Theoretically, yes, but in a live recording situation you can't always predict the maximum transient level you'll need to handle. In addition, digital level meters on portable recorders aren't precise enough to capture the fastest peaks, they're only intended as a rough guide. The safe bet is to record in 24-bits with average levels around -18db. That provides at least 16 bits of resolution for even the quietest passages.
AVC Codec Curveball
- Thread starter Joe Lawry
- Start date
Homunculus
Carbonite Member
but then the point and question becomes, how do you differentiate between a 1000 and 5000 price point if both of your cameras, one consumer dslr, one prosumer cinecam have identical sensors and just about the same codec etc?
Meaning if you have a gh2 acvhd for 1000 then a af100 that has the same gh2 sensor with also acvhd, how do you reconcile it being 4000$ more expensive? what else is there inside that should in theory be making the af100 look much better than gh2 if it's NOT the sensor?
is it the optical filters or what
hjulenissen
Member
I thought it was the 18megapixel-optimized OLPF, low bandwidth sensor readout resulting in line-dropping (aliasing and reduced sensitivity) as well as low framerates.
If you could have the basic 5Dmk2 sensor properties only properly prefilterd/downsampled to 1080p24/1080p60, stored as high-bitrate h264, would this not make it quite good for what people try to use it for? I see that ergonimics, manual controls, viewfinder, audio i/o etc may still be lacking, but those are only indirectly affecting video-quality.
-h
Otis Grapsas
Carbonite Member
I believe a simple change to the OLPF would make it perform pretty well.
Fixing a dSLR for alias is not really an engineering challenge. The OLPF requires a new design, but I know two factories that can build the part and handle the conversion. The rest of the limitations would still break the deal for many people though and if you actually ask people if they want a permanent change that is not compatible with still mode, many will say no.
Otis Grapsas
Carbonite Member
The feature set alone would be worth the difference. I'm not sure AF100 looks better than a GH2, and I don't see how why it should look different on the sensor level. It has less aliasing, a better codec and better processing which explains any quality differences.
hjulenissen
Member
Video-optimized OLPF would fix the aliasing issues. But the camera will still throw away 3/4 of received photons or something due to line-skipping. It will also not do 60 frames/fields per second unless one use the 720p mode with even more line-skipping/aliasing issues.
But if a good 1080/720 OLPF was available, and 1080p50/60 at "180 degrees shutter" was possible (additional cooling? Firmware hacks?)
What do you think would be missing in terms of pro video IQ? (Nevermind the fact that most buyers are non-pro and dont want to ruin the still-mode). Is there something inherently bad about its demosaic, nr, color processing, 8bpp gamma, lossy encoding etc that seriously limits its use?
Like the audio-discussion has shown, I think it makes sense to discuss quantization, lossy encoding & friends in terms of a)What would have been needed in an ideal world (given perfect in-camera exposure, color-matrix etc), and b)how large additional margins makes sense for typical post adjustements.
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Otis Grapsas
Carbonite Member
A third party modification would only change the OLPF. The rest of the implementation is a given. If they could do better readout, they would be doing it.
Quality standards vary from person to person depending on the use. I wouldn't use a dSLR because I find the codecs inferior to those of a good camcorder. If they could fix aliasing and the codec quality issues, it would be very close to a camcorder in image quality, like the AF100.
If you can nail the look in-camera and skip all post processing, you can get very good results out of common lossy codecs, but motion quality will still be a compromise vs a high end camera. You know, many people read our posts and many absorb them as objective information, which is a mistake. When deciding on a camera model, it makes sense to rent for a day. There are many people who love the Sony EX1 and others who crossed EX1 out on their list when they noticed the motion quality. Renting for a day is very cost effective and saves a lot of time compared to listening to opinions on the internet. You never know where one is coming from, right?
RANT mode!
There are lots of people, reviewers, bloggers etc, that practically work for the manufacturers. You can tell by the actual words they use when reviewing a competitive product. I'm SO tired of these camcorder gurus who haven't written a gamma curve in their life but manage to shape the opinions of thousands, and it's always about pushing the lowest quality camcorders, the ones that make the most money in each segment. They sell the cameras before they are even manufactured! Practically anyone can see right through them after a couple of years of following their activity and most people suspect the type of relationship they have with specific manufacturers, but newbies are easy to influence. It's natural to trust those who appear to hold some weight in the discussion and environment. It is a measure of authority and we know how people respond to authority.
