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KarimNassar
05-09-2012, 05:15 AM
Hello everyone, I am new to video recording and I must say the subject is quite fascinating.

Regarding improving image quality on the GH2, we have the option of hacking to increase bit rate or the use of an external recorder.

Hopefully this is not a stupid question, but which is best?

When using the hack you increase the bit rate of the images thus improving quality but you still get the AVCHD 8 bit compression correct?

External recorders like the ninja, record the images via hdmi before they are processed through the internal codec of the camera and directly in 10 bit ProRes correct?

Would that not yield better image quality than hbr without the need to hack the camera?

thanks!

stoneinapond
05-09-2012, 07:26 AM
As far as I remember, the HDMI output for recording is next to useless because of the way it is implemented. Using it for monitoring is fine.

There was a lot of discussion on this topic a while back and perhaps you can search out the details.

mcbob
05-09-2012, 08:12 AM
I don't even like using the HDMI for monitoring because of how it kills ETC and 720. IIRC, the signal is always interlaced and only 8 bit 4:2:0, and as such nearly pointless to feed to a recorder.

Internal hacked lets you shoot in ETC and 720, at whatever bitrate, and you don't have to deal with powering some makeshift contraption and pray your HDMI cable doesn't get tweaked or unplugged.

Ian-T
05-09-2012, 09:55 AM
As far as I remember, the HDMI output for recording is next to useless because of the way it is implemented. ...

That's not quite true at all. I know some people have different opinions on the matter but the HDMI out is very useable. Matter of fact...Some of the best hacks (and there are some great ones) are not quite up to par with what comes out of the HDMI. Sure, the HMDI signal seems messed with by Panasonic...but the following thread shows a good workaround...especially for folks on a PC.

HDMI CAPTURE-PROBLEM SOLVED
(http://www.dvxuser.com/V6/showthread.php?237584-HDMI-Capture-Problem-SOLVED-AviSynth-RULES!)
It's been heavily discussed.

Who says it's 8 bit 4:2:0? People keep speculating that because it's at a funky 60i. But that's speculation. I don't use it myself btw. I'm good with the hacks.

stoneinapond
05-09-2012, 10:38 AM
That's not quite true at all. I know some people have different opinions on the matter but the HDMI out is very useable. Matter of fact...Some of the best hacks (and there are some great ones) are not quite up to par with what comes out of the HDMI. Sure, the HMDI signal seems messed with by Panasonic...but the following thread shows a good workaround...especially for folks on a PC.

HDMI CAPTURE-PROBLEM SOLVED
(http://www.dvxuser.com/V6/showthread.php?237584-HDMI-Capture-Problem-SOLVED-AviSynth-RULES!)
It's been heavily discussed.

Who says it's 8 bit 4:2:0? People keep speculating that because it's at a funky 60i. But that's speculation. I don't use it myself btw. I'm good with the hacks.

Wow, a 61 page thread. This from OP posted earlier this year. And I quote.

"Actually there are people using it, but yes, there is a lot of technical fear. As to whether it's still worth it, that's a question that can only be answered by how much of an insane perfectionist you are. The gap between the HDMI picture and the hacked H264 is very small now, whereas once it was huge, as you know. Just the other day I was watching one of my comparison tests projected onto a 10 foot screen. Fine detail was basically equal, which is a major achievement for the hack. But yet, there were still differences. At high ISO's the noise in the HDMI picture was less intrusive than the H264. The HDMI picture 'pops' more because of it's slightly different gamma curve. And the HDMI picture has a certain feeling of solidness that the H264 doesn't quite have.

But is that worth it to go the HDMI route? Damned if I know. I'm just being your reporter. For me personally, I'm more than happy with the hack. Nowadays I use the HDMI as a yardstick to see how far along we're coming. But I still maintain this thread for those few 'insane perfectionists' who may happen to come this way."

Ian-T
05-09-2012, 01:19 PM
Wow, a 61 page thread.
Yeah...it's a daunting task to read through all of that.



