Pro: GH2 AVCHD encoder settings

EOSHD

All very strange. Image quality seems to be going backwards with high bitrate settings. All quite different to the GH1. Not found any settings that really work yet.

Also - strange bug - now 1080/50p recording ends immediately and instead of crashing camera resets AVCHD settings to whatever they were on last boot. Also, I have found my GH2 just changed my AVCHD folder name to lower case 'private' instead of PRIVATE. Like I say... VERY ODD!!

All my current settings attached.

Sage

The second looks a lot worse than what I usually see out of the gh2. What settings do you use in concert with half gop? (is there any pulsing in bitrate?)

EOSHD

Thanks Vitaliy. Indeed image quality is not really much improved. Currently the bitrate settings only seem to effect i-frames and nothing else, meaning average bitrate and image quality stay roughly the same as default. After using standard GOP, average bitrate fell to normal levels again.

Had more mud with standard GOP 12 than low GOP 6 though.

Vitaliy_Kiselev

Higher bitrate means less compression only if all else is equal.
Lower GOP always means more compression if all else is equal.
I-frames are worst in compression efficiency (charts on your screenshots show it visually).
B-frames are best :-)

EOSHD

OK I will now test same bitrate settings with standard GOP.

My theory was higher bitrate means less compression, lower GOP means more i-frames and so also less compression (but at expense of efficiency). Am I wrong Sir @Vitaliy_Kiselev? :)

Vitaliy_Kiselev

@EOSHD

You are not gaining anything by lowering GOP and obtaining slightly higher bitrate.
As actual target is image quality, not bitrate number.

EOSHD

@APXmusic

Yes, higher. Not mega-ambitious but higher than I got in default 24Mbit. Here is latest findings. GOP size of 6 and aimed for 28mbit with PTools. StreamParser reports 5,040,000bit i-frames, GOP seems reliable (no odd results, stable). Average bitrate is 4-5Mbit higher than I was getting in standard 24Mbit mode.

Will share all PTools settings in a moment, just performing a 2nd tweak.
See StreamParser results below.

APXmusic

Has anyone gotten 1080/24p to show a higher AVG Bitrate in StreamParser? I'd be interested in seeing people's settings. Anything good on your end @EOSHD ?

alcomposer

@mpgxsvcd "I get an uneven cadence for 1080p, 1080i, and 720p most of the time with your settings"

Are you talking about the HDMI output (regarding Cadence) or simply the recorded video... I think that EOSHD mentioned that the HDMI mode was either changed- or was able to disrupt video capture?

Great work guys! (My body is on the way!)

plasmasmp

Yeah, it was the LA7200. Modified Cokin Diopter

EOSHD

He says it is LA7200 on Vimeo, with a diopter.

DrDave

@plasmasmp I would also like to know which anamorphic lens you used, tx ia

EOSHD

Have yet to get working 1080/24p at high bitrate, any luck with that @Angry_C? I'm ignoring 720p for now more interested in other aspects.

stoney

@mpgxsvcd I understood. So exciting to hear about fast progress. Awesome!!!

Angry_C

ok, I have to uncheck the 1080 boxes and check more files. I have 20 different clips now and no uneven cadence.

mpgxsvcd

@Angry_C

Your settings affect all modes. The settings may not say that they affect 1080p. However, they do. I get an uneven cadence for 1080p, 1080i, and 720p most of the time with your settings. Do some more testing and you will see the instability of changing the max bit rate settings.

Angry_C

@eoshd:

Yes, my setting ignores the 1080 modes.

I don`t talk about streamparsers "Stream max speed"
Streamparser displays two "min/average/max". One in Time-Mode, one in Frame-Mode.

This one in Time-Mode is the same as in Media-Info or in windows explorer and the same i can calculate!

mpgxsvcd

@stonebat

For now I would just watch from the sidelines. None of the changes so far are completely reliable. Give us a week or two. There should be a lot of great progress in the next two weeks. By then we should be able to make simple instructions for what can be done with the hack.

We could make the instructions right now. However, they might change by the end of the day after further testing. They might even change the next hour. Progress is happening that fast.

stoney

Hi Good People,

Can someone please post about GH2 Testing 101 for newbies? Or is there already a posting about it?

Thanks and keep up the good work! Woo-hoo!!!

mpgxsvcd

Yea I tried the settings and I got very uneven cadences for most videos. I did get 2 even cadences with a moderate average bit rate and very high max bit rate. However, the file was no better than stock. I still say a higher average bit rate and an even cadence is everything. It doesn't matter what stream parser says is the max bit rate.

EOSHD

@Angry_C

Tried your settings. Unfortunately no improvement to bitrate that I can see:

1080i
Average Total Bitrate = 17,782,378
Average Video Bitrate = 16,802,889

1080/24p
Average Total Bitrate = 15,788,523
Average Video Bitrate = 14,848,051

Ignore the stream: Max speed number in StreamParser, it is just a number. It is the average bitrates we should be looking at.

mpgxsvcd

I got the file to work and I am trying the settings now. I am afraid that your settings will adversely affect 1080p @ 24 FPS though. We shall see. Thanks for all of your efforts.

mpgxsvcd

@Angry_C

It says your .zip file is invalid when I try to open it.

Angry_C

@mpgxsvcd

I calculate your file:

73 Mbyte = 33sec.

73 * 8 = 584 mbit

584 mbit/33 sec = 17,96 mb/s

My settings are stable after a short recording in 1080i or 24p

mpgxsvcd

@Angry_C

Can you post the settings file for your charts. Those look great. I was not getting the smooth cadence you are getting when I increased max bit rate. I would love to see what you did differently. Are those settings stable after you record a 1080p file?

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