Problem and Question Encoding to SVCD

[Maui_Lover]

Hello,

I'm new here so take it easy on me if you could.

I am using TMPGEnc to convert some ripped movies (yes my own movies) that were ripped with smart ripper and frame served with DVD2AVI. That part all seems to go well.

First my question.. When using the 2 pass VBR and setting the average bitrate per the bitrate calculator I am unsure of how I should be using the min bitrate. My currect project has an average BR of 1617 and i use the calcs max of 2528. My question has to do with minimum BR? Should it be left at 0 or 300 which I have seen both as defaults or should I raise it to say 1200 or something higher than a standard VCD?

Secondly, the problem, on a couple movies during darker scenes with people in them I have noticed the shifting in the background and blockiness I take to be artifacts from the compression. I could deal with that but blockiness is introducing a green tint to the artifacting that should not be there. I have used the soften blocks from everything from 35 to 100 without a noticible difference. The bright scenes in the movie have looked great!

The artifacting appears only on my APex 1500 dvd player and not in the previews or source selection or PC playback so I take it to be a playback peculiararity with the player (it has not happened on every rip).I plan to mainly watch the vcds on this player so I would love any idea on correcting or lessening the greenish artifacting.

My settings (and let me know if I am screwing anything up with these)

The standard SVCD template with 2 pass variable bitrate (average near 1600 on both dvds with problems), non interlace (should I be using interlace? the orig DVD say progressive when frame served for NTSC.)and High quality motion search

On advanced, Non-interlace, bottom field first, 16:9 NTSC (both have been widescreen), full screen (keep aspect ratio, I usually deinterlace with the even field filter.

GOP I leave as is

Quantize I switch to Mpeg standard and check all three special settings.

Audio I leave standard.

Any pointers would be appreciated. Since it only happens on the Apex player I have to burn cds on every new test and that is getting old.

I hope I have given wnough info. I have read enough to know that the experts are always asking for more info.

<font size=-1>[ This Message was edited by: Maui_Lover on 2001-12-09 21:52:23 ]</font>

[Maui_Lover]

Bump

If nobody can help me with the more complicated problem how about theories for setting the minimum bitrate on a variable 2pass conversion? Keep it at the default low values or up it to greater than VCD quality?

I assume the higher you make the minumum the less likely you'll get the higher bitrates in order for the program to maintain the average?

Any thoughts on what is optimal?

[mpack]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
On 2001-12-09 21:50:10, Maui_Lover wrote:
I could deal with that but blockiness is introducing a green tint to the artifacting that should not be there.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

I've seen that, and I believe I know exactly why it occurs, but I don't believe there is anything you can do about it with TMPGEnc.

I assume you know that an MPEG encodes a color image as YCbCr (sometimes called YUV - incorrectly). I believe that when TMPEnc does motion compensation it searches the luma plane only (ie. it only compares the Y's), this makes it possible for it to find a close Y match when in fact the colors are slightly different. It is *possible* that when you use the "highest" option for "motion search precision" this forces it to do a more accurate color comparison, but I don't know that.

If my speculation is correct then the error would be just as large on bright areas as on dark, it's just that the human eye is more sensitive to small color discrepencies in dark regions of a scene.

[adam]

The min bitrate should be set to the lowest bitrate level you think you will need at any one point in your movie. If you set it to 0 the encoder will basically pick the value for you, and from my experience this always seems to work fine. 300 is fine to use also, I think the bitrate needed almost never drops below this point yet its still low enough to get maximum results. You should never set your min bitrate at a high value, like vcd bitrates. This just limits the effectiveness of vbr encoding.

I'm a little confused by your methods. You say your source is progressive and then say that you deinterlace. Are these dvds? If so chances are the film is stored in its original progressive format. Preview the vobs in dvd2avi and let it run past the opening credits. If it shows that it is %95 or higher film and it doesnt keep resetting, than check force film. Now in TMPGenc load the svcd ntscfilm template. This should greatly increase quality and reduce the blockiness as well.

If it is not %95 film or higher disable force film. From there you can encode interlaced or you can deinterlace, or you can inverse telecine, its up to you.

[Maui_Lover]

Thanks for the reply guys.

I will run a test tonight and encode a short bit at the high rate and then the highest and see if there is a difference in the greenish areas. I'll also make sure my min bitrate is low.

Adam,

It doesn't surprise me your confused with my methods because i am too frankly. I have read most of the guides and still have questions in regards to the first two tabs in TMPGenc. Mainly knowing exactly what to set based on the info in dvd2avi. The deinterlace I stumbled upon when I noticed jagged edges during action scenes in Tomb Raider. I used deinterlace to fix that problem.

I am at work so I can't check right now. When I get home I'll recheck the DVD2AVI info from the movie (Arlington Road) and keep an eye on that film setting. Is there some guide that has more in on how DVD2AVI's settings relate to settings in TMPGenc?

Thanks again guys!

[Maui_Lover]

Hello,

Last night I tried using the force film option in DVD2AVI and using the film template and ran tests at both high and highest level in motion search and while the greenish artifacting was lessened somewhat at the highest level it was still there.

I am not sure this was a problem with straight VCD so I wonder if it has anything to do with color option that looks to become available when you switch to Svcd?

I noticed that AVI2DVD uses 4:2:2 YUV when frame serving and the default SVCD template uses 4:2:0 YUV. What would happen if I changed the profile to one that accepted 4:2:2? Would it work? would it make the files too big?

Alternatively, what would happen if I set the DVD2AVI option to RGB instead of YUV?

I'll run more tests tonight but any more thoughst or ideas would be appreciated. I am guess there are others with the Apex 1500 who may have noticed this problem

<font size=-1>[ This Message was edited by: Maui_Lover on 2001-12-11 10:53:59 ]</font>