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AVCHD: Stable settings
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  • shrigg..
    I like your thinking bro!
    I also like your DSLR cage which I bought a couple weeks ago.
  • 3.62 will span and is recognized by Photofun at 32mb H and 24 mb L. 3.61 spans and is recognized at higher bitrate setting.

    Is there an inherent advantage to using 3.62 with lower bitrates rather than 3.61 with higher? I can adjust the Quantizer in 3.62 but it has been suggested that the limited bitrates of a 32H setting may not show much gain from those adjustments.
  • @schrigg

    I would recommend buying a few cheap 64mb SD card from somewhere (drawer, ebay) and put the stock firmware (with PAL/NTSC switch and 29 minute removal if you are in PAL countries) on one of them and your experimental, high-end settings on the other. Just keep a full original battery at hand and I think the risk you take is well covered with a good back-up plan.
  • @parkgt

    24H at 32M with AQ set to 4 can produce quite good results. I have noticed in my tests that the difference between factory settings and 44M is greater than the difference between, say, 44M and 66M. I would say go for it, even if you can only go to 32M - there will be a noticeable improvement. In fact, I would say that the improvement would be about the same as the difference between factory 24L and factory 24H.

    Chris
  • Over the top Long GOP 36 test. Passes the Pappas death chart with ease at 50mbps and LOng GOP at 36 with a few adjustments to buffers. AQ = 2.
    36 GOP 50bitrate test.png
    1311 x 704 - 89K
    driftwoods stable long gop 36 - 50mpbs bitrate test - seta.zip
    427B
  • @cbrandin

    Thanks for the reply, I was hoping that was the answer.

    I tried 34mb for H and it still spanned and was recognized. I will do some more informal testing and try to find the tipping point. Last time I tried 36mb H it didn't work out.
  • after much testing today and trying many different setting, ive settled on 24H at 66mb, gop3 and AQ3. the only problem im having is occasionally the clip wont play back and ill have to turn the camera off and then back on and it will play fine. with a 16gb card im getting right around 31min worth of footage per card which is good for me. whats even better is that these settings so far have been stable for me on both a silicon power class 10 and a transcend class 6.
  • i'm confused. this thread became an experimental settings topic in the meantime, isnt it?

    i'm still leaving my settings to:
    24H 44
    24L 32
    30 min removal
    (sandisk extreme 32gb card)

    thats it for now. stable.
    but i would appreciate some serious advice for GOP and quantizer settings.

    we're working on an documentary at the moment and i really need to count on this camera and my 5D ;)
  • @namlot could you post an ini of your 24H 66mbs Aq3 setting, I am searching for such a setting as the low gop topic is now only 100+ mbit, I think it is a bit high for me. Have you tested with stream passer that you are not getting cadence problem.
  • unfortunately im not a tester, just a user trying to get the best IQ with stability. im not sure what an ini is and ive never used stream parser.
  • @mrmukke @namtot I'm in your camp, too. As a working "film" maker, I welcome reliable settings that bridge the 4GB gap and produce better pictures. So far that goal seems yet to be achieved. Meanwhile, I can, at least, trust Panasonic's default settings to give me excellent usable images. But these are early days, and I expect there will be a Ptools version coming that will provide better images, stability, and no 4GB file limit. Patience is today's watchword, I think.
  • Edit: I had a spanning failure on 24H 80% with these settings - so don't trust them.

    @sdbest At the moment I've got settings using ptool 3.61 that, as best as I can test them shooting intense scenes (trees blowing in the wind) span and never crash or error out while improving on the stock image quality. Like you, I need reliability - in my case for videos of performances. I'm pretty sure these settings are fully reliable. They are conservative - 32mbit 24H and 28mbit SH/FSH, about about 1.5x and 1.75x the original bitrates, respectively. A modest but useful improvement I think. Only problem is the 'blip' that was fixed in 3.62.
    arvidtp conservative spanning settings for ptool 3.61.zip
    382B
  • If you set a buffer limit, you are trying to keep it occupied at its most safest /fullness /maximum stable picture to bitrate settings. The two set video buffers have to be able to cope with a variety of settings. Anything over creates write failure because youve gone over the limits of the buffers - hence buffer overrun - the opposite is buffer underrun where we are not utilising its full capabilities - if it reaches empty there will also be write problems. The frame buffer sizes should be kept as close as possible to the expected size of frames under extremely busy conditions again without maxing out its buffers. This is why a lot of people are testing multipliers to push the limits of the GH2. Very high bitrate settings as proven by Chris are not neccesary but its good to work out the maximiums and then work backwards until every setting is working. The spanning issue may well have something to do with buffers too. Obviously a good fast SD card is required to keep up with the data write size and speed. We just keep testing... ;-)
    A good AVC read on buffers albeit a tad old is found here;-

    http://www.google.co.uk/url?sa=t&source=web&cd=19&ved=0CGsQFjAIOAo&url=http%3A%2F%2Fciteseerx.ist.psu.edu%2Fviewdoc%2Fdownload%3Fdoi%3D10.1.1.130.5026%26rep%3Drep1%26type%3Dpdf&rct=j&q=frame%20buffers%20and%20video%20buffers%20avc&ei=DS9cTsj7Ooig8QOO4v3wDQ&usg=AFQjCNGWVl9YskP5NjZ_ItkPRylvf2JquA&sig2=udyEeqMHOqQkY_IDv9mq4Q

