Bitrates getting reduced

[elwood55]

What causes VS10 to compress a file at a far lower bitrate than set. I recently took a clip
that had an 1800kbps bitrate, added a couple of overlays, set the output bitrate as 1800kbps
and the resulting clip had an 1100kbps bitrate. Are bitrates affected by certain filters or certain codecs? If so, is there a way around this?

[Ken Berry]

We need to know exactly what the file properties were (right click on the video file either in the VS timeline or library pane and copy all the properties here please.) We also need to have an idea of the other project and output properties you were using, and what you were actually doing with the file. 1800 kbps seems a very low bitrate to start with if you are talking about DVD compatible mpeg-2, for instance, and this would translate into low quality output. On the other hand, it might be quite a reasonable or high quality bitrate for one of the more heavily compressed (and thus more difficult to edit) formats...

It would also be interesting to know whether the original file was compressed using Constant Bit Rate (CBR) of 1800 kbps and you have chosen a Variable Bitrate (VBR) which uses 1800 kbps as the maximum, but shows 1100 kbps as the average of all the varied bitrates used...

[elwood55]

It was a previously edited clip I had compressed using the the MS MP4v2 codec, 29.97 fps and no audio. I'm not creating DVD-quality clips. I didn't use project settings, but rather did the settings in the 'share' step (creating a video file saved to the hard drive). I don't recall seeing a VBR/CBR option. Where is that?

[sjj1805]

MP4 is a highly compressed format and is similar to DivX and Xvid where you get about 1 hours worth of video with a file size of about 700 Megabytes.

DVD Video uses a less highly compressed format MPEG2, file sizes vary Dependant upon the quality level chosen (bit rate). A guide to bit rate settings can be found by clicking this link.

MPEG4 / DivX / Xvid can be considered as internet sharing formats - high quality, small file size - difficult to edit. These formats are widely used by Television Stations who make their programs available on the internet.

I cannot find the MS MP4v2 codec on my system so I guess you have installed a codec pack. Please view: Problems with codec packs