Compression

ethrlblu wrote on 6/22/2004, 10:07 PM
Hi all,

Would someone kindly educate me about mpeg compression settings?

Whatever I am doing is obviously wrong because the files are WAY to large, especially for the duration of the clip. I don't want to use .wmv or .rm for compatability reasons.

In short, what's the trick to create a 5 min .mpg and it only be 68MB? Lord knows if I created a 5min clip it would weigh in at about 400+MB (laugh)

To anyone that can offer me advice, thanks so much in advance.

Comments

riredale wrote on 6/22/2004, 10:14 PM
You want compatibility with what? If you work through the numbers, you are asking for a file that runs about 1.8Mb/sec, which is way too low for full-resolution (480x720) MPEG2. Keep in mind that audio eats into that bitrate also; encoding your audio in AC-3 would need about 0.2Mb/sec, while full uncompressed PCM audio would take about 1.5Mb/sec, leaving nothing for the video.

Please give a few more details about your intentions.

By the way, even though you mention you want to steer clear of alternative compression formats such as wmv, this bitrate would be perfect for wmv, which is a much more sophisticated encoder than MPEG2.
guns1inger wrote on 6/22/2004, 11:02 PM
Sounds more like VCD quality at that rate.
ethrlblu wrote on 6/22/2004, 11:49 PM
Indeed, I used .wmv (default settings) and the file size is perfect, but am I not limiting my clients / users by using .wmv? What about the people who do not use windows? Apologies for my ignorance...

Ok, in a nutshell, I record some video imagery, I capture the video usingt mutimedia settings, I then drag my clips in, edit, then render as. I select mpeg1-vcd-ntsc, set vid quality low and let it rip... 352X240

besides everything, what am I missing? Its all good if I'm told, "dude go rtfm"

haha

And yes, guns1inger, after trying all the presets using mpeg-1 VCD seems to be much more efficient. I think the problem is my lack of understanding in regards to technical aspects, I-Frames B-Frames etc etc

Hope I am a little more clear in regards to what I'm trying to do and my knowledge base...

Thanks Guys...
John_Cline wrote on 6/23/2004, 12:23 AM
First of all, anything rendered to be viewed exclusively on a computer monitor should be rendered at the correct square-pixel-based aspect ratio. So, in the case of standard definition 4:3 video, this would be 320x240, not 352x240. 352x240 when viewed on a computer monitor will be incorrect and make everyone look short and fat.

Windows Media (.WMV) files at any given bitrate (particularly lower bitrates) will look much better than virtually anything else. However, MPEG1 files are probably more universally playable across various operating systems, but the last time I checked, about 95% of the world is running Windows. Your call.

John
farss wrote on 6/23/2004, 12:39 AM
I seems even OSX Macs can run WMP so it's not a bad way to go. Conversely Quicktime is available for Windows as well. Normal practice is to offer a choice of at least those two on most web sites.