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AVCHD maximum image quality settings and testing
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  • can anyone post a test clip of the 220 settings (preferably in comparison to camera unhacked)?
  • @driftwood
    It DOES have to do with the cards.... Sorry after such great news to pee on everyones parade...
    After filling the 2 different cards I was sure this was it.... Then tried overwriting... Format the full card and fill it again... Write errors :(
    If you need your files to span, I am afraid you will have to follow my instructions from the card formatting thread. Also @grunf has pointed to the tool I also use now, the official SDHC/XC format tool.
    My cards were immaculate, so that is why it spanned, if you just format in camera, the files are still there, but marked as zero. As the write happens, it has to unmark and delete before writing a new file, so no luck. I still find it amazing thet 132 will span on virgin cards (or any cards).
  • @allenswrench or can someone try this. Record on a lower setting (like the L setting first) then record H 132M and tell me if it works. I know this work if you suddenly lose the ability to playback in camera. Now see if it works for spannning.

    Second test, Format sd to full format fat32 using windows (not quick format/ camera format/MAC osx f32 format). Then, record and c if it spans.

    3rd test/ download & use this Panny recommended formatter (probs the same as yours allenswrench)
    http://panasonic.jp/support/global/cs/sd/download/index.html

    Update: Didn't realise there was a protected area of the SD card!
  • @allenswrench- well I could spand for at least 14 mins last night. I am going to test 720p, 1080i, 24p on spanning and ETC modes and see if it spans all the time.

    I post results.

    P.S. Its pissing down at the mo so the camea goe some work cut out.
  • Files are not spanning for me on Transcend cards even with the above suggestions. Trascend 32GB Class 10.
  • For some reason its not working now :-( and I have put the memory card in my laptop.

    I am trying to see if you have to keep the memory card away from the laptop and just use the usb cable to transfer the video files. 720p ETC just refuses to write to the card it comes with an error saying "cannot write to card because the limitation of the card".

    So I am going to completely format the card like it was new and then I am going to try and see if the spanning works. I may edit the firmare for 720p and just try to up lessen the limit so it does write all to deail.

    We will get there in the end bloody thing.
  • Every time I shoot a new 10 min or more shot (E.g. I format the card on the camera every time I shoot a new video file) It spans!

    I dont know why it does that but works every time I format the card for every new shot.

    Let me see if I do a full format on the Laptop and then see if it spans and for every 2,3,4 extra video files.
  • @chrimsbroome Good stuff. That's interesting. How many records did you try before you reformatted?
  • @driftwood- I did about 3 not a lot. The camera just wasn't spanning so I just formated and then it seemed to span then I narrowd it down to reformatting every time I want to shoot more than 10 mins.

    I haveing a problem with this 720p mode it just stops because of the limit of the card. Does that mean I need a much faster card?
  • Analysing the 44M / 32M AQ4 (12 GOP default) settings reports big drops on the buffer across the board on death chart & trees of death - it never crashes but the bitrate/bandwidth seems dire?!!! Ive tried 800 iso to 1600 iso test using 60 to 400 shutter speeds and seen rapid decline on the charts (close to zero) beyond 10 seconds. I am now going to analyse chris's tuned 44M/32M settings.
  • @driftwood Have been using your 220M GOP6 for few days now without any crash. Looks great i think. Also tried your 220M GOP1 and 132M GOP3. The GOP1 files are huge and give problems when converting but the 220M GOP6 was perfect in workflow. What is the big difference between the 220M GOP6 and 132M GOP3 patch? I'm looking for highest quality in image and nice movements for documentary style filming. Thanks for your great work... also to vitaliy.
  • @chrimsbroome the 55M? This is ratioed to work with 132M/110M on 24p. It should be stable.
  • @daimon youre gonna have to do some work on the GOP1 but its worth it. Make sure you bring it in on a decent NLE/conversion utitlity (look around), use pulldown and reverse telecine. It looks great when the works done. I'll put a few video tests up just as soon as I get a spare moment over the weekend.

    A quick test: record a gop1 220m clip, import to premiere pro (plays juddery, right?!) interpret it to 24p, place it on the timeline, reverse speed it - see the judder goes! Hope you got a powerful compute :-)
  • @driftwood Why run reverse telecine on 24p source ? Edit : er.. okay, I've read your explanation. What do you mean by 'reverse speed' it, and its already interpreted at 24p right ? And where does pulldown enter into this ?

