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GH2 Flow Motion v2 - 100Mbps Fast Action Performance & Reliability for Class 10 SD cards
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  • I just print out a couple of photos at the local drugstore and tape them to the screen. They are easier to see in bright light.

  • @GH2_fan Reducing Flow Motion v2 to a GOP-length of one will not only cause the videos to no longer play back in-camera. It also degrade the image quality and very likely undermine its reliability as well. FM2's 100Mbps bitrate is geared to produce optimal image quality with a GOP-length of 3. To maintain comparable quality levels with an all-Intra GOP-1 patch, you would need a peak bitrate of over 175Mbps.

    High-bitrate patches require complex and often delicate adjustments to operate properly as intended across the wide range of GH2 video modes and options. With Flow Motion v2, the only optional AVCHD encoder customizations I recommend are the 24L Video Bitrate and FH/H Video Bitrate patches. These patches affect only the 60Mbps 24L, FH, and H video modes, and can be adjusted without disturbing FM2's 100Mbps video modes. If desired, you can adjust the 24L and FH/H Video Bitrate patches to any peak bitrate below 95Mbps.

  • @peternap Thanks for the preview of your rough seas test. Will you be able to upload any original footage? YouTube's compression makes it hard to evaluate the details.

  • @LPowell I can as soon as I get to a town Lee. My farm is 100% off grid and I get Clearwire using a cantenna. Bandwidth is about like dialup. I have the file ready and will send it up ASAP.

  • @LPowell. Some feedback. Dealing with continuous saga of FSH/HBR/SH quality, write errors and so on.... I kept tweaking your FM 2.02 settings to find a good balance of detail and bitrate. Finally I settled on FSH/SH at 88mb and FH/H at 60mb with associated frame rates adjusted. This adjustment gave me a much more reliable 720p60 SH at 55-60 mbs and FSH/HBR at 55-65mbs. FH/H records averaging 40+ with very good quality. This is using Panasonic AFC, OIS lenses that pose more issues than the others. The cards used are Sandisk extreme 64gb 95mbs and 32GB 30mbs. Appreciate your hard work too.

  • @Zaven13 Since releasing v2.02, I haven't encountered any reproduceable problems with 1080 HBR or FSH modes in either PAL or NTSC frame rates, nor have I seen any issues with PAL 720p50 modes. With 720p60, I improved the reliability of SH mode up to the point where in extreme conditions, the encoder just begins to show a mild and virtually imperceptible form of fallback behavior. (Macroblock QP range begins to expand beyond +/-2.) With this setting, 720p60 mode remains failsafe, and isolated instances of recording failures have been rare and difficult to reproduce.

    On your patch suggestions, I'm not seeing the point in restricting the 100Mbps HBR, FSH, and SH modes to a bitrate of around 60Mbps. Since Flow Motion v2 already provides complete reliability at 60Mbps in FH and H video modes, these modes serve as secure alternatives in any situation where it's important to insure that recording will not halt, including cases where 4GB file-spanning is required. And in the case of HBR mode in Flow Motion v2.02, to date I have not seen any reliability issues at all.

    At this point, I've hit a high enough bar with v2.02 that further refinement of the settings would require a great deal of time and effort. In terms of reliability, the problem is that I can no longer find test subjects that will reliably provoke the camera into a failure pattern that I can test and analyze. While it's inherently impractical to confirm that any patch is 100% reliable, it's nearly as challenging to determine whether proposed new settings are in fact any more reliable (or less!) than v2.02.

    On the motion picture quality side, I've done enough pixel-peeping to confirm that FM2's Quantization Tables work as intended to significantly reduce the macroblock artifacts that plague low-bitrate AVCHD encoders. There are literally hundreds of tweakable adjustments that interact to produce these results, and it would have been wildly impractical to attempt to test all possible combinations. To bring this challenge under control, I used well-established psycho-visual principles to narrow down the possibilities to a working theory. In practice, my hunch turned out to be a good solution, not in general, but in the particular case of the GH2.

