Blinking Macroblocks

[Aaron407]

Hi all,

For about the past two months I've been using svcd instead of vcd for converting in tmpgenc, but have come across a very annoying problem. I not only have the dreaded macroblock noise when converting below about 2000kbps, but they're also blinking between normal and dark color when the converted file's played back. They blink about once every one to one and a half seconds and it makes the final svcd look terrible. The source files doesn't have these blocks and I've tried using the 'reduce block noise' feature in tmpgenc to no avail. If anyone has any solutions it'd be very, very appreciated.

407

[bbb]

Do the blocks appear when the file is played on your computer?

What color are the blocks?

Do the blocks appear at random or in fast motion scenes or fast color changing scenes?

[flaninacupboard]

i think i know what he means. I sometimes think i can see the degradation of a still scene down the I-P-B path, as every once a second the picture looks good, not so good, shitty, then back to normal. not worry though, as although its blindingly obvious (and damnned annoying!) on the monitor, its not likely to show up on your TV for a few reasons, such as further viewing distance so a greater distance to image size ratio, poorer contrast, less definition and of course the interlaced display. if you sit close to your TV you can still see it, but farther away and it's invisible.

[Aaron407]

Thanks for your replys, but it doesn't really help me since I'm watching it on a 53 inch sony and every blemish shows up. To answer bbb, the blocks do show up on the computer screen (although not as bad as on the 53") and the color cycles from normal to dark with whatever the color of the portion the block is covering. They mostly appear when there's a low contrast still scene like normal macroblocks. When I encode with just vcd there's no blinking but it is very obvious on svcd. Does anybody know if there's any cure for the actual blinking though?

[bbb]

I'm not sure if your experiencing dot crawl or macroblocks.

You can try to darken the video before you encode. I feed a captured AVI file into VirtualDub, change levels to 8 (levels plugin), and frameserve to Tmpgenc. It helps some for me. Maybe for you too.

Do these blinking blocks disappear above a certain bitrate? Maybe 2pass VBR can help you maintain a good quality to file size ratio.

[Aaron407]

I'm pretty sure it's macroblocks, but I'm not very familiar with the term 'dot crawl'. It's the same as the macroblocks seen on a normal bitrate vcd, but instead they seem to pulse dark then normal. The source is not captured material, rather downloaded divx. The blinking seems to disappear as the normal block noise disappears, as I go above approximately 2000kbps. I just don't understand what's different about svcd compared to vcd that would make the blocks pulse and not in vcd. Also, could you explain what darkening the video would accomplish? I hope I can get this fixed, it's driving me nuts.

[Aaron407]

Well, I've been trying to recreate the problem but have been unsuccessful. Is it possible that, since the (s)vcd format uses the error recovery blocks when burning that there were errors in the actual burned disc causing bad blocks?

[flaninacupboard]

it's probably just SVCD. if you do the maths, there are less bits per pixel in SVCD than in VCD, so obviosuly while the resolution is higher, the quality, or accuracy if you like is lower. a lot of people just ignore this, as being higher resolution any macro blocks are smaller on the same size tv than in vcd format, so less noticeable. i find the (i really can't think of a better way to describe it) "fuzzy shite" you get in SVCD unbearable.

[Scobo]

Aaron407,
Do you encode with TMPGEnc ?
If so I think this may be part of your problem.
I too find SVCDs suffers from macroblocks with TMPGEnc but the same clip encoded with either CCE or Vegas Video has no blocks.
My standalone DVD player plays XSVCD at 720x576 up to 4000kbps.
A lot of my video with a DV camcorder is of fast running water and this shows bad macroblocking with TMPGEnc at these settings.
Encoding at the same settings is much better (and quicker !) with CCE and Vegas Video.
Unfortunatley, I don't own either of these programs but surely there must be a way to set up TMPGEnc to reduce the blocking.

[Aaron407]

Yes, I do encode with tmpgenc. The blocks only blink when there's block noise to begin with, usually when encoding under 2000 kbps. I would use cce, but for some reason it isn't able to run on Celeron 366's. Anyway, I prefer the svcd format and using tmpgenc, so if anyone can help me finally figure this out I'd be extremely appreciative.