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GH2 Flow Motion v2 - 100Mbps Fast Action Performance & Reliability for Class 10 SD cards
  • 1036 Replies sorted by
  • DeShonDixonDeShonDixon

    @mozes whats the media player your using in that screenshot?

  • mpgxsvcdmpgxsvcd

    @LPowell

    Great job. Looks like a ton of effort went into this. Can't wait to test it out.

  • LPowellLPowell

    @Benibube Stream Parser bitrate plots are detailed measurements of the amount of data required to encode the frames in a particular scene, which is determined primarily by image complexity and illumination. If you're interested to learn more about how the encoder quantizes the image data in each frame, you can use Stream Parser's Tool menu to create and decode an elementary stream file of the video.

    @ahbleza Selecting the GH2's PAL mode sets HBR video mode to 1080p25 and SH mode to 720p50. Selecting NTSC mode sets HBR mode to 1080p30 and SH mode to 720p60. Each mode has been individually tuned to produce optimal performance at 100Mbps peak bitrates.

    @Meierhans The Scaling Tables used in Flow Motion v2 are explicitly customized core components that interact with virtually every stability and quality adjustment used in the patch. Replacing them with matrices designed for a different purpose would wreak havoc with the patch's tuning and undermine the performance and stability of the encoder in unpredictable ways. I'll provide more details shortly on how FM2 relies on its Scaling Tables to implement crucial aspects of its quantization strategy.

  • duartixduartix

    @Meierhans: Different Matrixes will have an impact on quantization and thus on bitrate. If you change them, I believe you are compromising the whole settings. If I were you I'd try these settings as they are because if you look close, you'll see that @LPowell has lowered the quantization from stock matrixes so the chances are there will be a lot of improvements in that field already.

    @LPowell: Thanks for you hard work! What are the Table Flag and Table High parameters for?

  • LPowellLPowell

    @duartix These tables configure the Deblocking Filter used in AVCHD encoders and decoders. It is another component that is intricately linked to the operation of FM2's quantization matrices. In Flow Motion, they are used to minimize banding and macroblocking of low-detail color gradients. An example of this is the smooth quality of the out-of-focus background in the screen shot provided by @matthere above.

  • mpgxsvcdmpgxsvcd

    Got the write error failure straight out of the box with SH(720p High) mode while shooting in S shutter priority stills mode. It failed 45 seconds into the clip using the 25mm F1.4. This was using a Sandisk Class 10 30 Mb/sec card. Is there a different class 10 card that you think would work better?

    I haven't tried the ETC mode yet but I suspect it will fail in that mode as well. Seems like most high bit rate low GOP settings fail when shooting video in stills mode. I fully understand that most people here don't shoot video in that mode. However, a lot of people like to be able to take stills during video which can only be done in that mode.

    Other than the reliability issue the 720p settings looked good. However, they didn't look that different from just raising the bit rate with the stock Auto Quantizers. Are the 720p settings optimized less than the other resolutions?

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  • GeraldGerald

    @LPowell i will taste as soon as my accu is reloaded. I like your philosophy "One hack for all flow motion settings". I need my GH2 just for motion. Maybe a Photographer needs something different. I was allready confused about all those different hack version for any circumstances. I dont like to reload the specila firmware for every shooting. There is enough i do have to think about. If i would like the best in every situation, i do have to buy a different camera for each one anyway.

  • fehafeha

    WOW, thank you very much.

  • mpgxsvcdmpgxsvcd

    1080p @ 30 FPS looked good until I shot in ETC mode. Sections of it kept the bit rate high. However, other sections dropped well below stock bit rates. In this example both the I and B frames dropped to below 170 kilobits(21 kiloBytes).

    The 24p settings seemed to do very well with and without ETC. It had a slight drop in one section but not nearly to the extent that the 1080p @ 30 FPS settings did.

    Just look at the min/average/max values for the I and P frames in the attached image. The minimum values for both the I and the P frames are almost the same. However, there are no P frames in this example. The I and B frames go essentially to zero at one point.

    00008_Frames.PNG
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  • mpgxsvcdmpgxsvcd

    @LPowell

    Got the write errors in standard video only mode with 720p @ 60 FPS as well. Any suggestions on how to avoid write errors with these settings and 720p?

  • luxisluxis

    @LPowell

    Thank you for all your hard work! The presentation of the FM2 seems also so well done, sounding almost like original commercial Panasonic release! ; ) i will buy it ; )

    This will be my first FM(freak'ency modulation;) use and i am excited to see what it could do. Every time i hear reducing of banding it makes me happy : ) its the real problem of the gh2 for me.

    @mpgxsvcd if you try the picture burst mode by itself even with the fastest card at 95mbs it can only take a few pictures before pausing(full buffer i believe?) so to record video at high bit rates and snapping a still image at the same time is very unlikely to be working smoothly. maybe with a (much) lower bit rate patch. and why not just take snapshots later from the video. the quality/frame size is the same.and you can really "capture" that moment ; )

  • luxisluxis

    @mpgxsvcd what setting is this? 1080p @ 30 FPS , mjpeg hd?

