Bitrates. I smell B.S.

[heavyharmonies]

In another forum, there's someone offering "3-hour DVD-Rs at full D1 resolution and 9000 average bitrate".

I cried foul. 9000 peak maybe, but not average.

His response:

"I know it doesn't compute, but there is a good reason. Many Panasonic DVD recorders have a feature called flexible recording. I'm not sure about other models, but the E-80 model allows you to set the flexible record for up to 6 hours. Setting it for 3 hours or more is equivalent to LP resolution, but setting it to 2 hours and 59 minutes allows it to record at a resolution of 704 x 480 and a bit rate of 9 MBPS. This has been confirmed not only by the software I use on my PC, but by several of the high-end users over at the AVS forum that know much more about this stuff than I do."

Either he's misunderstanding or I am.

In my experience, 9MBPS at full D1 gets you about an hour, not three... even taking into account the fact that the Panasonics record 704x480 instead of 720x480 doesn't get you to three hours.

I've used Panasonic's FR recording to maximize bitrate for oddball time lengths, e.g., for a video of 80 minutes, you're better off using FR to dub to DVD than SP, but I don't think it does what he thinks it's doing.

??

-Dan

[drjtech]

"flexible recording" is marketing speak for "variable bit rate"

As you surmised he's confusing average with peak bitrate.

-drj

[junkmalle]

You are right. It's 9 MBPS max bitrate, if that. Obviously the average is about 1/3 that.

By the way, file size = average bitrate * running time. That's all. Frame size, Frame rate doesn't come into the equation.

[Shocker Milwaukee]

His response:

I know it doesn't compute, but there is a good reason.

There's a reason he didn't share it....

You smell correctly.

[jimmalenko]

Yep, you can't argue with the maths ... unless he's using DVD-14 or DVD-18 discs.

[DRP]

Has anyone ever seen a DVD-14 or DVD-18 recordable disc for sale anywhere? Or for that matter even a DVD-10 disc?

[lordsmurf]

That's not MAX bitrate either.

That's more BS.

The header says 9.8Mb/s, but if you use something like BITRATE VIEWER, the peak never even comes close, not by a few thousand k's bitrate.

[adam]

Has anyone ever seen a DVD-14 or DVD-18 recordable disc for sale anywhere? Or for that matter even a DVD-10 disc?

They don't make recordable DVD-14's or -18's. There are DVD-10's on the market but they are rare mostly because of lack of demand. You can find them at some online retailers.

[vhelp]

There are various ways that software have used in obtaning bitrate
(min/ave/max) and that includes the graphs some use in addition.
for instance, vdubMOD vs. bitrate viewer is an example. And, as
an "for instance", after runing both, which do you believe ??

On another note. I sure would like to know how to exactly calculate
bitrate in a given MPEG file. That would be interesting. Anyone
know how ? I'd like to make a quick little calculator for what its worth

Anyways..

-vhelp 3469

[jimmalenko]

On another note. I sure would like to know how to exactly calculate bitrate in a given MPEG file. That would be interesting. Anyone know how ? I'd like to make a quick little calculator for what its worth

Isn't that basically what a bitrate calculator does now ?

Take the size of your given MPEG file, divide it by the running time, multiply or divide by a few things to get the units right, and voila - combined audio & video bitrate. Subtract audio bitrate and you get your average video bitrate used. or not ?

[vhelp]

I was refering to obtaining the bitrate inside an already made
MPEG - not the other way around

-vhelp 3470

[jimmalenko]

I was refering to obtaining the bitrate inside an already made MPEG - not the other way around

Is that not one and the same ?

One way you use the running time and filesize to work out what bitrate to use to make it happen. Now you're saying you have this file that's x MB, and goes for x seconds, and you want to know what bitrate must have been used to make it happen. It's exactly the same


Say for example you have a 800MB MPEG-1 file. You know the running time is 80 minutes (Yes, it's a VCD MPEG).

so 800 x 1024 x 8 / 80 x 60 = combined bitrate

therefore combined bitrate = 1365 kbps

You know audio is 224kbps, therefore average video bitrate = 1141kbps ?

Of course you can only compute a figure - you can't allow for encoders that don't hit the exact bitrate specified.

[DRP]

That's not MAX bitrate either.

That's more BS.

The header says 9.8Mb/s, but if you use something like BITRATE VIEWER

Anyone had any luck even getting this program to just install? I've downloaded it and run the BV.exe executable only to have it hang on me. So I extracted the SFX manually and ran the Setup.exe in there instead only to have that hang as well. Cleared all the stalled apps from task manager and tried again with exactly the same result.

[lordsmurf]

If it didn't work, I wouldn't suggest it. I've used it on 5 computers, works fine on them all.

[adam]

I've never had any problems with installing BitrateViewer but, assuming you do get it to work, you have to take its results with a grain of salt. It uses the flags in the stream, at least partially, to determine the average bitrate and as a result its basically always off and sometimes by alot. Min and max seem to be accurate and the general bitrate curve and Q seem about right, but the reported average is something that is best calculated manually yourself.

You'll also notice that the reported average bitrate is different when using the trial version versus the full version of Bitrate Viewer.

[DRP]

The install routine has just started - some three hours after I ran it. Dunno what the hell was going on there but I was browsing some newsgroups and up it suddenly popped and completed fine. Very weird.

I see what you mean by the average bitrate being inaccurate. I'm using the registered version to scan an m2v I made with TMPGEnc destined for DVD-SVCD using VBR bitrate of 1600<2222<3000 and DVD-lab PRO reports the average being 2228kbps which sounds about right. Bitrate Viewer is saying the average is 1707kbps. Not only that but the current frame is quite often below 1600kbps, which is frankly impossible since I told TMPGEnc to never go below 1600.

