Rendering for web

Neil G. Randall · May 5th, 2009, 03:32 PM

Hi,

I've been having a problem with rendering out a showreel from Vegas. The raw material has been captured from a variety of sources.

I want to render for the web. Thing is, no matter what I do, I get one or both of two problems - either I get interlace tearing, or an incorrect aspect ratio.

I've used various output formats but the problems are always present. For example WMV doesn't allow a choice of interlace or progressive, whereas a Quicktime (.mov) doesn't understand the anamorphic footage, displaying as 4:3.

As I said, the raw footage is from a variety of sources, but the interlacing problems only seem to occur on the clips from the same source that was shot 16mm, telecined, and printed to MiniDV. Yes, I realise this could be equated to 'worst print' but that's education for you. What's important is that it's the only source that was originated on film, not video. But, to my knowledge, once it's been telecined and put back to tape, it should make sod-all different - it's effectively video. Still, it's the only thing that separates those specific clips from the others, and may hold the key to why there are still interlacing problems.

Does anyone have any suggestions as to why I'm having these problems, please? Even curing QT's anamorphic misreadings would be a workround for now.

Of course, any other details required, please post.

Thanks in advance.

NR.

Jeff Harper · May 5th, 2009, 04:11 PM

Try rendering to an uncompressed avi file first and see what happens. If you must you can always re-render to a web delivery format from that. Should be relatively little recompression and your quality should be acceptable. I have to do that for all my flash videos and it works out fine.

Seth Bloombaum · May 5th, 2009, 06:30 PM

Generally speaking, when aspect ratio problems are encountered when rendering or encoding for web, the usual solution is to output as a square pixel format, which will, in some cases, mean a resolution change.

Eg, 640x480 for standard def, 1280x720 for 720p HD, 1920x1080 for 1080i/p, all with 1:1 Pixel Aspect Ratio.

Although several of the common encoders that Vegas uses (QT, WME) do have PAR and anamorphic flagging, some of it isn't perfect, to say the least.

If you're mixing different resolutions on the timeline, and experiencing interlacing artifacts at output, you might want to pre-render your 16mm/miniDV footage to something closer to the rest of your footage. This will help with any field dominance issues.

Jason Robinson · May 5th, 2009, 08:07 PM

You can force the aspect ratio by choose a custom resolution with a square pixel (PAR). For example, with a square pixel, a NTSC 16:9 image at full size (720x480 with a non square pixel) would be 853 x 480 with a square pixel (I think).

Neil G. Randall · May 20th, 2009, 12:47 PM

Thanks for all the answers, chaps.

I'll get on with the battle and report back.

NR.

May 5th, 2009, 03:32 PM	#1
Neil G. Randall New Boot Join Date: Jan 2009 Location: Yeovil, Somerset Posts: 16	Rendering for web - persistent errors. Hi, I've been having a problem with rendering out a showreel from Vegas. The raw material has been captured from a variety of sources. I want to render for the web. Thing is, no matter what I do, I get one or both of two problems - either I get interlace tearing, or an incorrect aspect ratio. I've used various output formats but the problems are always present. For example WMV doesn't allow a choice of interlace or progressive, whereas a Quicktime (.mov) doesn't understand the anamorphic footage, displaying as 4:3. As I said, the raw footage is from a variety of sources, but the interlacing problems only seem to occur on the clips from the same source that was shot 16mm, telecined, and printed to MiniDV. Yes, I realise this could be equated to 'worst print' but that's education for you. What's important is that it's the only source that was originated on film, not video. But, to my knowledge, once it's been telecined and put back to tape, it should make sod-all different - it's effectively video. Still, it's the only thing that separates those specific clips from the others, and may hold the key to why there are still interlacing problems. Does anyone have any suggestions as to why I'm having these problems, please? Even curing QT's anamorphic misreadings would be a workround for now. Of course, any other details required, please post. Thanks in advance. NR.

May 5th, 2009, 06:30 PM	#3
Seth Bloombaum Inner Circle Join Date: Sep 2003 Location: Portland, Oregon Posts: 3,420	Generally speaking, when aspect ratio problems are encountered when rendering or encoding for web, the usual solution is to output as a square pixel format, which will, in some cases, mean a resolution change. Eg, 640x480 for standard def, 1280x720 for 720p HD, 1920x1080 for 1080i/p, all with 1:1 Pixel Aspect Ratio. Although several of the common encoders that Vegas uses (QT, WME) do have PAR and anamorphic flagging, some of it isn't perfect, to say the least. If you're mixing different resolutions on the timeline, and experiencing interlacing artifacts at output, you might want to pre-render your 16mm/miniDV footage to something closer to the rest of your footage. This will help with any field dominance issues. __________________ 30 years of pro media production. Vegas user since 1.0. Webcaster since 1997. Freelancer since 2000. College instructor since 2001.

May 5th, 2009, 04:11 PM	#2
Jeff Harper Inner Circle Join Date: Jun 2005 Location: Cincinnati, OH Posts: 8,425	Try rendering to an uncompressed avi file first and see what happens. If you must you can always re-render to a web delivery format from that. Should be relatively little recompression and your quality should be acceptable. I have to do that for all my flash videos and it works out fine.

May 5th, 2009, 08:07 PM	#4
Jason Robinson Trustee Join Date: Mar 2006 Location: Boise, Idaho Posts: 1,997	You can force the aspect ratio by choose a custom resolution with a square pixel (PAR). For example, with a square pixel, a NTSC 16:9 image at full size (720x480 with a non square pixel) would be 853 x 480 with a square pixel (I think).

May 20th, 2009, 12:47 PM	#5
Neil G. Randall New Boot Join Date: Jan 2009 Location: Yeovil, Somerset Posts: 16	Thanks for all the answers, chaps. I'll get on with the battle and report back. NR.