GH2 100Mbps Flow Motion Patch v1.0 with 50Mbps File-Spanning

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Lpowell

Veteran
GH2 100Mbps Flow Motion v1.11 Failsafe Patch with HBR 25p & 50p support

Released below is a minor revision to Flow Motion v1.11, tuned and tested for failsafe operation in all PAL video modes, including ETC zoom mode. In addition, it also supports failsafe operation all NTSC modes except for ETC mode in HBR 30p and FSH 60i.

In short, this is the 100Mbps GH2 version of my Reliable In-Camera Playback Patch.

Congratulations once again to Vitaliy Kiselev for cracking Panasonic's recent firmware v1.1 update for the GH2! PTool v3.64 now provides support not only for the new HBR 1080p25 and 1080p30 video modes, but for custom Quantizer Scaling Tables as well. Custom tables enable patch developers to tailor the compression properties and image quality of each of the AVCHD 1080p, 1080i, and 720p video resolutions. In addition, cbrandin's invaluable Stream Parser and Scaling Table development tools have made it possible to quickly take advantage of these new PTool features, providing an unprecedented level of control over the GH2's video recording functions. Combined with the capabilities of Panasonic's v1.1 firmware, this has resulted in numerous improvements to the reliability and motion picture quality of Flow Motion v1.1. Here is a concise list of its features and specifications:


  • 100Mbps AVCHD in 24H 1080p24 and SH 720p50/60 at 8-10 keyframes/sec.
  • 75Mbps AVCHD in HBR 1080p25/30 and FSH 1080i50/60 at 8-10 keyframes/sec.
  • 50Mbps AVCHD in 24L 1080p24, FH 1080i50/60, and H 720p50/60 video modes
  • 100Mbps MJPEG 1080p Patch maintains high bitrates regardless of light levels.
  • Full support for all NTSC and PAL video modes.
  • In-camera playback of all AVCHD video files. (MJPEG HD videos not playable in-camera.)
  • 4GB AVCHD file-spanning in all video modes with 95MB/sec UHS-1 SD cards.
  • File-spanning in 24L, FH, and H modes supported on all Class 10 SD cards.
  • ETC zoom mode with failsafe operation in all modes except NTSC HBR 30p and FSH 60i.
  • 80% Slo-mo 24H video mode with ETC and file spanning in 24L mode.
  • Combines optimal I-frame size with compact, 3-frame GOP file size (GOP-6 in 720p modes).
  • Customized Scaling Tables produce P and B-frames that match I-frame quality.

As with any complex video camera, there are a number of considerations and limitations to bear in mind:


  • Listed bitrates are the maximum seen in practice, filming well-lit, sharply-focused, highly detailed scenes. Average shots will produce average bitrates. In low-light conditions, I recommend trying MJPEG HD 1080p30 mode for its ability to maintain high bitrates in near dark conditions.
  • If shutter speed is set longer than the frame rate (e.g. slower than 1/60 at 60p), low-quality video files may be produced. High shutter speeds will reduce motion blur, which may force the encoder to operate at higher bitrates.
  • ETC zoom mode increases the bitrate and puts significant stress on the encoder. With Flow Motion v1.11, Failsafe ETC mode is now supported in all PAL video modes, and in all NTSC video modes except HBR 30p and FSH 60i modes. ETC actually does work in all modes, but I've found that with Panasonic distortion-correction lenses, it's not 100% failsafe in HBR and FSH modes under the most extreme conditions. With manual-focus vintage lenses, it has so far proven to be failsafe in all modes.
  • Flow Motion v1.1 has been tested extensively at ISO 3200. It is not tuned to work reliably with PTool's extended ISO patch, but higher ISO can be used in underexposed, low-light conditions.
  • Panasonic Lumix distortion-correction lenses are now fully supported in Flow Motion v1.11. For smoothest results, I recommend using these lenses with a mild softening filter to reduce their over-sharpened edge artifacts.
  • The 24L, FH, and H video modes make use of a special "Trick Mode" that ensures reliable file-spanning at 50Mbps. It does this by setting the video file's transport stream bitrate to a much lower level than the video stream's bitrate. These files play back correctly in video editors with no need for post-processing. However, MediaInfo and Windows will report incorrect duration and bitrate for these files when examined on the desktop.
  • I recommend using the camera to format your SD card at the start of each shoot, to guard against SD card memory fragmentation.
  • This patch requires Panasonic GH2 firmware v1.1 and PTool v3.64d. For download, installation, and usage of these components, see the following FAQ: http://www.personal-view.com/faqs/ptool/ptool-faq

