75Mbps GH1 Peak Performance Patch

L

Lpowell

Veteran
75Mbps peak bitrate combined with high reliability @ 50/60 fps

At the time the original 75Mbps GH1 Peak Performance Patch was released, I along with many other patch developers had reluctantly concluded that a stable Native 24/25p video mode could not be perfected for the GH1. It was not long after, however, that I discovered new stabilization techniques that led to the development of the Blackout-Powell Native 24p Patch and the Max Latitude Native 24/25p Patch. More recently, with Vitaliy's release of PTool 3.56d and higher, all previously unhackable versions of the GH1 have been liberated for use with freshly upgraded versions of my patches.

The primary focus of recent patches has been the optimization of 1080p Native 24/25p FHD video modes. In order to achieve bitrates as high as 100Mbps, however, it was necessary to restrict the 720p SH video modes to 25p in PAL mode and 30p in NTSC mode. For 720p SH mode recorded at the standard 50/60p frame rates, the 75Mbps peak bitrate of the Peak Performance Patch remains the highest I've achieved. With the aid of new stabilization techniques provided in the latest versions of PTool, I have been able to significantly improve the patch's high-bitrate reliability as well. Based on the comparison tests I've conducted, the stability of the updated 75Mbps GH1 Peak Reliability Patch is second only to that of my Reliable In-Camera Playback Patch.

Here are short descriptions of the updated properties of this patch:

75Mbps AVCHD 1280x720 SH mode @ 50/60 fps
While the unhacked 720p50/60 SH video mode offers high frame rates, its low 17Mbps maximum bitrate and long-GOP frame compression hamper its ability to track fast-moving subjects. In 60p mode, this patch reduces the length of each GOP to 20 frames, producing 3 key-frames per second. In addition, the codec's 75Mbps peak bitrate allows it to encode a large amount of image detail into each key-frame. Compression efficiency remains high enough, however, to limit average bitrates to less than 50Mbps.

75Mbps AVCHD Interlaced 1920x1080 FHD mode @ 24/25 fps
For those who do not require Native 24/25p video files, this mode produces the highest quality images available from the GH1 in both 24p and 25p interlaced FHD video modes. Turbo-charged with a 75Mbps maximum bitrate, the codec's ability to track moving objects without producing mud is significantly improved. As with the 75Mbps SH patch, the FHD encoder maintains an average bitrate no higher than 50Mbps.

75Mbps MJPEG 4:2:2 Color 1536x864 HD mode @ 30 fps
The MJPEG Intra-frame codec's unique advantage is its ability to produce highly detailed images in 4:2:2 color depth. This is especially valuable in green-screen rotoscoping, where you want to use the highest chroma resolution available. To maximize its usefulness, I've increased the MJPEG frame size to 1536x864 pixels, while maintaining the camera's normal16:9 aspect ratio. This frame size is exactly 20% taller than SH 720p mode, and 80% as tall as FHD 1080p mode. While it is non-standard, the intermediate frame size allows you to either flexibly crop the edited frame down to 720p, or upsample it to 1080p with minimal loss of resolution. And at 75Mbps max, the MJPEG encoder maintains consistently higher bitrates than the AVCHD encoder, particularly in dimly lit situations.

30Mbps MJPEG 960x720 VGA mode @ 30 fps
This iPod-compatible video mode produces HD-resolution 960x720 videos in a standard 4:3 aspect ratio. Its bitrate averages around 30Mbps.

Overall Patch Considerations
While no GH1 patch can claim to be absolutely bulletproof, I have tested these settings in a wide variety of extreme circumstances. However, with bitrates as high as 75Mbps, the safety margin is inherently narrower than my Reliable In-Camera Playback Patch. This patch is designed and tested only for the fastest Class 10 SDHC cards currently available.

Additional points of interest:

* The 75Mbps Peak Reliability Patch is compatible with all hackable GH1 cameras, and is switchable between NTSC and PAL modes.

* I recommend using the camera to format your SD at the start of each shoot, to guard against SD card memory fragmentation.

* Peak bitrates are obtained only with well-lit, sharply-focused, highly-detailed subject matter. Average scenes will produce average bitrates.

* High bitrate AVCHD videos may not play back reliably in-camera. The MJPEG videos produced by this patch will not be playable in-camera.

* 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.

* AVCHD 4GB file-spanning for long video takes may not work reliably at high bitrates. For reliable recording of takes longer than about 12 minutes, I recommend selecting the "H" video mode instead of "SH". This will produce average bitrates of about 28Mbps in 720p50/60 modes.

* For extended recording times at moderate bitrates, selecting the "L" video mode instead of "SH" will produce bitrates comparable to the camera's unhacked SH video mode.

* While AVCHD bitrates may drop to very low levels in extremely dark situations, this patch should continue to record even in total darkness.

