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Re: Compression ratios of MJPEG, MPEG1, MPEG2, MPEG4, H.263, and
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| Michael Schöberl 2006-01-18, 3:55 am |
| > I was currently given the task to see how many minutes/hours I could
> record on varying sizes of CompactFlash disks (from 512MB to 12GB). The
> resolution is 640 by 480 at a frame rate of 30 fps and a 24bit color
> space. In order to figure out how much I could record for each
> different codec I need to get a good idea of a decent compression ratio
> for each codec. I hope someone can help :)
the compression ratio does not only depend on the codec but on the
quality level you select and the video itself ...
You could search for standard applications like DMB, DVB-[C|S|T|H] or
regular DVDs and average a bitrate commonly used in those standard
applications ...
If your typical video is different then you can't say anything without
your own compression tests on your typical source ...
bye,
Michael
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| Nicholas Sherlock 2006-01-18, 6:56 pm |
| Reuven wrote:
> Thank you Michael.
>
> I guess I'm showing my newbieness when it comes to digital video. I
> thought it it was as simple as each codec having a range of compression
> ratios, and of those compression ratios there was a range that provided
> decent video (in between really bad and really good). The task is
> proving harder then I initially thought. I will however search for t
> hose standard applications you mentioned.
Most codecs allow you to set your bitrate, which defines how much data
is required for each second of video. Take your sample video, then for
each codec, choose a bitrate that gives an acceptable quality. If there
are no other restrictions, just pick the one with the lowest bitrate
with acceptable quality.
Cheers,
Nicholas Sherlock
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| Grumble 2006-01-23, 3:55 am |
| cypherswipe wrote:
> Is this project restricted to the formats you listed? What about
> M-JPEG2000 (the JPEG2000 version of MJPEG), or DiVX/XViD?
DivX implements MPEG-4 Part 2 Advanced Simple Profile.
XviD (DivX, backwards) implements MPEG-4 Part 2 Advanced Simple Profile
and MPEG-4 Part 10 (aka H.264, aka Advanced Video Coding).
http://en.wikipedia.org/wiki/MPEG-4_Part_2
http://en.wikipedia.org/wiki/H.264/MPEG-4_AVC
Thus, DivX and XviD are not new formats.
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