4.7 GB = 2 hours?

[Harad]

Just starting writing DVDs and I find:

1. a 4.7 GB disk doesn't really hold 4.7 GB--seems to hold 4.4 GB

2. even though it says it will hold 2 hours of video it seems to hold only about 1 hour 50 minutes at standard DVD resolution (e.g. Ulead)

Is it just false advertising on all the blank DVDs or am I adding 0.3 GB overhead unnecessarily?

Thanks.

[thayne]

DVDR's hold 4.35GB's which comes out to 4,700,000,000 bytes

How much you can fit depends on the resolution and bitrate of your video and the audio format. PMC audio is uncompressed where AC3 or mp2 audio is highly compressed.

From what I have seen, most comsumer grade authoring apps limit you to about 90 minutes per DVD due to limits of the software.

[andkiich]

The 4.7 GB disks hold 4.4GB of USER DATA, the rest is overhead.

You can fit up to 8 hrs on a single consumer DVD. This is all dependent on the bitrate used. I know of no authoring apps that set an arbitrary limit on how much can be fit time wise in a single DVD.

It's not false advertising, it's just that you still have a lot to learn and a long way to go for tue understanding, Grasshopper.

[housepig]

I've had no problem putting 2.5 - 3 hours on a disc...

... but I'm also not using an "all in one" app that hides the encoding bitrates from me....

[Harad]

Lets try this again.

I have used MyDVD which has 3 different DVD resolutions. It fits as much as 2.5 hours of video at its lowest resolution.

If I put VCD type resoluton on a DVD I can put 7+ hours. So I am not talking about degrading the resolution.

I am talking about "standard" DVD resolution. Maybe this is what Ulead uses. I don't know.

Ulead calls it: 720x480 24bit, 29.97 fps.

If you take the ratio of what fits on a disk=1hour, 50 min compared with what they say= 2 hours

110/120 * 4.7 GB = 4.3 GB or about what the shaolin master said was the USER DATA part of the disk. If that is more than a coincidence then it is false advertising to say these disks hold 2 hours at standard DVD resolution, because all 4.7 GB is not usable.

[Baldrick]

How much you fit is entirely based on the video and audio bitrate not the video resolution. You can fit about 3 hours 720x480 on a recordable DVD with pretty good quality(depending on your source).

The problem are the all-in-one authoring tools, you can' select the video bitrate exact in some and mydvd always convert the audio to pcm(10MB/min compared to compressed ac3/mp3 2-3MB/min). Instead try other authorings tools with better converting support or use an encoder like tmpgenc, cinema craft encoder to convert to dvd mpeg with.

[housepig]

what Baldrick said.

the problem is not resolution, it's bitrate, both video and audio. If MyDVD reencodes your audio to PCM (which I believe it does) you are wasting a ton of space on the disc for bloated audio data, instead of using a leaner encoding like AC3 or MP2.

if MyDVD has it's "best quality" encoding bitrate set to 6000, you are not going to fit 2 hours on that disc... more like 80 minutes with PCM audio.

go to the Tools section and check the Bitrate Calculator. You can put in various time / bitrate ratios and see how they stack up.

bottom line - don't blame the media - it's your authoring program and it's lack of flexability that's hamstringing you, not the discs.

[shimmergloom]

If MyDVD reencodes your audio to PCM (which I believe it does) you are wasting a ton of space on the disc for bloated audio data, instead of using a leaner encoding like AC3 or MP2.

So does this mean that PCM is not better quality than ac3 or mp2?

and what is mpeg-1 audio layer 2 from the tmpgenc dvd author program? Is it ac3 or mp2? and is it just as good as PCM?

[Adder_78]

The 4.7 GB disks hold 4.4GB of USER DATA, the rest is overhead.

It's not overhead...

(4 707 000 000B / 1024 = about 4 596 679KB / 1024 = about 4489MB / 1024 = about 4.38GB)

Just like thayne said...

[mats.hogberg]

So does this mean that PCM is not better quality than ac3 or mp2?

Yes, PCM is better than AC3/MP2, since AC3 and MP2 are two "not lossles" compression techniques.

and what is mpeg-1 audio layer 2 from the tmpgenc dvd author program? Is it ac3 or mp2? and is it just as good as PCM?

mpeg-1 audio layer 2=mp2, and not as good as PCM (see above).

/Mats

[housepig]

of course, "better" is always subjective.

if the average user cannot tell the difference, is one format "better" than another? If you have an mp3 file encoded well, the original cd audio is technically "better", because it's not compressed, but if you can't tell the difference, then "better" would be whichever format serves your purposes more fittingly.

if it's a technical compliance issue (ie "my player won't play mp2 audio, it needs pcm") then yeah, one is "better".

but on my player, which will play pcm, ac3 or mp2, I find ac3 is better because it doesn't cause audio problems (like mp2 can) and it takes up much less space on the disc, so I can devote more space to the video bitrate.

maybe I'm weird, but I don't hear the difference, so I use the format that takes less space.

[mats.hogberg]

of course, "better" is always subjective.

Yes, but the operating word here was quality. If we're taking aspects such as compatibility with player, personal preferences, disc space needs etc - there's no simple answer!

[shimmergloom]

I'm just asking cause I don't want to use two dvdr's for a project cause of pcm, when I can fit it on one with mp2. I've burned it both ways on dvdrw to test it out and to my ears at least, I don't hear any difference. And for some reason my home theater system displays pcm 48 whether I burn it using the linear pcm setting or the mpeg 1 audio layer 2 setting.