    Improving motion picture quality further would require coordinating a comprehensive series of subjective viewing tests, with multiple patch variations, test subjects, and reviewers, followed by a statistical analysis of the results. This is how the perceptual quality of lossy audio encoders is certified in professional work, using suites of MUSHRA tests to generate quantitative data. To my knowledge, no comparable methodology has yet been developed for evaluation of video encoders. It would be a far more extensive project than I'm prepared to undertake.

  • @LPowell. Please don't get me wrong. FM 2.02 is great setting. I consider it one of the top three. I reduced FSH/SH from 99 to 88 NOT 60. I increased FH/H from 55 to 60. So I still get great quality. It just gave me a longer/more reliable recording results with SH and slightly higher bitrate with FH/H (remember, I am using Panny lenses). I perfectly understand the GH2 limitations and where the point of diminishing return is. You, Driftwood and others have done exceptional work to make GH2 a much better camera and I personally could not ask for anything more. I certainly am not suggesting that you put a lot more effort into very little in return. You guys have given us the option to tweak things to make it more workable for our individual use and card types that we have. And for that, I am grateful.

  • @Zaven13 Thanks for your praise and recommendations. What I want to emphasize is that rather than experimenting with the FSH/SH peak bitrate, it is better to use custom bitrate settings in FH and H modes. You can freely set the FH/H peak bitrate to anything below 95Mbps without affecting the 100Mbps bitrate of HBR mode. Aside from the peak bitrate, there is no inherent image quality drawback to using FH and H modes - they work exactly the same as FSH and SH modes.

    There is also a technical reason why I can't guarantee the reliability of adjusting the FSH/SH Video Bitrate setting. In FM2, peak bitrates of 1080i and 720p modes are determined by balancing a combination of internal settings, rather than simply setting FSH/SH Video Bitrate to the maximum desired bitrate. For this reason, lowering FSH/SH to 88Mbps may produce suboptimal results, such as lowering the threshold of Fallback Mode. (One very notable testing hazard with 720p60 is that you can produce a significant, but spurious, improvement in apparent reliability by prematurely forcing the encoder into Fallback Mode.)

  • @LPowell. Thanks for the new information. I will take your recommendation and experience with FH/H mode bitrates rather than the FSH/SH. I never thought of that. Cheers.

  • If I may draw a parallel from the audio world, there are many microphones that have great specs, but only a few that are musical. The flow motion patch to me has a cinematic, visual appeal that transcends the specs. I'm not going to blow up frames and look at still images--no one is going to look at stills in the final product. Flowmotion is a great gift to videographers. We all have lots to choose from.

  • @LPowell. thanks for your work Test new film project,(Int.Night)

  • Amazing direction and acting!

  • @LPowell Thanks for that info, I went ahead and reapplied your settings 'as-is' but yet again changed the bitrates to 100M and 50M, and interestingly (all done in 50i) the 50M seems to have recorded all the way through, however not so much luck again with 100M, whilst it did much better it did cut off at 19mins and 9mins when attempting this twice, both of which was done on a formatted card (meaning I formatted the card everytime I did a new record setting).

    Now I havent yet seen the files on my PC yet (battery died) but why do you think the camera cut off at the higher bitrate on random times perhaps?

    Mind you, this was all done statically, no movement and at ISO12800.

  • @GH2_fan I'm not sure what you're looking for. A recording more than 9 minutes long will most likely need to span across more than one 4GB file. Before experimenting with untested patch alterations, I'd recommend testing your SD cards to determine their spanning capabilities. While 95MB/sec Class 10 SD cards should be able to span in all Flow Motion v2 video modes, slower Class 10 cards have only been verified to span reliably in 24L, FH, and H video modes.

  • @Lpowell

    It's time of lake of death :)

    I'll bring with and FM and SEDNA both 24p

  • @vesubio

    Amazing cinematography!

