells the burning program to look for a specific chapter mark when changing layers? Or, maybe that's just my crazy wish.

I always believe the "maximum sharpness" in DVDShrink is to optimize the video quality. I will have to read the instruction again.

[redwudz]

Most likely Nero doesn't do much more than divide by two to set the layer break point. If you still have the DL VIDEO_TS folder, try burning with ImgBurn in 'Build' mode and it will likely give you fair amount of choices of layer break locations.

[lordsmurf]

I used Memorex DL discs and Nero 6 to burn the original uncompressed DVD (5.5GB).

The DVD was authored with TMPGEnc. Chapter marks were made at the end of each piano piece.

But Nero seems not to pay attention to the chapter mark when it goes from layer 1 to layer 2. Maybe there is a feature in Nero that tells the burning program to look for a specific chapter mark when changing layers? Or, maybe that's just my crazy wish. .

Memorex re-brands low-quality discs (RITEK).
Nero doesn't burn discs correctly. Period.

That's the problem with your DL.

Use PcgEdit and ImgBurn, with Verbatim DVD+R DL media. That does work.

[SCDVD]

Do not pass Go. Do not collect $200. You have been given some great advice. Follow it and you will be happy. Don't follow it and you won't be happy. There is ONE brand of DL media that is any good; that is Verbatim DVD+R DL media. ImgBurn does a wonderful job handling layer breaks that are completely in-spec, and it's FREE.

[moviebuff2]

Thank you!

[manono]

I thought the video bitrate would go down, too.

But I used VideoRedo to open 2 vob files (an orginal and a shrunk), the program provided me exactly the same video bitrate for both vob files. That's what surprised me.

I don't use VideoRedo, but it most likely gives you the figure in the header, probably 9800, and if not, then the max bitrate and not the average bitrate. That figure won't change after shrinking. Since average bitrate is entirely based on the average number of bits available per second of video, if the final size shrinks but the length remains the same, it stands to reason that the average number of bits per second, and thus the average bitrate, will decrease.

[moviebuff2]

My 2-cent

I used Memorex to burn many non-musical DL DVDs without any problems. Only with musical videos do I encounter the problems of briefly freezing during playback.

I can't explain why.

However, because many commercial DVDs made by Hollywood studios have the warning that some DVD players will experience a brief pause going from layer 1 to layer 2, I told myself: "If the big studios experience this kind of problem, I am no exception."

Now there is suggestion that the pausing problem comes from inferior burning software and cheap medium.

So, big studios use cheap stuff to sell their trashes to the consumers? Well, pirates everywhere have more reasons to continue their trades. Hm...

[redwudz]

Big studios 'stamp' their DVDs, not burn them. They are produced with equipment that costs hundreds of thousands of dollars, and those discs have no comparison with burned discs done on a computer.

If you mean the layer break 'pausing', that's almost always from a burning program that handles the position of the layer break improperly. Pauses in other parts of the DVD may be a result of the media quality.

[moviebuff2]

Of course, the studios use the more expensive and more scientically advanced stuffs than Nero or Memorex(*). But the fact that they have that warning indicates their "expensive stuffs" are not expensive enough, i.e. not perfect, to produce a flawless DVDs.


(*) though I would not be surprised if later someone reveals the true quality of their stuffs. Remember "bottled tap water" made by Coke?

[CrayonEater]

Your assumption about commercial DVDs is logical, but not necessarily correct: Your equipment plays a role. How much read-ahead, or buffering, plays a role too. Remember the anti-skip walkman-type portable CD players back in the 90's? The way they work is to read data off a CD faster than it can be played; they have extra memory, so even if the CD skips or malfunctions, there's still a few seconds worth of data stored in memory, or a buffer, which gives the CD reader time to recover from errors and skips. Up to a point, this allows the CD to play seamlessly. Not all players had this because memory is expensive, although it gets cheaper as time goes on. It's the same with DVD players. Unfortunately, depending mostly on when your DVD player was made and by who, the amount of buffer memory may vary. I have a Toshiba DVD player made circa 2002, which only buffers about 1 second worth of video and audio. Since it takes a minimum of 1 second to do the layer transition, it will sometimes play seamlessly, but often the layer break takes 2-3 seconds, and the player will freeze. On my much newer Philips DVP-642 (circa late 2004), the break is usually seamless and more tolerant of breaks, skips, etc. (Sidenote: The Toshiba's video quality is much better than that of the Philips, which was notorious for having poor video quality, although newer versions of that and other Philips players has apparently improved, so video and audio quality can depend in small part on your player as well.) The point is, ALL DVD players freeze on the LB; it's a question of whether or not they have enough buffer memory to let the video and audio to continue to play seamlessly, and for how many seconds.

