Mpeg-2 encoding question

[Chad Rego]

Hello Board,

I was wondering what is a standard bitrate that movie studios encode their movies in?

I know it varies from DVD to DVD but has anyone noticed a standard bitrate which most mpeg2 are encoded?

Another thing Im trying to figure out. I got a hour 45 minute home video about to put on a 4.7GB DVD. What bitrate should I encode at to get it all to fit on there?

Thanks,
Chad Rego

[Rob Lohman]

There is no standard bitrate. To be even more truthful, the bitrate
is not one number.

The three main things that involve DVD quality are:

- the quality of the MPEG-2 encoder
- the chosen bitrate(s)
- the algorithm used

To begin with the latter, the algorithm all the big boys used is
VBR encoding, which stands for Variable BitRate encoding. Which
is why there is no one number.

With VBR you are typically talking about the minimum, average
and maximum bitrates. Which I think usually are in the range of
2000 - 8000 - 9000 for example. You usually also tell the encoder
how many passes it should do, this is why it is usually called
multipass VBR encoding. The more passes the more efficient and
better the encode will be, but the longer it will take to encode.
You need at least 2 passes to do VBR encoding.

The quality of the MPEG-2 encoder is the most important though,
and I really cannot tell you what is good on the Mac platform.
Currently the three best encoders for the PC platform are
Canopus ProCoder, CinemaCraft Encoder (CCE) and TMPGEnc.

A DVD boosts 4.5 GB of information (single layer). That is around
4600 MB. Now if you have 1 hour and 45 minutes of footage that
is 105 minutes or 6300 seconds.

4600 / 6300 = 0.73 MB/s

So every second can only use 0.73 MB which is around 7.3 mbit
or a bitrate of 7300.

This is the number if you where using constant bitrate encoding.
If you are going to use VBR encoding you will have to do some
trial and error, try a number like:

2000 - 6500 - 8500

I hope this has explained a few basic MPEG encoding things for you.

[Dave Perry]

Rob covered the question very well but I can suggest a good encoder for the Mac: BitVice.

[Patrick King]

<<<-- Originally posted by Rob Lohman :

Currently the three best encoders for the PC platform are
Canopus ProCoder, CinemaCraft Encoder (CCE) and TMPGEnc.-->>>

Rob,

I've heard the tribal lore about the TMPGEnc codec being good, but do you have a study, report, article or such that supports those three being the 'best' codecs for MPEG?

Is there a previous thread that compares the Main Concept codec to those three? Do you have first hand experience rendiering in these three from which you can give us a subjective narrative about the attributes of each that lead you to say they are the 'best'?

I'd truly appreciate any info because if I need to upgrade I will, but if the only difference isn't subjective or negligible. Otherwise I'd prefer to spend the money on other tools to improve my craft. Thanks in advance and thanks for taking the time to 'Wrangle' such an unruly crowd.

[Chad Rego]

Thanks so much for your answer, very detailed and very informative! =)

I currently use cleaner xl. Does that work as good as the other encoders you talking about?

Thanks,
Chad Rego

[Roger Andersson]

Here is an MPEG-2 encoder shootout from VideoSystems

http://videosystems.com/mag/video_mp...out/index.html

Click on the link called "The Tale of the Tape" at the top of the page for a quick comparison chart/table.

[Greg Boston]

<<<-- Originally posted by Rob Lohman :

...You need at least 2 passes to do VBR encoding. -->>>

Rob,

With all due respect, I have to differ with you on this just a little bit. I am on a mac system now and the QT Pro encoder that's included will do CBR as well as single pass or double pass VBR.

With CBR you get a known calculated file size which tells how much material you can fit. You set only one bitrate.

With single pass VBR, you cannot get a true file size in advance, so you encode and hope it fits when you see the finished filesize. You set the minimum and maximum bitrates. You get no motion estimation choice cause it can't do that with only one pass.

With two pass VBR, you get to have a known file size and you get to select the quality of motion estimation. Per the recommendations in my manual with regards to most feature DVD releases, I set the minimum bit rate to 5mb and the max to 8.5mbs. This way, the quality will average above 5 and will jump to the max for scenes with lots of motion.

I was able to use the above settings because I had a fairly short video file on this project which would easily fit with menus, transitions and uncompressed PCM audio on a single layer dvd.

regards,

-gb-

[Roger Andersson]

<<<-- Originally posted by Greg Boston : <<<-- Originally posted by Rob Lohman :

...You need at least 2 passes to do VBR encoding. -->>>

Rob,

the QT Pro encoder that's included will do CBR as well as single pass or double pass VBR.

With CBR you get a known calculated file size which tells how much material you can fit. You set only one bitrate.

