Hacked GH1 for live events?

[Vitaliy Kiselev]

You just do not get how GH1 encoder works.

It looks like it have fixed quantization matrixes. And can only reduce overall bitrate up to the certain point (by multiply matrix cooficients to some number).
So, if you are shooting low detailed scene it need to raise bitrate, but it just do not have such logic implemented. Why? Because it is not an easy task. If you raise quality to good levels and suddenly details in frame go up you'll get bitrate overflow error. because you can't know detaild before compression. and you don't have resources to recompress too detailed scene.

 

[rmk]

OK, so does that mean that the only way one can get the best out of low-light/low-detail shots is to have a separate firmware version with super-high bitrate settings which would probably freeze on high-detail motives and then change the firmware depending on the motive?

 

[timbook2]

I used the c settings in 720p on class 6 cards and it was broadcast in tv ...no problems!

 

[Lpowell]

OK, so does that mean that the only way one can get the best out of low-light/low-detail shots is to have a separate firmware version with super-high bitrate settings which would probably freeze on high-detail motives and then change the firmware depending on the motive?

For low-light scenes, I'd suggest trying MJPEG @ 720p. Even at a 35Mbps bitrate for in-camera playback, MJPEG does quite well:
http://dvxuser.com/V6/showpost.php?p=2036744&postcount=3

 

[rmk]

For low-light scenes, I'd suggest trying MJPEG @ 720p. Even at a 35Mbps bitrate for in-camera playback, MJPEG does quite well:
http://dvxuser.com/V6/showpost.php?p=2036744&postcount=3

This looks really nice! I'd be more than happy with that quality. Will try it once I get home. Thanks!

 

[svecher]

I don't see any mud improvement or difference between them, I may be doing something wrong during the Ptool preparation, or perhaps I need to run some tests on a scene with foliage?
http://vimeo.com/14020652

In this test shot you will not see any "mud improvement", because there is no mud present The scene has low enough detail for stock encoder to not exhibit the mud problem. The only issue I see is significant underexposure. There was a thread, which I can't find quickly, that showed how well does MJPEG 4:2:2 mode deal with +3EV adjustment.

If you want to see mud, pan at moderate speed across a field of flowers or foliage or any other high detail scene.

 

[Rockroadpix]

major stress test- ignore the sound, I was aiming for vid quality plus, I was in the pit next to the pa.

 

[Beernardo]

Thanks Svecher, I'll change my testing scene and run another comparison with those same settings.

I underexposed the video on purpose because that's how I experienced the presence of mud during the wedding ceremony. Regarding the MJPEG mode, after reading this post I decided to stick to AVCHD http://www.eoshd.com/content/260-High-ISO-GH1-AVCHD-vs-MJPEG

 

[Beernardo]

For low-light scenes, I'd suggest trying MJPEG @ 720p. Even at a 35Mbps bitrate for in-camera playback, MJPEG does quite well:
http://dvxuser.com/V6/showpost.php?p=2036744&postcount=3

But what happens when you try to color correct it? does it brings out some mode? I need to have some settings that will let me do some color grading

 

[Beernardo]

major stress test- ignore the sound, I was aiming for vid quality plus, I was in the pit next to the pa.

Very nice footage, did you have to do any color grading? if not, how do you think it will handle it? will it bring out some compression artifacts which we are not seeing in the out of the camera footage?

 

[Lpowell]

But what happens when you try to color correct [MJPEG 720p video]? does it brings out some mode? I need to have some settings that will let me do some color grading

The MJPEG settings in my Reliable In-Camera Playback Patch record 720p in 4:2:2 color depth, the same color resolution as ProRes 422, but limited to 8 bits of precision. This will produce better color grading results than AVCHD, which only supports 4:2:0 color. I've also found that the GH1's MJPEG encoder maintains higher bitrates under low-light conditions than the AVCHD encoder.

It's important to fine-tune the color temperature and color correction as much as possible in-camera, rather than in post. The sensor has a raw 12-bit Bayer output and the camera's spectral equalization is very good when properly tweaked. Since the encoded output data is at best 8-bit resolution, you don't want to have to push it any farther than necessary.

 

[Beernardo]

Thanks LPowell, I'll try your MJPEG settings and report back

 

[Beernardo]

The MJPEG settings in my Reliable In-Camera Playback Patch record 720p in 4:2:2 color depth, the same color resolution as ProRes 422, but limited to 8 bits of precision. This will produce better color grading results than AVCHD, which only supports 4:2:0 color. I've also found that the GH1's MJPEG encoder maintains higher bitrates under low-light conditions than the AVCHD encoder.

