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updated on Friday, October 13, 2006 at 9:45:58 AM
MPEG Encoding - the Effect of Different
Bitrates
Whilst trying to ascertain what bitrate to encode
sub-TV's MPEG movies at, I encoded many different
versions of the same AVI file to see what it would
look like.
The less the original AVI is compressed, the
better, as an MPEG encoded from an Indeo encoded AVI
looked awful, whereas a Cinepak file leads to much
better results.
The dimensions of all the encodings are 160x120
(actual size shown). The MPEGs are all
downloadable.
This was encoded at 100kbps video, 64kbps
audio, and weighed in at 1.24M.
Far too big a file for such a small
frame!
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Next up we have a clip at half the video
bitrate with the same audio rate (50/64
kbps).
This halved the file, now at
640k.
If the audio bitrate was halved, this saved
just over 40k - at 32kbps the file size was
597k.
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Taking drastic measures, I dropped the video
rate to 8kbps, the audio at 32kbps and all
B-frames are being skipped.
If the audio is set any lower it sounds
awful, and it seems that the eye has more fault
tolerance than the ear, something employed by
RealVideo.
The MPEG 'blocking' effect is now making
itself apparent but the clip is still
watchable. The size of this one is
134k.
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Then I just went crazy-ape-bonkers and
brought the video bitrate down to 4kbps (all
other settings same as in the previous
movie).
However, my copy of Windows Media Player
refused to play the end of the clip, and
clipped it. Xing MPEG player coped fine.
Sure looks like RealVideo to me :-)
This one is 91k - I think, for the
extra few k, it's worth encoding at 8kbps.
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