Re: 720p 50 on MxM Card - Works?

[Martin Phillips] "You can happily overcrank up to 720p/48 fps, but will not work at 720p/50-60 fps.'

....... so I got confused at this point. So I think that overcranking is causing the confusion here"

Yes overcranking is at a much higher data rate. What's not explained very well (even in Sony manuals) is that overcranking is at a higher data rate.

The basics are that the playback is targeted to 35mbps VBR so, for example, if you record 720p24/48 (overcanking at 48fps to playback at 24fps slow mo at 50%) the overcrank data rate would be about 70mbps to playback at 35mbps. The cards, courtesy of Sony's designed bus/interface controller management, can't sustain that speed.

To put it simply:
All HQ frame sizes at rates are supported at 35mbps
720p24/48 would be recording at 70mbps and generally can't be sustained (some have claimed exceptions)
720p24/60 would be recording at 87.5mbps and can't be sustained.

People have found that 720p24/42 recording at 61.25mbps can be sustained. Some have found cards that can sustain 44mbps and I've heard a couple of people claim that they've had cards that can sustain 48fps. Hoodman makes that claim for their SDHC cards but the one report I've heard so far says otherwise.

Apparently JVC has designed a better controller for their HM EX cameras because I've heard those can sustain 720p24/48. They also have about a 3 second record cache. My own hunch as that these two features are related as they may indicate how the internal buffer is handling things (record data).

If you compare SDHC to SxS on the EX you'll notice the little record light takes longer to go from red to green after you stop recording on SDHC card. Make sure you don't pull the SDHC card too soon as it's taking longer for the data write to finish. I think this is also an indication of buffer management (rather than just the write speed of the card).