bitrate and quality question

[moon_lizard]

Hi people,
first of all forgive me if this has been answered in forums, tried to search but...

I have an AVI 1.4GB (DivX), my player reports average bitrate about 2000. I want to convert it to DVD with best possible quality.

It can fit 1 DVD with bitrate about 3000, logically that would be enoung, but I am not sure if I can compare bitrates like this.

I can split it to 2 DVDs with higher bitrate, but maybe it's just a waste of media?

So, the actual question: is recording DVD 3000 kbps enough to keep original quality of 2000 kbps AVI? Are there any other variables I should consider?

TIA

[guns1inger]

Generally, no, however it does depend somewhat on the original AVI specs.

As a general rule, mpeg2 requires between 3 - 4 times the bitrate/amount of space that the source avi used. 2000 is fairly high for an avi, which suggests that the avi's resolution might be higher than many others. That might allow you to get away a lower bitrate.

Can you post the avi specs ?

A bitrate of only 3000 implies a very long avi - 3 hours +. A three hour or longer movie on a single layer DVD is pushing the qualiy envelope anyway.

[celtic_druid]

That isn't much of an increase and DivX is MPEG-4 which is more efficient than MPEG-2. Also if you are encoding at full DVD res, then you are probably increasing the numbers of pixels by a bit so your bitrate increase might not even be an increase at all.

[ZippyP.]

A bitrate of 3,000 means you should use 1/2 DVD resolution (352x480 ntsc) which can still look very good.

[moon_lizard]

Generally, no, however it does depend somewhat on the original AVI specs.

As a general rule, mpeg2 requires between 3 - 4 times the bitrate/amount of space that the source avi used. 2000 is fairly high for an avi, which suggests that the avi's resolution might be higher than many others. That might allow you to get away a lower bitrate.

Can you post the avi specs ?

This is what my player reports:
Video: XVID 512x384 25.00fps 1351Kbps [Video 0]
Audio: MPEG Audio Layer 3 48000Hz stereo 161Kbps [Audio 1]
the AVI is just over 2 hrs in total time

In my understanding this is a PAL AVI and I am converting it to NTSC. I don't want to jump into PAL-NTSC conversion topic (I am a novice at this) but rather try to understand general concept of bitrate:

Let's say I have an AVI 720x480, 30fps and average bitrate is 2000 kbps. If I convert it to mpeg2 with 2000 kbps, would that mean that the result will be near original quality? Or I should reserve "3 - 4 times" more bandwidth for the DVD in this case?

Is bitrate (in AVI) a speed of final binary stream after decompression? Or is it something else?

Guys, maybe can you throw couple of links where birtate in convertion is explained for dummies like me?

[mats.hogberg]

If your video is 2.10 long, you get away with >4450 kbps video with 224 kbps audio. That should in most cases be enough even at full D1, even if it to some degree depends on movie content. At this bitrate it's best to do a multi pass VBR encode with 4450 as average, ~2000 as min, 8000 max.

Let's say I have an AVI 720x480, 30fps and average bitrate is 2000 kbps. If I convert it to mpeg2 with 2000 kbps, would that mean that the result will be near original quality?

No. 3-4 times still apply. Bitrate is the compressed bitrate. After decompression, the bitrate is always the same, given the same frame size, frame rate and color depth.

/Mats

[moon_lizard]

No. 3-4 times still apply. Bitrate is the compressed bitrate. After decompression, the bitrate is always the same, given the same frame size, frame rate and color depth.

/Mats

I think I got it. Thanks so much!