Original Flow Motion v1.11 sample videos may be downloaded from the following links:


Looks even better in the original MTS clip, downloadable from Vimeo!


GH2 100Mbps Flow Motion v1.11 downloadable INI patch file, for use with PTool v3.64 :
 

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How Long Has This Been Going On?

While it seems like forever since the GH2 was first hacked in a hardcore tour-de-force by Vitaliy Kiselev, it's actually been just six tumultuous months. During that time, an overwhelming amount of GH2 research, experimentation, and testing results have been shared by numerous contributors to this and other websites. Athough I contributed a 100Mbps MJPEG 1080p patch in the early days, I have not previously released a patch for any of the GH2's AVCHD video modes. One of the main reasons has been the wide variety of patches that others have already developed for the GH2:

cbrandin: 44Mbps AQ4 and 66Mbps AQ2 patches with the standard 12-frame GOP.

driftwood: Quantum 150-176Mbps 24p Intra-frame patches for max image detail.

bkmcwd: 154Mbps 24p short-GOP patches for maximum I-frame quality.

Stray: 88Mbps AQ2 24p patches using the standard 12-frame GOP.

Ralph_B: Sanity long-GOP high-quality, moderate-bitrate patches.

GH13Timelapser: Low-frame-rate MJPEG patches for time-lapse videography.

These patches all produce excellent results for the specific purposes they were designed to serve. Unfortunately, the GH2 can make use of only one AVCHD and one MJPEG patch at a time. What makes this severely limiting is the wide variety of video modes and unique features that are packed into the GH2. For a patch developer, one of the most difficult challenges has been how to optimize performance of the GH2's most popular video modes without crippling or destabilizing the rest of its modes and functions. Here is the full list to consider:

Always Room for One More Mode

  • 24H & 24L modes: 1080p @ 24fps
  • FSH & FH modes: 1080i @ 50fps PAL & 60fps NTSC
  • SH & H modes: 720p @ 50fps PAL & 60fps NTSC
  • 24H & 24L 80% Slo-mo: 1080p @ 30fps
  • HD mode: 16:9 MJPEG mode in 720p - 1080p resolution
  • VGA mode: 4:3 MJPEG mode in 480p - 960p resolution
  • Extra Tele Conversion mode: digital zoom in all modes above
With both NTSC and PAL, I count 14 different video modes, and that doubles when you throw in ETC digital zoom mode as well. By comparison, the GH1 had ten PAL and NTSC modes, but its H and L modes were merely low bitrate versions of 720p mode. If you consider how long it takes to fully test a comprehensive GH2 patch in all possible combinations of video modes, you may get an idea of how I've been spending my free time these past few months...

The Great Intra-mural Debate

In the early days of GH2 patch development, an unexpected debate emerged around the AVCHD encoder's use of P and B-frames. As with the GH1, the GH2 encodes video in fixed-length sets of 12-30 frames, each called a "GOP" (Group Of Pictures). Each GOP starts with a self-contained key frame called an "Intra-frame" or "I-frame", followed by partially-encoded difference frames called "P-frames" and "B-frames". While I won't digress into much technical detail here, P and B-frames provide more compact compression than I-frames, but with debatable drawbacks in image quality and motion tracking. One of my early GH1 patches introduced the concept of an ultra-short 3-frame GOP for fast motion-tracking in 720p30 videos. While this sparked some debate on its effectiveness at the time, it was nothing compared to the short-GOP crusade that emerged with the GH2.