    Edit: I'm now thinking 88M is the top workable setting for the GH2 looking at the buffers and available memory with two differing multipliers employed for Video Buffer and Video Buffer 24p.
  • For good stable settings for 66 and 44 you could look at Cris Brandins settings from august 28:
    http://www.personal-view.com/talks/discussion/comment/13692#Comment_13692
    and modified seti from august 29 the day after here:
    http://www.personal-view.com/talks/discussion/comment/13792#Comment_13792

    I find them very good.
  • cbrandin: great work with your last 66 mbits stable settings (29 august) . Do you think that to avoid span issue can I use a xdhc card? Thanks a lot and sorry for my bad english.
  • @parkgt - So currently the highest bitrate is 34 megabit with 3.62 in which spanning still works? Is that for all framerates?
    Thanks,
    Shawn
  • @shield

    I have only been playing with 24p. I have had spanning and Photofun recognition at 34mb and 35 mb with GOP 6 outside on pretty static yard and tree scenes with some camera panning. I need to test in other environments just haven't had the time lately.

    I will report back on more test when I get a chance.
  • @Vitaliy_Kiselev / @cbrandin I know you guys are extremely busy but can you confirm any further details to what the two settings Time Value 1 and Time Value 2 mean?, I'm particularly thinking about how they affect the timing of the initial_cpb_removal_delay_offset / timing errors whilst analysing buffer trends.
  • >Time Value 1 and Time Value 2 mean

    They had been called overall bitrate in previous versions :-)
    But they are time constants really.
  • just wanted to let people know that the settings i posted above (http://www.personal-view.com/talks/discussion/comment/13847#Comment_13847) for 3.61 that I claimed spanned fine, turn out not to, at least with my SD card. I lost half a video of a performance :( - it spanned fine to a 2nd file, but failed going into the 3rd file and stopped recording. And that was 24H 80% at only 32mbit/sec…

    Back to the drawing board. I'd love to see some more results from people with better SD cards relating to spanning (tested while filming something that pushes the codec to its limits - ie high ISO or blowing trees, etc).

    Edit: Just did a test with 3.62 at 30mbit 24H 80%, AQ of 2 that successfully spanned across 6 files and was pushed to full bitrate the whole time by the tree out my window. Shot with single automatic focus, f22, 1/640 sec and ISO 3200 for lots of sharpness/noise. And it worked. Yay!

    So here is my assessment: I'm thinking it's not that anything specific has changed in 3.62 from 3.61 that directly affects spanning, just that 3.62 better utilizes the full bitrate specified, and therefore more often is above the limit where the GH2 will reliably span across files.
  • Right now I am trying to push the limits of my GH2 to get the best video quality possible while maintaining stability. I am not really interested in miniscule quality gains, but at the same time I do not want to sacrifice a lot of "potential" quality due to settings that may be too conservative.

    That being said, I have observed the AQ adjustment to play a role in the stability of the recording. With AQ left unchecked, I am able to record the test pattern without crashing using my Sandisk Extreme Class 10 SDHC card (about 25 MB/s sustained write). I also have a Sandisk Ultra Class 4 SDXC which has 5 MB/s sustained writes, and that will work reliable with settings below 40 Mbps (makes sense because 5 MB/s is exactly 40 Mbps, but there is overhead).

    I see that a lot of the people here focus on 24P mode but I don't think that is wise. We should be testing ALL video modes for AVCHD including the 1080i and 720p, which are just as relevant for personal and professional shooting. Film-like footage is not ideal or appropriate for every situation.

    What I have noticed when attempting to record with 1080i/720p at higher bitrates is that the initial start seems to cause a large spike of data if the camera's lens is pointed at a high detail subject, such as a test pattern. Relatively modest 24 Mbps settings (stock GOP, AQ3) would consistently fail if I started recording while the camera was zoomed in on the test pattern...BUT if I started recording on something like my TV screen, and panned over to the test pattern, I would be able to record indefinitely without failure. This would happen with both my Class 4 and Class 10 SD cards.

    With AQ unchecked I did not observe this problem to persist, and I was even able to get the bitrates for 1080i/720p up higher using settings posted by Kae (42 Mbps for FSH/SH, GOP12, AQ unchecked). These settings also involve doubling the video buffer sizes for all modes and doubling the "high" and "low" bitrate values.

    I would like to end up with settings that provide stability with AQ set to 3 or 4 for all of the AVC recording modes and these seem to be on the right track.
  • Are folks lowering the GOP for 720p, or is it just being left at 30?

    btw...I ws having previously having write problems at 42Mbps and the issues were cured with new memory card.
  • @WeBcYtE
    I'm not sure what's going on with your setup, but I've not seen the issues you are describing.
    There may be an issue with your class 10 card. I have the same card with no issues.

    Also, of course most of the attention is for 1080 24P. LOL
    I'm sure 80% of us or more would not of bought this camera if it did not offer 1080 24P.
    We want the best possible with this setting.
    Once we dial in 1080 24P, there will be more focus for 720P. Of course we want high quality on all the modes.
    But, if I had only one option for best quality, 1080 24P wins for me.
  • I agree skyak.
    My PNY class 10 cards could not wite fast enough and failed all the time.
    My Sandisk Extreme Class 10 30MB/s card works great.
    Although, be careful with these cards since there are "fake" Sandisk cards sold all over then net.
  • so is GOP12 recommended for 720p?