Using Project Size or Forcing a Size - BIG DIFFERENCE!

venomhed wrote on 7/3/2002, 11:23 PM
I just rendered a tv special, David Bowie Live, which is about 1.5 hours when you cut out the commericals. The original format was MPEG-1, 320X240 with a fairly high bitrate. The whole show was around 3 gigs which is fine by me cuz I wanted a reasonably high quality source with Mpeg1.

In Vegas I created my custom Divx 5.02 codec, I chose bitrate at 1000, and Use Project Size. I rendered, took about 6 hours.

The file was ultimately too big for a cd, getting it at about 833 mbs :(. But close!

I redid my Custom settings and rather than Use Project Size I forced it to 320X240. Now the show was recorded at 320X240 so no big deal right? Use project size I assumed meant use the same size as the source.

Wrong!

The show was rendered at around 2/3 the time! Why is this? I have no idea but I was getting a guestimate of over 23-25 fps! I mean when it was rendering it was almost the same speed as watching the show, slightly slower. When I had the Use Project Size the show was horribly slow and of course unwatchable (is that a word?) at a guess of 10fps.

Anyone know why Use Project Size is so much slower than 320X240 or another forced size? Now granted maybe I did something wrong here? But I retested this several times with the only variable chaning was Use Project size or choosing 320X240.

Thanks

Comments

Chienworks wrote on 7/3/2002, 11:36 PM
Are you changing the Project Size? If you don't set it manually, it will probably default to 720x480. This means that your original 320x240 source will be resized to 720x480, then resized again back down to 320x240. That's a lot of extra work! Set the project size to 320x240 to match your source material and it should go faster and better quality.
venomhed wrote on 7/3/2002, 11:40 PM
Yes I wasn't aware that it would do that. That seems un intuitive but clarifies the reason why it was taking sooo long.

Thank you!
Stiffler wrote on 7/4/2002, 2:02 AM
<<<In Vegas I created my custom Divx 5.02 codec, I chose bitrate at 1000, and Use Project Size. I rendered, took about 6 hours.

The file was ultimately too big for a cd, getting it at about 833 mbs :(. But close!>>>
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It would be nice if you knew it would be too big for a CDR, don't you think? But you rendered for 6 hours to find out it was too big (for your CD-R)?

I'm only asking because with VideoFactory it would have told you how big the file will be before you rendered it.

Nice feature, but hidden in VV.
venomhed wrote on 7/4/2002, 2:58 AM
What is Video Factory? And you metioned this was hidden in VV, where is yet? YES this would be a nice feature to know before hand! As nice as VV is there are so many little, common things missing.

Thanks!
Chienworks wrote on 7/4/2002, 6:32 AM
Video Factory is the smaller, stripped down, cheaper version of Vegas. It only allows 2 video tracks and 3 audio tracks, and a few other advanced features are missing. It's much more of a "take you by the hand" style and tells you all sorts of nifties like the amount of space you'll need on the CD for your render.

Vegas will only do this in very specific situations. Check this forum thread: http://www.sonicfoundry.com/forums/ShowMessage.asp?ForumID=4&MessageID=102268
jeffy82 wrote on 7/7/2002, 7:12 AM
Stiffler,
When you are referring to Video Factory, what codec would you be using, and is it a VBR or CBR. If its a CBR, of course, just multiply it out. Just like calculating DV size.

Divx is not CBR codec, its variable, so I don't even think is possible, for a program to calculate with perfect accuracy what the bitrate should be set for to guarantee it a particular size with only 1 pass encoding. That's what 2 pass encoding is for. If you set your final target sized, its first pass just analyzes the content, and best arranges the varying amount of data to best duplicate the original.

Venomhed,
If you are ever stuck in a predicatment like that again, do not use VV to reduce the size. It's much faster to use Virtual dub and then select under AUDIO - Direct Stream (this way, the audio isn't recompressed it's just passed through compressed) and for Video, select Recompress or Fast Recompress, and finally adjust your Divx Codec accordingly so that it will better fit. By thin method you will encode at nearly Realtime, if not faster.

Jeffy82@aol.com
venomhed wrote on 7/7/2002, 2:55 PM
Again thanks for all the help and info.

Jeffy the only reason why I am not using Vdub is that it does not support Windows Media WMV. WMV with all my tests has been totally superior in every way. Visual quality, size of file, audio never losing sync, performance as in you can jump anywhere in a long video and you have about a 2 second delay! Divx is about 10-15 seconds.

Vdub does have some superior option compared to VV and VV has many more than Vdub. If we could only combine the two! Anyways thanks again, but i need a WMV friendly video editor and VV so far has been great....but not perfect.
jeffy82 wrote on 7/7/2002, 5:53 PM
Venomhed,

Whatever format works for you, and you feel most comfortable with, IS the best choice for you. And stick with it. I figure, that's the only way you will get the best that that particular codec has to offer. Switching all the time and using the default settings of any codec usually WON'T give you the results you want.

I will agree that the delay encountered when you jump forward or backward in a video should not be more than 1-2 seconds. And in all of my divx videos that I've encoded, the wait is never more than 1 second. The long delays you experienced is from the lack of Keyframes in the compressed video. The person who encoded the video, in an effort to sweeze the file even smaller, increased the maximum interval between keyframes, and threfore the resulting video has fewer keyframes.

I've seen some movies that had keyframes every 30 seconds....causing up to a 30 second delay. The Current version 5.02 I believe default to Maximum keyframe interval of 3 seconds, and in addition to the 3 seconds frequency, it adds keyframes at all scene changes. I personally set it down to 1 second.

I mainly use VDub for the video filters/resizing/etc. in preparing a video for web streaming, and I have yet to find a program that can even match Vdubs flexibility & Speed with various filters.

Jeffy82@aol.com
venomhed wrote on 7/7/2002, 8:31 PM
Yes Vdub is super fast. There is an older version of Vdub that does support Windows WMV/ASF I should look into it again.

Now that you mentioned Divx, I have no problems with Divx 5.02 at all other than I am confused on there options (quantizers and all.)

But the HUGE problem i have had with Divx is that when i compress to Mp3 audio the audio is either totally out of sync or if i jump from a scene and back anf forth it all get out of sync.

Do you have any advice for me on this? Probably has something to do with Keyframes again. If you could let me know that would be great and if you have the info on how it applies within VV "and" Vdub it would be most appreciated.

Thanks!