http://www.personal-view.com/talks/discussions/tagged/avchd/p2/feed.rss Thu, 02 May 24 00:11:34 +0000 Tagged with avchd - Personal View Talks en-CA http://www.personal-view.com/talks/discussion/1423/422-color-sampling-for-gh13-in-avchd-1080p-23.97fps Fri, 11 Nov 2011 14:27:02 +0000 kronstadt 1423@/talks/discussions I'm wondering about the roadmap of future developments for the GH13 hack. I'm a relative newbie, so if this question sounds stupid, just say so.

I noticed that for MPEG there's a checkbox for 4:2:2 color sampling. And MPEG videos (with Powell's 100mbps and with Blackout-Powell's patch) do look somewhat richer in color. The trouble is that MPEG does not come in 1080p 23.976fps.

So I'm wondering, Vitaliy, do you plan to introduce 4:2:2 color sampling also for AVCHD in 1080p24 ??? (would be awesome to have this)]]> http://www.personal-view.com/talks/discussion/1383/gh2-red-interlace-issue-or-is-it-a-premiere-cs5-issue Mon, 07 Nov 2011 09:15:47 +0000 RRRR 1383@/talks/discussions
I've found out a very strange phenomenon with gh2 footage in (at least) premiere cs5. The reds look interlaced (jagged) while everything else is normal. Iv'e found that the same footage looks better in VLC aswell. I've of course matched the sequence to the footage and it has occurred with several different camera settings - it becomes obvious only with strong reds.

I wonder if someone else have encountered a similar problem and if you have any suggestions as to why it happens? (possible solutions?)]]> http://www.personal-view.com/talks/discussion/637/st-avchd-encoder-team Wed, 10 Aug 2011 05:19:09 +0000 Vitaliy_Kiselev 637@/talks/discussions
Who is strike team member:
1) First, it is very systematic tester, doing all tests accordingly to the provided list in time.
2) Second, all team members will have access to prerelease beta versions.
3) Third, prior testing expirience is required.
4) Forth, strike team members are responsible for making recommended settings before release.

You can apply below. ]]> http://www.personal-view.com/talks/discussion/699/avchd-maximum-image-quality-settings-and-testing Thu, 18 Aug 2011 12:29:27 +0000 cbrandin 699@/talks/discussions
Maximum bitrate and low GOP are not virtues in isolation; rather they are tools for achieving results. Taking maximizing bitrate, for example: if that is the only goal you are unlikely to achieve optimum results from an image quality standpoint. If you set the bitrate so high that you can’t raise the AQ value individual frame image quality won’t be improved much. Raising AQ results in smoother and finer details, and that’s a good thing. Without raising AQ the image will remain harsh.

What about testing with low-contrast subjects? One of the benefits of the new patches has to do with smoother rendition of gradients. This arguably has more to do with the beauty of images than extreme edge detail.

I’m going to take a somewhat different approach to developing settings – at least some of the time. The steps that seem logical to me are as follows:

1. Increase bitrate to a relatively conservative level; 44M for the 24H bitrate, for example.
2. Raise AQ to 3, or maybe even 4.
3. Increase FB1, FB2, and frame limit so that individual I frames can be bigger if needed.
4. Raise the bitrate to the highest stable value that supports these settings.

You could do a similar sequence involving low GOP. Set the bitrate to a higher – but not extreme - level, set the GOP, set the quality related settings, and then start raising the bitrate to higher levels.

For testing:

1. Test for stability under a variety of scenarios. One test of extreme importance is to put the camera on a tripod and use manual or AFS focusing –this can cause a failure instantly that may never show up when the camera is hand held.
2. Test for detail, but also test for smoothness (subtle gradients, low contrast subjects, etc…).
3. Test for motion fidelity. Make sure subjects in the frame all move smoothly from frame to frame; especially in low-contrast portions of the frame.
4. Test with very high shutter speeds as well as normal ones – this really stresses the codec.

If there are motion problems, back off on the AQ and try again, etc...

