Some Mainconcept MPEG Encoder questions.

[scott274]

I have recently been trying to create VCDs (PAL) out of some DAT files on my harddisk. The encoder used was TMPGenc 4.0 Xpress in the encoding step, but the problem was that the VCD when played in my VCD player had jerky video playback problem (slight stop & play and some distortion now and then). The VCD video quality was fine though here.

Then I switched to Mainconcept MPEG Encoder v1.05.01.00
During the encoding process, everything went fine except in the logs box of mainconcept I got this single line in red (possibly an error) in the end.
Frame 21825: Underflow possible!!!, bits_to_use=84152, in_picture=94616
But inspite of this, the VCD now when played in my VCD player didn't have any jerky video playback. But there was a lot of pixsation in the video ie. the VCD video quality had become noticably soft and bad.

So far I had kept all the advanced options in mainconcept as default. Now can something be done in MC so that not much video quality is lost & it doesn't become more soft after encoding (like in TMPGenc). For eg. enabling motion search pixel movement, changing other detailed and further advanced video settings etc. (With respect to VCD PAL in my case)

[Midzuki]

Just a wild guess: the default quantization matrix for the MainConcept encoder
compresses more than the default matrix for TMPGenc and CCE --- perhaps
this is the cause of the "surplus" macroblocking of your re-compressed videos.

[scott274]

So can anything be done about this "surplus" macroblocking or even to make the video quality a little better. There are so many minute detailed settings in mainconcept to change if someone could just direct me please..

[Midzuki]

MainConcept uses the matrix below:

08 16 19 22 26 27 29 34        16 16 17 19 20 21 22 23
16 16 22 24 27 29 34 37        16 16 18 20 21 22 23 24
19 22 26 27 29 34 34 38        17 18 19 21 22 23 24 25
22 22 26 27 29 34 37 40        19 20 21 22 23 24 25 27
22 26 27 29 32 35 40 48        20 21 22 23 24 25 27 29
26 27 29 32 35 40 48 58        21 22 23 24 25 27 29 31
26 27 29 34 38 46 56 69        22 23 24 25 27 29 31 33
27 29 35 38 46 56 69 83        23 24 25 27 29 31 33 35

CCE and TMPGenc normally use this one:

08 16 19 22 26 27 29 34        16 17 18 19 20 21 22 23
16 16 22 24 27 29 34 37        17 18 19 20 21 22 23 24
19 22 26 27 29 34 34 38        18 19 20 21 22 23 24 25
22 22 26 27 29 34 37 40        19 20 21 22 23 24 26 27
22 26 27 29 32 35 40 48        20 21 22 23 25 26 27 28
26 27 29 32 35 40 48 58        21 22 23 24 26 27 28 30
26 27 29 34 38 46 56 69        22 23 24 26 27 28 30 31
27 29 35 38 46 56 69 83        23 24 25 27 28 30 31 33

You will have to manually enter the numbers of the second sub-matrix
in the appropriate window of MainConcept.

[scott274]

OK I will manually change numbers of the second sub-matrix in Mainconcept.

But will doing this only affect the video quality or frightfully other things as well. I mean like in TMPGEnc I experience the jerky video playback problem which is not so in Mainconcept. Changing the sub-matrix in Mainconcept won't introduce the same problem in it as in TMPGenc, will it? Your thoughts..

[Midzuki]

scott274 wrote:

But will doing this only affect the video quality or frightfully other things as well.
I mean like in TMPGEnc I experience the jerky video playback problem which is not
so in Mainconcept. Changing the sub-matrix in Mainconcept won't introduce
the same problem in it as in TMPGenc, will it?

Somewhat improbable, IMHO. I suppose your VCD player simply doesn't like
the way TMPGenc wraps the video stream in the MPG container but likes to swallow
the "MainConcept way", so to speak --- which would explain the jerky playback.
The MPEG specs give some degrees of "freedom" during the encoding process,
but they allow no "freedom" at all during the audio/video decoding process.
Unfortunately there is no such a thing as a "100%-compliant MPEG decoder", I'm afraid.

[scott274]

And apart from changing the sub-matrix in Mainconcept, could tweaking some advanced options in it help the video quality. Like enabling line filtering, motion search pixel movement (what values) and slightly changing other additional video settings without making the mpeg VCD (PAL) noncompliant.

[lordsmurf]

Have you narrowed down all other possible errors? What you describe as the original flaw points more towards cheap media than an encoder matrix.

[scott274]

The original movie DAT file I am working is a VCD rip 770 MB, 1:17:14, PAL.

This thread is actually an extension to my VCDs creating problems thread in the newbie section. As far as all other possible errors are concerned you can try to briefly go through the 3 pages to get an idea what I have done so far to resolve my problems.

https://forum.videohelp.com/topic351860.html

Moving on; as stated in the first post, when I use TMPGEnc encoder in the encoding step instead of MC, the VCD video quality when played in my VCD player is fine but only problem is that there is jerky video playback problem in it alongside. But when i use Mainconcept encoder, the jerky playback problem is gone for some reason but the VCD quality is not so good. It has a lot of pixsation.

Now if I originally have cheap media, then no matter what encoder i use, the final VCD quality should be equally bad for all but not so for TMPGEnc, unless TMPGEnc is such a good encoder video qualitywise that its standard VCD mpeg template actually raises the quality of the mpeg video from the original when encoded in it.

Basically the idea I am working on is that since for me Mainconcept is one encoder most probably somehow overcoming the jerky playback problem, I am trying to bring up its encoded mpeg video quality upto atleast TMPGEnc standard by tweaking some of it's detailed and advanced settings (along with changing that sub-matrix as advised before) for which i need advice as stated above please.

Unless somebody has any new idea to get rid of not only the jerky playback but also in Midzuki's terms "surplus" macroblocking.

[scott274]

Video quality problem (ie. surplus macroblocking) solved to much extent.

In the encoding step, encoded the source mpeg video to NTSC Film 23.976 FPS in Mainconcept MPEG Encoder. Further in detailed settings, checked "Enable Line Filtering" option. And in advanced options checked "Motion Pixel Search Movement" and set its value to horizontal 11 & vertical 11. Also set "Motion Search Mode" to 10 and manually changed the quantization sub-matrix by checking "User Quant Matrices"
For audio advance settings checked, "Set private bit", "Set copyright bit", "Set original bit and "Enable CRC". Used VCDgear for authoring the VCD image and Nero 6 to burn the image at 4x speed.

The VCD had fine quality with much less pixation and no jerky playback. TMPGenc still beats Mainconcept in video quality though has jerky playback in my VCD player for some reason.

What is it in TMPGenc that makes it videos better in quality than most VCD mpeg encoders and what more is not in it to cause the jerky playback which is not so in Mainconcept. I have so far kept "Motion search Precision" at "standard" and haven't tried "Highest with error correction". But what is it and will it make any difference to the jerky playback problem. Or is something else internal in TMPGenc to cause this problem. Something for the experts here to discuss further...