  • @LPowell This was shot with a fairly cheap CP (Tiffin) I still got good results. Amazing setting for 720-60 as well as 24P. Nikkor 24 2.8 lens

    flow motion 2.2

    The next frame fm 2.2 cannon 2

  • @LPowell Well what I'm actually after is probably what all of you are after as well, to be more definitive what I'm saying, I obviously want to capture footage at the bestest quality the camera is capable of but without any fault i.e. random cut-offs at any decent bitrate setting and high ISOs which was my problem when trying out Driftwood's patches. Also, wanted to try and keep it (as close to) Intra-frame recording to help things in editing and keeping frames of high quality.

    My SD card seems to span well when recrding on 50M (lower bitrate) in 1080i50 but not so on 100M (higher bitrate), this seems to be my only problem. Could it be because I raised it to 100M from 95M as you set it?

  • @GH2_fan It's because the slower Class 10 SD cards cannot reliably support 4GB file-spanning at bitrates much above 60Mbps. That's why I recommend using FM2's 60Mbps 24L, FH, and H video modes when you need file-spanning on Class 10 cards rated lower than 95MB/sec. With the fastest SD cards, Flow Motion v2 supports file-spanning on all of its video modes.

  • @LPowell But I am using a 16GB Sandisk 95Mb/s SD Card that I bought specifically (from Amazon) for applying these patches, I have mentioned this in my previous posts here. The fact that when recording at 100M at ISO12800 in 1080i50 and for it to stop at slightly random times, just got me wondering...

  • When creating a bin file with Flow Motion 2.02 (and all other patches), many of the options are pre-selected but a few of them are not. I'm guessing that those that are not checked were left that way for a reason. Can you shed any light on why they were not included and whether any of these options should be checked? For example Auto Quantizer for 1080 modes and for 720 modes? If yes, then which level from 0 to 4? And audio AC3 compression, yes or no? What are the pros and cons for selecting or not selecting these items? Thanks for the help.

  • @RockHunter Flow Motion v2.02 is an integrated PTool patch file that is designed and tested as a complete, self-contained update to the GH2 firmware. It is intended to be used exactly as delivered, with no changes made to any of its settings, both checked and unchecked. High bitrate GH2 patches are complex and difficult to optimize and test thoroughly, and are not really designed for end-user customization.

    There are, however, two settings that may be freely adjusted without running the risk of destabilizing Flow Motion's 100Mbps 24H, HBR, FSH, and SH video modes. The 24L, FH, and H video modes have been set to about 60Mbps peak bitrate to support 4GB file-spanning when using Class 10 SD cards rated lower than 95MB/sec. If desired, you can adjust the 24L Video Bitrate setting or FH/H Video Bitrate to any reasonable value up to 95,000,000.

  • @LPowell. Thanks for the explanation. That certainly clears up the questions I had.

  • @LPowell Hello again, I have just discovered something, I am currently doing another (static) shot recording at 100M in 1080i50 at ISO3200 and it seems to be going along fine, at the moment it's got 6mins remaining and it has not failed on me yet...sooo...it probably means that having it at ISO12800 seems to be the trouble, can this be your next fix? :D

    Also I forgot to mention, when analyzing the video files (I left the GOP at 3), I saw that the frame type structure was I-B-B. Shouldnt it have been I-P-B may i ask?

  • @GH2_fan When the GH2 stops after filling up a 4GB file on a slow SD card, it is a card limitation rather than a patch failure, and there is nothing to fix. If you want to record lengthy videos at 100Mbps, you'll need to invest in a 95MB/sec Class 10 SD card. Even with that, there may well be certain conditions at the extremely noisy ISO 12800 that interfere with file-spanning, as it is one of the camera's most poorly implemented features. In cases where file-spanning at 100Mbps proves unreliable, I recommend using Flow Motion's 24L, SH, or H modes, which are limited to 60Mbps for this purpose.

    Regarding your technical question, the AVCHD encoder always uses an IBB frame sequence, it is a built-in feature of the encoder.

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