720p 50 on MxM Card – Works?

[Craig Seeman]

[Martin Phillips] “even though it is not really meant to according to the MxM spec.”

All HQ settings are 35mpbs and they all work according to MxM spec. HQ frame rate and frame size is not related to data rate at all.

Overcrank is a much higher data rate. That’s different.

[Martin Phillips] “Has anyone else found this to be reliable on these cards?”
??? I think you’re seriously misunderstanding something.

[Martin Phillips] “The jittery look of 720p 25 makes this not an option. “
This has nothing to do with data rate. Again I think you’re seriously misunderstanding something.

MxM site plainly states:

Supported Video Formats in NTSC area:
· HQ1080/60i · SP1080/60i · HQ1080/30P · HQ720/60P · HQ720/30P · HQ1080/24P · SP1080/24P ·
Supported Video Formats in PAL area:
· HQ1080/50i · SP1080/50i · HQ1080/25P · HQ720/50P · HQ720/25P ·

[Martin Phillips]

Thanks Craig – yes, I am quite likely misunderstanding quite a few things at this stage, so thanks for bearing with me.

I had noticed on their FAQs that it says:
‘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 ……… please excuse my ignorance on this!

Martin

[Craig Seeman]

[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).

[Martin Phillips]

Craig – this is most helpful and much appreciated.

I think for now, all I wanted to ensure was that I could record 720p 50 without any problems. This is great news for now – the 6 MxM cards + 16Gb Sandisk Ultras I’ve just received should serve well on location. Will need to look more into the overcranking though ….

Thanks again,

Martin.

[Craig Seeman]

[Martin Phillips] “16Gb Sandisk Ultras I’ve just received should serve well on location.”

Let us know about the Sandisk cards ASAP.
I have 32GB Sandisk Ultra II Class 2 cards that work fine.
Many people have reported that the newer 32GB Sandisk Ultra II Class 4 cards do NOT work.

Please post whether your 16GB Sandisk Ultra II cards are Class 2 or Class 4 (there’s a little circle with a number in the middle of it on the card) and whether they work.

Sandisk apparently changed something in their 32GB cards and I’m wondering if they’ve also did it to there 16GB cards?

[Rafael Amador]

[Craig Seeman] “Sandisk apparently changed something in their 32GB cards and I’m wondering if they’ve also did it to there 16GB cards? “
What is clear is that there is something that makes different the Class 6 with the Class 4.
I think that SanDisk just have withdraw the Class 6. And they did it as soon as hey new how the people was using the cards. The Class 4 can not make the job.
I ordered Class 6 but they sent me Class 4.
I could send them back the cards, but for me is almost cheaper to buy new cards that return them.
Do anybody want some SanDisk 16 Gb class 4? Good price.
rafael

http://www.nagavideo.com

[Craig Seeman]

[Rafael Amador] “What is clear is that there is something that makes different the Class 6 with the Class 4. “
[Rafael Amador] “I ordered Class 6 but they sent me Class 4. “

Strange for me that the online store had Class 4 card. The online store had a physical store 30 minutes by train so I went there and what the online store had as Class 4 was actually only Class 2. I bought the Class 2 cards and they work. You would think that if Class 2 worked certainly Class 4 would work. Sandisk is doing something very odd with changing Classes around.

So it seems 32GB Class 2 works but 16GB and 32GB Class 4 do not work.
I heard from one person who got 32GB Class 4 card from a different store in New York City and theirs worked.

So it seems
J&R Sandisk 32GB Class 2 works (but Class 4 not).
but
Adorama Sandisk 32GB Class 4 works.

Either Sandisk has different manufacturing locations not all keeping to the same spec or maybe it’s the date of manufacture because Sandisk keeps changing the spec.

[Martin Phillips]

I’ve used 5 of my 6 Sandisk 16Gb Ultra II cards – they are all class 4. Don’t seem to have any problems recording to them. I’ve had one clip that has gone weird (as discussed on another thread).

I am in the UK so whether this makes a diference, I don’t know.

Thanks – Martin.

[Rafael Amador]

Hi Martin,
I had problems with one card (Class 4) after one week using it every day. Other card crashed after only 20 minutes shooting.
In both cases, luckily, I was filming for my self. I was able to recover almost all the clips (one corrupted in a card, two in the other) but I can not risk any more.
rafael

http://www.nagavideo.com

[Craig Seeman]

Keep in mind that there are counterfeit Sandisk cards out there.

It also seems that Sandisk cards seem to be good or bad by lot. I’m wondering if it’s different manufacturing locations. It almost seems to be all or nothing depending where one bought the cards.