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Avtex L236DRS USB port won't reliably read camera jpeg files



 
 
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  #1  
Old September 19th 13, 11:30 PM posted to uk.tech.digital-tv
Neil[_5_]
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Posts: 4
Default Avtex L236DRS USB port won't reliably read camera jpeg files

Hi.

Hoping very much, that someone here can help out with this problem.

My old caravan TV screen gave up and I have
replaced it with an Avtex L236DRS - megabucks!

After teething troubles, most of which(not all) are sorted, I am
having a problem with the use of the USB to read pictures(.jpg files)
from my little Praktica 4Mp camera.

Basically the TV cannot reliably read the installed SD card as an
external storage device, which my other domestic TV will do without a
problem. It will show some of the files as thumbnails, and some it
won't - but it isn't always the same files that will and will not
display!

Also it will not display any of the files at full screen size. The
Avtex people cannot figure out the cause yet, because this model is
fairly new.

Just a further bit of info though - in the same week as I bought the
Avtex, I also replaced the domestic TV with a Panasonic plasma set.
This also has the facility to read .jpg picture files from any USB
device, and will read from my camera perfectly! Go figure!

So, the bottom line is:-

Does anyone here have any problem looking at their digital pictures
directly from their camera's USB port?

All comments regarding Avtex compatability with cameras could be
useful.

Thanks in advance people!

Neil
(Reply via group please)
  #2  
Old September 20th 13, 12:43 AM posted to uk.tech.digital-tv
Steve Thackery[_2_]
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Posts: 2,552
Default Avtex L236DRS USB port won't reliably read camera jpeg files


Can you clarify something for us? You mention the use of USB to read
pictures, but refer to the "installed SD card".

Does this mean you are using a USB lead to connect the camera to the
TV? Or are you taking the SD card out of the camera and putting it
into one of those SD card readers that plugs into a USB port?

--
SteveT
  #3  
Old September 21st 13, 02:05 AM posted to uk.tech.digital-tv
Neil[_5_]
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Posts: 4
Default Avtex L236DRS USB port won't reliably read camera jpeg files

On Thu, 19 Sep 2013 19:43:39 -0500, "Steve Thackery"
wrote:


Can you clarify something for us? You mention the use of USB to read
pictures, but refer to the "installed SD card".

Does this mean you are using a USB lead to connect the camera to the
TV? Or are you taking the SD card out of the camera and putting it
into one of those SD card readers that plugs into a USB port?


Of course I can, thank you for the fast response!

The camera has its own rather limited memory plus a slot for an SD
memory card. In this slot I have installed a 512MB SD card, it is
this that I refer to. In use, I never normally need to remove the SD
card from the camera. The camera has a mini USB connector, which I
use to connect the camera to a PC in order to transfer the pictures to
a laptop and then, once saved, I erase them from the camera. I've
been doing it this way for years.

Both laptops I have, recognise the camera as a mass storage device
when I plug it in using a USB lead, so there's no problem with that.
I can also connect the camera to my domestic Panasonic plasma TV at
home, and this TV also recognises the camera as a USB device, and I
can view the pictures on the card(still in the camera) using the TV's
media viewer function.

It is probably relevant to point out that in order to appear as a USB
device on any USB input, it is necessary to power the camera up.

Where it all fails, is trying to view the pictures on the Avtex by
connecting the camera. I have also tried removing the SD card from
the camera and inserting it into a small card reader that has a USB
connection. This works with the domestic TV just the same as plugging
in the camera, but plugging this into the Avtex results in it not even
being recognised as a USB device.

Oddly, if pictures are on a USB memory stick, then they can be viewed
without any problem, but then the whole point of getting an Avtex TV
is to take it away in the caravan, and not need to take a laptop in
order to view the pictures you've just taken

I hope I've explained everything fully. The thing is, I can't see why
on earth the Avtex, which is suposed to be able to view jpegs and
various video formats via USB, will just not do it when the Panasonic
will!

