Concern about using cheap USB memory sticks to record video 6GB/hour

[jimdagys]

I recently bought from Walmart a $29 Ematic on - air digital recorder that has a USB port to record TV shows. I am using a $3 Monster Digital 16GB USB memory stick from Microcenter to record HD TV shows that write 6GB/hour on to the memory stick.
There was some discussion that it would be better to use a portable USB hard drive instead of USB memory stick, because of the concern that the memory sticks may not be able to write/read fast enough. However when recording/playing HD programs, I didn't see any problem using the memory stick. Here is a speed test for the Monster Digital memory stick. The speed test seems to say the memory stick can handle 40.5 (see screenshot red circle) GB/hour write speed, which is way over the required recording of 6GB/hour. According to this test, it would seem to me that the memory stick should be able to handle recording/playing the HD video with no problem.

[Nelson37]

Totally meaningless information.

Recording requires sustained, hi-capacity file transfer with no interruptions. Run that test for 2-3 hours continuously and that might give you some useful information, but then, that port wouldn't be the same as on the recording device.

Standard speed tests are simply not designed to evaluate drive suitability for capturing. The only real test is to capture several long vids and see if they come thru perfect, or nearly so. VideoRedo's quickfix function is excellent for this.

[pandy]

AFAIR DTT in USA use 8-VSB and as such netto TS bitrate is 19.3904Mbps i.e. anything able to provide 2.5MB/s is OK from source perspective.

Different problem is wear resistance in case of cheap FLASH drives.

[theewizard]

I was part of that discussion, I prefer to use a USB hard drive, I had trouble with my cheap memory stick
Your test showing 11.25 mbs , does fit the needed range, I remember posting that it should be 10~20mbs write speed
Since I usually save what I record, (not just time shift/watch later)
I don't have to transfer the file some where else, I have a 2TB drive just for recording
As long as you can record your 1 hour tv show, without burps or mishaps, keep using your USB stick
Dec 2014 I recorded the 3 hr live nbc broadcast of the sound of music 16.4GB
Not something I would want to try with a memory stick
Things like that you usually only get one chance at, until the network replays their recording of the live broadcast..if ever
Xmas eve I recorded 7 hours of old 1960s tv Xmas specials
Yes SD 4:3 720*480 about 1.3 gig per hour
Your stick would easily hold the 9+ gb
But would it last for 7 hours of continuous recording, with out heating up and malfunctioning

[jagabo]

Your test showing 11.25 mbs , does fit the needed range, I remember posting that it should be 10~20mbs write speed

His test is showing 11 MB/s, not 11 Mb/s. So a 20 Mb/s ATSC stream will use less than 1/4 of the memory stick's write bandwidth.

There might still be issues with random writes (two streams being written to different parts of the memory), turnaround time (flash memory can be slow to switch between reads and writes), and small read/write requests, when watching one stream (with rewind buffer) and recording another.

[pandy]

Your test showing 11.25 mbs , does fit the needed range, I remember posting that it should be 10~20mbs write speed

His test is showing 11 MB/s, not 11 Mb/s. So a 20 Mb/s ATSC stream will use less than 1/4 of the memory stick's write bandwidth.

There might still be issues with random writes (two streams being written to different parts of the memory), turnaround time (flash memory can be slow to switch between reads and writes), and small read/write requests, when watching one stream (with rewind buffer) and recording another.

This can be teted i assume by some random R/W stress testing software.
Nowadays most (if not all) FLASH USB drive are equipped with own uC (usually 32 bit ARM uC) that perform wear-leveling, there is some RAM cache on board also.

[theewizard]

Yes..pausing live tv..it keeps recording, then play's from the pause point when you resume play
So it's writing and reading at the same time
No problems with my USB hard drive..but a flash drive memory stick might not respond as well

[Southstorm]

Yes..pausing live tv..it keeps recording, then play's from the pause point when you resume play
So it's writing and reading at the same time
No problems with my USB hard drive..but a flash drive memory stick might not respond as well

I agree. I have a Mediasonic 180 and had faulty recording using a thumbdrive and pausing live tv. Switched to a hdd and all problems went away.

Sent from my 831C using Tapatalk

[pandy]

Yes..pausing live tv..it keeps recording, then play's from the pause point when you resume play
So it's writing and reading at the same time
No problems with my USB hard drive..but a flash drive memory stick might not respond as well

I know that some companies using FLASH memories (SD card) embedded in STB as HDD substitute... they perform time shifting (so perfectly R/W at different location)... I would be glad to see some source (FLASH card vendors?) with information that this is not recommended or forbidden.

[boardbuilder]

The USB sticks advertised as USB 3 (not the ones advertised as USB 2 & 3 compatible) are significantly faster at writing, even in a USB 2 slot. These are the results of my tests:

Condition: approx 10 gig file copied to stick through a USB 2 port. (Number of bytes in file / number of seconds for transfer to complete) * 8 = bits per second.

SanDisk Ultra USB 3.0 32 gig stick, $14.99 at WalMart store:
Write Transfer Rate = 226 Megabits per second, Read Transfer Rate = 237 Megabits per second.

Sandisk Cruzer Blade 16 gig stick, $4.79 at WalMart store:
Write Transfer Rate = 41 Megabits per second, Read Transfer Rate = 174 Megabits per second.

Since I don't have a computer with a USB 3.0 slot, I can't say if these speeds would improve when used in one; I doubt it though. These speeds aren't even half USB 2.0 max bandwidth. Would be interesting to try though.

In my opinion, the USB 3.0 (as opposed to USB 2.0) sticks are the way to go for applications requiring speed, assuming you want to avoid the drawbacks of hard drives. I know that flash memory has wear issues, but I still like the idea of no moving parts. And I doubt that the power supplies in these cheap set-top-boxes can handle the drain of even a 2.5 inch hard drive. Even if they could, it would probably reduce product lifespan. Also, hard drives have startup lag, which can be annoying.

[theewizard]

I'm not using pocket portable drives
I'm using drives such as Toshiba Canavo? And western digital my book that have 120v supply bricks
No USB power from pvr is needed or used

[boardbuilder]

Understood. And I'm definitely not knocking hard drives (that would be hazardous to their health!). But USB sticks are very convenient. No power cords/bricks/USB Cables, more rugged, no start lag, no moving parts, more portable etc. I guess it depends on what you want to do. I only record occasionally to watch later. If I want to save the program, I transfer it to my archive drive.

[Steve(MS)]

I followed the iview 3500 avsforum thread early on. Time to time someone would post about recording problems and some of those times it was due to using usb sticks. Not to say they won't work but after some over-writes/ erases, general wear and tear will cause recording glitches.
Besides after a few hours, those sticks will be filled @ 1080i.

Here is the first page, read note #21, "Use of a "USB stick" is NOT recommended."

http://www.avsforum.com/forum/42-hdtv-recorders/1465875-iview-3500stb-tuner-dvr-owners...l#post23143523