Capture settings

[chrislo]

Hello, I am a relative novice to Video editing and am looking for some elementary guidance in Capture settings.
I am capturing Hi8 (PAL) via a Belkin USB 2.0 DVD creator and into Ulead Studio Video 7 and wish to edit and output to DVD.
I have a number of CAPTURE questions to ask:
1. Does it make a difference at which Frame size to capture at?
2. Should I use VBR or CBT, and what bitrate?
3. Which field should I choose?
4. Which mode should I capture in, AVI, MPEG2, DV?

I have tried a few different settings suggested by other posts in this Forum, and have had mixed results. I am now totally confused ( and so are my default settings)! I would like to start all over again.

It is worth mentioning that I did a test capture using a Ulead template for DVD PAL and the capture quality seemed excellent but have not edited or worked with yet, I now have so many coasters I didn't want to take the chance! The settings for this capture are as follows:
DVD PAL
720x576
Field order A
VBR

Thank you for looking
Chris

[Richard_G]

You've got it about right. PAL DVD framesize is 720 x 576 and encoding can be either VBR or CBR at anything up to 9500 kbs. Anything better than about 6500 kbs will give perfectly good results. There are advantages to both CBR and VBR. With CBR the encode bitrate stays the same no matter what the content on the video so you know exactly how big your finished files will be. VBR adjusts the bitrate depending on how much movement there is in the shot so you can use a higher bitrate when needed and a lower one when it isn't.

If you are just going to burn straight to DVD then you may as well capture as mpeg. If you intend editing the footage your best bet is to capture as avi and then encode after the editing is done. Editing mpeg is not a good idea, fades and transitions often look horrible.

As your original is Hi-8 it may be overkill to use full frame DVD. You could drop to what is known as half D1 (352 x 576) and use a bitrate of 3000 - 4000 kbs. Half D1 is a DVD compliant framesize so your player will still play it but you'll get around 3 hours per DVD disk.

The only other comment I'll make is that numerous people have had problems using USB for capturing but as you are using USB 2.0 and haven't had a problem, it must be OK.

[chrislo]

Hi Richard
Thanks for your prompt and detailed reply, but you will have to be patient with me at my lack of knowledge and understanding! I'm afraid I am still confused as to what I am actually capturing in!
As I said the results on the ULead template (DVD PAL) were excellent, is this AVI format? If it is why are there separate templates for AVI capture in the drop down list?
I have already atttempted a capture in mpeg the results were very jerky, my settings were as follows:
MPEG2
vbr (8000bits)
720x576
Field B
25fps

I also did an AVI capture, (720x576) but on 6mins of capture it took an age for any of the scenes to open in the editing stage!

If the DVD PAL template is my best option, are you suggesting that I reduce the frame size to 352x576 in this template? Also you say to use a bitrate between 3000 to 4000, do I set this a variable or constant?

Once again I really appreciate any help and guidance.

Chris

[Richard_G]

Chris

I'm going to have to make some assumptions here as I don't use Video Studio but I do use (all the time) Ulead Mediastudio Pro. I'm going to have to assume you have similar settings available.

Using the Ulead DVD template, you should also have a drop down for Plugins. This will be set for either MPEG plugin or Directshow plugin. Mpeg saves, as it suggests, as mpeg, Directshow saves as avi. The template sets up the framesize, etc. If you are saving as avi, you will also have an option to set up Video Compression. If none is selected you will be capturing uncompressed video and will end up with HUGE files (about 30Gb per hour).

For avi I use the MJPEG compression codec from PicVideo set at quality 18 or 19. If unregistered (not paid for!), you get an advert overlaid on your picture, but it isn't expensive. I think it cost me about £13 to register (the best 13 quids worth I've ever bought!). This keeps the file sizes much smaller and more managable so won't take forever to load. Others recommend the Huffyuv codec which is lossless and free but doesn't compress as much so the file sizes are still a little on the large size.

To find out what you have captured in, just look at the file extension on your saved files. It will be .mpg for mpeg or .avi for avi.

The reason your latest test was very jerky is because the field order is wrong and should be set to Field A. It doesn't matter if you use CBR or VBR. To understand the differences you need an understanding of how mpeg encoding works. To compress file sizes you can't send each frame (for PAL that is 25 frames per second and 2 fields per frame) in it's entirety. It breaks each frame down into blocks and then it sends an I frame, which is the complete picture, subsequent frames are a data stream that says something along the lines of "the same as the last one except for this bit, this bit and this bit". Default settings are one I frame in every 12 frames. Then when the next I frame comes along it goes back and adjusts the changes it has made so the final video is smooth.

Because of this, scenes with fast movement in them need a higher bitrate (more bits have changed in each frame) than a static scene (not a lot has changed). If you use CBR, the bitrate is constant so you can end up with a situation where normal footage looks fine but anything with very fast movement starts to pixelate and look grotty. Using VBR, the bitrate varies between a lower and upper level, so still schenes can get away with using a very low bitrate while the faster bits use a higher bitrate. The average works out to whatever it is and the filesize is the same as if you had used CBR but with the same fixed bitrate as the average.

The mpeg encoding method also explains why editing mpeg isn't such a good idea. As not every frame contains the full picture, you can't easily cut footage at anything other than an I frame because the other frames don't contain all the information. For this reason, some software won't allow you to cut at anything other than an I frame.

If you choose to use the Half D1 framesize, you can do it two ways. You can capture at full frame and then convert, or simply capture at 352 x 576. Some people claim to be able to see a difference using the first method but the second is far quicker as you don't have to resize later. I regularly capture from Digital TV (Freeview) at 352 x 576 as mpeg using a bitrate of 3500 kbs and then simply author to DVD format (this converts the single mpeg file into .ifo, .bup and .vob files that A DVD needs) and burn to DVD-R or RW. I use DVD-R if it is something that I want to keep or RW if I'm simply using it as a high quality video recorder.

Good luck

Richard

[chrislo]

Hi Richard

Thank you once again for your reply, it has been most helpful.
My extremely limited knowledge has increased dramatically thanks to your detailed remarks.

I will have a play around again tonight and try some of your suggestions.

What would we do without generous people like you?

Best wishes

Chris

[Richard_G]

What would we do without generous people like you?

Struggle like those of us that have been doing it for a few years had to!