> I thought that DV was 1:1 with the raw data, and that it is MPEGx
> (among other codecs) that gives the [567]:1 compression.
>
> Or am I thinking of AVI?
Uncompressed video is 1:1.
DV25 5:1 (I'm not going to go to differences of DV25 and DV50)
Other video formats the compression ratio depends on the codec and
settings used during compression.
AVI and MOV are pretty much exactly the same, except the file headers.
Filesize is always determined by which codec and what settings within the
codec are used (+ complexity, resolution and length of the piece). DV
itself IS the codec and it is always the same compression. (Naturally
there are differences how loosely the word DV is used within proprietary
movie formats. Some vendors just choose to use it because it is more
"common" language, while they use their own codecs wrapped in the DV. (For
example matrox)
MPEG1 and MPEG2 are older codecs than DV, and the copression rate in both
can be set to almost whatever.
MPEG2 does better filesize/quality ratio than for example DV. Naturally
depending on the settings and whether the Variable Bit Rate (VBR) was used
or not. Another factor that also makes better size/quality ratio is to use
multi-pass compression instead of single-pass. These are not options in
DV.
As always with video compression, there is no good-for-all setting. One
has to consider the targeted playback machine capabilities as well. How
well the video is played back on target machine, often is different from
what the clip was created.
BTW. DIVX just released their version 5.2.
And (surprise) M$ is "open" with their windows media 9 compression system.
I'm anxiously waiting to see windows media 9 coder and streaming solution
for linux. It makes helluva good filesize/quality ratios.
P
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Received on 07/22/04
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