With an unhacked GH2, its most popular 1080p24 video mode uses a 12-frame GOP, containing I, P, and B-frames, at bitrates up to 24Mbps. This orthodoxy was first challenged by kae with his 66Mbps 3-frame GOP patch that worked with the initial GH2 version of PTool. The effects of such a short GOP on image quality and motion rendition were heatedly discussed, with advocates claiming that long-GOP P and B-frame image quality could never match that of I-frames.

The debate simmered for months, seemingly at a stalemate, when a completely unprecedented development blew everything away. After much experimentation, Nick Driftwood discovered a technique that could eliminate P and B-frames entirely, producing videos with 1-frame GOP's that contained only Intra frames, at bitrates up to 176Mbps. The resulting videos packed a huge amount of data into each I-frame, for maximum image detail at the cost of equally unprecedented storage requirements. Since the bitrates were far too high for AVCHD file-spanning to work, the maximum duration of each take dropped to around 3 minutes per 4GB of SD card storage. Any doubts as to whether high-bitrate Intra-frame encoding really produced better image quality were soon laid to rest by Ralph_B's brilliant series of tests comparing driftwood's results to direct HDMI frame grabs.

Although GH2 Intra-frame videos can be recorded at bitrates lower than 176Mbps, image quality is inevitably reduced as well. This is the reason P and B-frames were designed into the GH2's AVCHD encoder in the first place: to reduce video bitrate to the point where 4GB file-spanning can work without noticeably degrading image quality. But somehow this goal fell short, because the stock GH2 clearly cannot match the quality of 176Mbps Intra videos.

GH2 Quantum Mechanics Revealed

Those familiar with video encoder technical details know how the GH2's AVCHD encoder works: it compresses video data by storing it in coarsely approximated data formats. It does so using cleverly devised tables of "quantizers" that slice and dice the data without visibly degrading it. Soon after the GH2 was hacked, Chris Brandin worked with Vitaliy Kiselev to develop a custom patch that would automatically boost quantizer quality at increased bitrates. He then used these "AQ" patches to develop his classic 44Mbps and 66Mbps patches, combining enhanced quantizer quality with moderate bitrates, while retaining the GH2's standard GOP lengths.

While the AQ patches provided important pieces of the GH2 puzzle, they were designed to work properly only with long-GOP encoding, not on ultra-short 3-frame and 1-frame GOPs. At the next layer deep within the encoder lie the actual quantizer tables used by the AVCHD codec - the core of the compression engine. After much research into the firmware, Chris extracted these tables into a spreadsheet, providing for the first time a complete overview of the encoder's inner workings. It was after I studied these tables in detail that I discovered the reason why P and B-frames had never looked as good as I-frames.

Panasonic designed the GH2 as a consumer camera using the limited 24Mbps bitrate dictated by the AVCHD standard. For this reason, their top priority was not achieving the highest image quality, but compressing the video data into the smallest amount of file space. To accomplish this, they minimized the size of P and B-frames by using significantly coarser quantizer tables to encode P and B-frames than they used on I-frames. It was no wonder that Driftwood's strategy of eliminating everything but the I-frames improved image quality!

Fortunately, Vitaliy had the foresight to hack the location of the GH2's quantizer tables, providing patches to reassign the tables used by I, P, and B-frames. In one fell swoop, I was thus able to optimize the quantizer tables for all three frame types, matching P and B-frame image quality to that of I-frames. This provided the key to combining Intra-frame quality with short-GOP motion tracking and compression efficiency.
 
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What Good is a GOP?

Intra-frame proponents rightly point out that encoding each video frame separately insures that no undesireable inter-frame motion artifacts can degrade the video. With long-GOP encoding stretching over a half-second per GOP, image quality can suffer when large amounts of object motion produce major discrepancies between P and B frames and their reference I-frames.

