Home > Archive > Compression > October 2006 > Re: 2-hour length, 148.50 Mhz, 1920 x 1080 progressive scan image, 1-bit object data,
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Re: 2-hour length, 148.50 Mhz, 1920 x 1080 progressive scan image, 1-bit object data,
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| Radium 2006-10-30, 6:56 pm |
| Bob Myers wrote:
> Why are you hung up on sample rate per se?
Because I dislike aliasing.
> Question:
> if I could decrease the sample rate by eliminating "dead"
> time in the original video signal (for instance, by cutting out
> excess blanking time in which no image information was
> being transmitted), would you find that acceptable?
Yes. As long as no aliasing -- at *any* level -- occurs.
> Oh, OK - in that case, I can give you an infinitely-degraded
> image in no bits at all! :-)
LOL. There needs to be at least one bit. Otherwise the data doesn't
exist.
So it is true that 1-bit movie cannot exist. What about a WMV file that
is 148.50 Mhz sample-rate, 1920 x 1080 progressive scan image, whose
object data rate is a CBR of 1 bit per second? Could this exist? In 2
hours or this video, the file size would be 7,200 bits.
> And why do you think that "color depth" is something
> you can compress the daylights out of, but by Gawd, don't
> touch there OTHER things?
Because I hate pixelation and alaising with a passion. Pixelation and
aliasing make me make me sick. I don't mind the artifacts -- that I
think -- are associated with a WMV whose color-depth has been
compressed even to extremes while the sample-rate and pixel resolution
are left alone. It looks similar to what a WMA file with a 44.1 khz and
20 kbps sounds like -- I think.
What would be to the human eye what 44.1 Khz, 20kbps is to the eye?
The human ear needs at least 20 hz to hear the sound. The human eye
needs at least 60 hz for the light to appear solid. E.g. a hummingbird
wing flap is to high of a video-frequency for the human eye to see,
much like the sound of a dog-whistle is to high an audio-frequency for
the human ear to see.
WMA is my preferred type of perceptual encoding. Both WMAs and MP3s
will produce artifacts with a too-low bitrate. However, WMA's artifacts
are rather pleasant, while MP3's are digusting.
I have Adobe Audition 1.5. I generate a silent file. I save it as WMA
20 kbps, 44.1 KHz, mono. I convert file this to WAV and then back to
WMA several times. I make my last conversion to WMA and save it. I then
open this WMA file. Finally I increase the volume of the audio in the
WMA file and play. Intrigueing tones result. These tones are typical in
low bit-rate, high-sample rate WMA files. I believe something analogous
could be done to WMV video.
Not really. I've tried doing my Adobe Audition experiment with MP3. How
sickening MP3's audio artifacts are. Much like non-WMV video
compression of pixels are. Those pixelations are just nasty.
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