Converting divx/xvid to dvd

[Tomeryos]

Hello all, I'm new here so I hope that I am writing this post in the right section, if not please refer me.
I have been collecting these questions for like a month now, please don't look at this post length and back-off, it's realy important to me. thank you.

I have one major problem and some questions around it, if you may :
I have Tmpgenc plus 2.59.47.155. I use it to convert Divx/Xvid to NTSC LOW QUALITY (352*240). I care more about space than with quality so I use 800kbit video, 224kbit audio stereo, 10dc component, VBR 2-pass, MP2 audio.

I first strip the audio from the divx/xvid with virtualdubmod to PCM and then when loading to tmpgenc I use that audio file, and the video file of the original.

I have had some video-clips converted successfully, but now having this file I cannot convert - keep getting memory problems, invalid pointer operation.. you name it.

1. The original file audio is VBR. the rest i think are CBR. does it matter anything? If I'll choose instead of VBR 2-pass, CBR. will that work? (In other words : why am I getting this frustrating problem?)

2. As already mentioned, I would like to get the most playback time on dvd but not to wait 8 hours for 1 hour coding.. so where should I comprmise:
a. on DC component (or that doesn't change encoding time?)
b. change VBR to CBR
c. lower the audio
d. other I don't know about
If you could, just tell me what to choose and ignore this question. just tell me something like : use 750kbit video, 192kbit audio, 8dc component etc.
I view the videoclips on a dvd with no special speakers - only the TV's speakers (just to show you guys that I dont care about the quality that much)

3. If the source resolution is 200*200 for example and I make it 352*240, how does that realy works? enlarging each pixle by two or so? and how does that realte to the video kbit? If for example, source is 544*272, according to question 2 where I said that i don't care about quality - what is my best choise?

4. In tmpgenc, what will happen if I change the "source aspect ratio"?

I realy hope that's it (I'm so confused with this..)
Thank you all for reading this post, if you got something to add, please do!

[junkmalle]

1. The original file audio is VBR. the rest i think are CBR. does it matter anything? If I'll choose instead of VBR 2-pass, CBR. will that work? (In other words : why am I getting this frustrating problem?)

Just use Constant Quality mode. It's faster than 2-pass and minimizes file size. You pick the image quality you want and the program uses the minimum bitrate to get that quality.

2. As already mentioned, I would like to get the most playback time on dvd but not to wait 8 hours for 1 hour coding.. so where should I comprmise:
a. on DC component (or that doesn't change encoding time?)
b. change VBR to CBR
c. lower the audio
d. other I don't know about

The single biggest effect on encoding time is motion search precision. For speed use the faster settings. Second biggest is 1-pass vs 2-pass (2-pass takes twice as long). Avoid the temporal and spacial filters.

3. If the source resolution is 200*200 for example and I make it 352*240, how does that realy works? enlarging each pixle by two or so? and how does that realte to the video kbit? If for example, source is 544*272, according to question 2 where I said that i don't care about quality - what is my best choise?

TMPGEnc uses a bilinear resizing filter. Not the best, not the worst. Generally the bigger the frame size of the file you're creating the more bitrate you need to get the same quality.

4. In tmpgenc, what will happen if I change the "source aspect ratio"?

The shape of the encoded image will change. With AVI files you will usually want to use 1:1 VGA for the source aspect ratio (DV AVI files excepted).

[Tomeryos]

First of all I would like to thank you for replaying.

I do not want to use CBR because I would like to give it more time for better quality. If you could tell me something like : change motion search percision to this instead of that - then you will get the same as CBR vs VBR then I can see what to choose.

No matter what resolution I use, I get the same on screen. Should I use the lowest possible then? - because as you said : "the bigger the frame size of the file youre creating the more bitrate you need to get the same quality"
I understand that some considerations as to fast-movie and slow-movie frames relate to the quality. I could read alot of tutrials as to the I P and B frames (which I have read, but there's alot more to learn) but since I don't want to become an expert in this - just to burn some movies, if I will receive instructions such as :

fast movie : motion search X, Y bitrate for audio, Z bitrate for video

I will be happy

Do notice that most of the videos that I'm coding from aren't dvd but much lower quality.


