DVD Authoring

[Tafflad]

Not come across the issue before as all my bits of video have only been around an Hr Max.

For a mate will be authoring vieo to standard MPEG 2 video 720x576 25 fps with 2 ch stereo audio .... 2 questions ...

1. is there a recommended bitrate setting, above which there is no gain in quality, no point setting to for example 9.8Mbps if that sis not needed.

2. given the optimum setting in Q.1 what is then the max minutes of video that will fit onto a standard 4.7GB DVD



I know I can use 'fit to disk' option ......... but if I have a guide from 1 &2, I can give him option at least get him to trim running length if too much over limit (or keep & reduce quality)

[Kerry56]

You'll want to use variable bitrate encoding. I've found that 8500mbps max and 2500mbps minimum work very well when using the HCenc encoder. Setting the video stream encoding too high can cause some issues in a few players. And you do have to leave some room for the audio.

Using these settings, and starting with an excellent source, my rough guideline for high quality video is to keep the run time at approximately 90 minutes for a single layer DVD. This can be increased to 120 minutes for good/acceptable quality DVD-video on a single layer disc. Once you push it beyond 2 hrs, it starts to show some real problems. But this is subjective, and there may not be many who agree with me here at Videohelp.

[newpball]

1. is there a recommended bitrate setting, above which there is no gain in quality, no point setting to for example 9.8Mbps if that sis not needed.

I am sure you are a quality conscious person, thus why not aim for the highest quality? DVD spec allows a max bitrate of slightly under 10Mb/s so the closer you can get there the better your material will be!

What is then the max minutes of video that will fit onto a standard 4.7GB DVD

I'd say if you want to go for quality I would target 1.5-2 hours for a DVD5 and 2.5-3 hours for a DVD9.

And obviously if you are tight on the space you would automatically opt for a DVD-9.

[Tafflad]

Thanks for the above - great answers ...

newpball: how compatible is DVD9, I have only ever used DVD5, would DVD9 discs be playable in most players ?

[usually_quiet]

To add to what Kerry56 wrote...

There are as you know limits as to what is allowed. The maximum bitrate allowed for video on a DVD is 9.8 Mbps. The DVD spec also only allows a maximum total bitrate ( for video + audio + subs together) of 10.08 Mbps, so that number shouldn't be exceeded either.

The number of minutes that can be put on a 4.7GB DVD at a given level of quality depends on the subject matter. A lot of movement and detail (or noise) requires more bitrate. A rule of thumb is that 1 hr of video and audio per 4.7GB disc would provide a very high quality end result, and anything from 1.5 hours to 2 hours would be acceptable to most. Most DVDs are encoded using variable bitrate so very high bitrates will be allocated only where needed.

[usually_quiet]

...how compatible is DVD9, I have only ever used DVD5, would DVD9 discs be playable in most players ?

Most players can play DVD9, but the cost may be a consideration if you have no use for DVD 9 after this project. Verbatim DVD+R DL (the most reliable product of its type) costs $1.00 per disc in cakeboxes of 30 or more discs and more if purchased in lesser quantities. I think prices are likely to be significantly higher in the UK.

[Cornucopia]

And, as usual, one calculates such things with a "bitrate calculator", many of which are available that cater specifically to DVD constraints, including at least one linked to on this site. Of course, all of them are based on the simple formula:

Filesize = Bitrate * RunningTime

Scott

[Skiller]

DVD spec allows a max bitrate of slightly under 10Mb/s so the closer you can get there the better your material will be!

Yes, but it's important to note that this maximum of 9800 Kbit/s is shared between video and audio, so the maximum you can actually use for the video alone is 9800 minus [bitrate of all audio streams combined]. And I would subtract another 100-200 Kbit/s as a safety margin.

What is then the max minutes of video that will fit onto a standard 4.7GB DVD

Depends on the complexity of the content but with typical handheld camcorder footage or analog sources (VHS and similar) I would aim for 80-90 minutes if you want excellent quality. 2 hours for that kind of footage is pretty ambitious in my opinion, unless you're willig to accept a quality loss.

2. given the optimum setting in Q.1 what is then the max minutes of video that will fit onto a standard 4.7GB DVD

Well, if you want to max it out (bitrate constantly at the maximum), without leaving any unused space on the disc, you can put just slightly over 60 minutes on a DVD5 (~64 minutes).

[Cornucopia]

No, the 10.08Mbps is the Stream Total Max (Video+Audio+Subs+Text+Nav). 9.8Mbps is the Video (only) max. This is verified by authoritative sources. I do agree, you should back off a bit for cushion anyway, particularly since many settop players aren't as forgiving as they ought to be.

Scott

[Skiller]

Right, thanks for the correction. Although it doesn't really hurt to pretend the combined total max is 9800 for the reasons you mentioned.

