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Confused about patch and SD card write speed limitations
  • disease8disease8

    Hi. I recently hacked my GH2 on my own just applying the recommended settings fror the bitrate for AVCHD. It gave me the card speed limitation error and crashed my camera. I then used the Driftwood settings and it ran fine but gave a bigger overall bitrate (analysing with Videospec) than when I just put in the recommended settings. When I say recommended I mean the box that appears next t the setting you are tweaking in ptool and says (suggested settings). I went through all the AVCHD settings and applied the "suggested settings" from the help box that appeared on the right. I am confused about what settings are allowing the driftwood patch to create more bandwidth yet not peak the card bus limitations.

    Why is this?

    Its just annoying because I thought it was my card (Transcend class 10 45mb/s write) and I bought a Sandisk Extreme Pro 16 gb 95 mb/s but this didn't solve the problem because obviously it was something I was doing with the patch. I hardly touched anything in the patch as I say just increased the max bitrate for all AVCHD...

    Any advice would be great just to get my head round all this and get more control and reliability in understanding the patching process. I don't get the error now with either the Transcend or Sandisk...

  • 7 Replies sorted by
  • griplimitedgriplimited

    wrong 95mb/s card. If you go to the Hacks and Patches menu on the right, it'll lead you to a post that only the 64gb version of that card is the one working. 32gb and lower do not provide the same results.

  • LPowellLPowell

    There's probably nothing wrong with your SD card, 45MB/sec is fast enough to handle all but the most extreme bitrates the GH2 can reliably produce. The problem you're having is that PTool's "suggested settings" are only the tip of the iceberg, and are not necessarily stable in all permutations. In order to achieve 100Mbps peak bitrates in Flow Motion v2, there were four separate settings I adjusted to set the bitrate for each video mode. Insuring reliability was a more challenging project, requiring independent research and countless tests over several weeks' duration. To learn more about this craft, I'd suggest starting with one of the more conservative patches, examine its settings and observe what happens when you alter them.

  • BlueBomberTurboBlueBomberTurbo

    The limitation is the camera. It's not UHS-1 compatible, so it only runs those cards at half the rated speed. The 64GB 95MB/s version's internal setup is different than the 16 and 32GB cards', so it's the fastest performing of the three on a GH2.

  • neokooneokoo

    I'm using custom settings on my GH2, not as fancy as driftwood et al., but achieves around 138Mbps (24p), 90Mbps (25p/50p) and 66Mbps (30p/60p) with good IQ and perfect reliability so far on 32GB SanDisk 95MB/s cards. Took a month of testing, writing results in spreadsheets, testing again, calculating estimates for next test, testing them… you get the idea.

    As far as I understand (correct if wrong), GOP settings seem to decide the rate of writes to card and frame limits seem to decide the amount of data per write. I've pushed Q setting to give near-constant bitrate no matter the GOP setting, and it has allowed to make good estimates for testing...

  • disease8disease8

    This is all fascinating stuff. I never knew the camera couldn't handle UHS-1 and thought that the Sandisk Extreme Pro 95mb/s was the recommended purchase.

    When you guys are saying MBps you are meaning megabytes and not megabits right?

    If the hacked patch is going up to 138megabytes per second and the card writer in the camera is only, what USB 2 speeds or something? You said half so around 45 megabytes per second at least, how is it writing 138 megabytes per second with that patch? Is there a sort of "buffer" in the camera preventing the writing speed from crashing the camera by maxing out the max write speed? Or is it entirely due to the settings done in Ptool?

    Anyway its stuff I would like to understand better and I really appreciate the time you have taken to help me. I love the GH series cameras and will probably stick with them for the future, so I appreciate learning as much as possible.

    Hope you guys are looking forward to xmas!

    Cheers, Dom

  • inqb8trinqb8tr

    @disease8

    Avchd datarate is expressed in Mbit/s - megabits. SD cards speeds are usually in MB/s. So 95MB/s card writes at 95*8Mbit/s. In theory.

  • fatpigfatpig

    just get the cheap sandisk 45 mb/s 32 gb card. It is marvelous! No problems with Intravenus, running at ~150 mbit/s

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