[whatwg] media elements: Relative seeking

Eric Carlson schrieb:
>   QuickTime has used this method this since it started supporting VBR 
> mp3 in 2000, and in practice it works quite well. I am sure that there 
> are degenerate cases where the initial estimate is way off, but 
> generally it is accurate enough that it isn't a problem. An initial 
> estimate is more likely to be wrong for a very long file, but each pixel 
> represents a larger amount of time in the time slider with a long 
> duration so changes less noticeable.

Well, I do believe this works fine for audio (which usually hasn't a 
wildly fluctuating bitrate if you e.g. average over a second or two), 
I'm mostly concerned about video. An example for an outrageously off 
estimate would be the trailer for "Generic space-pirate movie".

The first few seconds would be mostly a static green/red/yellow/whatever 
screen ("This pirate movie has been rated ARRRRRR!") - this part would 
be coded with like 100 kbit/s or less. The next few scenes (this is a 
trailer, after all) would mostly show exploding ships, genetically 
engineered mutant parrots attacking space-adventurers and a few cuts 
into random love scenes - so this part can be multi-megabit/s. After 
this the bitrate would dramatically decrease again as the last few 
seconds will just show "Summer 2010".

Does QuickTime also handle such content gracefully (e.g. display a 
position slider that doesn't jump around wildly)? Am I overestimating 
the problem?


Received on Sunday, 23 November 2008 23:45:19 UTC