[theora] Why Our Civilization's Video Art and Culture is Threatened by the MPEG-LA
Basil Mohamed Gohar
abu_hurayrah at hidayahonline.org
Wed May 5 07:42:16 PDT 2010
On 05/05/2010 10:09 AM, Lino Mastrodomenico wrote:
> 2010/5/4 Basil Mohamed Gohar <abu_hurayrah at hidayahonline.org>:
>> At acceptable bitrates,
>> e.g., 25Mbps+, at HD resolutions, MJPEG with a good quality encoder does
>> not look significantly worse than other, more modern codecs
> I'm completely out of my depth here, but isn't 25 Mbps at 1920x1080
> and, say, 25 fps only 0.5 bits per pixel? For low complexity scenes
> that's enough for a pretty good-looking quality, but not even close to
> the near-losslessness that some people expect from a camcorder.
> And for high-complexity videos that's awfully too low (remember it's
> only 125 kBytes per frame). Try e.g. compressing this image (with lots
> of small details like the hair and the dress) down to a 125 kB JPEG:
> Again I'm not and expert in the field, but I would expect that for
> very good quality in worst-case scenarios a 1080p 4:2:0 MJPEG stream
> may need 100-150 Mbps or even more, and a good denoising filter before
> the compression.
I did some informal testing with some HD content I've made myself, and
25Mbps for MJPEG wouldn't really cut it. We'd need closer to 50Mbps to
get something acceptable, but yeah, I think I overestimated MJPEG's
suitability at these rates.
>> I thought about keyframe-only Theora, but then, if we're going
>> to do that, why not just fall back to MJPEG?
> One reason is that if you use Theora you can offer to the user the
> option to switch to a full intra+inter stream with dramatically lower
> bitrates. Plus doesn't MJPEG have a lower quality than intra-only
Well, now we're talking many different things! If we want intra-only,
such as DiracPro or MJPEG, then intra-only Theora is a possible player,
but having the ability to switch up to full intra+inter Theora will add
the full complexity of the spec, so why bother with the inefficiency of
The way I see it, if we're going to go for a freedom-friendly camcorder,
we can have the option of supporting more than one codec (at least on a
technical level). Whatever hardware can do intra-only Theora, I'm
reasonably confident can also do MJPEG as well.
Having said that, as I mentioned elsewhere, I'm going to play-around
with some intra-only Theora and see how it performs vis-a-vis MJPEG.
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