MSP8 HDV Mpeg contains artefacts after rendering with texts

sigir · Post by **sigir** » Wed Oct 25, 2006 9:01 am

I have always artefacts in the destination MPG video when using text overlays.
I'm using MSP8 trial but tried it also with MSP8 and SP1 full version but with the same result. I have installed MSP8 on an image from Windows XP Prof SP2.
The complete project is on my home page at this url ( its 35 Mbyte big, sorry for all modem users).
http://home.arcor.de/siegfried.rauch/pack.zip
I have only one clip in 1440x1080 resolution and two text overlays with a text fade in and a fade out. At the end of the second text overlays two pictures have artefacts after rendering and viewing (see file PictureBlockOrientHDV.jpg in the file pack.zip on my home page or here in the posting).
I played with the settings at "create video file" but without any success.
Changed project settings have no influence in the result.
I'm wondering why such a simple video project leads to such results.

When I render the complete video as MPEG with 720x576 pixels, the effect described above is not visible.

Does anybody have the same effect? I can't find a solution by myself.

Best regards
Sigi

------------------------------------
System: Athlon 2600+1 Gbyte Ram,
Software: Ulead MSP7 full version with SP3 german, MSP8 Trial, DVD MF 5 english
Camera: Sony HDR HC1, Grundig LC875 HE Hi8
Capture: Firewire for DV/HDV and Canopus ADVC 100 for analog video.

Devil · Post by **Devil** » Wed Oct 25, 2006 10:59 am

I don't have HDV myself, but is this simply because the compression ratio is so much higher than for SDV? There was a long discussion about this on the MURC video forum. See http://forums.murc.ws/showthread.php?t=58865 in which I wrote

Applying a little thought to the problem. SD and HD take, within much less than an order of magnitude, about the same bandwidth. But the data in HD should be up to 12 times greater. That means the HD signal is compressed, say, 8-10 times more than SD. Something has to give.

DV is already compressed about 8:1, if I remember correctly, but each frame is an Integral one. Provided that the field order is respected, this means that motion is respected very well. HDV does not have every frame as I, but also has P and B frames, to obtain the required extra compression; this is a given. The P and B frames have to be generated in the cam in real time, something that requires enormous CPU and RAM performance. As it is in real time, there is no possibility of multi-pass encoding; it is CBR. A compromise has to be made and this compromise is translated into artefacts to reduce the P and B frame sizes, such as poor motion control.

This does not require an Einstein to work out.

robtywlak · Post by **robtywlak** » Wed Oct 25, 2006 11:32 pm

What is the bitrate and GOP structure of the source file and your rendered file?

1080p HD is marginal for artifacts at the broadcast bitrate of 19MBits and should have been higher - say 25 MBits.

Editing any MPEG stream and re-encoding to MPEG will result in some additional artifacts depending on how good the encoder is and the source file's quality of encode. Keeping the bitrate high and quailty setting high minimizes the artifacts but will not get rid of them 100%.

Also try to keep the same GOP structure as the source so smart render can be done.

Regards,

Rob

luc · Post by **luc** » Sat Dec 09, 2006 12:34 pm

Please try to untick Smart Render option when you create the file

cgould · Post by **cgould** » Sun Dec 10, 2006 5:15 pm

Those giant macro?blocks in the sample photo don't look like artifacts, they look like corruption/errors in the stream (like when my Tivo HDD hiccups.)
They don't look like compression issues, unless the stream got corrupted during compression...

I added some titles to a captured HDV MPG of mine, w/ fade in/out of the overlay, and saw no errors or compression at all.
I can't download the sample .zip file any more (file not found) so can't compare your direct clip...

mmponline · Post by **mmponline** » Mon Dec 11, 2006 8:37 am

Same problem in PAL DVD formats.

Please try to untick Smart Render option when you create the file

Why then use smart rendering. Not a great solution. The purpose of smart rendering should be to improve speed of rendering. At the moment I'm doing it without using smart rendering as the results are poor, but this is obviously not the solution, otherwise smart rendering can be removed as an option.

neonbob · Post by **neonbob** » Mon Dec 11, 2006 9:23 pm

I just mentioned in another "artifact" thread that this must be related to PAL only because I do nothing but HD work in NTSC and I have never seen this before.