With single pass VBR, you cannot get a true file size in advance, so you encode and hope it fits when you see the finished filesize.

regards,

-gb- -->>>

Sorry for disturbing, I'm new here, but I feel I have to support Rob's opinion.
One pass VBR? That is just ridiculous hype. Please, don't let yourselves be fooled around in absurdum.

Just try to imagine, how on earth should a piece of software, or hardware, be able to anticipate (and on top of that accurately analyze) the nature of footage hours ahead of time? You can dismiss that, just by using common sense.
Apples' QT MPEG-2 encoder, predating the Compressor, also carried similar verbiage along with it. Obviously Apple wanted their poor Mac customers to believe in ghosts too.

It is absolutely NOT true that a 2-pass VBR encoder cannot accurately tell the final file size. I don't know how well other encoders do, but BitVice will do this within a few kB. Is it really true that you still cannot trust Compressor with such a basic requirement??

I know that when Compressor first came out it couldn't keep anyway near the average target bitrate. There were actual cases (which I saw with my own eyes) where the actual average bitrate was twice the rate the user asked for.

I assumed this had improved considerable since then, but You can easily check this on your own. Just take the resulting file size, in number of bits (not bytes) and divide by the duration of the video, in seconds. That is how you get the average bitrate used. It is very simple, a 10 year old kid can do the math, as long as he/she is not afraid to try.

Roger

[Rob Lohman]

Let's try to work down everyone's comments <g>

Patrick: I have no such links, but there was one posted here. The
reason CCE/TMPGEnc crop up everywhere is because it is being
used by DVD rippers a lot to re-encode stuff. I also have a couple
of good friends who have done lots of encodings with both products
and have much more sensetive eyes than me for things like
compression issues etc.

They always said those two product where the best. If they say
so, then I will follow that advice blindly. Again, that everybody in
the not so legal scene is using it as well is a good indication of
quality.

Since about probably a year ago Canopus ProCoder has been
tauted as the number one encoder (without paying thousands
and thousands!) currently available quality wise. Again, I trust
the people making these claims.

I have seen and done encodes myself with CCE/TMPGEnc and
I can attest to the quality of those. I haven't had an opportunity
to work with ProCoder, unfortunately. (I don't do many MPEG-2
encodes).

But, all have trial versions available, so you can always see and
test for yourself. Do keep in mind that MPEG-2 encoding is an
art form which takes a lot of patience and practice to perfect.
The article linked to above says ProCoder is best as well, but says
the interface is difficult...

If you do a search on these boards for "TMPGEnc CCE ProCoder"
you should find numerous threads in which I reply with guides
etc. to help you get started.


Chad: I've once tried Cleaner XL and really hated what it wanted
to install and how it worked. I haven't done any serious encoding
with it so can't attest to quality. But according to that article linked
to above it seems to be good.


Greg: yes, some products offer single pass VBR indeed (as does
TMPGEnc). What I meant was that you really don't want to do
single pass VBR if you are going to use VBR. I know people who
do 9 (yes, 9!!) passes in something like TMPGEnc for maximum
quality at the given bitrates.

In the end it all boils down to quality, time and money. I believe
that the encoder that comes with Sony Vegas and Adobe Premiere
is pretty good (for my needs at least). But if you want top notch
quality then look at the top of the line products, spend the money
and more importantly spend the time!

Time to LEARN the product and the CRAFT of MPEG-2 encoding, but
also the time to have it do an encode properly.

The commercial DVD's are all made with multipass VBR encoding
and use systems where they can hand optimize the VBR encoding
for specific frames, scenes or sections. How much time do you think
they (sometimes) spend?

Make a choice of what kind of quality you want for yourself or your
clients and create your workflow around that accordingly. If you
start to know your product you can guess bitrates without any
problems.

Good luck to all the people encoding out there! <g>


p.s. Roger: thanks for the link! I'll see if I can find some time this
evening to read through the article. Unfortunately I simply don't
have the time to (really) test encoders myself and write a (good)
article or search the web for search articles....

[Greg Boston]

<<<-- Originally posted by Roger Andersson : <<<-- Originally posted by Greg Boston : <<<-- Originally posted by Rob Lohman :

...You need at least 2 passes to do VBR encoding. -->>>

Rob,

the QT Pro encoder that's included will do CBR as well as single pass or double pass VBR.

With CBR you get a known calculated file size which tells how much material you can fit. You set only one bitrate.

With single pass VBR, you cannot get a true file size in advance, so you encode and hope it fits when you see the finished filesize.

regards,

-gb- -->>>

Sorry for disturbing, I'm new here, but I feel I have to support Rob's opinion.
One pass VBR? That is just ridiculous hype. Please, don't let yourselves be fooled around in absurdum.