One theortical question though:
If I use 1000kbps video for a source video of 1000kbps. will I get the same quality or lower? It's divx/xvid to mpeg2

Thanks again, though if you could be more specific I will appreciate it very much

[mats.hogberg]

One theortical question though:
If I use 1000kbps video for a source video of 1000kbps. will I get the same quality or lower? It's divx/xvid to mpeg2

No. You can't compare bitrates. In theory, using infinite bitrate when encoding, you'll achieve the same quality as your source. Lower the bitrate, and you'll get lower quality.
In reality, DVD mpg @ 4x DivX/XviD bitrate usually will produce "good enough" results.

/Mats

[Tomeryos]

One story I find intersting :
A video I recorded looks much much better on one dvd,34 inch tv and looks bad on dvd with 14inch

the first dvd in this story cost alot more (although it is quite old so..)

Ins't there a guide to tell people according to the movie, their expectations, the file size etc - what to choose in the options? I could use that one

[junkmalle]

No matter what resolution I use, I get the same on screen. Should I use the lowest possible then?

If you have a high resolution source then you will get a clearer result with a high resolution encode. If your source is low resolution there's not much point in enlarging it. If you don't care at all about picture clarity then just convert everything to 352x288 (I think you're system is PAL right?). A good compromise would be 352x576. For best picture clarity (assuming a high quality source) use 720x576.

I understand that some considerations as to fast-movie and slow-movie frames relate to the quality.

There is no way to predict what bitrate is required for any particular video. But if you use Constant Quality mode you don't need to worry about bitrates. TMPGEnc will use whatever bitrate is needed for the quality you specify. If the movie has all still scenes and little detail it will come out with very low bitrate. If it has lots of high action scenes with lots of detail it will come out with a high bitrate. I recommend you encode some short clips at different quality settings to see what's acceptable to you. You'll probably want something between 60 and 90.

The down side to Constant Quality encoding is that you don't know exactly how big the file will turn out. So constant quality mode is not the best choice if you want to make a file that's exactly 800 MB for an SVCD.

I could read alot of tutrials as to the I P and B frames (which I have read, but there's alot more to learn)

Stick with the standard IBP structure that TMPGEnc uses. You won't get huge changes in size or quality fiddling with that. You may end up making a DVD that some players have trouble paying.

but since I don't want to become an expert in this - just to burn some movies, if I will receive instructions such as :

fast movie : motion search X, Y bitrate for audio, Z bitrate for video

I will be happy

Unfortunately it's not possible to give you one set of parameters that is best for all situations.

In my experience using high motion search estimate settings doesn't gain you much. The "low quality (fast)" or "Normal" settings are about all you ever really need. Although results will vary depending on the video I ran a quick test. I encoded a short video at different motion search precisions (constant quality encoding) and got the folowing:

lowest quality (very fast): 109 seconds, 27.17 MB
low quality (fast): 112 seconds, 24.25 MB
normal: 125 seconds, 23.74 MB
highest quality (slowest): 318 seconds, 23.71 MB

As you can see there's not much increase in encoding time going from lowest to low, but a fair decrease in file size. Going up to highest increased the encoding time nearly 3 fold but the file hardly got any smaller.

As far as audio is concerned, all PAL players can play MPEG audio so you can use TMPGEnc's audio encoder (MPEG audio isn't included in the NTSC spec but just about all players can handle it). I can't really hear any difference at anything over 192 kbps (for stereo) but I usually encode at 224 kbps to be safe.

One theortical question though:
If I use 1000kbps video for a source video of 1000kbps. will I get the same quality or lower? It's divx/xvid to mpeg2

No. Different codecs require different bitrates to get the same quality. In general, MPEG2 for DVD will need about twice the bitrate that MPEG4 (Divx, Xvid) uses. Again, if you use single pass, constant quality encoding you don't have to worry about what bitrate to use for each video.