[_Al_]

You can use HcEncoder 1pass quality encoding (constant quantization, quant value 3) to encode a scene or clip. You can set start and end frame and encode. Drop encoded video onto bitrate viewer and you would see distributed bitrate. That gives you an idea what bitrate you need for particular video and its scenes.

This quick analysis gives you an idea about DVD lenght so quality would not started to be compromised too much.

[johns0]

Use 9800 for fast moving videos,use 5000 for people sitting around,then calculate for videos in between.

[Cornucopia]

@_Al_ and johns0, I disagree.

For DVD, maximize the usage of the disc. It has to be burned anyway. That entails not using 1passVBR, nor CQ, but 2pass VBR (or for short vids, high bitrate CBR). That also means not guessing on what MIGHT be appropriate for a given content situation and just throwing all the available bits at it.

So using that aforementioned formula: If your titles are each ~60 min. as you said, and you are only putting 1 title per 4.37GB disc, that means...

4.37GB=35799.04Mb
60 Min.=3600 sec.
35799.04 / 3600 = 9.9417777Mbps

Clearly that is too high for what is allowed for video on DVD, so just give it 9.8Mbps (or maybe with cushion, 9.5Mbps) at CBR, and know that it is at the max available for DVD. And obviously, you couldn't give it anymore even if you used a DL disc (it would be wasted space).

If, however, you wanted to put 3 1-hour titles on the SL disc, your equation changes to 10,800sec. This equates to a (average) bitrate of 3.3147Mbps, and for this you would want to use 2pass VBR and make the Max=9.800 (or 9.500...) and the Average=3.314 and the Min=0, or more likely (and usually more allowable) 0.5Mbps. DL average rates would be raised accordingly (no need to change max & min).

Make sure you are keeping track of the data rate for the audio track(s) as well. If you need LPCM, it will likely be 1.536Mbps (2ch16bit48kHz), which means you might need to lower your amount allocated to video a bit further to not hit the 10.08Mbps limit and to not inordinately approach the disc capacity limit. If AC3 (Dolby Digital) or MP2, you have much less to worry about in the bit budget.

Scott

[johns0]

Too much calculating for me,as long as the video looks okay after doing a encode then burn away.

[Tafflad]

So for current project for mate .. the run time is 55:40 its going to fit on Type 5 and remain good quality
... using "Marks Bitrate DVD Calc" it gives me for VBR:

[_Al_]

Corucopia - he will use 2pass VBR for a DVD, especially for longer DVD, that is the way to do it, but using that CQ just couple of scenes, he can get an idea how demanding HCEncoder could be. So he can know what encoder would do if he had shorter DVD etc. Just to know what bitrate encoder would prefer to have for this scene or for still pictures etc.

[Tafflad]

My normal approach on any DVD work has been to carry out a 2-pass VBR render of video stream only. Then separate AC3 audio render.
This was advice I had from some guys here.
I use Sony Vegas and the MainConcept MPEG-2 plugin for encoding

[Cornucopia]

For <64 minutes on a type 5 disc, you might as well just encode CBR at full highest bitrate. Going 2pass VBR will just waste an extra (& unnecessary) pass (unless this cannot be avoided,e.g. HCenc encoder). Note that CBR at 9.8mbps is equivalent to VBR at 9.8mbps max, 9.8mbps average, so the quality and filesize should be ~the same, even if not identical.

But if your process isn't broken (which it doesn't seem), you don't need to fix it.

Scott

[Tafflad]

Looking at that BitRate calc and switching to CBR it gives me Bitrate of 9608 so if I used that for CBR .. no problem.

Read comments elsewhere about not going above 8,000,00, but this should not be an issue then ?

[Cornucopia]

I hear reports of it being an issue, but in my 15 years of doing DVD authoring, I have only had a few cases where it was a problem and ALL of those were in the first 2 years.

Scott

[_Al_]

Actually , with 55 minutes running time, he has a opportunity to do 1pass with Constant Quantization encoding, just as I said then he loads that mv2 into bitrate viewer and he would see "Holy grail". Meaning real distribution of bitrate for a scene.

Hcencoder - Setting1 tab check Constant Quantization, Quant value 3, P an B factor for Quant 1, check VBV max bitrate, AQ 2, dead zones auto and set maximum bitrate in Main page to something like 8500


CBR is pretty solid, never fails also just some space waste but that is not an issue with DVD, perhaps only if it is stored on hardisk. Long time ago, CBR was safe because encoder were so bad that using VBR and cross disolve from still for example could pixelate, then CBR usually guaranteed better result. Today encoders are fine and using that Constant Quantizer is not a bad idea, it can be learning experience to actually see real bitrate demands for scenes (unless encoder hits max values).