Simply by reducing the amount of image movement that can take place within each GOP, short-GOP encoders boost image quality by minimizing motion tracking discrepancies within the encoder. With a 3-frame GOP at 24fps, a new keyframe is produced eight times per second, limiting encoded motion to only what can occur within 1/8th of a second. Residual differences in frame-to-frame image details can then be encoded with much greater compression efficiency at potentially the same level of image quality as I-frames. And with PTool's Quantizer Table patches, it's now possible to configure the encoder for optimal P and B-frame image quality.
To produce optimal motion picture quality, however, it's not enough for individual frames to be encoded in high detail. A sequence of frames must also blend together in a seamless simulation of movement. To produce this illusion at low frame rates, there must be a high degree of frame-to-frame continuity, especially when it comes to high-contrast edges. If not, minute edge discrepancies can cause moving or panning objects to appear to flicker in a distracting manner. Rather than prioritizing still-frame image quality over all other considerations, the Flow Motion Patch is tuned to produce smooth continuous movement.

GH2 100Mbps Flow Motion Patch

This version of the 100Mbps Flow Motion Patch uses a 3-frame GOP in 24H and FSH modes, and a 5-frame GOP in SH mode. This produces 12 keyframes/sec in 720p60, which is 50% more keyframes than you get in 24H mode. In terms of motion flow, it's not the GOP-length, it's the keyframe rate that really counts.

Here are Stream Parser graphs of the Flow Motion 24H patch, first with a test chart:

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The test chart shows Flow Motion near its peak I-frame bitrate - 8Mbits per I-frame. To sustain this I-frame data rate in an all-intra patch would require 192Mbps. The test chart is too boring to stress the codec very much, so I tried to strangle it with a gnarly bush:

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The bush I shot handheld without image stabilization, but nothing I tried would make Flow Motion crash. Notice how much it boosted the B-frames to handle my jittery grip - this is what good quantizer tables look like. The I-frame height dropped because of how I throttled the bitrate to 100Mbps. That is the sweet spot for this patch, if you push the bitrate much higher the encoder will start to spaz out.

Here is Flow Motion at 720p60 in SH mode. Since a 720p frame has half as many pixels as 1080p, these 4Mbit I-frames are just as beefy as the 24H mode I-frames. P-frame consistency looks healthy as well.

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Here is no one's favorite mode, 1080i60 in Flow Motion. FSH mode is entangled in some unpleasant ways with both 24H and SH modes. This makes it rather neurotic and I had to straitjacket it a bit to keep it stable. As a result, its B-frames aren't quite as robust as 24H mode.

722dcbbfb5a9132ff1ea9ae7b1cd7c.jpg
 
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Here is a set of sample videos shot at ISO200, 1/60 sec, f4.0. These clips show how Flow Motion produces smooth, continuous motion pictures with minimal flickering, even at 24fps.

Flow Motion 24H 1080p24


Flow Motion SH 720p60


Flow Motion MJPEG HD 1080p30


Unfortunately, Vimeo seems to be unable to display interlaced 1080i60 videos. However, you can still download the original Flow Motion FSH 1080i60 MTS file from its Vimeo page.
 
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Thanks for summing it up for those new to GH2, like myself. One question, though. Have you experimented with GH1 GOP1 settings? The GH1 still haunts me and the GOP3 patch did not quite produce the motion rendering I was after, so I tested GOP1 settings posted by Ryan Kozicki http://vimeo.com/25218308

Now motion looks fine and I get average ~40 mbit/s in barely adequate lighting. Will GH1 continue to work at 75 mbit/s for GOP1 AVCHD as it does for MJPEG? Obviously it is almost time to migrate fully to GH2 but the GH1 is still useful too.
 
