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-   -   If SDHC card is 20mps, and camera is 24mps recording. Hows that working? (https://www.dvinfo.net/forum/panasonic-lumix-s-g-gf-gh-gx-series/503061-if-sdhc-card-20mps-camera-24mps-recording-hows-working.html)

Tyson Persall November 27th, 2011 06:58 PM
If SDHC card is 20mps, and camera is 24mps recording. Hows that working?
 
I just realized my GH2 SDHC memory card is only a 20mps card. IF the GH2's 24p mode records at 24mps then its data rate exceeds the memory card. Yet i am able to record video w/o any warnings. I wonder though, how this is working? Is the camera making a sacrifice?

Bill Koehler November 27th, 2011 08:02 PM
Re: If SDHC card is 20mps, and camera is 24mps recording. Hows that working?
 
The answer is most cards from a reputable manufacturer exceed the advertised specification. To put it another way, the advertised specification is the absolute MINIMUM that the card will do. The manufacturer has built in a margin of error. So while skating on the edge, so far the card has been fast enough to let you get away with it :-) But now that you realise that is the situation, are you comfortable with that?

Tyson Persall November 27th, 2011 08:18 PM
Re: If SDHC card is 20mps, and camera is 24mps recording. Hows that working?
 
Thanks. Nice answer. Good to know... I was just wondering if it was dropping frames to accomplish the recording or something. I did notice that when shooting RAW stills after 2 or 3 shots it freezes up for about 20 seconds while saying writing to card. Guess thats where a faster card helps for sure.

Chris Medico November 27th, 2011 08:32 PM
Re: If SDHC card is 20mps, and camera is 24mps recording. Hows that working?
 
Look carefully and you will see the card is rated at 20mB/sec not 20mb second. 20mB/sec is about 160mb/sec which is much greater than what the camera requires.

Tim Polster November 27th, 2011 09:18 PM
Re: If SDHC card is 20mps, and camera is 24mps recording. Hows that working?
 
Yes, megabits and megabytes. The codec is in megabits (1/10th the size)

Jordan Nash December 3rd, 2011 12:51 PM
Re: If SDHC card is 20mps, and camera is 24mps recording. Hows that working?
 
Quote:
Originally Posted by Tim Polster (Post 1699995)
Yes, megabits and megabytes. The codec is in megabits (1/10th the size)
Actually, 1/8 the size. A byte is a group of 8 bits.

Tim Polster December 4th, 2011 09:01 AM
Re: If SDHC card is 20mps, and camera is 24mps recording. Hows that working?
 
Yeah but 1/10th sounds better! I was rounding to make a point but that is wrong as it is important to get the facts straight.

Jordan Nash December 5th, 2011 05:04 PM
Re: If SDHC card is 20mps, and camera is 24mps recording. Hows that working?
 
Quote:
Originally Posted by Tyson Persall (Post 1699976)
I just realized my GH2 SDHC memory card is only a 20mps card. IF the GH2's 24p mode records at 24mps then its data rate exceeds the memory card. Yet i am able to record video w/o any warnings. I wonder though, how this is working? Is the camera making a sacrifice?
Don't forget that your recording is compressed, so perhaps it's 24Mbps when played out, but less than that as compressed data?

Chris Medico December 5th, 2011 05:24 PM
Re: If SDHC card is 20mps, and camera is 24mps recording. Hows that working?
 
The video is played out uncompressed via HDMI. At 1080p24 the data rate is about 100MB/sec (800Mb/sec). The rate of 24Mb/sec is the compressed rate.


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