Just try to imagine, how on earth should a piece of software, or hardware, be able to anticipate (and on top of that accurately analyze) the nature of footage hours ahead of time? You can dismiss that, just by using common sense.
Apples' QT MPEG-2 encoder, predating the Compressor, also carried similar verbiage along with it. Obviously Apple wanted their poor Mac customers to believe in ghosts too.

It is absolutely NOT true that a 2-pass VBR encoder cannot accurately tell the final file size. I don't know how well other encoders do, but BitVice will do this within a few kB. Is it really true that you still cannot trust Compressor with such a basic requirement??

I know that when Compressor first came out it couldn't keep anyway near the average target bitrate. There were actual cases (which I saw with my own eyes) where the actual average bitrate was twice the rate the user asked for.

I assumed this had improved considerable since then, but You can easily check this on your own. Just take the resulting file size, in number of bits (not bytes) and divide by the duration of the video, in seconds. That is how you get the average bitrate used. It is very simple, a 10 year old kid can do the math, as long as he/she is not afraid to try.

Roger -->>>

Roger, you misunderstood a couple of things. I said that multi-pass VBR CAN give you a final file size. Only single pass VBR doesn't offer up a final file size in advance.

As to 'poor Mac customers' , I am only a mac customer for less than one month at this writing. I have been a user of the pc platform since the IBM PC first appeared on the market. Whether or not I believe in ghosts is a subject for another forum.

Finally, since you are new here I would like to point out that DV-INFO maintains a code of conduct that doesn't allow for personal attacks, platform wars(brand x is great and brand y is worthless), or flaming of other members. It's OKAY to disagree and discuss technical matters, but we do so in a polite, respectful manner. See the first sentence in my response to Rob. I respect him and his knowledge. I only responded because the information contained in my software manuals was slightly contradictory to what he posted.

Rob,

I agree about why would you want to do single-pass VBR. I think this was an early on solution for cheaper encoders(consumer use) to offer more storage for home video projects on DVD. Never meant as a professional encoding method.

-gb-

[Chris Hurd]

Thanks Greg,

Proof that there's usually more than one way to correctly do something!

[Dave Perry]

I would like to welcome Roger to the DVInfo Forums. I've never met him but am a user of BitVice, the product he produces, and have found it to be the better of the two, Compressor being the other, MPEG2 encoders for Mac.

I also visit the support forums at the Innobits Web Site and have found his and others advice quite helpful.

I feel very lucky to have the input from seasoned video professionals that we have at DVInfo. Everyone from directors, DPs, software manufacturers, hardware manufacturers, etc. seem to end up here and I can truly say it is where I start my search for anything video related.

Welcome aboard Roger!

[Ethan Cooper]

Ok guys, this has been eating at me all weekend and my searching has brought me to this discussion.
At my place of business we edit with FCPHD and encode our MPEG2 stuff with either compressor or the qt encoder in DVDSP2 (both around 7bps 2 pass vbr). We also have a Philips standalone dvd recorder (with firewire input) we use for quickie client proofs. The problem is that the cheap ($350) Philips dvd recorder to my eyes looks cleaner and more accurate than the software encoded mpeg files, with the added benefit of real time encoding.
If it were not for the nasty preset menu screen on this Philips dvd recorder I would use it ALL the freakin time for quality sake and for the time aspect (which is a much bigger issue at this point).
I mean come on, it takes the better part of an hour, hour and a hald to fully encode and burn a 13-15 minute project in DVDSP2 and it dosesn't look as crisp or clean as the realtime burns on the dvd recorder.

All that to ask this question:
Do any of you know of a device like the DVD recorder that has a firewire input and encodes realtime but instead of burning to a disc, saves the file to a hard drive? You could then transfer that file back to your authoring program of choice thereby having the best of both worlds.

To clarify, I'm NOT looking for another great software encoder because those take freakin forever to encode. I'm looking for a realtime hardware encoder (like the one that comes in a $350.00 dvd recorder) that accepts a firewire input and saves the file to a hard drive.

It seems to me that this can be done for easily under $2000.00 if they can have that kind of technology in a $350.00 device.
Personally, I'd be more than happy to pony up the cash for something like that.
Maybe I'm just a little slow, but I cant find that solution out there. PLEASE someone point me in the right direction.


-Ethan Cooper
NY Productions

[Dave Perry]

Ethan,

Lacie is now shippinga a real time hardware MPEG2 encoder.

It was supposed to ship this time last year but was held up because of changes in Panther and LaCie's reluctance to import the device not having complete compliance with Panther.

Bob Hudson has an in depth review of it. He was one of, if not the only, US testers for it.

As for a software based encoder, I use and recommend BitVice

[Roger Andersson]

<<<-- Originally posted by Dave Perry : I would like to welcome Roger to the DVInfo Forums. I've never met him but am a user of BitVice

Welcome aboard Roger! -->>>

Thanks Dave
I'll try to keep popping in here once in a while.
Roger