constant for 1080p test

[blue72]

I have tested "constant for 1080p" several days. At first I was astonished at the stability of the "constant for 1080p" setting.
I could record the pappasart chart for 5 minutes without recording speed error.(on tripod) So I recorded the complicated situation (full of grass ground).
I could record without recording speed error. But, when I played the movie on computer, it seemed that the movie was flickering somewhat.
So I analized the movie files and found that the file was not perfect. Like the "picture 1", there are blank frames.

Picture1 : stream parser shot (tripod recording)

I think that blank frame make the movie flickering. Because of the flickering the quality of the movie is lowered, and the merit of the 24P mode was lost.


When I record the pappasart chart on hand held, the blank frame occurred less than that recorded on tripod.("picture 2")
But there was blank frames occurred as ever.

Picture2 : stream parser shot (hand-held recording)

The setting I tested was like this.
[Settings]
Prevent version compare=Checked
Third-party battery=Checked
All Interface Languages=Checked
720p30 420->422 color sampling=Checked
E1 Quality=386
E1 Table=24
E2 Quality=330
E2 Table=24
E3 Quality=300
E3 Table=24
E4 Quality=276
E4 Table=24
Native 24p/25p=Checked
720p59,94fps->29,97fps=Checked
Video Bitrate FHD/SH=41000000
Video Bitrate H=40000000
Video Bitrate L=24000000
Overall Bitrate=42000000
720p60 GOP Size=3
1080p24 GOP Size=6
Preset bitrate=180
Preset bitrate 2=180
Constant for 1080p=422160
Constant for 720p=561600


I supposed that if the bitrate is too high, the blank frame occurrs. So I changed the Video Bitrate FHD/SH=253000000, Overall Bitrate=25500000.
But the result was same as ever. (Picture 3)

Picture3 : Video Bitrate FHD/SH=253000000 (on tripod recording)

When I setted the GOP size as "12", the write speed error occurred. But the write speed error did not occurred on GOP size "6".
The result was same as the other settings. When the GOP size was similar to "6 or 5" the stability was high, but on big GOP size,
the stability was low regardless of Video Bitrate FHD/SH.
So I changed the Video Bitrate and constant for 1080p. When I setted the constant for 1080p as "422160",
I could record the pappasart chart (on tripod) without recording speed error regardless of Video Bitrate. And the movie flickerred as ever.
Recording time was about 6 minutes at best. But when I changed the constant for 1080p as "466560" or "544320", and others the recording speed error occurred.
Now I suppose that "constant for 1080p" can improve the stability of the GH1 but the blank frame occurs. The stability of movie is almost perfect.
There were a few speed errors on recording. In that case the error did not ocurred in the mean time of recording but occurred on starting
(i.e. write speed error occurred on pressing recording button - So I could avoid freezing GH1)
If the GH1 start recording, GH1 is not shut down in the mean time of recording. Nevertheless the quality is not good, GH1 record the movie to the end on this setting.
Of course, on simple situation(low bitrate situation) there is no blank frame and the qualty of movie is good.
I think that if the weakness of "constant for 1080p" can be complemented, 24P recording matter will be cleared. I hope it can be achived.

 

[Lpowell]

I used the "Constant for 1080p" patch to help stabilize my Fast Action 3-Frame GOP Patch. Examining the settings I used in that patch may give you a head start on understanding the errors you've encountered.

http://www.dvxuser.com/V6/showthread.php?222791-50Mbps-AVCHD-Fast-Action-3-Frame-GOP-Patch

 

[blue72]

I have tested your setting and applied only the value 544320 (the value you have applied in "Fast Action 3-Frame GOP Patch") with other setting. But my GH1 stopped recording and got freezed in several seconds. I think it's odd only when I apply constant for 1080p as 422160 my GH1 could record pappasart chart without stopping. I have applied "422160", "544320", "466560". Only value"422160" gave stability in recording. I don't know why this happen. When I applied several setting appling constant for 1080p as 422160, on all situation my GH1 could record movie without write speed error. And on all case blank frame matter occurred. I recommend you to apply the "422160" to your setting and test. I think it can be the clue to solve the 24P move matter. This is the video bitrate and Constant for 1080p that I have applied. All the settings could record pappasart chart on tripod exceeding 3 minutes.

Video Bitrate FHD/SH Overall Bitrate Constant for 1080p
41000000 42000000 422160
41000000 43000000 422160
25300000 25500000 422160
32000000 34000000 422160

 

[dasbin]

Just to clarify for testers, it appears that these blank frames are *NOT* the same as the 192 (empty) frames we're used to occasionally seeing in 24N mode in really high detail situations. Those occur at the *end* of the GOP when the codec thinks it's going to go over the set bitrate. These appear much earlier in the GOP and are something different entirely, I think.