AC160 avccam vs other codecs?

J

Josh Bass

Veteran
Hi. Have been thinking about getting an hd cam (still only own sd, believe it or not). i've been a canon owner in the past but was looking to go panasonic this time. this is based on my long ago experiences with the dvx series and how amazing that footage often looked. that "panasonic" look. i would assume thats carried through to their latest cameras. so was looking into the ac160a (second choice a used hpx170). im not really on the shallow depth of field bandwagon, especially for the kinds of things i tend to do, so the small sensor cams are cool with me.

however, asked a client about his experience with the avccam codec via the af100 he used when we worked together, and he surprised me by saying he's thought pana's more recent cams have been underwhelming. said he finds the codec "soft and artifacty," and got to work with the ex3 recently and thought the xdcam codec was "crisper and brighter". now i know the ex cam lenses are sharper than than the hpx (which i know is dvcpro hd, not avc, by the way), would think it would depennd on lens whether sharper than then af100. im surprised though because i thought you really couldnt tell one codec from another unless the codec was pushed too far, e.g. with color correction or poor shooting conditions. could my client be experiencing something deficient in the af100 itself, rather than the codec ? what are your thoughts on one codec vs another? can you really tell the difference between one codec and another?
 
AVCHD does poorly in dealing with very fast motion in my experience. I just got finished with shooting womens bball and compression artifacts show up anytime there is fast motion (when the cheerleaders do backflips, there are very noticeable artifacts on the feet and leg area for example).
 
Thats too bad. Not that i shoot sports but im sure that could apply to something as simple as a guys gesticulating arms during a talking head interview. Motion is motion, right?
 
AVCCAM (and all non-iframe codecs) struggle more under motion than not, sure. But in any equivalent situation AVCCAM will hold up better than the XDCAM-EX codec used by the Sony.

I certainly wouldn't think the codec was to blame in what your client noticed. It was likely more due to the EX1 just being an inherently sharper camera than the AF100.

Might be interesting to show your client side-by-sides of the EX1 vs the AC160, which is a comparably sharp camera.
 
Josh Bass said:
Thats too bad. Not that i shoot sports but im sure that could apply to something as simple as a guys gesticulating arms during a talking head interview. Motion is motion, right?
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From my time with the AC90, that was the only time I noticed the severe artificing. I mostly shoot stuff with little to no motion (landscapes, talking heads, etc) and the AC90 performs fine. I think it might be that 1080 60p might be too much for the codec to handle. I shot beach volleyball with the HMC150 at 720 60p and HS and college football at 1080 30p and I don't recall there being any artifacts at all. It also could be that the AC90 is just a much sharper camera so every little thing shows up.
 
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niw um looking at the hpx250. all of the goodness, with the stronger codec. of course big price bump especially considering media prices. maybe ill break down and rent a 160 when im ready, to see how it holds up real world. its all speculation right now as im not ready yet to throw down the cheddar for anything st the moment
 
I have noticed severe visible artifacts (on AC160) only in scenes with fast and chaotic motion, like waves on the lake shot very zoomed (50mm / 0.33") from hand. More artifacts are also on the first few frames of the shot, but it's not visible in realtime playback. The only problem with compression is when you do strong secondary corrections, because the CbCr channels are apparently much more compressed than Y channel.
 
Those were his words. It did sound weird to my brain meat but they have the full fledged production company while i shoot a handful of days a year so what do i know? Anyway, did the head math and the hpx250 is more like $7000 with bag, several batteries and 3 32 gb p2 cards (b&h has a special right now where the the cam is $4600 AND comes with a free 32 gb card). Id like to have at least two hours of media at the highest quality. So i wont be spending that kind of money any time soon. Guess i'll just shoot on my xl2 and cry into the underwear i stole from the apartment's laundry room.
 
Forgot to mention. . .someone above mentioned AVCCAM holding up better than XDCAM EX (regarding fast motion). Keep in mind the EX1, for instance, can shoot at either 25 mbps or 35 (HQ mode). Do you think this still applies at the higher quality bitrate then?
 
Yes. Definitely. XDCAM is 35 megabits, but it's 35 megabits of MPEG2. AVCCAM is 24 megabits of MPEG4.

The AVC codec is much more advanced and more efficient than MPEG2. Sony says that to match the quality of 25mbps MPEG2, you only need 9 mbps of AVC. 24mbps of AVC > 35 MBPS of MPEG2 any day of the week.
 
Barry I agree with you on that. But I am at a loss then as to why some manufacturers still persue MPEG 2 based formats. Even with Canon's 50mps 4.2.2 format, since it is still MPEG 2 based, it would not render motion better than MP4, could it?
 
huh. news to me. the sony ex line seems so much higher end than the pana avchd stuff for some reason. guess its all in my head. good to know.
 
sewolla said:
Barry I agree with you on that. But I am at a loss then as to why some manufacturers still persue MPEG 2 based formats. Even with Canon's 50mps 4.2.2 format, since it is still MPEG 2 based, it would not render motion better than MP4, could it?
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Canon's codec is the same as Sony's. Canon always persists with last-generation technology. They stayed with HDV long after everyone else had moved on. It is their style to be a late adopter, not an early adopter.
The
50mbps version of mpeg2 is fine. It is a broadcast-approved codec and does the job that needs doing. 50mbps of AVC/MPEG4 would be better, undoubtedly, but the MPEG2 version is an established standard that is good enough.
 
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