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Titling degrades and video noise increases as program proceeds

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vincent lynch
Titling degrades and video noise increases as program proceeds
on Oct 10, 2009 at 9:12:02 pm

I shot in 1080i and digitized in the same format. I exported the the finished FCP timeline to the ProRes422 format and formatted it in the 90 min DVD setting in Compressor.

I compressed four programs of with running times of 85.5 (3.7G), 75(3.7G), 65(3.1G), and 60(3.0G) minutes. The last three came out perfectly with razor sharp titles.
In the first 85.5 min program the titles started to degrade and become more pixelated and video noise increased in the background after about 39 min. Prior to that the titles and video were razor sharp. In Compressor in the encoder settings/quality window it states "allows up to 80 minutes/layer of video on DVD-5". I then tried the 120 min setting in Compressor and it developed the same artifact but to a lesser degree. The file size was reduced to 3.5G on the 120 setting.

I have check rechecked and rechecked again all the settings and they are the same. The source ProRes422 movie is perfect. In the other three titles the result looks great. At first I thought it was file size on the DVD, but the second 75 min title is the same size as the first compression attempt on the 85 min title and it looks perfect.
Ironically the second compression attempt on the 120 min setting, which was 3.5G looked better that the 90 min compression that was 3.7G.

Can anyone enlightened me on this subject or have a codec to try to avoid this artifact?


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John Fishback
Re: Titling degrades and video noise increases as program proceeds
on Oct 10, 2009 at 10:55:28 pm

I have no explanation for the artifacts, especially since everything's good with your other encodes. I don't know why quality would degrade over time. Perhaps there's a corrupt render or media file. However, in Compressor's Inspector > Frame Controls Tab, turn on Frame Controls and set the quality settings to Best and try your encode again. Hopefully that'll help.

John

MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.5 QT7.5.5 Kona 3 Dual Cinema 23 ATI Radeon HD 3870, 24" TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
FCS 2 (FCP 6.0.5, Comp 3.0.5, DVDSP 4.2.1, Color 1.0.3)

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Tom Brooks
Re: Titling degrades and video noise increases as program proceeds
on Oct 11, 2009 at 12:38:42 pm

I suggest you try a constant bitrate encode on the problem movie to see what happens.

Your post implies that you exported a movie and encoded in Compressor. Is your source ProRes422 movie self-contained or is it a reference movie?

Did you look at the resulting mp2 files and was the problem evident in those prior to building and formatting the DVD?


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vincent lynch
Re: Titling degrades and video noise increases as program proceeds
on Oct 12, 2009 at 3:00:17 am

Yes the compressed Mpeg-2 files have the negative artifact. I shot in 1080i and exported it to ProRes422. It's self-contained and an enormous file. Looks great.

It's an 86 min program. I first tried the 90 min DVD setting in Compressor and also the 120 min setting. The 120 had less video noise and the titles didn't degrade as much.

Since I also did 3 other programs with exactly the same settings and they are perfect, it's really weird. Titles are razor sharp. The only difference in the other programs was RT ranged from 60 to 75 min. With the 90 min Compressor setting they look great.

At this point tomorrow I'm going back to the timeline. I going to re-export it and repeat the process even though in the current version of the 422ProRes format looks flawless.


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Rafael Amador
Re: Titling degrades and video noise increases as program proceeds
on Oct 12, 2009 at 8:27:50 am

Hi Vincent,
The DVD Compressor Presets are designed to allow a PCM audio channel.
If you use AAC you can increase a lot de video data rate.
Rafael

http://www.nagavideo.com


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vincent lynch
Re: Titling degrades and video noise increases as program proceeds
on Oct 12, 2009 at 2:53:39 pm

Rafael,
I used the ac3(dolby) setting in the "encode" window in the Compressor audio settings window on all the titles.
I'm going back to the original timelime to export and repeat the process to see if I get a different result. This is in spite of the fact that the 422ProRes self contained movie version looks like it doesn't have any flaws.
Thanks for responding.
with fingers crossed,



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Tom Brooks
Re: Titling degrades and video noise increases as program proceeds
on Oct 12, 2009 at 3:27:00 pm

Vincent,
I suggested a test with CBR encoding instead of VBR. My hypothesis is that the VBR might be running out of variability early in the video and doesn't have enough left near the end to properly encode. It may not work that way, but I'm searching here. If you have a lot of cuts or fast-moving video in the first half of your program, this hypothesis might hold up. Anyway, it would be worthwhile to make a copy of one of the VBR presets and change it to CBR and set the data rate as high as you can to fit the material. Perhaps you could add a CBR encode to your next batch and compare results with the VBR version.
- Tom


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vincent lynch
Re: Titling degrades and video noise increases as program proceeds
on Oct 12, 2009 at 4:14:38 pm

it's a taichi video (vol.53 - http://www.onehand.com/pages/volumes_53-54.html) so the motion is not as fast as one of my martial titles. I used the 2pass VBR setting at 6.2 average and 7.7 max. I used a bit rate calculator and got the following values: average value was 6.5 and 7.8 max. I thought the setting was well within the limits, ergo OK.
I was also thinking along the same lines as you in regard to it running out of steam aat the end. Vol.54 is 75 min, however, and the DVD size is 3.7G. This looks great. The 90min Compressor DVD default setting for Vol.53 was 3.7G and another version I did at the 120 min setting that looked better and it was 3.5G. This totally popped my theory balloon.

I'll try the CBR 1 pass to see if there's a difference, and I'll respond with results
Thanks,


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