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Official Low GOP topic, series 4
  • 586 Replies sorted by
  • driftwooddriftwood

    @onionbrain There will be a higher bitrate version of the XDCAM implementation later which could be what you need. I'll take a look at the old AVCCAM standard but Lee is right, its nothing special. However, its nice to try and emulate different codecs using the GH2. I'll give it a shot as it won't take long.

  • LPowellLPowell

    @onionbrain - "They key to the above is that AVCCAM is replicated as closely as possible and that the bitrate remains relatively constant."

    Sorry, but there's nothing special about AVCCAM, it's just an early version of AVCHD that Panasonic chose to implement in their pro video cameras. A constant bitrate is useful for broadcast and streaming media, but offers no technical advantages in video capture applications. Long-GOP formats are likewise effective for commercial delivery formats such as DVD and Blu-ray, but are not optimal for real-time encoders with constrained resources and time frames.

  • onionbrainonionbrain

    @driftwood

    I just tested the XDCAM patch -- primarily for image quality (viewed on a calibrated production monitor), and I'll react to that after throwing a thought at you.

    A few days back I wrote a long request complete with reasoning requesting a replica of AVCCAM (Panasonic's "professional implementation of the AVC/H.264 codec") except with the bitrate multiplied by three -- meaning a stable bitrate between 63 and 72 Mbps. In the unimaginative and conservative broadcast world this could be considered the rough equivalent of 144 Mbps intraframe, yet would capitalize on the efficiency of LongGOP. In theory, the above replicated AVCCAM multiplied by 3 would trounce the new Nikon codec "with B frames," beat the XF codec (yes, it's not 4:2:2, but 4:2:2 doesn't mean the same thing it meant four years ago now that editors (NLE's) are ingesting, correcting, and editing at 12 bit 4:4:4), vaguely be equivalent in image quality to the new Canon "All-I," and trounce many varieties of XDCAM.

    I decided to sit on the above request to see what the new Ptools brings and the new patches.

    SO -- when I saw this XDCAM patch -- I was very, very intrigued. In theory, I'm convinced the winning formula for the hacked GH2 is a high bitrate LongGOP -- that capitalizes on the efficiency of LongGOP while reducing compression. For example, in theory, a 100 Mbps LongGOP is equivalent to a 200 Mbps intraframe stream.

    So -- if any of the above makes any sense to anyone -- I'm grateful if you pros will think about it. The key to the above is that AVCCAM is replicated as closely as possible (don't lower the GOPs) and that the bitrate remains relatively constant.

    OK -- regarding the XDCAM patch... the first thing that screamed out at me when I looked at the files in the folder was the extremely low bitrates. Most of these files were coming in around the 17 Mbps range.

    Image quality was good, on par with a stock GH2, and there was, essentially, no banding in blue skies. There was, however, blocky noise in the blue skies.

    In some shots image detail was very, very good. It handled motion perfectly well.

    So, it didn't look like a 17 Mpbs stream, but it also didn't look like a 50Mbps stream. Frankly, the not-joke here is that it looked like a 35 Mbps EXDCAM EX stream, except with elements of mpeg-4 detail.

  • cpliu60cpliu60

    Just run a quick recording on 'XDCAM' patch indoor, total 11 mins were recorded consum around 1.3G SD card. The video quality seems no visible change in such low bit rate when compare with Q100 patch IMHO, kind of strange feeling myself >"< ...

  • driftwooddriftwood

    @bkmcwd Yeah, have a play with the settings see what works under 3 GOP... You never know it might work out.., let me know mate.

    LOL @duartix ! Actually, Its pretty good at 720p60 that patch... may incorporate a final version of its kind in a version of Quantum ... I'd like you to test it further - maybe play with the settings a bit more? Thanks mate.

  • fatpigfatpig

    @Rszanto: if you want to have your look even more not-DSLR-like, you should definitely use a 180 degree shutter, which would be 1/50th for most cases. reduces the "stuttering", also.

  • duartixduartix

    Hei!

    Won't we be needing an "Official High GOP topic" now? :)

  • bkmcwdbkmcwd

    @driftwood Your new theory is very interesting. Thanks Nick! :-)

  • plasmasmpplasmasmp

    I'm sure you'll get 4:2:2!

    On the hacked GH4

  • proaudio4proaudio4

    Thank you Nick!

  • driftwooddriftwood

    If I did a long gop patch.... A new theory for Long GOP fans in patch vault. ;-)

  • OedipaxOedipax

    @LPowell, don't forget the global shutter hack ;)

  • GH2_fanGH2_fan

    @sohus Newbie topic???

