That is a big project to fit on a single disc--even if it were a dual layer (DVD-9). Unfortunately there is a lot of 'urban legend' type myths about recordable dvds, and your 8Mbps average story is one example. In fact, the opposite is probably closer to fact--high sustained bitrates on recordable media can tax set top players to the point were is causes stuttering playback, and long pauses, if not frank failure to play. Ralph LaBarge did a study a couple of years ago for DV magazine and suggested limiting the ceiling to 7Mbps. I use quality media and 8Mbps all the time, and personally haven't had a problem, but I also use a high quality software encoder to do my encodes. The short answer to your question is that lower bitrates than 8 Mbps will definitely work.

The bigger issue will be for you to figure out how you are going to fit your content on a single disc. Even if you use VBR with an average of 3.5 Mbps, you will be very close on being able to fit it on a disc. At that low of a level, quality can take a major hit--even with the best of encoders. The software encoders that come with Premiere, Vegas, DVD-A, and the like do reasonably well at high bitrates, but fall off significantly when one tries to push very low bitrates like this. With a dual layer disc you could fit your project and not suffer a quality hit, but they unfortunately don't exist for the the consumer with recordable media at this time. Your best bet would be to split it into two discs (about 80 minutes a piece) if that seems to be a practical split point (60 +20 videos on one, and the 80 video on the other). Another option would be to encode at half D1 with CBR of 2 to 2.5 Mbps, which would allow for your material to fit on one disc, and half D1 at these bitrates are better looking than full D1 that is set higher (ie 3.5 Mbps). The only drawback with this is that DVD-A doesn't support half D1 (although it's within the dvd spec), but you might have another authoring app that does.

Jim

If you use the bitrate calculator found here:

Bitrate Calculator

you will find that your 20+60+80 = 160 min project requires that you encode at 3582 Kbps. If your source is NTSC 29.97 video, this is going to look pretty bad. I stronly suggest you consider putting it on two discs. If you absolutely must put it on one physical entity, you could use a double-sided disc (which still requires splitting the project into two parts).

Your information on compatibility and bitrate is exactly backwards. See this post for more info:

Does bitrate and burn speed affect DVD compatibility?

I generally like to burn at the highest rate possible, because I don't think that most modern players have a problem with the higher bitrates, but as you can see from the posts referenced in the above link, not everyone agrees, and I have definitely never seen ANY information that suggests that compatibility is better if you burn at a higher bitrate; all the information states exactly the opposite.

I can burn 4 episodes of my favorite SciFi show (that I 'tivo'd)...took out the commercials, intro and ending - on to one DVVD. One eps is (roughly) 45 minutes. Two eps....90 minutes. 4 eps 3 hours.

I render everything with Vegas with the normal DVD template.

I separate the audio (the the video has no audio) and make it an AC3 file.

I put some music on the motion menu - and I never have a problem making all for episodes fit without having to optimize (well, maybe once or twice I had to optimize one of the files, but it never lost that much quality that it made a visual difference).

So how on earth is someone saying you can't fit 2 hours and 40 minutes on one DVD and not have it look decent?

I mean, unless I missed somethign in the math....one 20 minute video....one 60 minute video - and one 80 minute video - comes to a whopping 2 hours and 40 mintues. That can fit on a DVD rather nicely without any problem.

What looks 'decent' I guess is in the eyes of the beholder. I can put nearly 8 hours of mpeg1, dvd compatible video on a single sided disc (multiple kid cartoons and the like) for viewing in the family car's dvd player. With just one disc we can travel nearly a days worth without changing the disc. The screen is small, so visible artifacts are barely noticeable. However, that same disc on my 50" screen has a lot of blocky artifacts, and for a client would be totally unacceptable. Half D1 is a more efficient, and the encode will be superior, for anything that you would drop the bitrate below 3.5 to 4 Mbps. In scott's case, to fit 160 minutes with compressed audio, would require you to drop the average bitrate for VBR down to 3.5 (john and I got the same ~ calculation). As an example, Procoder's dvd setting for encodes blocks you from setting it below 4 Mbps--because the quality will drop off. You can override it, but there was a reason why it was set that way.

In the end, it really depends on what any particular viewer is willing to accept. If one wants to put a bunch of their favorite shows on a single disc and the viewing of the disc is on a screen that results in a 'decent' image, then who's to argue with anyone's personal preference? I personally find stuff encoded that low to be visibly inferior, and I guess I have a right to my opinion. The original poster can certainly cram it all on one disc without fear of the lower bitrate causing any issues with playback. He can decide for himself if he thinks the end result is 'decent'. I know I wouldn't give a client a disc encoded at that low of a rate, but we all might be willing to accept something less for personal use.

