The Digital Video Information Network - View Single Post - How to Convert EX-1 to SD for DVD ?????

Bob Grant · December 3rd, 2008, 05:21 PM

William,
you firstly need to understand the nature of the problem.

Interlaced video is limited in vertical resolution to prevent problems of line twitter and aliasing. This is achieved in a SD camera by two means. An Optical Low Pass Filter between the lens and the imager(s) and line pair averaging. Sampling theory and Nyquist explains part of the problem but doesn't exactly cover issues of line twitter.

The EX1 records video, especially in progressive, with very high resolution, greater than what SD interlaced video can cope with for the reasons above. You'll get the same issues with high resolution still images in SD video unless you're careful. This isn't a fault in the EX1/3 unless you consider it being better than any other camera a fault.

So when downscaling you need to wrangle / simulate what happens in a SD camera's OLPF and line pair averaging. Not an easy task without doing more damage to the image than is absolutely necessary. I can get very good results using Vegas Pro 8 but you need to know the magic recipe. Out of the box you will indeed have the issues you're seeing.

1) Drop your MXF files into a matching HD project.
2) Apply Gaussian Blur in the vertical direction only 0.001 to 0.003 should be enough. Best to monitor what you're doing on a SD CRT but not vital.
3) The order in which the GB is applied is important. From memory out of the box Vegas will apply the FX after downconversion. This is not what you want, you want to reduce the resolution before downconversion. In the GB FX window you'll see a little yellow triangle at the start of the FX keyframe T/L. Click that and it'll change direction so the FX is applied before anything else i.e. before downconversion.

The above should get you out of the woods. I'm still not 100% happy with the outcome. It looks pretty darn good on my 16:9 CRT. It still doesn't look quite as good as content from 16:9 SD DigiBetacam cameras which it should. A better filtering system running in AE might be the answer to wrangling every last bit of resolution from the EX into interlaced SD video. There was some time ago a post indicating they'd found the magic formula but no details were forthcoming. So far though I'm very happy with the results from my EX and Vegas 8 although shortly I'll install CS4 and see what I can get out of Adobe's effort.

December 3rd, 2008, 05:21 PM	#6
Bob Grant Trustee Join Date: Nov 2005 Location: Sydney Australia Posts: 1,355	William, you firstly need to understand the nature of the problem. Interlaced video is limited in vertical resolution to prevent problems of line twitter and aliasing. This is achieved in a SD camera by two means. An Optical Low Pass Filter between the lens and the imager(s) and line pair averaging. Sampling theory and Nyquist explains part of the problem but doesn't exactly cover issues of line twitter. The EX1 records video, especially in progressive, with very high resolution, greater than what SD interlaced video can cope with for the reasons above. You'll get the same issues with high resolution still images in SD video unless you're careful. This isn't a fault in the EX1/3 unless you consider it being better than any other camera a fault. So when downscaling you need to wrangle / simulate what happens in a SD camera's OLPF and line pair averaging. Not an easy task without doing more damage to the image than is absolutely necessary. I can get very good results using Vegas Pro 8 but you need to know the magic recipe. Out of the box you will indeed have the issues you're seeing. 1) Drop your MXF files into a matching HD project. 2) Apply Gaussian Blur in the vertical direction only 0.001 to 0.003 should be enough. Best to monitor what you're doing on a SD CRT but not vital. 3) The order in which the GB is applied is important. From memory out of the box Vegas will apply the FX after downconversion. This is not what you want, you want to reduce the resolution before downconversion. In the GB FX window you'll see a little yellow triangle at the start of the FX keyframe T/L. Click that and it'll change direction so the FX is applied before anything else i.e. before downconversion. The above should get you out of the woods. I'm still not 100% happy with the outcome. It looks pretty darn good on my 16:9 CRT. It still doesn't look quite as good as content from 16:9 SD DigiBetacam cameras which it should. A better filtering system running in AE might be the answer to wrangling every last bit of resolution from the EX into interlaced SD video. There was some time ago a post indicating they'd found the magic formula but no details were forthcoming. So far though I'm very happy with the results from my EX and Vegas 8 although shortly I'll install CS4 and see what I can get out of Adobe's effort.