It's important to fine-tune the color temperature and color correction as much as possible in-camera, rather than in post. The sensor has a raw 12-bit Bayer output and the camera's spectral equalization is very good when properly tweaked. Since the encoded output data is at best 8-bit resolution, you don't want to have to push it any farther than necessary.

What's the longest you've been able to record with your MJPEG settings without crashing the camera? This guy says he haven't found a safe settings for MJPEG yet:
"I've still not found a flavour of MJPEG that doesn't occasionally crash the camera though" (http://www.dvxuser.com/content/260-High-ISO-GH1-AVCHD-vs-MJPEG)

 

[Lpowell]

What's the longest you've been able to record with your MJPEG settings without crashing the camera?

I first published the settings for my 35Mbps MJPEG In-Camera Playback Patch two months ago:
http://dvxuser.com/V6/showthread.php?t=215624

This same MJPEG patch has also been distributed in MarekV's Perfect Project:
http://www.dvxuser.com/V6/showthread.php?t=216063

So far, I haven't seen any reports of MJPEG recording failures on Class 6 or higher SD cards that were attributable to this patch. Since it's designed for reliable in-camera playback, the patch's 37Mbps maximum bitrate is significantly lower than the maximum bitrates than can be used to record MJPEG videos (50-100Mbps max).

When recording MJPEG videos, the maximum file length limit is only 2GB. On an unhacked GH1, this is long enough for about 8 minutes of 720p video. The 30-35Mbps MJPEG videos I've recorded can run up to about 5 minutes. The camera does not crash when it hits the 2GB file size limit, it simply stops recording.

 

[Rockroadpix]

No color grading, yet. That was the raw footage. grading to happen this week. Sorry for the late reply. I think it will handle it pretty well.
& Thanks!

 

[dirkmm]

I've done three (3) weddings (indoor and outdoor) using the 'C' settings on the latest PTool without issue. I've only shot in 1080p24 (no native 24p hack). But, I've had the cameras run for 40 minutes straight without issue. This is on a cheapo Transcend Class 6 16GB card.

I did have one problem where an exceptionally long clip (about 45 minutes) was not able to be played back in-camera for some reason, but it worked fine in Final Cut.

 

[Beernardo]

I've done three (3) weddings (indoor and outdoor) using the 'C' settings on the latest PTool without issue. I've only shot in 1080p24 (no native 24p hack). But, I've had the cameras run for 40 minutes straight without issue. This is on a cheapo Transcend Class 6 16GB card.

I did have one problem where an exceptionally long clip (about 45 minutes) was not able to be played back in-camera for some reason, but it worked fine in Final Cut.

You are the first person I've read about that didn't have any problem using the C settings. What's the average mbit/s you got with those settings? Also, how much recording time can you fit into a 16gb card? Without the hack I can fit almost 2 hours of footage.

 

[Lindenberg]

When using my SanDisk VideoHD Class 6 card with the B setting I get an error after 4gb of data has been written to the card. In between the A and B settings at A.5 everything works perfectly. Looks like I need to get some faster cards.

 

[dirkmm]

You are the first person I've read about that didn't have any problem using the C settings. What's the average mbit/s you got with those settings? Also, how much recording time can you fit into a 16gb card? Without the hack I can fit almost 2 hours of footage.

Average seems to hover in the low 30s. I've seen it spike high enough to give me a card write error, but that was only on a filler shot of a bouquet of flowers. The last indoor wedding I did only had average around 22, but that's expected as there isn't a lot of changing detail in a semi-controlled situation like that.

I've been finding I can get an hour, maybe a bit more depending on detail level, with those settings on the card. Again, with AVCHD it will just depend on how detailed/changing the scene is. If you were able to max the bitrate out, you'd only get 45 minutes of footage (if you didn't error out first).

 

[Beernardo]

Average seems to hover in the low 30s. I've seen it spike high enough to give me a card write error, but that was only on a filler shot of a bouquet of flowers. The last indoor wedding I did only had average around 22, but that's expected as there isn't a lot of changing detail in a semi-controlled situation like that.

I've been finding I can get an hour, maybe a bit more depending on detail level, with those settings on the card. Again, with AVCHD it will just depend on how detailed/changing the scene is. If you were able to max the bitrate out, you'd only get 45 minutes of footage (if you didn't error out first).

That's some good information there Dirkmm. Indeed, there are not much changing scenarios during the ceremony, except for when the couple walks outside the church at the end of the ceremony, there's a los of contrast there, do you think it will mas up the bitrate?