At any rate, there are lots of good points made in this thread. Stick with Verbatim if you're going to burn DLs. Nero may or may not be a good DL burner. I do know for a fact that versions including and prior to mine (7.0.8.2 and earlier) are totally worthless at burning DLs; however, the lack of complaints I've observed with newer versions (I can't tell you exactly which, but roughly, I'd say, 7.5.x.x. and later) seem much better and suggests that Nero is finally trying to address Nero's historic problems with DL discs, although I can't say that for certain. In any case, IMGBurn or PGCedit/IMGBurn is the way to go as far as I'm concerned. I use PGCedit/IMGBurn and have had almost no problems with Verbatim discs. This allows you to set your own layer break. Another great thing about this, and especially since your material nowhere near fills the disc, is because the outer edges of the disc are most likely to get damaged by normal wear-and-tear. If you set your LB about, say, 60% of the way in, you can keep data from being written to the extreme outer edge of the disc, enhancing survivability. So, yes, go with PGCedit/IMGBurn, and add a chapter mark if necessary to get the layer break to work out right.

[ntscuser]

Of course, the studios use the more expensive and more scientically advanced stuffs than Nero or Memorex(*). But the fact that they have that warning indicates their "expensive stuffs" are not expensive enough, i.e. not perfect, to produce a flawless DVDs.


(*) though I would not be surprised if later someone reveals the true quality of their stuffs. Remember "bottled tap water" made by Coke?

As redwudz pointed out, they don't use recordable discs of any kind so the quality of the brand is irrelevant.

[moviebuff2]

Hello again

I followed the wise instruction and got the IMGBurn and Verbatim +R double-layer DVD (it took me one week to get 20 discs at $1.60 each, after rebate).

Using TMPGEnc, I combined and authored 2 video recitals of mine. There are 9 chapters in the DVD and each chapter of the DVD is at the start of a piano piece.

Using IMGBurn and my Philips SPD2410BD (a double-layer DVD re-writer for computer), I burnt the video onto the Verbatim +R, DL.

Here are the results:

My +2y/o Philips DVP642:

The disc skipped, froze like mad. Even after just 15 minutes into playback, troubles with freezing and skipping already began. Well, what can I expect with this OLD player which I bought for less than $50.00 brand new? Time to get a new player.

My +1y/o Philips DVDR 3390:

The disc paused very briefly at the layer break position which was created by IMGBurn in the middle of one of those "polite" applauses. This layer break was chosen by me at the step of "Create Layer Break Position". I had only 2 choices, both had stars of the same color: one was during the applause, the other during a piano piece. Well, although not completely happy, I can live with this minor annoyance.

And my last test...was...an APEX that was given to me from my bank as a promotional gift. No skipping, no freezing...no troubles whatsoever. The disc played from the beginning to the end without any problems.

So, that's my report.

Thank you for all your help.

[ntscuser]

The disc paused very briefly at the layer break position which was created by IMGBurn in the middle of one of those "polite" applauses. This layer break was chosen by me at the step of "Create Layer Break Position". I had only 2 choices, both had stars of the same color: one was during the applause, the other during a piano piece. Well, although not completely happy, I can live with this minor annoyance.

That's nothing. I bought a DVD movie once where the layer break had been placed in the middle of a line in a song. Don't remember the title other than it was an early Paramount DVD release and I think a romantic comedy. Perhaps someone here can remember the title?

[oldandinthe way]

Moviebuff2

I am not surprised that the APEX yeilded the best results. It probably newer and uses a commodity chipset - which is probably in more players than any "brand-name".

[MysticE]

It seems that the OP should try his original shrunk SL DVD on a larger set and see if the results suits his needs. We are talking about a piano recital not some high action, complicated video. It appears it's the sound that counts the most here and multiple player compatibility.