  • duartixduartix

    @mpgxsvcd Your Streamparser log looks OK. It's looking like a good VBR patch should behave reacting to content, except for one tiny bit from near frame #1560 and for about the next 12 frames where the encoder is probably going into Fallback mode (can you try logging that section in Streamparser's Elementary stream decoder to see how the quantizers are reacting?) The P-Frame stats are normal as there is usually a rogue P-Frame in the first GOP.

  • wigginjswigginjs

    Is NTSC HBR spanning supported?

  • mpgxsvcdmpgxsvcd

    @luxis

    I wasn't taking a picture during recording at all. I was recording in the mode that you can take a picture I just wasn't taking any pictures during that video.

    It also failed in regular video only mode 3 times for 720p @ 60 FPS SH. I haven't been able to record a single successful 720p @ 60 FPS video with the 25mm F1.4 or 14-140mm lenses in AFC mode yet. I have shot indoors and outdoors and both failed with the 30 mb/sec Class 10 card.

    All other video modes stability seems perfect. It is just 720p that is failing.

  • mpgxsvcdmpgxsvcd

    @duartix

    Isn't the point of these settings to prevent it going into fallback? I thought that was what the optimized quantizers were for?

  • mpgxsvcdmpgxsvcd

    @luxis

    The 720p settings are giving the write errors and the 1080p @ 30 FPS HBR mode appears to be going back into fallback mode in some scenarios.

  • LPowellLPowell

    @mpgxsvcd Thanks for your reliability testing of Flow Motion in 720p60 and HBR 30p modes. Please post an example of a Stream Parser chart that shows the encoder entering Fallback mode, along with a frame grab if possible. "Fallback Mode" is not merely a temporary dip in bitrate of the type seen in the Stream Parser chart 00008 that you uploaded above. Stream Parser specifically identifies Fallback Mode malfunctions in its elementary stream reports.

    One point I haven't mentioned is that it's important to use the camera to format the SD card each before shooting a series high bitrate test footage, in order to guard against SD card memory fragmentation.

    In evaluating Stream Parser bitrate charts, bear in mind that bitrate is only an indirect measure of motion picture quality and can vary dramatically as the subject matter or camera position changes. Without reference to a relevant frame grab (or MTS file) of the original video, there's no way to evaluate the context of a Stream Parser bitrate chart. A more direct gauge of encoding quality can be obtained by using Stream Parser to generate an elementary stream file of the video, which will list the base DC quantization factors used to encode each frame.

  • mpgxsvcdmpgxsvcd

    @LPowell

    Working on getting the sample and elementary stream file now.

  • peternappeternap

    Everyone is faster than I am. I spent the last hour testing it against Sanity 5 with different lenses in 720-60. It flat kicks butt. No errors although I don't get them with sanity either.

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  • LPowellLPowell

    @mpgxsvcd I just tried to reproduce your 720p60 test in S still-frame mode using a Lumix 45-200mm lens operating in AFC mode. This was the first time I've tried taking a snapshot while shooting a video, and it worked for me each time, and the video continued to record. I haven't been able to induce any recording failures so far.

    Edit: I was able to get recording to stop on two occasions in 720p60 S still-frame mode with the 45-200mm in AFC mode, by panning between highly detailed objects at different distances. So far, however, I've haven't been able to reproduce this failure under any conditions when shooting in Manual Movie Mode or when the lens is set to AFS or manual focus mode. Can you see if you can reproduce the error in non-AFC and/or Movie Mode as well?

  • jrdjrd

    @LPowell

    It's a frequently asked question, I know, and you're bound to get is sooner or later, so here goes: is there anything to be gained -- or lost, other than card space and reliability-- if the user raises the bit rate for 24p? And would that change actually lead to higher frame sizes/less compression? Thanks.

  • peternappeternap

    @LPowell Did you test this in low light?

  • LPowellLPowell

    @jrd In 24H video mode, Flow Motion v2 will automatically shift into 140Mbps turbo mode whenever a peak bitrate higher than 100Mbps is required. This occurs most often when using 80% Slow-Motion 24H mode (which uses 25% more bandwidth), but can also occur when shooting well-lit, highly detailed subjects in regular 24H video mode.

    In my testing, I found that 24H peak bitrates higher than 140Mbps would not record reliably on Class 10 SD cards and offered no significant improvement in perceptible image quality. With the 3-frame GOP used in Flow Motion v2, the I-frames produced by a 140Mbps peak bitrate are comparable to an all-Intra encoder running at 280Mbps.

    @peternap I've tested Flow Motion v2 in low-light underexposed by as much as two stops. In those conditions it maintained optimal image quality, typically with average bitrates in the 40-50Mbps range.

  • mozesmozes

    @DeShonDixon i use splash http://mirillis.com/en/products/splashexport.html

    @mpgxsvcd @LPowell i did try to reproduce mpgxsvcd problem in still mode, in pal with sandisk 10 extreem 30mb/s.
    There where no problems.

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