Thank you

Neil

(Reply via group please)
  #4  
Old September 22nd 13, 01:40 PM posted to uk.tech.digital-tv
Steve Thackery[_2_]
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Posts: 2,552
Default Avtex L236DRS USB port won't reliably read camera jpeg files

Neil wrote:

I hope I've explained everything fully. The thing is, I can't see why
on earth the Avtex, which is suposed to be able to view jpegs and
various video formats via USB, will just not do it when the Panasonic
will!


I don't know for sure, but this sounds like a compatibility issue to
me. SD cards come in a variety of classes, to do with their read/write
speed. You will probably find this useful:

http://en.wikipedia.org/wiki/Secure_...d_Class_Rating

I can't say for sure that this is the trouble, but the symptoms you
describe do match up very closely. Not all reading devices will read
all the different classes of SD card, which I think is the issue here.
Sometimes they just refuse to see it, other times they do weird things
like reading only half the file, or letting you list the files but not
view them.

The class of most (but definitely not all) SD cards is marked on the
label, with a number inside a 'C' symbol. For instance, I've just
checked and the one in my camera is a 2G class 2.

When I bought a new card reader for my PC I had to make sure it read
all the classes of SD card - some don't.

The only suggestion I have is to buy another card with a higher class
rating and see if it works more reliably.

Hopefully someone else will come along with some more suggestions. I
claim no expertise, merely some experience!

--
SteveT
  #5  
Old September 23rd 13, 02:30 AM posted to uk.tech.digital-tv
Neil[_5_]
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Posts: 4
Default Avtex L236DRS USB port won't reliably read camera jpeg files

On Sun, 22 Sep 2013 08:40:12 -0500, "Steve Thackery"
wrote:

Neil wrote:

I hope I've explained everything fully. The thing is, I can't see why
on earth the Avtex, which is suposed to be able to view jpegs and
various video formats via USB, will just not do it when the Panasonic
will!


I don't know for sure, but this sounds like a compatibility issue to
me. SD cards come in a variety of classes, to do with their read/write
speed. You will probably find this useful:

http://en.wikipedia.org/wiki/Secure_...d_Class_Rating

I can't say for sure that this is the trouble, but the symptoms you
describe do match up very closely. Not all reading devices will read
all the different classes of SD card, which I think is the issue here.
Sometimes they just refuse to see it, other times they do weird things
like reading only half the file, or letting you list the files but not
view them.

The class of most (but definitely not all) SD cards is marked on the
label, with a number inside a 'C' symbol. For instance, I've just
checked and the one in my camera is a 2G class 2.

When I bought a new card reader for my PC I had to make sure it read
all the classes of SD card - some don't.

The only suggestion I have is to buy another card with a higher class
rating and see if it works more reliably.

Hopefully someone else will come along with some more suggestions. I
claim no expertise, merely some experience!


Thank you for the time and effort - it is appreciated!

Since last post, I have tried a different SD card, a 1GB one. Neither
card is HDSD, still no joy. I have tried different formatting FAT 32
as an alternative to FAT in case that was the cause, but the camera
won't work with anything other than FAT. My cards are not marked with
anything other than their capacity, they are Sandisk branded.

Hopefully someone with an Avtex TV, and a digital camera will see
this thread and can do a test on theirs. I live in hope ;o)

Neil

(Reply via group please)
  #6  
Old September 23rd 13, 06:47 AM posted to uk.tech.digital-tv
David Woolley[_2_]
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Posts: 526
Default Avtex L236DRS USB port won't reliably read camera jpeg files

On 22/09/13 14:40, Steve Thackery wrote:


I don't know for sure, but this sounds like a compatibility issue to
me. SD cards come in a variety of classes, to do with their read/write
speed. You will probably find this useful:


There is quite a complex chain between the SD card and the USB port and
the only effect that I would expect card class to have would be on the
speed of access, and that probably only for writing.

