DVD playback times

[droopy]

Hope that any of you guys can shed a light on this one.

I've been searching for an answer for some time now but unfortunately was not able to find it. Basically the question is simple.

On many a DVD you find the remarks:

HQ = 60min
SP = 120min
LP = 180 min
EP = 240min
SLP = 360min
SEP = 480min

Normal use of a DVD recording is with SP, where you can then put 120minutes of video thereon.

What I'm basically looking for is what the encoding parameters are for the the others like LP, EP, SLP, SEP and HQ? I understand them to be a combination of bitrate and video resolution, but which ones?

Hope any of you can give me some answers or a direction to look as so far I've not been able to find it.

Thanks a lot.

All the best, Leon

[Brian Ellis]

It's not as easy as that. If yiue use variable bit rates or constant quality, there is no forceable correlation. The glib answer is to aim for filling ~4.2 Gb of the DVD (menus etc. included). Obviously, if you have a sophisticated authoring with multiple audio, motion thumbnails etc., then your menu will take up more space and your video bitrate has to come down to make room for it.

As a rough guideline, up to about 80 minutes, try constant bitrate 6000 (shorter ones can be recorded at a higher bitrate, but you get no visual advantage). Above 80 minutes, you will have to slowly reduce the bitrate.

As for your "EP to SEP", don't think about it! At 720 x 576, 180 mins is about the max with quality not much better than VHS.

[droopy]

Hi Brian,

Thanks for the reply.

I would have thought though that by e.g. lowering bitrate on 720*576 would increase amount of video to be put on the DVD. More importantly, apart from 720*576, I thought that 360*576 and 360*288 were also legal resolutions for DVD (PAL country). For these the bitrates can be lowered significantly to achieve, at least with the 320*576 resolution, compareble quality as with SVCD?

Am I wrong in these assumptions??

It's just that I can't find any information on default specifications though for LP, EP, SLP and SEP like you have for SVCD and VCD. That's basically what I need to use as a basis for experimenting to find a for me acceptable compromise in video quality and playback time, while still staying within the boundries for DVD specifications. So no XDVD or something which can be played on one player ad not the other.

Hope someone has some ideas or place for me to look.

All the best, Leon

[Dr Mordrid]

DVD legal resolutions:

NTSC MPEG-2: 720x480, 704x480, 352x480, 352x240; VBR or CBR
NTSC MPEG-1: 352x240, 352x480; CBR only

PAL MPEG-2: 720x576, 704x576, 352x576, 352x288; VBR or CBR
PAL MPEG-1: 352x288, 352x576; CBR only

DVD legal frame rates:

NTSC = 24 or 29.970 fps
PAL = 25 fps

Audio:

16 bit stereo at 48khz using LPCM (linear pulse code modulation; basically uncompressed), MPEG-1 Layer 2 (normal for PAL) or AC3 (Dolby digital & normal for NTSC). Most sources will do fine encoded to a bitrate of from 160-256 kbps. In the real world 160-192 kbps is more than enough for most purposes other than music or fancy audio f/x.

Bitrates:

DVD supports a total bitrate (audio+video+subtitles etc.) of up to 9800 kbit/s, but video is capped at 9600 kbit/s.

To really get a good estimate of playback time vs. capacity vs. bitrate you need to use a bitrate calculator that also includes the audio bitrate. There's a pretty good one here;

http://www.dvline.com/cfwebstore/pages/support/reference/dvd/BitrateCalc/bitrate.htm

You can save this page to your HDD from IE and use it locally. It can do everything from DVD, SVCD and VCD to DivX disks.

You'll want to use a few hundred kbit/s less of a video bitrate than the calculator says to leave room on the DVD for menu's etc. The fancier the menus the more you should undershoot what the calculator says.

MPEG analysis

I've found it very handy at times to have an MPEG analyzer. This tells you what MPEG stream properties you're actually getting vs. what you set in the encoder. Yes...sometimes you get suprises.

I use Bitrate Viewer;

http://www.tecoltd.com/bitratev.htm

The freeware version will give you the basic stream properties and graph bitrate and Q (quantization level; basically the quality) vs time.

The commercial version will show you the GOP IBP settings of an encoded file along with if the individual GOP's are open or closed, among other useful things.

Dr. Mordrid

[droopy]

Thanks Dr Mordrid for the reply.

I know the sister of that calculator. Downloaded it from...

http://www.dvdrhelp.com/calc.htm

Probably exactly the same one.

From what I understand though it's basically just experimenting within the DVD specifications for bitrate and resolution to get the desired results. So the terms LP, EP, SLP and SEP are just empty terms for which no specific bitrate and resolution parameters are set as like with VCD and SVCD.

Pitty though, would have been a nice base to start from with experimenting.

Thanks again both Brian and Dr Mordrid for the information.

All the best, Leon

[Technoid]

hm, wonder what kind of sound encoding the stand alones use

[Flying dutchman]

And one can always use Pinnacle Instantcopy to shrink a DVD project so it'll fit exactly on one DVD.

P.I. doesn't re-render, it only re-quantizes and produces VBR. It eats bitrate where it isn't really needed and leaves the more complex or fast-moving scenes intact. Quality loss is mostly invisible which is a remarkable feat.

My experience is that using P.I. on a DVD project that has a too high bitrate will actually produce better image quality than re-rendering the whole thing at a lower bitrate. I'm VERY enthousiastic about this tool.