This from OP posted earlier this year. And I quote.
"Actually there are people using it, but yes, there is a lot of technical fear. As to whether it's still worth it, that's a question that can only be answered by how much of an insane perfectionist you are. The gap between the HDMI picture and the hacked H264 is very small now, whereas once it was huge, as you know. Just the other day I was watching one of my comparison tests projected onto a 10 foot screen. Fine detail was basically equal, which is a major achievement for the hack. But yet, there were still differences. At high ISO's the noise in the HDMI picture was less intrusive than the H264. The HDMI picture 'pops' more because of it's slightly different gamma curve. And the HDMI picture has a certain feeling of solidness that the H264 doesn't quite have.

But is that worth it to go the HDMI route? Damned if I know. I'm just being your reporter. For me personally, I'm more than happy with the hack. Nowadays I use the HDMI as a yardstick to see how far along we're coming. But I still maintain this thread for those few 'insane perfectionists' who may happen to come this way."





Sure, I understand. I am also pleased with the hacks. But, at least for me, it's good to know that we do have an option. I just wish someone would clarify once and for all if the HDMI output is really 4:2:0 or actually a mangled 4:2:2. Not that it's important because I am liking what I see either or.

WielkiCzarnyAfgan
05-09-2012, 02:17 PM
I think recording to some external uncompressed recorder is more stable than recording to SD card, other issue is- external recorder gives 10bit colour instead of 8bit.

gonzo_entertainment
05-09-2012, 02:35 PM
Seems like extreme hassle and expense for at best marginal difference in quality.

Ian-T
05-09-2012, 03:23 PM
If you are color grading your stuff....then it's more than just marginal IMO.
Also when it comes to tracking or green screen effects.
For general use...sure....overkill.

KarimNassar
05-10-2012, 03:08 AM
I appreciate the input everyone very interesting!

Ian-T brings up a crucial point that I found has been missed a lot based on what I have read on the subject online.
A lot of people compare the raw footages and say that there is not a visible difference and move on. I've seen the same reasoning with hacked vs non hacked GH2 footage.

It's when you push the image in post that the difference will be noticeable.

As far as I am concerned an external recorder brings an interesting feature which is instant back uping as you shoot, since you have to record on your sd card simultaneously when you shoot you get an instant back up via hdmi which is convenient.

Now I have decided to wait on the release of the atomos ninja 2 (solely based on the new hdmi out port that is a must have imo) and maybe purchase it then.

If I do I will share with you guys a comparison with hacked footage, but the footage will be heavily graded to see if the quality difference is worth the spending.

ed_lee83
05-12-2012, 10:08 AM
I just recently snagged a NanoFlash recorder and did some prelim tests comparing the 180-220mb footage (highest I can go with my 400x card) with the Sanity and Flomotion hacks (can't do the high Driftwood stuff cos no SDXC card). While the bitrate from the NF is obviously higher, it appears the noise is heavier. Which is a bummer. I guess I can upload that test footage but don't know if the online compression would mask it
There's also differences in colour tint when you switch from LCD and viewfinder. My initial observation suggests the colours are more in-line while the LCD on (which the only downside is that eats more battery life).
There is a way to get rid of all the on-screen display without pushing the record, but the image is very crushed and well, very interlaced? I'll need to do more tests. If anyone has any good tips on what/how to test let me know.
I didn't get the NF solely for the GH2, I do plan to get the Sony FS100 or FS700 if I'm feeling impulsive. But while I have it now just thought I'd give it a spin on the 'ol GH2

KarimNassar
05-14-2012, 01:56 AM
I just recently snagged a NanoFlash recorder and did some prelim tests comparing the 180-220mb footage (highest I can go with my 400x card) with the Sanity and Flomotion hacks (can't do the high Driftwood stuff cos no SDXC card). While the bitrate from the NF is obviously higher, it appears the noise is heavier. Which is a bummer. I guess I can upload that test footage but don't know if the online compression would mask it
There's also differences in colour tint when you switch from LCD and viewfinder. My initial observation suggests the colours are more in-line while the LCD on (which the only downside is that eats more battery life).
There is a way to get rid of all the on-screen display without pushing the record, but the image is very crushed and well, very interlaced? I'll need to do more tests. If anyone has any good tips on what/how to test let me know.
I didn't get the NF solely for the GH2, I do plan to get the Sony FS100 or FS700 if I'm feeling impulsive. But while I have it now just thought I'd give it a spin on the 'ol GH2

