Here's my understanding on Flash Video encoding:
When I specify 300 kilobits/second for the video data
rate and 50 kilobits/second for the audio data rate, I
should get and FLV file that NEVER goes beyond 350
kilobits/second.
So if I encode a 30 second video with those settings,
I should get and FLV file that weighs 1.28 MegaByte.
If I decide to double the frame size for exemple (from
320x240 to 640x480), I should still get the same file
size (1.28 MegaByte) but the image quality should
obviously be badly affected.
That's not the case.
Can someone please help me shed some light on this
data rate vs. file size dilemma?
Your anderstanding is correct.
BTW, the amount a data that a second of sequence will get is not stable.
This is the reason of the 2 passes VBR encoding technique.
Encoding use macroblocks to compress image.
One could double the size, not the macroblock.
ffmpeg permit such type of settings.
To conclude, there is not a rule that link datarate and filesize.
You'd have knowledge about your encoding tools and the way the flv were
encoded.
Does that make sense to you ?
-----------
Eric Priou
(aka erixtekila)
In progress tech blog : http://blog.v-i-a.net/
Oregano XML Socket forum : http://forum.v-i-a.net/
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