Bytes, bits, bitrates, FPS, codecs (compression) and Samsung PRO Endurance microSD cards

I took what I have gathered from research to speculate on the encoding profiles that are used in the Wyze firmware.

This reveals some interesting details. I have further speculated on the bitrate on the audio encoding in order to subtract audio and reveal the underlying video bitrate.

I have then taken the Samsung PRO Endurance microSD card in order to derive the life expectancy of the microSD card in a Wyze camera. This gives some clues into the controller on the SD card as TLC is generally rated for 1000 writes, so there is likely multiple layers (3D) of TLC with a controller doing wear leveling.

I speculate that the h.264 bitrate are as follows:

  • SD and HD profile is between 0.9-1.45Mbps during daytime (15 FPS) and 0.5Mbps for nighttime (10FPS).
  • 360p profile is between 0.24-0.39Mbps during the daytime (15FPS) and 0.1Mbps for nighttime (10FPS).

This assumes 32Kbps or lower audio encoding (hence the really bad audio quality).

It is easy to see that if the Wyze devices support a good audio codec (e.g. AAC) that there is an opportunity to increase the bitrate for audio. Mono CD-quality audio can be had for 64Kbps using AAC with minimal impact on the storage requirements. This would go a long way to improve the quality of the overall product in my opinion. However, it is possible that the hardware does not have modern codecs implemented and/or the tuning by Wyze is what resulted in a necessary compromise in audio quality.

I did this analysis not owning a Wyze device. I just took the published specs as well as some of the reviews I have read. What do you think?

Edit: I have since purchased a Wyze v2 and 128GB Samsung PRO Endurance microSD card.

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Samsung PRO Endurance microSD card.

This analysis works to speculate on the number of layers of TLC and the size of each layer (32GB, 64GB, 128GB). The analysis takes the published endurance specification (green) and calculates the number of GB written for a microSD card with 1,2,3…20 layers. From here we can see then there are patterns (yellow, blue, orange). This gives us a clue as TLC generally has endurance of 1000 writes. We can easily reveal the number of layers and the capacity of each layer that these microSD cards have. The controller will then use this RAW storage and do wear leveling.

For example, if each layer is 128GB (yellow), then

  • a 32GB microSD card has 2 x 128GB layers (238.4GB RAW storage)
  • a 64GB microSD card has 3 x 128GB layers (357.6GB RAW storage)
  • a 128GB microSD card has 5 x 128GB layers (596.0.4GB RAW storage)

This rational provides basis to speculate how the card is able to support the published endurance rating.

My last comment is that physically the three versions of this card might be identical, all having 596GB of RAW storage (5x128GB layers) and the controller is configured to access the quantity of layers which determine the available logical storage. That would streamline manufacturing and drive efficiencies which in turn make it possible to drive down cost.

The table shows the same calculations for the scenarios of each layer being 64GB (blue) and 32GB (orange).

In the interest of full disclosure, I have no information on the architecture of this card beyond Samsung support stating that these cards are TLC and the knowledge that TLC has endurance of approximately 1000 writes. The analysis is pure theory.

All the math behind the analysis of the Wyze camera bitrates. All green is the stated specification. The other data is expanding stated specs to be within the rounding limits. e.g. 4MB/min could be from 3.5-4.49MB/min and rounded to 4. Keep in mind that a typical camera will have daytime hours and nighttime hours, so it’s the combination of this that determines the number of days recording that a 32GB, 64GB or 128GB card will hold. The right hand column is the same data using the stated specs of the Samsung PRO Endurance microSD card at continuous writing at 26Mbps. I like the sound of the microSD card having endurance that will far exceed the life expectancy of the camera (rows 3-8).

Edit: Since originally posting I learned there is a 360p profile, so I believe the calculations that I labelled SD in the table might be 360p

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have you had any trouble with the 128GB in your Wyze cams?