Did you go through the correct steps to record via hdmi?
There is a couple steps you need to do in the correct order otherwise there is some quality issue in the recording I believe:
"I also recommend rolling the camera first, then starting the external capture. And stop the external capture before stopping the camera. This will give you the cleanest signal and avoid the discontinuity that occurs when the GH2 switches into and out of record."
Here are the official guidelines for the atomos ninja, I believe they apply for the nano flash:

http://atomos.activehosted.com/kb/article/input-sources/dslr-cameras/panasonic-gh2

Also did you convert the footage via AviSynth?

http://marvelsfilm.wordpress.com/2011/04/27/gh2-hdmi-recording-avisynth-script-update/

Definitively very interested in your tests.
Please do share once you do them.

yoclay
05-14-2012, 02:12 AM
One of the real questions for me revolves around output for PAL. I have never found the hacks quality up to par with the NTSC stuff. It puts out an interlaced signal at 50i which is nowhere near the bitrate of Driftwood's best 24p hacks. Wondering if going down the recorder route wouldn't improve things considerably for us PAL people. Any comments from those among us working at 25p?

CRFilms
05-14-2012, 03:16 AM
There were some weird things happening with PAL vs NTSC on GH1. If you tried to do interleaced at 60i with low GOP, it wouldn't even remotely look right. HOWEVER, you could run as low as GOP2 in 50i.

I do wonder if you captured at 50i on the GH2, do proper deinterlace in post, if it would give you a better image than capturing 25p native? If anybody has a recorder and would be willing to test 50i that would be awesome.

ed_lee83
05-14-2012, 06:02 AM
Did you go through the correct steps to record via hdmi?
There is a couple steps you need to do in the correct order otherwise there is some quality issue in the recording I believe:
"I also recommend rolling the camera first, then starting the external capture. And stop the external capture before stopping the camera. This will give you the cleanest signal and avoid the discontinuity that occurs when the GH2 switches into and out of record."
Here are the official guidelines for the atomos ninja, I believe they apply for the nano flash:

http://atomos.activehosted.com/kb/article/input-sources/dslr-cameras/panasonic-gh2

Also did you convert the footage via AviSynth?

http://marvelsfilm.wordpress.com/2011/04/27/gh2-hdmi-recording-avisynth-script-update/

Definitively very interested in your tests.
Please do share once you do them.

Thanks for that. Will try that method.
The NanoFlash has built-in 3:2 removal

ed_lee83
05-14-2012, 09:59 AM
I haven't tested it to the hacks yet (don't really know which one?) but here's a test comparing it to a stock v1.1 GH2:

42134866

KarimNassar
05-15-2012, 12:47 AM
thanks for the test! :)

Now to make things interesting you have to push the image out of its comfort zone.
The difference in bit depth and codec *should* be more noticeable when pushing the image in post and not when comparing raw footage.

If you are willing to do another test one I think would be interesting and easy to setup is the following:

An orange with a light on the left side (key light) and a white piece of paper on the other side (bounce card) resting on a white piece of paper.

Expose the image so that the left side of the orange lit by the key light is properly exposed and retains texture and color information. Place the bounce card in a fashion so that the other side is lit and has some detail but very little and should look very dark but not black when shot.
Similar to this:

http://www.drawandpaint.net/wp-content/uploads/chiaroscuro.png

Now record the orange once with the hack and once with the nanoflash.

Take both footage in your video editing software and bring up the shadow information ( usually via a filter named shadow highlight ) in a couple different increments.

This test will demonstrate if the nanoflash retains more shadow information and provides less banding/artefacts or noise when pushing the image.

Should be interesting!