  • LPowellLPowell

    @pinger007 - "Even if it is a joke, everyone asking for 4:2:2 is getting kinda old..."

    LOL, yes, and it's hard to resist the temptation to prolong their torment. Here's a short, hopeless wish list of GH2 features that you'll have to find some way to live without::

    1. 4:2:2/10-bit color
    2. Live RAW HDMI output
    3. 64-bit SD card file system
    4. Anamorphic frame sizes in AVCHD mode
    5. 24p frame rate in MJPEG mode
  • cosimo_bullocosimo_bullo

    My guess is Mr Driftwood already has the new ptool and is tweeking away!

  • pinger007pinger007

    Even if it is a joke, everyone asking for 4:2:2 is getting kinda old... It's gotta be grating on the ears of those who do the hacking.

  • troyjasontroyjason

    I think driftwood is waiting for the new version of Ptools before tweaking and releasing version 10.

  • AlexAlex

    I did a few test with Q9c. - Shot a 40 min live performance in 1080p24 L ISO1600 with 14-140 in etc to a Sandisk 32GB 30MB/sec. Spand nice, no issues. - 1080p24 H ISO640, 1.7 20mm. Outside run and gun. Did Not test spanning. No errors - tried to shoot 720p50 snow falling. Failed.

  • sohussohus

    @GH2_fan

    newbie topic

  • GH2_fanGH2_fan

    @MrEdd From what I'm gathering from you, I take it like there is 3 versions of Driftwood's Quantum? this being:

    • Quantum 9b (why this being Best Quality?)

    • Quantum 100 (what do you mean exactly when you mentioned Long Play and DocStyle?) &

    • Quantum 50 (I take it that this is just an increased bitrate and Intra-frame?)

    ???

    In general, does all of Driftwood's Quantum versions/patches apply for all the different recording modes? Thus will i have true Intra-frame recording at 1080i50? and quite possibly 25p if its available???

  • spacewigspacewig

    @Rszanto

    I really like the feel of the footage, good job!

    Question: When you underexpose, how do you bring the footage back up to proper exposure in after-effects? i.e. what is the process to lighten up the whole image? Just add brightness? I would love to experiment but am just starting to learn how to use AE.

    Thanks in advance. Cheers!

  • RszantoRszanto

    @blackspot

    I'm with you on the encoding. Vimeo's non-pro 720p uploads are fairly horrifying.

    The clip was shot at 1600 ISO, and underexposed by about a stop and half. That gave me plenty of grain to form a decent profile with Neat Video. I tend to hate the sterilized look of denoised GH2 footage, so back in After Effects I placed a custom grain profile on top (made from actual 35mm scans of Kodak grain), which really helps to even things out again.

    The CC is a bizarre combination of several LUTs and various contrast enhancers. It takes two minutes to render out each second of footage, but with a little bit more tweaking, I think that the results are more than worth it. I really love the anti-DSLR look the process gives my footage.

  • MrEddMrEdd

    @GH2_fan For what I understood Driftwood´s Quantum aims to be the best in diferent modes (24p,1080i,720p). Currently there are 3 flavours:

    -Best quality Quantum 9c (test patch), you can also try 9b

    -Long Play Quantum 100 DocStyle

    -Most Compatibility Quantum 50 (better than stock)

    "how does it differ to the current version as it is?" For what I´ve read in previous post it will take use of the new version of Ptools

  • GH2_fanGH2_fan

    @MrEdd You see, this is what I'm talking about, because I've missed quite alot, I dont understand when you say 'Quantum' or in prevcious discussions, it was always about 50Mbit or 100Mbit but then 'AQ' came in after I didnt read for awhile, and started to get confused :( And for this new version, how does it differ to the current version as it is?

    @onionbrain That was very informative, thanks for that, I myself own this 7DayShop 32GB Class 10 SDCard which at the moment hasnt failed me yet. I am aware to obviously invest well in my equipment and media. And what exactly do you mean your class 6 Sandisk Extreme Pro 30 MB/s cards dont work on your hacked GH2? what was the error in that?

  • blackspotblackspot

    @Rszanto

    Hello! What kind of pre-/postprocessing did you use for that clip? Encoding is somewhat bad and blocky, but it has very nice but unusual texture of noise. Did you add noise afterwards? what kind of CC? Also very nice compressed highlights.

    -Petri

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