SVCD sanity check ...

[tobyed2]

I am capturing from VHS using a Matrox G400 marvel. This is a PAL system. I am using VirtualDub to capture and Tmpgenc (v2.01.30.116) to convert to SVCD.

I am looking for highest quality end result being shown on a TV using a DVD player.

I am able to capture 706x576 MJPEG (no frame drops), I have tried Huffyuv (as compresion using VirtualDub) but the highest resolution I can grab is 400x360 (source 24bit RGB). YUY2 capture is "unofficialy" supported by the card but I get approx 12 frame drops a sec (!).

SVCD the size is 480x576, (PAL) if I have captured at a higher res I am making more work for Tmpgenc, which will resize the image from 706, is there any gain in quality doing this or do I just capture in 480 ?

The quality of the Huffyuv caps are better than the MJPEGs (lossless helps I guess). BUT surely the end quality would be WORSE to resize the capped image of 400x360 to 480x576 ?

Bitrate, in the "What's SVCD" section of this site it lists a comparison table of the format. It list bitrate as being VARIABLE, but I have read a post (and the AVI SVCD example) both state to use Constant Bit Rate (CBR), what are the supported bitrates for SVCD ? Can Auto VBR be used or ONLY 2 pass VBR as in the example ?

And finally,
What on earth is Quantize ?
In my example clip everything looks great until an explosion, it is made up of square boxes. These as I understand it are Macroblocks ? Correct ? I incorrectly at first believed this to be a shortage of bitrate, using a bitrate viewer the graph displays a green line for Quantize which peaks at where the explosion is. The exact figure is 23.87. BUT if I encode the clip as non-interlaced the Quanitze figure drops to 17.71 and the blocks are hardly noticable. I have tried setting "soften block noise" intra 35 non intra 40, not much difference. THOUGHTS ?!?!?

The final result being TV dictates that the SVCD must be encoded interlaced (right ?), otherwise I would just encode it as non interlaced ...

[Baldrick]

Both CBR and VBR(auto or 2-pass or any VBR but with the 2-pass you can calculate the filesize) can be used in SVCD.

[stanwebber]

any resolution that fails to capture both fields(?x576) will be vastly inferior so stick with mjpeg. as to capturing above your target resolution & resizing there is an argument to be made either way. my personal view is it's a waste of time capturing above your target resolution(all bets are off if target is less than ?x576). svcd does not necessarily need to be encoded interlaced; however, if your source is true 50hz interlaced video then it MUST be encoded interlaced. i'm hopelessly uninformed as to how pal treats film sources....my impression is the film is speeded up to 25fps instead of a telecine pattern. i guessing this type of source could be encoded progressive

<font size=-1>[ This Message was edited by: stanwebber on 2001-11-25 14:49:47 ]</font>

[FM]

The quality (and frame rate) of YUY2 with G400 highly depends on the driver version. In some old drivers you could capture only 1 field of two. This will give you 12 frames (strange but true).

What you should do is upgrade drivers from Matrox web site and try YUY2 with Huffyuv. If you still drop frames, try with some other codec (just to make sure it works).

As to me, it works fine with latest drivers. But I have pretty good config: Athlon 1.2GHz, 512 Mb RAM, Promise RAID with 2xMaxtor drived in stripe 0 mode...

[FM]

Forgot to say about "soften block noise"... Try to switch it off, create a movie and play it on TV (not on a PC screen!). then switch it on, create movie and play again. You'll see the difference. It's hard to explain but very clear to see.

[Shabubu]

PAL film source is usually sped up to 25fps, sometimes DVD authoring studios can be pretty annoying and do odd stuff, but mostly that's the way.