X4 vs X2 DVD Disk Space Calculation

[mark9422]

I assembled a 1 hour 30 minute slide show with a music track, one transition and a title slide. I attempted to burn an AVCHD dual layer DVD (8.5 gig) at 1920x1080 resolution with a Dolby 2 channel audio track---nothing fancy. In VS X4, it showed I had way too much material for the dual layer disk at those settings. It was not until I reduced the resolution to 720x480 that it would fit. However, I still had a copy of VS X2 on my machine so I opened the project there and it fit with much room to spare on the same disk at 1920x1080! (and all the same settings that I originally tried when first attempting to burn in X4). This doesn't seem to make sense. They only difference was the bit rate. In X2 the default bit rate was 15,000 but in X4 it was 16,000. Still that (to me unless I'm wrong) doesn't seem enough of a difference to send the content meter off the scale.

Last year I burned an AVCHD disk with 90 minutes of content on a dual layer with no problem in X2. I purchased X4 since it handled HD much better than X2. I have another annual project I've been working on since January which will also have about 90 minutes of content and I have assembled it in X4. I am almost sure now it will not fit if I burn in X4 based on the calculations I saw today.

Can you offer any advice?
Thank you
Mark

[teknisyan]

AFAIK.. bitrate of a video controls the quality of your project. So overall that 1000 difference that you see will surely affect the quality and size of your project. Have you tried changing the bit rate to 15,000 on VS X4 to check if it will change anything?

[Ken Berry]

I made most of my hybrid AVCHD disks using X2. And when I did so, I used the highest possible bitrate which in VS is currently 18 Mbps (as it was also in X2). That maintains the highest quality you can get out of VS for that format -- even though the current international standard is 24 Mbps for interleaved AVCHD camcorders and 27 Mbps for 50/60p and 3D camcorders. But with that bitrate, I could never fit much more than about 22 minutes of video onto a single layer DVD. That implies that at that bitrate at least, I would only get at most under 45 minutes on a dual layer DVD (and again, using X2).

As Abiel indicated, dropping the bitrate implies lowering the quality and the size of the resulting video. When originally experimenting with X2 and AVCHD discs, I found that a bitrate of around 12 Mbps max would allow me to burn about 56 minutes of video to a single layer disc. I don't know what the equivalent size might be using X4 instead of X2 because I simply have never tried it because the resulting quality was far less than anything I could easily accept.

But my basic point is to fit your 90 minute project on a dual layer DVD, you would need a lower bitrate than X4's default 16 Mbps. So first off I would follow Abiel's advice and see what 15 Mbps gives you. And if will not fit, then drop the bitrate a bit further.

You could also consider using two-pass encoding which should enable you to fit more video in, especially if there is a lot of fast moving action in your project. Fast action will also usually increase the bitrate used at those points and thus increase the size of your overall project.

[mark9422]

Thanks for your responses!
I did lower the bit rate in X4 to 15,000 (the same rate as X2s max bit rate for this type of project). Still, X4 tells me I have way too much content for the dual layer DVD disc. X2 calculates I have plenty of room on the very same disc at identical settings. Again, I made a complicated 90 minute AVCHD video last year in X2 and had room to spare on the disc.

I simply don't know why the two programs calculate disc space differently. I wondered if you have an explanation for that?

A side note: I purchased a Blu-Ray burner this year and tested it with X4. I was able to create a Blu-Ray disk back in March with (then) only about 25% of my project's material. I would imagine (and hope) a Blu-Ray with 25 gigs of space will work fine for my final project. I would just like the option to burn AVCHD discs in X4 for this and other projects as Blu Ray discs are still on the expensive side.

Any other thoughts? Thank you for your input in advance!
Mark

[mark9422]

Anyone? Corel?

I just wondered if there is any reason the two versions of the program calculate DVD disc space (seemingly) completely differently and other than bit rate, are there any not mentioned settings that might bring the programs in line with one another to calculate available DVD space. Or is the render of such greater qualitty in X4 (and thus needing larger files) that the final disc is much improved over what X2 would yield (I haven't noticed any difference in the final disc). As mentioned above, even when both X2 and X4 have identical bit rates, X4 alwlays tells me there is not enough room for my above project while X2 tells me there is plenty of room.

Thanks again

Mark

[Ken Berry]

Have you actually ignored the oversize warning in X4 and gone ahead and burned a disc? You could always choose to burn a Folder instead of a disc to see what size it is. That creates the full BDMV structure of an AVCHD hybrid disc. Then it is simply a matter of transferring that Folder onto a disc if the size turns out to be right.

[mark9422]

Thank you Ken. I will give that a try and report back.

Mark

[GLOBETROTTER]

How are you burning HD 1920 X 1080 to DVD? This can't be done. Software will automatically downrez your files from HD to SD to fit DVD format (unless you're just placing files on a Data DVD for PC use). The max rez any DVD disc will take, even dual layer, is 720 X 576.

[Ken Berry]

No. You can definitely burn AVCHD 1920 x 1080 to a standard DVD in its HD format by choosing Share > Create Disc > AVCHD. This burns what is called a hybrid disc. It has a Blu-Ray BDMV/Certificate structure on it instead of a SD video DVD's Video_TS folder. The downside(s) are that it can only be played in a Blu-Ray player rated to play hybrid discs (though most recent players will do so). And the maximum bitrate which can be used on such discs is 18 Mbps -- which I think is the international standard for such discs. Using such a bitrate nevertheless produces very high quality output, but it limits the amount of video you can burn to a single layer DVD to about 20 minutes plus a menu.

Definitely a cheaper way to go if Blu-Ray discs are still very much more expensive than DVDs for you.

[GLOBETROTTER]

I was meaning discs for normal use DVD players. I produce DVDs for worldwide commercial sales, but could never produce the same in HD format unless on BR discs. I don't see any point in making a short semi-HD version on DL DVD that can only be played on certain BR players.

[Ken Berry]

First, this thread was specifically about hybrid discs. They exist, and quite a few people use them as an alternative to expensive Blu-Ray discs.

And they are not semi-HD. They are full HD. No upscaling is required.

[GLOBETROTTER]

Hybrid or not, I still don't see how 90mins of full HD video plus music tracks is ever going to fit inside 8GB of DL DVD disc space and maintain full HD quality.

[Ken Berry]

And I have never claimed it could. If you read my posts above, I make the point that using the highest quality setting permissible for these discs of 18 Mbps, you will only get around 20 minutes of video (including audio) plus a menu on a single layer DVD -- so notionally, 40 minutes on a DL disc, not that I have ever tried burning one with DL. You can certainly jam in more video by lowering the bitrate, just as you would with a DVD, but of course the quality also lowers. And I would agree that you soon reach a point where the quality is not very good -- still better than DVD, but not at all the best HD output.

[GLOBETROTTER]

I assembled a 1 hour 30 minute slide show with a music track, one transition and a title slide. I attempted to burn an AVCHD dual layer DVD (8.5 gig) at 1920x1080 resolution with a Dolby 2 channel audio track---nothing fancy.

Last year I burned an AVCHD disk with 90 minutes of content on a dual layer with no problem in X2.
Thank you
Mark

When I mention 90 mins it is in reference to Mark's views in Post 1.

[Ken Berry]

Yes, I realise that. And my own comments were in response where I talked about the fall in quality being unacceptable (to me) if you reduced the bitrate too far to squeeze too much in.