Help - Rendered Video Explosion

Blackconure wrote on 7/31/2014, 7:06 PM

I have a very simple project that all it really does is adds some still images to the front and back of an existing video with a fade-in/fade-out effect. The source video is from Camtasia and has the following properties:

Size: 1024x768
Data rate: 145kbps
Total bitrate: 199kbps
Frame rate: 14 frames/sec

Audio bitrate: 53kbps
Channels: 2
Sample rate: 44kHz

On disk, this MP4 file takes up 27.1 MB.

If I try to match the original settings as closly as possible, the video comes out absolutely unwatchable. Only until I get to 768kbps (variable bitrate) do I get somewhat of a reasonable image quality but the file size explodes to 114MB. Even with a two pass render the file size is 97MB.

I expect it to be a little larger because of the fade-in/fade-out on the transitions from the still images, but to explode 4x its size, or to not be able to mach the source video setting with little quality loss? What gives???

Here are my settings for Media Studio:

Size: 1024x768
Data rate: 768kbps
Frame rate: 14 frames/sec

Audio bitrate: 48kbps
Channels: 2
Sample rate: 41kHz

P.S. It seems strange that you can set the project settings to match an existing video, but you can't seem to set the output to match a specific video.

Comments

Chienworks wrote on 7/31/2014, 7:37 PM

The output size is determined by the bitrate and duration. That's fixed, as in a law of nature, so that's what you have to deal with. So the file sizes you are seeing aren't "explosions", they're just the result of plain old math.

The real problem is that your initial video is an exceptionally low bitrate. It's already rather poor quality, whether you notice it or not. When you render it again to any compressed format it's going to look much more awful at any bitrate.

Honestly, 114MB is just not a big size for a video file.

musicvid10 wrote on 7/31/2014, 9:08 PM

Maybe try Handbrake?
Upload 30 sec of source somewhere.

* You need to check your Camtasia settings. Source bitrate is ridiculously low.
Should be more like the 768 Kb/s you got from Vegas.

Blackconure wrote on 8/5/2014, 7:11 PM

I realize the bit rate seems slow, but in reality, I think it is just better optimized than what Movie Studio is generically applying to the images.

My suspicion is that Camtasia better understands what is changing between frames and compresses only what is changed. The quality is absolutely perfect in the source video, but when Movie Studio gets ahold of it, now I get pixelated transitions as it bumps up against the maximum frame rate.

I did a small test. I created a video, one with camtasia and the other from Movie Studio. In Movie Studio I set the bitrate to maximum 768k, with an average of 384k, and a two-pass variable bit rate compression. The file size was 2.1mb.

The original camtasia was 1.4mb. Data rate 300k, total bitrate 300k.

Take a look at the quality of video between the two:

http://demo.carpedatuminc.com/files/camtasia.mp4
http://demo.carpedatuminc.com/files/moviestudio.mp4

Clearly Camtasia is MUCH better quality, lower framerate, and lower file size. I did nothing to the included MP4 in Movie Studio, other than add it and then render it.

Thoughts?

Blackconure wrote on 8/26/2014, 9:53 AM

(crickets).............

Can anyone shed some light on this?

musicvid10 wrote on 8/26/2014, 10:08 AM

last chirp . . .!
Tried a higher bitrate capture?
Tried Handbrake?

Oh, it works flawlessly.