Maybe you have some ideas about testing procedures that measure image quality rather than a single metric like bitrate or GOP.

[EDIT] Per Vitaliy's suggestion I'm posting my 44M and 66M settings here - I'll keep them updated.

The main issue with both settings is spanning. At 24H neither set span - hopefully there will be a solution soon. The other modes with the 44M settings, as far as I know, do span with a good SD card. The 44M settings operate at 44M AQ4 for 24H, and the 66M settings operate at 66M AQ2 for 24H. The main difference between the two is that motion is handled more robustly with 66M. The other modes have been stable for me - but I have to confess that I have not tested the PAL modes very much. You can change the AQ settings without having to make other adjustments. Note, however, that 66M AQ4 is harder on the codec than 66M AQ2 and may pose stability, in camera playback issues, etc....

Chris
]]> http://www.personal-view.com/talks/discussion/1150/unable-to-import-some-files-in-fcp Tue, 11 Oct 2011 19:31:32 +0000 jonblon 1150@/talks/discussions http://www.personal-view.com/talks/discussion/568/2.351-1920820-cropped-avchd Tue, 02 Aug 2011 13:04:20 +0000 lolo 568@/talks/discussions i have a question, i´m quite a newbie here, and i really don´t understand too much of the hacking,
so i have a question :D
i have many, but here is only one:

-can i change the aspect ratio in avchd
from:
1920x1080
to:
1920 X 820
to get the cinematic 2.35:1

by only cropping the frame? (with no anamorphic lens atached), this is only to get the framing right within the camera, is that possible?

and of course, as i dont have any anamorphic lens to try, this is a solution for me, if it is possible, is it?


-or perhaps being able to see guidelines with the 1920x820 crop would be better

can i do any of this two things within the available hack?

Greetings to all, from Chile!
]]> http://www.personal-view.com/talks/discussion/486/what-is-going-on-with-the-blip Mon, 25 Jul 2011 12:01:36 +0000 cbrandin 486@/talks/discussions
At the beginning quantization values for frames vary widely, from a minimum (best quality) of 18 up to 51 (worst quality). By the time the 34th frame has passed the codec settles into a pattern where all P and B frames use a quantization value of around 20 (an entire P or B frame uses a single quantization value). I frames typically use a range of 5 quantization values; it is usually in the range of 18-22. The absolute values can vary one or two values, but the pattern is consistent. For example, for highly detailed scenes I frames range from 18-22 and P and B frames are at 20. For lower detailed scenes those values may go to 19-23 for I frames and 21 or 22 for P and B frames.

Dark scenes seem to cause the quantization values to be low. Currently, the lowest quantization value I've seen is 18 in I frames and 20 in P and B frames. This is true with both hacked and unhacked cameras. Currently, Vitaliy and I are working on trying to lower that. It's not as simple as we had hoped so it may take a while.

The conclusion I have come to is that it might not be possible to eliminate the "blip" because that is when the codec in configuring itself. Note that the blip exists in an unhacked GH2 as well, though not as visible. I think Panasonic made the choice to at least record something, even though the codec isn't really ready yet. I think it was a good decision.

Chris ]]> http://www.personal-view.com/talks/discussion/424/gh2-avchd-encoder-motion-testing Tue, 19 Jul 2011 13:46:16 +0000 cbrandin 424@/talks/discussions
Shutter speed will be an important consideration, as the slower it is the more blurring (and the less detail) there will be. At fast shutter speeds minute detail will change considerably between frames.

With a static scene I frames dominate, and B and P frames don't play much of a role so quality improvements concerning those won't show up.

I'm going to play with this a bit. In the meantime - any thoughts?

Chris]]> http://www.personal-view.com/talks/discussion/337/avchd-format-version-2.0-licensing-started- Wed, 06 Jul 2011 01:34:37 +0000 Mihuel 337@/talks/discussions for 3D and 1080/60p,50p. New trademarks; "AVCHD 3D", "AVCHD Progressive" and
"AVCHD 3D/Progressive" are introduced."

from : http://www.avchd-info.org/]]>