A real newbie question

[waterfall0]

This might be answered somewhere, I did search, but no luck, if someone can answer me, Thanks in advance.

I bought a Divx DVD player, I need to convert some wmv files to avi, so I can burn them and watch them on tv, not my computer.

I am not very clear about the bit rate in video files. I know higher the bit rate higher the quality, and I have to consider speed and size. I know the source is very important. my question is that if I have a wmv or rmvb file with 300kbps bit rate and I put 1200 Kbps for the avi on converter, do I get better quality, same quality or worse?

for example: this wmv file for testing,

Video : 30 MB, 753 Kbps, 23.946 fps, 320*240 (4:3), WMV3 = Windows Media Video 9, Not checked.

I got this output:

Video : 40 MB, 1011 Kbps, 25.0 fps, 320*240 (4:3), DX50 = DivXNetworks Divx v5, Not checked

from my own eyes, I would say they are almost the same in quality, the avi might be a little bit worse than the wmv. it might be just in my head.

should I put same bit rate for avi as in wmv, or I should put it higher, so I will get better result when I watch it on tv? or no matter how high I put it, I will get the same or worse in video quality?

and for the frame rate, I cannot put the same, is there a difference? I tried to put 30, but the avi playtime is about 10% longer, anyone knows why?

Thanks!

[Soopafresh]

Can't polish a turd, as much as you might try. Most of that stuff will look decent on a regular TV, however.

[guns1inger]

Different codecs compression differently, and give different quality for different bitrates. For example, mpeg4 variants like Xvid produce comparable quality to mpeg2 at bitrates of between a third and half the size. WMV9 encodes at around the same quality at the same bitrates as Divx/Xvid.

That said, you have heavily compressed, low resolution source. Any encoding to another lossy format will cost you quality, regardless of the target bitrate used. Make it large enough, and the loss may not be noticeable, but the size may be much larger. Eventually the bitrate will reach a level where the only effect it has is on the file size. Only trial and error will tell you where that is.

I am assuming your TV and player are NTSC, so the best framerates are 23.976 and 29.970. That said, most NTSC Divx players will force playback to 29.970 regardless of source, although this may produce jerky playback from anything that is not one the two aforementioned rates.

If your TV will accept PAL input, set the player to auto (if it has such a mode), and 25 fps material will be output as PAL (25 fps) instead on converted to 29.970.

[waterfall0]

Thank you very much for replying!

the most difficult part is to balance among quality, size and speed. I guess I will go with 3 times of original bitrate with Divx, it looks like it's the best.

very useful info on frame rate, I did not know that. my tv and dvd player are NTSC, your answer explaines why I have some dvds would jerk when I play them. Thanks again.