FORUMS: list search recent posts

mpeg2 via compressor/episode contrast issue

COW Forums : Compression Techniques

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
philippe muller
mpeg2 via compressor/episode contrast issue
on Oct 17, 2008 at 11:10:23 am

Hi!
In order to play a paintings movie in a museum through a hard disk Canopus I've compressed a dvcpro-hd sequence in mpeg2 1080i50 via compressor/episode. The problem is there is too much contrast with black shadows when the dvcpro-hd is correct (calibrated with control monitor and wave display).

The settings are :
- output format : MPEG-PS (mpg)
- encodage mpeg2 quality based (peak :27000 Mbits/sec, average rate 19000)
encoding quality 100%
colour space same as source
8 bits
resize : 1920x1080
I've made before a version in standard mpeg2 for a dvd via only compressor and it was correct the HDV exports are correct too.

Could you help me ?


Return to posts index

Daniel Low
Re: mpeg2 via compressor/episode contrast issue
on Oct 17, 2008 at 2:08:08 pm

Could be that some trickery around BT.601 and BT.709 colour-space conversion between is going on somewhere in the chain.

What Canopus device is playing this back?

__________________________________________________________________
Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!


Return to posts index

philippe muller
Re: mpeg2 via compressor/episode contrast issue
on Oct 17, 2008 at 2:50:20 pm

Thank you Daniel I will explore this way. But I' haven't found anything about BT601 BT701 on the episode user guide. What does it mean ?
I don't know yet for the Canopus. I will receive it tomorrow. I've just notice the problem with quicktime player and another hard disk video player : the DVICO M-6500



Return to posts index


Ed Dooley
Re: mpeg2 via compressor/episode contrast issue
on Oct 17, 2008 at 2:54:30 pm

What's it being displayed on? Have you calibrated the monitor or projector?
Ed



Return to posts index

philippe muller
Re: mpeg2 via compressor/episode contrast issue
on Oct 17, 2008 at 3:15:49 pm

On a calibrated monitor (JVC DTV24L3D via Kona 3). The dvcpro-hd and hdv playbacks are ok on it and on QTplayer on the Mac as well as mpeg2 from compressor compressions but not from compreesor + episode



Return to posts index

Ed Dooley
Re: mpeg2 via compressor/episode contrast issue
on Oct 17, 2008 at 3:26:24 pm

I'm not sure what you mean "compressor+episode". All I can say is that Episode and Compressor both have pre-processing tools (gamma, restore black, etc.) to get the video looking the way you want. I use both products, and Bit-Vice and others, and they all look different (especially Bit-Vice's gamma).
Ed


[philippe muller] "On a calibrated monitor (JVC DTV24L3D via Kona 3). The dvcpro-hd and hdv playbacks are ok on it and on QTplayer on the Mac as well as mpeg2 from compressor compressions but not from compreesor + episode"





Return to posts index


Daniel Low
Re: mpeg2 via compressor/episode contrast issue
on Oct 17, 2008 at 3:39:34 pm

BT.601 and BT.709 are colour spaces used for standard def and High def video.

It's common for problems with contrast to happen when this conversion is done or not done correctly.



__________________________________________________________________
Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!


Return to posts index

philippe muller
Re: mpeg2 via compressor/episode contrast issue
on Oct 17, 2008 at 3:46:35 pm

I mean episode compression launched from compressor (in fact an export from FCP via compressor with episode settings).
OK Daniel but how can I tuning them? I haven't found any settings for chosing them on Episode. (for coulour space there is only 'same of source' or the coding depth 4.2.2 and 4.2.0) I set same of source (dvcpro-hd) and the result is bad.



Return to posts index

Daniel Low
Re: mpeg2 via compressor/episode contrast issue
on Oct 17, 2008 at 4:09:57 pm

Try using the colour space of 4:2:0, which is what this MPEG-2 will likely use.

You can also adjust your colour settings using the filters in compressor to compensate for the errors you are getting.

__________________________________________________________________
Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!


Return to posts index


Ed Dooley
Re: mpeg2 via compressor/episode contrast issue
on Oct 17, 2008 at 4:54:19 pm

4:2:2 is only used for High Profile MPEG-2 anyway. Here's a link to gamma, contrast, black and white restore, etc. that you might find helpful:
http://www.kenstone.net/fcp_homepage/preprocessing_hodgetts.html

Ed



Return to posts index

Daniel Low
Re: mpeg2 via compressor/episode contrast issue
on Oct 17, 2008 at 5:49:39 pm

In my experience, black and white restore are best avoided unless you have the time to step through every frame of your clip looking for excesses in the restore processes, or the setting are at the absolute minimums

__________________________________________________________________
Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!


Return to posts index

Ed Dooley
Re: mpeg2 via compressor/episode contrast issue
on Oct 17, 2008 at 5:57:48 pm

I don't use it much either, but it's there as a tool to use if you need it. I find that after doing the CC in FCP and exporting, then the main tool to use is the gamma setting. It almost always fixes the problem. In the example cited in this thread though, he's having problems with his blacks, not overall gamma. Black restore can help that.
Ed

[Daniel Low] "In my experience, black and white restore are best avoided unless you have the time to step through every frame of your clip looking for excesses in the restore processes, or the setting are at the absolute minimums"





Return to posts index


philippe muller
Re: mpeg2 via compressor/episode contrast issue
on Oct 18, 2008 at 11:54:39 pm

Thanks Daniel and Ed but in fact the current solution for this task i s simply to use episode stand alone without compressor. In this case the contrast black level and luminance are correct. Now I must understand why there is this kind of troublesooting with episode used thru compressor. I will give some news.



Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]