[thayne]

I can't tell the difference between 2 channel mp2, PMC or AC3. I usually use MP2, but not all NTSC dvd players support it. If you want maximum compatability use AC3 or PMC. AC3 and MP2 offer similar file size, while PMC is uncompressed

[trhouse]

The confusion about 4.38 g and 4.7 G is that the "g" refers to gigabytes in th e base two number system ( 2 to the 30th power which = 1,073,741,824 ). The "G" refer to billions in the decimal system ( 10 to the 9th power = 1,000,000,000 ). So 4.38 * 1,073,741,824 is about equal to 4.7 * 1,000,000,000.

As for the two hours, in discussions with Sonic which makes MyDvd, they said their software places about 3.5 G of video on a disk, the remainder is used for PCM sound, chapters, menus, etc. How much video can go on depends on the quality just like with VHS tape, the same tape can be recorded as SP/LP/EP with progressively lower quality but longer record times.

[Adder_78]

The confusion about 4.38 g and 4.7 G is that the "g" refers to gigabytes in th e base two number system ( 2 to the 30th power which = 1,073,741,824 ). The "G" refer to billions in the decimal system ( 10 to the 9th power = 1,000,000,000 ). So 4.38 * 1,073,741,824 is about equal to 4.7 * 1,000,000,000.

That has been already explained...

(4 707 000 000B / 1024 = about 4 596 679KB / 1024 = about 4489MB / 1024 = about 4.38GB)

[trhouse]

Adder,

I saw your post. I was just expanding on it without assuming that everyone remembers their math well enough to see where your numbers came from.

Regarding recording times, video can be recorded in mpeg2 in cbr ( constant bit rate ) or vbr ( variable bit rate ) formats. VBR can create a longer video at the same quality.

[andkiich]

I stand corrected. I just assumed that there was some system overhead, as there are a lot of bitrate calculators that have some space set aside for what is defined as OVERHEAD.

This info I got from the bitrate calculator on DVDRHELP.com

Other ISO Files - Define how many MB you wanna leave for extra iso files, default Overhead is 5 MB for SVCD/CVD/XVCDs and 50 MB for DVDs and 5 MB for DivX. If you want more data files/iso files then increase this value.

[handyguy]

I use a dvd recorder & I get 4 hours in LP mode on one dvd. You can get 6 hours on a dvd in EP mode but it's kinda choppy.

[housepig]

Yes, but the operating word here was quality.

Mats -

you are quite correct.

I was looking in the macro sense of "is it better to have pcm audio, or can I use ac3 or mp2" rather than the absolute sense of "this one is uncompressed, that one is compressed, so this one is better".

although I'd still stand by my statements - this whole thread, at base, is "is it possible to put more than 2 hours on a dvd-r, and why can't I seem to do it?". At that point, compromise becomes essential... we could argue that an uncompressed avi would be the highest quality, but it's not going to fit much material on a disc

[Nelson37]

If you can't tell the difference, and since size IS a consideration, AC-3 would be the choice over PCM, and over MP-2 for compatibility reasons.
Otherwise you might as well consider Ogg Vorbis.

I've only had my DVD burner for 2 weeks, and am still experimenting, but I think MyDVD will acccept a muxed file with AC-3 audio without creating the PCM file.

As fas as maximum time, its all bitrate and what you are willing to accept. I find about 3-4 to be optimal, with 8 - 10 at VCD res about the absolute max, and at that it's barely acceptable and hardly worth doing.
Now when the blanks get to 20 cents a pop I might start putting as little as one hour per disk.

[lpn1160]

2. even though it says it will hold 2 hours of video it seems to hold only about 1 hour 50 minutes at standard DVD resolution (e.g. Ulead

I have personaly gotten well over 4 hours of very xcellent quality on 1 dvd-r disk using settings: 352x480 cce vbr 2500-8000, ac3 audio @ 224. (which is also considered "dvd standard")
Just gotta test.

[Thorn]

To summarize, getting past whatever limit you're hitting on a DVD probably requires some extra work. You may or may not be able to get the level of control you need from Ulead's entry level products. Many people complain here about ulead always re-encoding your video, and ac3 audio often requires more expensive programs.

You should read some of the encoding guides (to the left)and authoring guides and see what applies to you. Getting a DVD exactly like you want it can be a long process of tweaking the way you make it. Or it may just involve buying better software

On the subject of disc size: measuring 1GB=1,000,000,000 bytes is the standard media industry lie. All hard drive manufacturers measure it this way, as does the DVD industry. I guess this is because we get the tech specs from the marketing folks... and they always want to pimp out their product as much as possible.

[Nelson37]

Have confirmed that Sonic MyDVD will accept a file muxed with AC-3 sound, and does NOT create the PCM file in that case. This will save a LOT of space.

[SatStorm]

4 hour VHS/SVHS tape using 1/2 D1 and mp2 @192 ( the lowest DVD audio standard for mp2, not that lower ain't playable....) is the best I can do with perfect picture. And I talk for real bad quality tape, which means each frame differs the next one, because of noise etc.
Filtering is neccessary to succed good results ofcourse.
I can't go lower without degration.

A good alternative for PAL users, if the source is VHS, is also 352 x 288 (interlace, it is possible for PAL) with 1500 average bitrate. That results a picture like a 3000kb/s average 1/2 D1 picture or 6000kb/s average full D1 picture in much smaller filesize. This resolution ain't good for anything non VHS of course.

mpeg 2 @ 352 x 288 is a legal PAL DVD resolution