CBR is better than VBR if you are at a high bitrate, say 2100+. If the bitrate is high, a lot of info goes into the frames throughout. All VBR does is to save SPACE and acheive a lower file size while having higher bitrates when needed ONLY. So if you split a move in two, set at a high CBR so that you fill the entire CD, CBR is faster and the best method.
The BIT RATE is how many bits is encoded per FRAME, so CBR always buts in the same amound, regarless if the frame needs it, while VRB only puts it there if it is need, thus, the encoder has too look ahead and decide. This takes more time and also saves space.
If you set the max bitrates of VBR the same as CBR, you will get the same results, just the VBR will have smaller file size, also, the VBR could actually lessen quality.
Didnt you guys learn anything from MP3 encoding? CBR gives better results then VBR. Why do you think the release groups all use CBR?
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PLEASE SEND IN AN EXPERT.IF THE MAX IN VBR IS SET AT 1500 HOW THE HELL DO U GET 2000?IT SOUNDS LIKE U GUYS R CONFUSING MAX WITH AVERAGE.1500 IS 1500 NO MATTER WHAT.SEFY OR BALDRIC PLEEEEEEEEZE HELP.THIS IS GETTING MESSY.VBR AS FAR AS I CAN ONLY ALLOWS U TO GET MORE MOVIE PER DISC BY CONSERVING SPACE IN LOW MOTION SCENES.WHILE CBR IS CONSTANT
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What we are trying to say really isn't that complicated:
VBR always allows more intelligent utilization of bits. If the max bitrate for VBR is the same as the CBR bitrate, you will fit more movie into the same space. Blindly stating that CBR is better simply because it always allocates the same amount of data to frames isn't a real intelligent way to go about it, because a VBR encoding mechanism determines that you don't necessarily need all those bits to maintain a constant quality level. In a sense, CBR is wasting bits comparatively. Otherwise, why would 1-pass VBR even exist?
Multi-pass VBR encoding will always be better, but depending on what you are doing the benefit may not justify the increased encoding time. It also grants you the luxury of VBR with a predicatable filesize. In particular, multi-pass VBR with the same average will allow conservation of bits in some places to be applied to areas where more bits are needed. This will always be substantially better than CBR at the same bitrate. -
I COULDN'T HAVE SAID IT BETTER,I ONLY USE CBR BECAUSE DISC SPACE IS NOT A PROBLEM AND I WANT 2 SAVE TIME ENCODING I ONLY BURN VCDS.THANKS KINNEERA WELL SAID.FINALLY SOME CLARITY ON A SIMPLE ISSUE.
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For a video clip in VBR compared to one in CBR, the VBR will look better than the CBR in the scenario where the average bitrate is equivalent to the CBR (and avg does not equal to max. for the VBR). I believe that this is self-evident.
However, for a VBR clip whose max. bitrate = CBR, the CBR clip will always look either better or the same as the VBR clip all other things being equal. The CBR clip will always be larger than the VBR clip though in size.
In the scenario for a VBR clip where average = max. bitrate, this is mathematically equivalent to a CBR clip of the same bitrate. Thus, all other things being equal, it will be the same quality as a CBR clip except for the encoding time...
Rule of Thumb for VBR MPEG encoding
VBR will always look better than the equivalent CBR clip at a given average bitrate. This is simply as kinneera stated as it is more efficient in its bitrate distribution. The only time when this isn't true is if you use an average bitrate equal to the max. bitrate.
Regards.Michael Tam
w: Morsels of Evidence
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