[adam]

Well unless you enable the padding option in TMPGenc then your bitate will drop below your min setting occasionally. But as for the average bitrate, yeah that's the kind of stuff I get from BV too.

[DRP]

I always have the padding option enabled in TMPGEnc

[Nelson37]

Why in the world would you assume that specifying a minimum bitrate in any software means that it is absolutely impossible for the bitrate to drop below that setting?

Experience and simple math have taught me that specified bitrates are a rough estimate only, and most certainly NOT definite limits not to be exceeded, in either direction.

I have this bridge I want you to look at....

[DRP]

Because it's what the documentation for the encoder says. So sorry for believing what the people who wrote the software say it will do. I should have consulted you first. You obviously know better than the people who wrote the program.

Maximum Bitrate
The maximum bitrate setting restricts the encoder to an upper bitrate limit during encoding. The higher the value, the better the quality of scenes with rapid motion will become at the expense of file size.

Minimum Bitrate
This minimum bitrate setting guarantees a minimum bitrate for scenes with little motion if "Enable Padding" is enabled. If this value is set too low, even scenes with little motion will be of a poor quality.

Enable Padding
If this is enabled, padding (extra data) is added to scenes which would otherwise be below the minimum bitrate. VCDs and DVDs require a minimum bitrate, which is set from the media. It is suggested that this be enabled.

[lordsmurf]

Because it's what the documentation for the encoder says. So sorry for believing what the people who wrote the software say it will do. I should have consulted you first. You obviously know better than the people who wrote the program.

Before you get an uppity attitude, realize most documentation written for most hardware and software sucks. I would not at all be shocked if the encoder documentation was wrong. Especially if it's some crap translation like TMPGENC.

[jimmalenko]

Before you get an uppity attitude, realize most documentation written for most hardware and software sucks. I would not at all be shocked if the encoder documentation was wrong.

RatDVD, anyone ?

http://www.ratdvd.dk/faq.htm#AsGood

Is the reconverted ratDVD (to DVD) as good as the original?
Yes! There might be some small limitations to the quality based on the settings chosen, but it is a fully functional, compatible, high quality DVD-Video.

coughcoughbullshitcoughcough

[Nelson37]

No, dickhead, I've just been doing this for well over five years and I know how to use a calculator and a bitrate viewer. Encode a few thousand files and do some checking, you may actually learn something.

I suppose you believe you will actually achieve the miles per gallon rating on your car, cause it says so right there on the sticker, eh?

I repeat, I have this bridge I want you to look at...

// Don't call names. Informal warning.
// -- moderator lordsmurf

[jimmalenko]

Who are you talking to ?

DRP ?

[Nelson37]

Sorry, jim, thought it was obvious. Yes, that reply was directed to DRP.

[jimmalenko]

NP

[zworg2]

Because it's what the documentation for the encoder says. So sorry for believing what the people who wrote the software say it will do. I should have consulted you first. You obviously know better than the people who wrote the program.

You mean you not only believe the documentation....

.........but you ACTUALLY read it in the first place

Best way to learn is play, screw up, play again and then ask.

Such things are best used as reference material IF and when u get stuck.

The only other use i can think of for the instruction manual is as a doorstop.


Get off your high horse and accept that the users put 1000's more hours of testing into a product than the manufacturer would ever dream off putting in, and therefore in general the user has a MUCH better knowledge of the abilities, capabilities and limitations of any product.

oh and a significant proportion of such documentation is only proof read by a layman and so and technical mistakes (which inevitably creep in) dont tend to be picked up by proofing

1+1=3

Just because i have typed it doesnt mean it is true.

Documentation has mistakes. END OF.

[vhelp]

As far as the spicy bitrate goes ...

In short.., the unpridicallity is on account of each given Encoder's
min/max level of its Algorithems performance. Think about it for a
moment.. just because there are min and max does not mean that
those numbers will hold (though they should, if you input them) but will not
in most cases. It's a matter of the Algorithem used in a given Encoder, and
in a given encoding Mode/Routine being used for the particular encoding.
The source Noise Level is another factor to consider as well, here.

Please excuse my OT.. but, fwiw mentioning here.. has anybody ever
wondered why the developer of TMPGenc has NEVER come here
to help us with this encoder ??

They could help explain a great number of things, such as this issue
going around with the Bitrate settings and the behaviour there-of.

This is an Encoder that has gone through the mills (us, users) for many
years, since 2000, I think. And not a peep from the developer. I find
that strange, considering how many BETA stages it went through, before it
finally even left the 12x patouge. I was amongst the many users here
who was a part of this long BETA testing period. And this web site helped
promot it to what it was then, and is now today, and probably tomorrow.
Well, here it is, 2005 and still not a peep from the TMPGenc guy

Anyways..

There are many developers who have created Fair-to-Good tools and things
here. And many of these peoples are registered with vcdhelp .. and give
their support, etc.

-->

It would be an honor (and pleasure) to finally meet (through vcdhelp)
the developer of TMPGenc, once and for all .. (just to shake his hands
through words of thanks) And, I would be proud to say I stuck it out with
them as a loyal and faithful user ..fwiw.


-vhelp 3473

[adam]

Well good ole Hori speaks zero english so I assume that's why he doesn't post here. He's only done a very limited number of interviews ever so I think he's just a very private person. Maybe he replies to responses on the TMPGenc forum, but I think he has an employee who does that too.