Which video bitrate is to low for good quality?

[trueman]

I am using dvd author TMPGenc source creator to create mpeg files from AVI's.

Ive added 3 avi files and noticed that it shows my average video bitrate at 2399kbits per second. The audio is set at 256k/bits and I selected PCM Mpeg layer 2 audio at the start.

I was just wondering what would be considered to low a video bitrate to get a decent quality dvd. Ive noticed that the more files I add the lower the bitrate drops.

Whats too low and whats about normal?

[gadgetguy]

I've not used that program, but the bitrate selected is based on the duration of the video and the size of the destination video. So if your destination is a single layer DVD and you're trying to put 4 hours worth of video on it, the bitrate will be around the 2300bps figure. Whether that bitrate is high enough or not depends on the resolution that your video is in. Click Here for a chart of optimal bitrate/resolution relationships.

Edit: The content of the video also affects the required bitrate. High motion requires more bitrate than low motion.

[mats.hogberg]

At full D1 resolution, no less than 4000 kbps IMO. 4-2000 kbps 1/2 D1, anything lower, VCD res. But as GadgetGuy says, the content also dictates what bitrate is needed. When doing DivX/XviD to DVD, a rule of thumb is to use 3-4x AVI bitrate to make the AVI full justice.

/Mats

[trueman]

Okay so I added two avi divx files to tmpgenc which were both 350mbs each.

AT 720x 576 res and an audio bitrate of 224 using vbr and mpeg-1 layer 2 audio it has set the video bitrate at 3018. But as this is a varibale rate would this be suitable?
It just sems that to only get 2 x 350mb avi files on one dvd isnt very much. I would have thought I would get at least 4.

[lordsmurf]

Full D1 minimum = 5000
Half D1 minimum = 2500
SIF minimum = 1500

These values include stereo audio in the 192-256 range.

When you go lower, you get blocks. You absolutely MUST have an excellent encoder too. TMPGEnc is NOT a good encoder for pushing bitrate limits. Procoder is, 2-pass VBR.

[mats.hogberg]

to only get 2 x 350mb avi files on one dvd isnt very much

The file size of the AVI has absolutely nothing to do with how many you can fit on a DVD (as Video DVD). Only how long in time they are matters. The rule of thumb (encode to mpeg @ 3-4 times AVI bitrate) implicitly assumes the AVI is of OK quality (and who in their right mind would even think of converting a low q AVI to DVD?) - generally meaning bitrates in the 1000 kbps range.

/Mats

[trueman]

I forgot to mention that my avi's were 961kb so at 3-4 times that Im looking at 2800-3800 bitrate.

But should I be using VBR at say 3300 or CBR at 3800?

[jimmalenko]

How do they look to you ?

Encode some samples, and see how they look. You're the one watching them, after all.

[guns1inger]

Personally, I would not use CBR at bitrates that low unless using a lower resolution. If you can squeeze any extra out for motion scenes, you should do it.

[trueman]

Okay so I should stick with VBR? And PCM audio or mepg2?

And should I set the bitrate to about 3300 so I am inbetween the maximum and the minimum of 4 x my avi bitrate?

[mats.hogberg]

PCM audio is huge so stick to mp2 audio @ around 224 kbps. It's the average bitrate that determines how big the file will be, so calculate a bitrate that lets you fit the time (the sum of all AVIs time) you want on the disc, then use this value as average bitrate. Set min to 1000 kbps, max at 8000 kbps. At least, that's how I'd do it if I was tight for space.

/Mats

[guns1inger]

Depening on the bitrate of the audio you have, you can even go as low as 192kbps, to put a little more back into the image. If you have MP3 audio at 128 - 150 kbps, I would use 192 kbps MP2 or AC3 audio.

[Nelson37]

There is no correct answer to your question.

Do it and see what it looks like.

There are too many variables and subjective evaluations. The number will vary dramatically with the quality and type of your source, as well as resolution. Most downloaded internet videos will look fairly crappy no matter what bitrate you pick.

Use VBR, do NOT use PCM, use Hi-Quality source, get some RW disks, and experiment.

Your question is equivalent to asking someone else what is the correct amount of ketchup to add to your fries. Season to taste.

[jagabo]

Get a Divx/DVD player and you can fit about a dozen 350MB Divx/Xvid AVI files on a single layer DVD. And you won't waste time or lose any quality by re-encoding them.

[mats.hogberg]

Get a Divx/DVD player

As the price has dropped to almost nothing for a relatively good AVI capable stand alone DVD player, I too think that's the best option. (If you insist on viewing AVI material on your TV). Hell, you probably would have earned enough for buying one had you been at work instead of posting! (Or maybe you do as I - both at the same time! )

/Mats

[jman98]

Nelson37 is dead on and I am amazed at how several of the forum's best members have provided "definitive" answers to this question when really, there is no correct answer. Is your source animation such as The Simpsons? You can get really good quality out of much lower bit rates for animation than live action. I've seen some amazing encode jobs done with CCE at surprisingly low bit rates. Just as a test, I encoded an old DVD I own of the original Star Trek series to SVCD using CCE (Cinema Craft Encoder). Actually I encoded one episode and burned it in SVCD format to a 90 minute CD-R. There isn't a lot of action in this particular episode and the bit rate average is a little below 2000, but it looks almost as good as the original DVD. TMPGenc is a fine encoder, but I think you can get better MPEG-2 quality out of CCE and get superior results at lower bit rates. I have some old laserdiscs I burned to DVD. One of them is a movie that's over 2 hours long. I recorded the laserdisc at a bit rate of about 9000 and then re-encoded it down using CCE to an average bit rate somewhere just below 4000 I think so it would fit on a single layer DVD+R disc and I think the quality is quite good.

Each person has his own idea of what "decent quality" means. I have a friend who routines makes VCDs of TV shows he likes because the process is very easy for him and the quality is "good enough" for him, yet I think most people would be disappointed with his results. I would say as a very general rule that you probably should stay above 4000 for MPEG-2 video of live action in D1 resolution that is not letterboxed with TMPGenc. Letterboxing, half height resolution, animation and so on can enable you to drop this value. Using CCE instead of TMPGenc can too.