I'm with Spot on this one. I usually set a max of 8,200,000 to avoid playback problems.

Gary

That is unbelievably too high, I would never go above 6Mbps unless there is tons of intricate detail or fast motion in the video. Even then I would try it at a lower bitrate and most often it will look fine unless the video is really dark. If you view the bitrates on most hollywood DVD's they rarely go above 5Mbps. That is why encoding is sometimes called an "art form" You need to be able to use the appropriate bitrate and not just max it out all the way just becasue you can. Most likely something you encode at 9Mbps, there won't be a noticeable diffrence if you encode the same video at 6Mbps. The trick is to get good quality at the lowest bitrate possible. People who have been doing this for a long time like myself can pretty much look at a video and know exactly what bitrate it should be encoded at to give the best results, and a reasonable bitrate.

Thanks all...I'm an Audio guy..Protools etc...entering the vastly complicated video world. Your pro recommendations are most appreciated. My source video is not of the highest quality and I was just trying to get the most from it. I'm sure I'm appling Audio thinking to video which I'm discovering has little in common.
Thanks again.
Bryan

True that Hollywood DVDs have a lower bitrate, but you can't bring that into the discussion as a baseline. Hollywood uses hardware and frame sequencing for encoding, and it's not accessible to most users. Since we're in the software encode world, we can't consider much about how Hollywood does things. They are also starting out with MUCH higher grade source material than we are, so they can get away with lower bitrates.

Thats funny, my bitrate viewer usually shows about between 7 and 8
megs on Hollywood stuff.

JJK

True, I guess I'm just used to useing more professioanl tools, haven't done a lot of "consumer level" stuff in a while :)
But still 9Mbps is just too high.

People just need to remember that if they are starting with not so great quality video, rendering a MPEG 2 at 9Mbps isn't going to improve their video quality. They will get basically the same quality rendering at 6Mbps with no noticeable diffrence. Poeple seem to think that just becasue their video is on a shiny little disc instead of a VHS tape that it should magically just look better, when in actuality it won't.

Hollywood DVD's usually depend on the amount of extras they have for the disc, the average is normally around 5-6Mbps.

I knew my video wouldn't look any better ..I just didn't want it to get any worse. What are some good VHS tape improvement plugins since we've mentioned it? I seem to remember an email from the COW forum about them.
BPB

There was a "Ultimate VHS Tape Restoration recipie" thread a while back, I can't remember who posted it, but if you do a search for that you will find it. I haven't tried it myself but people seem to think it works.

I know my intial reaction to rendering ..once again coming for an audio point of view .is MPEG means compression and loss of quality..I hate MP3's..I think they sound awful...I guess I'm applying that prejudice to video
BB

Hollywood can use a lower bitrate because they only need to encode 24 fps, not 30 fps. In addition, the frames are progressive. The combination makes a BIG difference.

The DVD spec allows bitrates slightly over 10,000 bps (9,800 for the video portion). However, many players get higher error rates when reading DVD-R or DVD+R compared to what they get reading the shinier pressed commercial DVDs. As a result, they have to do error correction to replace "damaged" frames, and this can cause them to miss frames entirely, if they fall behind. The theory is (and I am not sure this is actually correct), that the higher bitrates create more errors per second (e.g., if you double the number of bits per second, and the error rate is the same, you will also double the number of errors that need to be corrected each second). This in turn means the player must do more correcting, and this causes the player to not be able to spend enough time turning bits into video.

I disagree that you have to keep the data rate as low as 6,000 bps for most players. I just distributed DVDs to twenty people that included a seven minute introduction done with 8,000 average VBR, with the maximum set to 9,200 and the minimum set to 192. Not one complaint. The video was extremely fast moving (which is why I used the high bitrate), and people would have noticed immediately if there was a problem. This is not to say that some older players don't have problems with high bitrate DVD-R or DVD+R, just that most don't.

Higher bitrates produce video that is more faithful to the original. The only reason NOT to use high bitrates (other than compatibility with a few older players, as discussed above) is because you need to put more minutes of video on one disc.

With good, clean DV source material, I personally find the quality starts to significantly degrade when I put more than about one hour and twenty minutes on a single DVD, using the Vegas/Mainconcept MPEG2 encoder. With the external Mainconcept encoder and 2-pass encoding, and a bunch of other settings, I can get another twenty minutes or so before the differences become significant. I have done DVDs of over two hours, but the quality is definitely compromised. Others may disagree but, for better or worse, I've been looking at MPEG2 -- sometimes with a magnifying glass -- ever since I was "involved" with a videoconferencing company back in 1992. Unfortunately, once you know what to look for, the problems "jump out" at you.

If you want to read about DVD bitrates allowed by the MPEG spec, click here:

mpeg.org

I'm not saying you shouldn't use higher bitrates if you need too, I'm just saying that just because you have a 10 minute video doesn't mean you should set the bitrate as high as you possibly can becasue you feel some desire to fill up the disc. With the compatability problems that are already out there with recordable DVD's, there is no need to add uneccesary high bitrates into the mix. There are a few occassions where a higher bitrate like 7Mbps or so is needed, but for most things a CBR of 5-6Mbps will work just fine. I don't even mess with VBR unless you have a 2-pass option becasue it is basically useless. Also with most laptop DVD drives if you go above 6-7Mbps you will most likely experience a lot of playback problems.

