ProCoder only, commercial, difficult, creates

andy

Hi!
I've a very quot;bigquot; dilemma.
I've a video that is very quick with very difficult scenes. ProCoder output a very good mpeg but in that scenes it creates noticeable blocks due to the strong speed and chaotic scenes.
To improve the quality I'm thinking to make encoding discarding the B frames (keeping only I and P frames). Could this improve the quality? Also... since the video go to a commercial DVD I need a 100% DVD compliant stream... but I don't know if only I-P frames are allowed on DVD or if all standalone dvd player are able to decoding a I-P stream. Any suggestions? Thanks very much!

but I don't know if only I-P frames are allowed on DVD or if all standalone dvd player are able to decoding a I-P stream.

Yes, all players should be able to play such a stream, it's DVD compliant.
But I don't think you will get better quality doing it this way, dumping all B-frames also means the 'easy' parts will take more bits leaving less bits for the high motion scenes.

Thanks for the quick reply. So is there a way to improve the quality? Could reducing the min bitrate improve the quality? ATM I don't have DVD space problem so I'm keeping the bitrate at 2-pass VBR in Mastering Q. at (min-avg-max) 6000-7000-8000 (I can't go over 8 Mbps due to audio bitrate limitations)

try drop the min rate to 4500 or 4000, but this probably wont help if the 2-pass ratecontrol is up to scratch.

if possible, re-encode the problem scenes at CBR, max bitrate and re-insert these into the already encoded stream.  i'm not sure if your authoring software supports this, but you may be able to do it with cuttermaran (i use dvdmaestro for this feature.  segment re-encodes are a very powerful tool for difficult scenes).

you could even apply some noise filtering to the action scenes only - this shouldn't be noticable on playback, but will increase compressibility, hopefully enough to get the tough scenes through without blocking out.

Thanks for the tips Mug Funky. The source is an AVS where there are already some filters (convolution3D and others). I'll try the segment re-encoding. Thanks again!

Segment re-encoding doesn't seem to produce better results. The problem is that the action scene is 8 seconds long so 8 Mbps seems to be not enough. I've tried MSmooth to lowering the detail but without success. The scene is from Soultaker Episode 13 (anime) where there's the main character stopped and in the background there are church's stained glass windows moving at high speed. The encoder put the max bitrate to the glass windows and less to the stopped character... but the main character is in foreground so the blocks are noticeable... whereas in the glass windows the blocks are imperceptible due to the high movements. Is there a way to make a quot;maskquot; to keep the detail on the main character and lowering (smooth) only the glass window to minimize the blocks on the character?
Thanks again for support!

Hi mp3dom,

is there a way to get a hold on these problematic 8 seconds of source material?
If so please provide me a temporal download link (I will enable my PM for a short period of time for that).

I am a specialist for problematic mpeg2 encoding and for ProCoder and CCE.

To improve the quality I'm thinking to make encoding discarding the B frames (keeping only I and P frames).

In the past I have already proved that this could improve quality for a lot of cases near upper dvd bitrate limits (say above 7 Mbps).

I would like to test my latest tricks with this kind of difficult material and try to help you out.
Maybe you could provide your best result so far, too.

I'll try to provide you a download link if possible. The source is an Huffyuv AVI, 260 MB about in size about (is a problem for you?)

No, this is no problem for me. I have dsl flat.
Please provide your best result so far, too.

Thanks in advance.

I'll send you a PM ASAP. Thanks for support!

PM sended to you mb1. Thanks!

@ mb1:  that's a pretty good idea.

unfortunately when i find bitrate problems it's on multiangle stuff, so changing the GOP structure isn't kosher

it'd be cool if some encoder supported coding b-frames, but only using p-blocks within them, so GOP structure is maintained but effectively changed to suit .  i guess encoders should really be doing this automagically if they found it improves quality.

btw, if you want difficult samples, try the gateway scenes in cowboy bebop.  maybe even standards-convert them first, to get it all nice and blendy and interlaced.