    When it comes to tuning I've discovered that framebuffers and the framelimit have a hard limit that causes the camera to not record at all and require the battery to be removed. Dunno exactly where it is but it's somewhere between 4x and 6x, just an FYI. You know, I think these high bitrates, excluding the GOP1 which is a special case, aren't really worth it at all. They seem to be resulting in bloating P and B frames and not actually improving the image quality at all. Ralph Bs comparisions with HDMI output show that we're pretty much there at 132M GOP 3. As @cosimo_bullo has also noted other strange things seem to occur, such as bitrate actually drops more than running at lower bitrates. I've seen similar things with changing AQ2 to AQ3 with certain settings. Such that the AQ3 version produces streams with lower bitrates on the same shot, but then at AQ4 the streams bitrates are higher again. Odd. Theres something else going on, either wrong or a compensation (throttling) is being done when some conditions are being hit.
  • @ driftwood - No this is at 720p 50i mode. Either ETC or no ETC just crashes 4 secs onto recording. I am running at 56 megabytes per second. Do you think I should adjust the megabytes a second to 55M and it might work?
  • @driftwood Thanks for your fast response. Sorry for asking again. What do I gain with GOP1 over GOP3 or GOP6. All settings are high bit rates and looking amazing. Just to understand what the difference are. I have done some shooting at the seaside and the files are 175Mbits after conversion to Proress 422HQ. I have some banding in the sky. This is the 220M GOP6 AQ1 setting. If I change to AQ2 will this look better or can the GOP resolve this? again thanks!
  • Oh, also 132M GOP6 AQ2 seems to be perfectly stable with the video buffer at 3000000 and nothing else changed, 96M not so much however. Looks pretty good too.
  • @daimon The motion rendering is better (to some of us) with lower GOPs as the frequency of I-Frames is increased. Also, arguably, image quality increases, but I'm not convinced it does as the codec maintains image quality very well (and more efficiently) with it's B-Frames and P-frames with a GOP of 12 anyway.

    If you were to change the 220M GOP 6 to AQ2 it may improve the image quality, but may not cure the banding issue which is mostly down to the 8-bit colour space the codec is working in. Increasing the AQ will also probably affect stability, though pointing the 220M GOP1 at a highly detailed scene may do that anyway in that unless your card is very fast its going to give you write errors. If you check the streamparser output of Driftwoods test with 220M GOP1 in the lowlit room you'll see it only averages about 110M, upping AQ will increase this average. However, an average of 110M is so good you're better leaving the AQ alone, the shadow detail is damn fine already. In short, such a bloody large average bitrate kind of indicates it isn't going to get much better tbh.

    Edit : Another effect of a lower GOP is that noise seems to get less smeared and therefore easier to clean up.
  • Well put @Stray. And this illustrates my point why you have to go high on the bitrate if you want sustained quality. If you get averaging of 110m (or 130odd - which I get on some of my filming) you cant simply cap the bitrate down to your average because thats not how it works - it'll simply die to zero on the buffer analysis. This is why it needs the high ratio to maintain the bandwidth. Alternatively you can fine tune the settings like Chris has done to achieve high framebuffering - but guessing those is like looking for a needle in a haystack. And Ive found instability of the buffers using toyed with settings.

    @Stray be careful with using 3000000 buffer at 132M GOP 6 - it looks stable but I have found on the analysis of buffers big drops.
  • driftwood,

    I tried the 88/66 AQ2 (Video buffer 24p=0x3600000), it worked with Pappas Death chart /Static and motion / ISO3200 / (1/1600 shutter speed) without crashing.

    BUT, on a static scene using pappas death chart, streamparser chart developed a cadence issue after about one minute.

    I then tried adding the T4 to T1. This seemed to fix the cadence issue, but shooting static on pappas chart, the i-frames start out large, but for some reason something happens and the I-frames drop down a bit. very strange?
    So the T4 to T1 seems to help the cadence issue (viewed in streamparser), but this either causes the I-frame drop after a bit, or there's something else going on.


  • I think if youre happy with good stable settings just stick to chris's 44M. Those fine tuned settings with frame buffers/limits doubled and high top/bottoms quadrupled bring it close to 44m/32m untouched on a 360000 buffer. Ive never checked the 44M for cadence issues though.

    You could now try fine tuning those 88/66 settings with FB/FB limits/ hilo tops etc.... to see if you discover anything.
  • driftwood,

    As much as I like the overall quality of 44M and 66M, I believe when these are set to AQ4, motion suffers a bit and there's visual loss. Raplh, HDMI vs 66 AQ4 motion tests shows this issue clearly. AQ2 seems to be our best bet at these bitrates.

    Yes, I'd REALLY like to get (24H 88 / 24L 66) AQ2 settings optimized.

    I wish I had a better understanding of how the buffers and limits are used.

    So far Chris's 66 AQ2 posted on 8/29 seem to hold up fine on all tests (e.g. i-frames size stay during static shot; No cadence issue (streamparser); AQ2 holds up fairly well on motion).

    But, I'd like to see 88M AQ2 optimized! This may be the "good enough" not hogging too much SDHC disk space and also offering real strong static and motion.
  • Here's my pappas test showing my untuned 1080p24H 44M AQ4 on the 3600000 as opposed to chris's tuned on the 24000000 buffer. ie I didnt have to do anything to reach the same stable setting.
    Chart 1 cbrandin 44m on 24000000 buffer. Chart 2 driftwood 44M untuned on 36000000 buffer.
    cbrandin 44M vid buffer is 0x2400000 tuned - elecard vid analysis .png
    1681 x 931 - 130K
    c08bin - test mts0044 - untuned 44Mbps GOP12 AQ4 0x36000000 buffer -elecard buffer analysis.png
    1679 x 942 - 120K
  • @driftwood

    The purpose of my tuning parameters was to be able to increase I frame size while avoiding the cadence issue. Stability was not the primary goal - the I frame sizes was. Without the patch to increase I frame size, the other tuning parameters aren't necessary. It doesn't surprise me that stability would be the same without these patches.
  • @driftwood- I been thinking about this spanning issue. From what I been reading up on about defult allocated size unit when you format a Flash Disk might be causing this spanning. The Panasonic GH2 formatting system must be formatting the card to a spec that is not either fast enough or big enough to handle the large amounts of data bandwith.
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