With the GH1, I was able to achieve stable results up to 100Mbps max bitrate. Even if a one-frame GOP could be made reliable, 100Mbps would not be enough to produce the highest image quality. My recommendations for the GH1 are to try the 100Mbps Max Latitude Patch, especially if you need Native 24p. If not, the 75Mbps Peak Reliability Patch delivers the most dependable high-bitrate results. Links to both patches can be found below in my signature.
 
I did a quick comparison with my own current patch (based on driftwood´s quantum 7 with lower bitrate). It´s hard to see differences at 1080p24 but at 720p60 and 1080i60 you can perceive a slight bit more detail with Q7 in the scene. As an example a side-by-side comparison (2:1 crop) with 720p-lpowell on the left side:

 
Thanks Ipowell for the write up. It really puts the most important information in one spot. I have read the personal-view threads till my head spin but realize I don't have the technical knowledge to understand. Cheers!
 
This is great!

So at 1080 24p, with the H mode set, we get 100MBs? How do we bring that down to the 50/30?
 
Holy Crapola!!!

I just did a fill-the-card-completely test with the 100 Mbit/sec patch with my affordable Patriot LX Pro 32 GB SDHC card and was able to record one 86 minute clip!

Using StreamParser my clip was averaging 105 Mbit/sec throughout. So 105 Mbit/sec motion optimized shooting with spanning on a $50 Patriot 32 GB card.

Can't wait to use this for a real shoot!

NewEgg.com : Patriot LX PRO Series 32GB for $50

EDIT: Something must be wrong here, as there's no way to fit 86 minutes of 105 Mbit/sec footage on a 32 GB card - Ignoring stream parser and just going with the 31 GB file on the card divided by the 86 minutes gives me 369 MB per minute, or 6.15 MB per second, which is 49 Mbit/sec. I was shooting on the 24H setting which is supposed to be 100 Mbit/sec, or does this vary by how busy the image is, meaning a static image will drop down to 50 Mibt/sec ?
 
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TheDingo said:
Something must be wrong here, as there's no way to fit 86 minutes of 105 Mbit/sec footage on a 32 GB card - Ignoring stream parser and just going with the 31 GB file on the card divided by the 86 minutes gives me 369 MB per minute, or 6.15 MB per second, which is 49 Mbit/sec. I was shooting on the 24H setting which is supposed to be 100 Mbit/sec, or does this vary by how busy the image is, meaning a static image will drop down to 50 Mibt/sec ?
Click to expand...
100Mbps is the max bitrate for Flow Motion - that's one of the things that insures stability in all video modes. If your subject matter lacks details or illumination, the average bitrate can indeed drop below 50Mbps and allow file-spanning even in 24H mode. For guaranteed file-spanning, 24L mode is set to 50Mbps, but will often produce I-frames nearly as tall as in 24H mode.

Make sure to download the latest version of Stream Parser, earlier versions are not able to interpret all parameters in Flow Motion files correctly. For an example of the minimum image quality you can expect in sub-50Mbps bitrate in 24H mode, here's a low-light comparison I did with Flow Motion 24H, cbrandin's 66Mbps AQ2 patch, and driftwood's 100Mbps Quantum patch:

 
lpowell said:
Make sure to download the latest version of Stream Parser, earlier versions are not able to interpret all parameters in Flow Motion files correctly.
Click to expand...

Can you tell me what the latest version number of Stream Parser is ?

And what is the recommended card speed for 100 percent guaranteed stability with Flow Motion 24H ?

Thanks!
 
lpowell,

Thanks for your hard work!

Does this patch work Panasonic's m4/3 lenses that rely on software correction of distortion?

I'm currently testing Sage's Nine patch, but haven't got to all the Lumix lenses yet, & will be testing yours soon.

Best,
Bern
 
Bern Caughey said:
Does this patch work Panasonic's m4/3 lenses that rely on software correction of distortion?
Click to expand...
Yes, definitely, all lens functions are supported just the same as the stock Panasonic GH2 1.0 firmware. In fact, I recommend using a lens with OIS in ETC mode to minimize jitter.
 
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