TMPGENC: Source aspect ratio 704 or 720 for DV?

[johnells]

Before we start I am using an NTSC Digital 8 video camera in NORMAL aspect.

I have dumped my footage to my PC (firewire) and I will be converting it from AVI (Sony DV codec) to MPEG 2 with TMPGENC to create an SVCD.

My question is why does the source aspect ratio load in TMPGENC as 4:3 525 line (NTSC 704x480)?

The source is DV which is 720x480! What gives? And what should I be using for playback on a 4:3 TV?

PS: Under Video Aspect Ratio I am selecting 4:3 525 line (NTSC) which seems right.

John

[Gazorgan]

TMPGEnc read the header and goes from there. It may be 720x480 with overscan, which means it's 704x480 viewable. Try it each way and see if there's a difference (1 minute test encode).

Your source is 1:1 VGA (all AVI's are). Use the SVCD template and you should get a useable result.

[johnells]

I don't have any overscan. I have captured a few stills from the DV file and they have image information right out to the L/R edge. All 720 pixels! The captures are coming out as 720x480 by default.

I am using the SVCD template but I don't understand why you said to use 1:1 (VGA) for the source. So you are saying to override TMPGENC? It is coming up with 4:3 525 line (NTSC 704x480) all on its own when I load the source AVI.

A new question arises now! Are the pixels in DV square? And if they are then will I have to crop or re-sample to obtain a true 4:3 aspect ratio?

John

[SatStorm]

If you don't crop anything and if you set "keep aspect ratio (2)", just use the simply 4:3 option and you are always right!

[johnells]

Well I found the answer at TMPGENC.NET. It has to do with tv overscan and the non-standard aspect ratio.

John

[berru]

So what is the correct setting? 704x480 or 720x480? I actually had the same question.
Thanks!

[johnells]

If TMPG chooses 4:3 525 line (NTSC 704 x 480) for your 720x480 source then this is the correct setting. Do not use 4:3 525 line (NTSC).

It is 4:3 525 line (NTSC) which causes a slight aspect ratio change when encoding to SVCD/DVD because an 8 pixel padding region is added to either side of the video. (You may want this if you detest CRT overscan).

You can see this effect in wmp as a test. Encode 2 small test mpegs, one using 4:3 525 line (NTSC 704 x 480) and the other 4:3 525 line (NTSC).

Play your source movie in wmp at full screen and mark with stickies the corners of the video. Now play your test encodes.

You will notice the first setting should more or less create an image exactly the same as your source, but the latter setting creates a slightly narrower image than the source. To be exact 8 pixels either side narrower.

So I am using NTSC 704x480 to maximize my image. Which also results in some image loss due to overscan.

What is also confusing about all of this is the 525 lines for NTSC versus the 480 active lines plus the overscan making the AR difficult to visualize.

[schematic2]

I've been toiling over this issue for some time. Finally I had a good look. This is a selective setting. It happens to be in view when you import any file. Ignore it, as it is an uncommon setting. It simply is visible in the wizard. Stick with the 720 or some DvD authoring software won't accept the non conforming format. 720x480 will come up and is used.. . .

[energy80s]

As SatStorm says, if your footage is fullframe 4:3 just use the 4:3 setting. Final picture width is not affected by this as this is the input setting. For output settings, use either 704 or 720 wide as these are standard DVD resolutions.