*** WARNING ***

The 75Mbps Peak Reliability Patch will not work properly with previous versions of PTool. My thanks once again go to Vitaliy Kiselev, for his pioneering work on PTool, and to cbrandin for his invaluable Stream Parser tool.

The best way to insure that you have the latest PTool release is to download it directly from the following link:

Download PTool here: http://www.gh1-hack.info/ptool3d.zip


75Mbps Peak Reliability Patch Settings File:

This zipped INI file can be used to apply complete patch settings to firmware loaded into PTool. To use, unzip the INI file into the same folder as the PTool application. Launch PTool and load the firmware for GH1 v1.32. The settings contained in the INI file will automatically be installed in the "H" button at the bottom of the PTool main window.

Note that with the following PTool Settings File, you may at any time re-install the original Panasonic GH1 v1.32 firmware into the camera. You may also copy each type of patched or original firmware to separate SD cards, and use them to quickly switch between patches as often as you like.
 

Attachments

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75Mbps Peak Performance Patch Sample Videos

75Mbps Peak Performance Patch Sample Videos

Here are a serious of short videos I took to showcase the image quality of each of the high-definition video modes using the 75Mbps Peak Performance Patch. The original MTS and MOV video files should be downloadable for a time from my Vimeo page.

AVCHD 1280x720 @ 60fps


MJPEG 1440x810 @ 30fps


AVCHD 1920x1080 @ 24fps
 
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Thank you LPOWELL!! For 1080, I noticed it is in 60i and not 24p. I shot the same scene(my fish tank) for one minute and 1080 and 720 file sizes are about the same. Both max speed about 73.5 and avg. 33. I prefer that detail in 720p and has been looking for a reliable 720 until now. Thank you again!!
 
n210s said:
For 1080, I noticed it is in 60i and not 24p.
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Yes, while the GH1's FHD video mode records in 24p (or 25p PAL mode), it wraps the 24p video inside an interlaced 60i container (50i PAL). So far, no known combination of patches has been able to produce a reliable non-interlaced FHD video mode on the GH1.
 
MJPEG is neat! I like the color but you definitely need a correct exposure as it doesn't like to be underexposed. I am getting a flickering on the last horizontal line.
 
thanks for another great series of patches lpowell my cam in on the green progress bar as we speak :smile:

as StreamParser will not install on my MAC, i've been using VLC's "statistics" tab (cmd+I) that seems to show Live Bitrates...

does anybody know if this is a close to reliable readout?

just tested lpowell 75Mbps patch looks good out my bedroom window.
 
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lpowell said:
75Mbps AVCHD Short-GOP 1280x720 SH mode @ 50/60 fps
While the unhacked 720p50/60 SH video mode offers high frame rates, its low 17Mbps maximum bitrate and long-GOP frame compression hamper its ability to track fast-moving subjects. This patch reduces the length of each GOP to 20 frames, producing 3 key-frames per second at 60p. In addition, the codec's 75Mbps peak bitrate allows it to encode a large amount of image detail into each key-frame. Compression efficiency remains high enough, however, to limit average bitrates to 50Mbps.
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Lpowell, thanks for doing this, been patiently waiting. I do have one question though. The mts file on vimeo for this SH mode only has a bitrate around 33Mbps. In your description above you state the average is 50Mbps with a peak of 75Mbps. Why not 50Mbps? and isn't 33Mbps about what you would average in the 40Mbps high reliability patch for this particular high detailed scene?

I''m just not understanding the advantage here over 40Mbps patch. Please, don't think i'm knocking it, just not understanding the difference.

Thanks for all the work you do.

R
 
Native has been OK for me... I only have problems in this scenario:

720p60 shutter around 1/400, lots of detail (leaves, buildings plus a fence, zooming and/or panning) the recording stops. And I only ran through this situation by accident while testing between shots.

Aside from that, no problems. I was using the bitrates:

50
32
22
Overall 86

I'm gonna try my old settings (with native checked, of course) changing to what this setting suggests:

54
42
24
Overall 72

Let's see if I still get this 720p60 high detail and motion crash.

Edit: Yeah... Really weird, it can't handle the 60 frames of 720 with high detail, however, switch to 1080p24 and it's without a hitch.

Still at 720p60 it even handles 1/125, but when it nears 1/400 it breaks. Strobing frames with too much detail must stress the codec.
 
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rambooc1 said:
The mts file on vimeo for this SH mode only has a bitrate around 33Mbps. In your description above you state the average is 50Mbps with a peak of 75Mbps. Why not 50Mbps? and isn't 33Mbps about what you would average in the 40Mbps high reliability patch for this particular high detailed scene?
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Good question, rambooc, the lower bitrate in my 720p60 video was at first puzzling to me as well. Working it out led me to a deeper insight into how the AVCHD encoder balances the bitrates of its I-frames and P-frames.