Jim

Personal like regarding what is decent aside for a moment - your post made it sound as if it it totally impossible to fit 2 hours and fourty minutes on a disc. Period.

Without having to optimize anything whatsoever...a 4.7 gig disc will hold 2 hours of video. Period.

The disc I just finished creating today....4 episodes, un-optimized, crystal clear video....4.3 gig. Period. That's 3 hours of video - as clear as you can possibly make it - all on one single sided, 4.7 gig DVD.

Mind you, I would agree that depending on the bit rate one wants to drop down to... you can fit 8 hours of video on a disc. It may look like crap - and you may not want to give it to a client - but it can be done.

Your post made it seem that the only way a person is going to walk away with fitting 2 hours and forty minutes on a disc is to split it to two different disc (or to set the bit rate so low as to make the video look like crap)...and this just isn't true.

Why are you so angry? Period.

I didn't say there was any particular limit to what you can fit on a disc. Period.

IMO, and again it's my opinion (and just about anyone who does this professionally), consider more than 2 hours on a single sided disc "pushing it". Period.

Your definition of 'crystal clear' and mine clearly are different. Period.

The only reason I mentioned 8 hours was to illustrate you could definitely fit a lot on a disc, and have it play back on a set top player. Period.

Obviously the more you fit on a disc, the lower the average bitrate has to be. Period.

There must be some threshold at which the lowering of the bitrate will result in a perceivable quality hit. Period.

That threshold is in the eyes of the beholder. I am glad you are happy with your results, but what you will accept and what I will, can be different. Period.

I personally think putting 160 minutes on a disc doesn't look good, especially on a high-resolution screen. That video would indeed look like crap on my 50" screen. It would look OK on my portable TV. It's my opinion, and no matter how many 'crystal clear' 3 hour dvd's you say you have made, it isn't going to change my own personal experience. Period.

In the end, the original poster can do whatever he likes. There is no restriction to trying the lower bitrates (which is what he was worried about in the first place). I say 'go at it' and see for yourself. If it looks good to him at that bitrate, then who am I to argue? If he doesn't like it, then splitting it into two discs is always an option. Period.

Jim

P.S. No particular reason to use so many 'periods', but I thought it made me sound as authoritative as you.

your post made it sound as if it it totally impossible to fit 2 hours and forty minutes on a disc.

Actually, I think it was my post you were referring to. JSWTS said it correctly. It all depends on what level of quality you wish to achieve. For me, if I can tell a difference between the original and the DVD, then I am not happy. Such perfection is impossible to achieve, of course, even at 8,000 Kbps, but you can get pretty close. Once you get below 7,000 Kbps, it becomes pretty easy to spot artifacts, especially on scenes with crossfades, smoke or lots of plain blue sky (actually one of the more difficult things to encode). At 6,000, you don't have to look for the artifacts, they will come looking for you. However, the video is still very watchable, even on a big screen. Once you get down to 5,000 -- and certainly by the time you reach 4,000 -- fast moving scenes get to be pretty dicey looking. I had to put exactly two hours of basketball on a single DVD, and I used the MainConcept standalone MPEG encoder, using every trick in the book (2-pass, higher motion search parameters, lower noise thresholds, etc.), many of which are not available in the Vegas version of the MainConcept encoder. The video was watchable, and none of the fourteen team members complained, but if any of them had seen the original DV footage, I am sure they would have all noticed the degradation -- it was not at all subtle.

So, it depends on the screen size, your quality expectations, the source material, and your skill in setting the encoding parameters.

JSWTS....I think you misunderstood my post. Period. Plain and simple.

There is no anger. That would be stupid. Silly in fact. Almost as silly as your post that a DVD can not be produced.

Whatever your opinion is of clarity is is your opinion. But that doesn't change the fact that your initial post was wrong. There are no two ways around that.

Spark all you like - can't change that fact.

And...it has just always amazed me how people, like you, seem to have nothing better to do than to sit up and try and flame other posters to threads. It's a game I don't really like to play - so have fun with your opinion- just leave fact to the people who know.

JohnMeyer...I apprecite your reply...but, no - I was referrign to JSWTS's post. It states:

That is a big project to fit on a single disc...

I guess I'm just a silly guy.

Maybe you could point to where my original post was wrong, with something other than your subjective opinion. I'm willing to admit that my thoughts on bitrate and quality can be a personal preference, but you seem to believe that your position is based on fact.

In terms of 'flaming', you're the one who 'attacked' my post with absolutisms. Everything seems to be black and white for you--you're right and everyone else is wrong. Mind you, you don't base this position on fact, but your own experience. Lots of people thought the world was flat and vigorously defended their position. They were still wrong.

A little bit of self reflection would do a world of good.

Jim