I don't even mess with VBR unless you have a 2-pass option becasue it is basically useless.

Jsnkc: I am still not sure about 2-pass either. Despite what I said in my last post, a lot of the quality in the Mainconcept external encoder may be the other settings I twiddled (which aren't available in the Vegas/MC encoder). If you have roughly the same amount of motion throughout your production, I don't think it will make much difference. However, if you have one scene of a talking head, and the next scene of horses charging down a hillside, a good VBR might make a difference.

I have yet to see a 1-pass encoder that can actually predict what the video will be like and adjust the bitrate accordingly. Most of the time it takes a second or two for the encoder to get up to the right bitrate and you will notice a second or two of pixelation before the bitrate gets to the right point. I have also seen a lot of problems with 2-pass encoding as well, that is why I rarely use them, I stick with CBR for pretty much everyting I can.

Thanks again for the informative replies. I selected 8Mbps constant as my happy medium.
BB

Make sure you use AC3 audio or you might run into problems.

But there's no reason why, in theory, a person designing a one-pass VBR encoder couldn't make it deliver excellent quality. The whole point of 2 passes is that the encoder uses the first pass to look over the entire project, and then says to itself, "Okay, I've only got xxxxx megabits available to me, and I've got to allocate those bits in the most effective manner, so I'll put some here and some there." As a result, your MPEG2 file is the best it can be for a given overall size (i.e. average bitrate).

By contrast, an MPEG2 encoder on a 1-pass VBR run doesn't have the luxury of looking over the entire file before allocating bits. Instead, it uses a different philosophy: "Okay, the guy has told me to hit a quality level of "z" for the whole project, so I'll allocate bits accordingly. I have NO IDEA how big or small the final file will be, since that all depends on whether he feeds me simple or complex scenes. But the results will be the best I can do for the file size I finally deliver."

By contrast, CBR means the encoder says, "I will encode each and every frame with xxxx bits, regardless of how simple or complex that frame is. If I hardly need any bits to do a simple frame, then I'll just throw in a bunch of zeroes to pad the encoded size for that frame."

I agree that the issue is moot for any DVD-5 project involving less than one hour of material, because then you can run the encoder flat-out without running out of room on the disk. Also, there are some times when a wildly-swinging bitrate can cause a DVD player to freak out momentarily.

I have two set-top DVD players at my desk. One is a very fancy progressive-scan Toshiba, and the other is a cheapo Apex. The Apex will play anything I throw at it, at any bitrate (after all, DVD players are supposed to be able to play anything up to the DVD spec limit of about 10Mb/sec). It does, however, hiccup if there is a wild swing in the bitrate.

The Toshiba, by contrast, hates any CBR or VBR average above 9.5Mb/sec, and will begin acting very erratically. It's now two years old. I suspect a newer player won't care.

Jsnkc, Is there a compatibility problem with 48k pcm?

Is there a compatibility problem with 48k pcm?

Jsnkc will have to answer what he meant, but I can answer that if you use a less compressed format, you have to use a lower video bitrate. The reason is that the DVD spec limits the TOTAL bitrate (video + audio). This is one reason why AC3 is so important. Even though the audio quality is not quite as good as PCM, it is pretty darn good, and it lets you use a higher rate for video or, lets you put more program material on a DVD without compromising video quality.

as to my specific session...is 8Mbps with 48k pcm going to exceed the total allowable bitrate? Is this a constant set figure or is it playback system (ie: the DVD player) dependent. I have done a few sample DVDs of this material at the above mentioned bandwith and did not experience problems...that being said is it the safer (or I should the professional way to proceed) to AC-3 encode the audio anyway?

BPB:

PCM audio has a bitrate of about 1.5Mb/s, so you could combine it with a video with a CBR of 8Mb/s and still stay under the 9.8 limit. But again, some DVD players hate a sustained high bitrate.

Where you really need AC-3 is when you are doing two hours on a single disk. Then, the total bitrate has to be no higher than 5Mb/s. With AC-3, your video can run at 4.8Mb/s (5 - 0.2), but if you used PCM you'd have to run your video at 3.5Mb/s (5 - 1.5). It's pretty much guaranteed that a 3.5 video bitrate with DV video and a typical consumer MPEG2 encoder would look pretty horrible.

Just look at it this way, there is only so much information that can be sent from a DVD disc through a DVD player and into your TV. If you use a high bitrate like 8Mbps, and PCM audio which is uncompressed at about 1.5Mb/s as stated before, they both add up to a even higher amount of data that needs to be sent through the pipe. If you use AC3 audio which is compressed there is a lot less information that needs to go through the pipe.

thanks riredale, so my 8Mbps constant plus my 1.5Mbps 48k pcm puts me at 9.5 really pushing the upper limit. What is AC3 Mbps ( if that's not a dumb question) My concert video is only 50min....so I'm ok there