In previous AVCHD patches I've used a only single figure to describe the expected bitrate, as in my 40Mbps High Reliability Patch. With that patch in particular, my aim was to set a safe maximum bitrate (44Mbps) and tune the encoder to maintain its average bitrate as close to the limit as possible. The result in that case was a typical bitrate of 40Mbps, which gradually decreases as illumination and image detail decrease.

With this patch, however, it quickly became clear that the 75Mbps maximum bitrate limit was far too high for the encoder to maintain for any sizeable length of time. After a number of tests, I had to conclude that the 50Mbps bitrate I achieved in my Fast Action 3-Frame GOP Patch was about the highest average bitrate the encoder can reliably handle. This forced me to reconsider whether there was any real value to pushing the maximum bitrate up to 75Mbps.

The answer dawned on me after staring at several hundred Stream Parser graphs. The AVCHD encoder's maximum bitrate peaks occur when it packs a large amount of bits into encoding each key frame. With a 75Mbps limit, it was able to produce much bigger key frames than it could with any previous patch. And with a shortended GOP length, the encoder has relatively more bits available for the I-frames (bits that it had previously used to encode P-frames). To put it simply: maximum bitrate sets an upper limit on I-frame image quality, while average bitrate is determined by how much data is needed to encode the P-frames.

If you examine the Stream Parser graph of my 33Mbps 720p60 video, you'll see a series of highly peaked I-frames followed by groups of P-frames encoded at much lower bitrates. This corresponds to videos of highly detailed, but largely static scenes with little motion. The encoder is producing a highly efficient video stream with maximum quality I-frames and can use relatively few bits to consistently maintain the same level of quality in its P-frames.

The Stream Parser graph of my 50Mbps 1080p24 video shows markedly different behavior. Here the I-frame peaks are not that much higher than the peaks of the following P-frames. In addition, you'll see that P-frame height is nowhere near as consistent - it tends to alternate levels between adjacent P-frames. This is a mark of interlaced video, and it forces the encoder to spend relatively more bits on its P-frames than the non-interlaced 60p encoder needs. As a result, the average bitrate rises to 50Mbps to accommodate the needs of the interlaced video stream.
 
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Comparing this patch to the 50mb AVCHD one. Would you see any difference in low light situations between the two?
 
Good work man. Vitaliy may have delivered the hack to us but your efforts have pushed it to its limits. Just imagine what you could do if we ever get a hackable GH2! A 75 mb/sec 1080p @ 60 FPS 40% slow motion mode would be absolutely incredible with some really fast glass.
 
Interestingly, I found a flaw in the GH2 last night. I am able to reliably reproduce a scenario where the GH2 fails to write to a high speed Class 10 card in 720p @ 60 FPS mode. It fails with the write speed error. This may be our opportunity to get a firmware update for the GH2! I will try to post a video showing the issue.
 
Thanks as always for the props, mpgxsvcd. In case you're wondering, I've been working on a separate 75Mbps patch for the GF1/G2 to optimize their AVCHD-Lite 720p30 SH mode.
 
lpowell said:
Thanks as always for the props, mpgxsvcd. In case you're wondering, I've been working on a separate 75Mbps patch for the GF1/G2 to optimize their AVCHD-Lite 720p30 SH mode.
Click to expand...

I was just going to ask that. We can always count on you. However, I haven't touched my GF1 since I got my GH2. The GF1 has been relegated to taking videos and pictures of the GH2. That is all I use it for now. I was going to sell it but you can barely get $300 for a decent shape used one now. I might just give it to a family member. However, I would have to give them a lens as well and those cost more than the camera now.

On a side note: If anyone is in the Raleigh NC area and they would like to compare a hacked GH1 or G2 with the GH2 or a hacked GF1 just let me know. I would love to do an ultimate shootout and film the exact same scenes with every m4/3s camera and see what the differences are. However, it might be hard to get all of those cameras in the same place at the same time.
 
tested the new lpowell patch today, unfortunately speed write errors and a bit of frame skipping plagued 1080 FHD for me, i was shooting foliage, grass, branches, very high detail shots trying to see how far it could be pushed, recorded for 1 second then speed write error appeared :o( it worked on everything else tho but i didn't have any luck on high detail. (Panasonic 8GB Class 10 card)

720 SH was error free and seemed unstoppable, handled very high detail scenes and quick motion with ease.

i had great success the previous day with near error free shooting and average bitrates of around 48Mbps/sec on high detailed scenes using a slightly modified lpowell 40Mbps high reliability patch & 35Mbps Mjpeg in camera patch (J button within ptool)

i changed the AVCHD to...
FHD/SH 60
H 50
L 32
OVERALL 62
GOP unchanged

i dont really know what i'm doing with all the numbers but i tried those above on the lpowell J button patches within ptool and seemed pretty good, maybes lpowell can shed some light on if they are good or if they have hidden flaws i'm not picking up on.

anyways peace and great patches lpowell :smile:

i uploaded the MTS file if anyone wants to download and check quality (vimeo playback is awful!)
http://vimeo.com/18928364
 
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