[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 21:44:05 PDT 2010
On 05/05/2010 10:42 AM, Basil Mohamed Gohar wrote:
> 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
> intra-only anyway?
> 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.
I've done some more casual testing of intra-only Theora, and ptalarbvorm
really has some beautiful intra-only video, even at a measly 25Mbps! I
am pulling down some 1080p clips from media.xiph.org right now to test
some more with, and I will let you guys know the results later.
Maybe we can call it TheoraPro...;)
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