There are also people who are so involved in specific implementations that they can't be objective any more. You will not hear good words about dSLRs from Jim Jannard. You won't hear good words about compression from me because I obviously love uncompressed imaging, I'm spending all my time on it, it's even a camcorder that might be a commercial product soon, in other words competitive to hm everything else? So take my words with a grain of salt, the involvement in my project is so strong that it must be pushing through. I do like uncompressed a lot, but I discuss with people that are only interested in shooting filmmaking. They want to shoot demanding material and make the most out of post. They don't want to keep people waiting on set in order to finetune gamma/matrix/etc and they don't want wasted shots. They will pay for the flexibility to handle these things in post and the creative possibilities that provides, because it's a good investment. They want to do film and digital cinema delivery so they appreciate the uncompressed high precision recording and get intraframe formats when they have an option. They come from digibeta, 16mm and 35mm, HDCAM, and DVCPROHD Panasonics. But that's not the typical customer for a camcorder. Cinematography is not the typical use for an affordable camcorder. It's quite possible that my perspective does not even apply to most of the people reading these threads, it refers to a different usage scenario. But I believe this is a filmmaking forum, and this is why I post here. Some people might be interested in the technical implications of camera formats in post.
To sum it up, I'm not the one to ask about what will work for a specific user and I can't quantify it in bits, PSNR or anything else. The discussion is technical and theoretical and it could also be misleading. You never know until you try the actual camcorder/implementation, take it through your type of post and put it against your personal criteria. It costs what? 5% of the camera cost? Very good investment vs blindly getting a $10,000 package that will not do what you expect it to do.
Otis Grapsas
Carbonite Member
A sample from Alexa and Ki-Pro (1080p version available):
http://www.youtube.com/watch?v=xixmVTz5nNc
In this case the limit is the format because Alexa has very good design and a very large pixel. It would look even better with uncompressed and higher precision recording. This must be the best lit Alexa sample so far. The quality of overexposure handling and color are evident even in the 1080p youtube stream. This is no cinegamma curve for sure
Use the same recorder with a consumer/prosumer quality camcorder and you will get results similar to the in-camera recording because the camera is the limit. Same clipping, same shadow noise look, same color response. The limit is the sensor quality and the design quality. I understand how sensor quality limits these cameras, but I don't understand why they don't invest a little more in improving the design of the processing, gamma, matrix etc.
http://www.youtube.com/watch?v=xixmVTz5nNc
In this case the limit is the format because Alexa has very good design and a very large pixel. It would look even better with uncompressed and higher precision recording. This must be the best lit Alexa sample so far. The quality of overexposure handling and color are evident even in the 1080p youtube stream. This is no cinegamma curve for sure
Use the same recorder with a consumer/prosumer quality camcorder and you will get results similar to the in-camera recording because the camera is the limit. Same clipping, same shadow noise look, same color response. The limit is the sensor quality and the design quality. I understand how sensor quality limits these cameras, but I don't understand why they don't invest a little more in improving the design of the processing, gamma, matrix etc.
Otis Grapsas
Carbonite Member
Heh... done in Israel..
this is words apart from avchd 24mbs
Yes, but it is actually inferior! AVCHD is Uncompressed->24mbit. This is Uncompressed->KiPro codec->4mbit for youtube. 1/6th the AVCHD rate and an additional compressed intermediate that also damaged quality.
What we are seeing in this sample (besides good lighting) is good pixel quality and processing quality. These two survive any codec and no codec or recording method will add these to the output of an affordable camcorder.
hjulenissen
Member
I believe that if the discussion contains measurable, physically sound stuff, along with "see for yourself examples", those problems are reduced.
Not saying that everything relevant about a camera can be (easily) measured, nor that every measurement is relevant. But doing that stuff in addition to subjective "how did it feel to your hands", "was the gui intuitive", "what did the noise look like to you" seems to aid the debate. Anyone can say that a video looks flawless or like crap. And they do on the net.
One could easily make a parody out of the opposite of what you are describing. Those that talk for hours about differences that are undetectable to the naked eye unless heavy edited first as if it is making the image unwatchable. Those that hypothesise about how good stuff they could make "if they only had 4:4:4 wide-gamut 10-bit progressive intra-frame lossless raw" (to use every current buzzword in a non-coherent sentence), instead of going out and using what they have. Those that seem to believe that broadcast or theatres have no limitations.
-h