My guess is that either the camera needs more current than the set is
prepared to provide, or that the 5 volts on the USB port is rather less
than 5 volts. Both of these can probably be resolved by the addition of
a powered hub.

Note that the set should refuse to connect at all if the power
requirements are more than it is prepared to cope with, so if you are
getting an uncontrolled overcurrent situation, you may be overheating
components in the set.

If you have access to a full Linux system (including Raspberry Pi, but
not the average set top box) you can us lsusb to find out how much
current the device claims that it needs. All USB interfaces should
provide at least 100mA.

  #7  
Old September 23rd 13, 07:32 AM posted to uk.tech.digital-tv
Paul D Smith[_2_]
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Posts: 720
Default Avtex L236DRS USB port won't reliably read camera jpeg files

"David Woolley" wrote in message ...

On 22/09/13 14:40, Steve Thackery wrote:


I don't know for sure, but this sounds like a compatibility issue to
me. SD cards come in a variety of classes, to do with their read/write
speed. You will probably find this useful:


There is quite a complex chain between the SD card and the USB port and
the only effect that I would expect card class to have would be on the
speed of access, and that probably only for writing.

My guess is that either the camera needs more current than the set is
prepared to provide, or that the 5 volts on the USB port is rather less
than 5 volts. Both of these can probably be resolved by the addition of
a powered hub.

Note that the set should refuse to connect at all if the power
requirements are more than it is prepared to cope with, so if you are
getting an uncontrolled overcurrent situation, you may be overheating
components in the set.

If you have access to a full Linux system (including Raspberry Pi, but
not the average set top box) you can us lsusb to find out how much
current the device claims that it needs. All USB interfaces should
provide at least 100mA.

++++++++++++
Personally I'd say responders are getting far too into interesting but
irrelevant details here. The TV is faulty by the sound of it, period.
Reading a "memory card" (whether directly, via a USB cable, via a USB
adapter etc) is the simplest type of USB operation and if the TV can't do
that, I would not trust it to do anything. Now "faulty" can have many
meanings but the fact that everything else can read the memory card via the
camera is the nail in Avtex's coffin.

And before anyone adds "yes but...", please remember "Postel's law":

"Be conservative in what you do, be liberal in what you accept from
others"

Or to put this into English, your product should obey all the appropriate
standards to the letter (in so much much as it is possible to do), but don't
expect others to - and if you want your product to survive in the real
world, you'll just have to suck this up and find a way to work with these
"might not be perfect" products.

So take the TV back as "unfit for purpose" and get one that does what you
want.

Paul DS.

  #8  
Old September 23rd 13, 09:36 AM posted to uk.tech.digital-tv
David Woolley[_2_]
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Posts: 526
Default Avtex L236DRS USB port won't reliably read camera jpeg files

On 23/09/13 08:32, Paul D Smith wrote:

Or to put this into English, your product should obey all the
appropriate standards to the letter (in so much much as it is possible
to do), but don't expect others to - and if you want your product to
survive in the real world, you'll just have to suck this up and find a
way to work with these "might not be perfect" products.

So take the TV back as "unfit for purpose" and get one that does what
you want.


Unless they specifically told the salesman of their intent to use that
camera, or the camera draws less than 100mA, or the current sourcing
capabilities of the TV are specified, you would be depending on the
goodwill of the seller.

Compliant USB ports don't have to source more than 100mA, although
devices can demand up to 500mA; on non-PC devices, it is common to rely
on this. There would be a fault in the host if it accepted a connection
from a device which specified a higher current than it could source, but
that would not affect whether or not it would work with the device;
refusing to up the power above 100mA would just as much prevent the use
of the camera.

It is also possible that the camera is sinking more current than it
claims to use, and other hosts have less efficient current limiting.

An actual fault specific to reading from mass storage class devices
would be a firmware bug, and, as everyone probably gets this code from a
very limited range of sources, seems an unlikely fault. The SD card
should not be distinguishable from other mass storage devices to the
firmware on the TV.

  #9  
Old September 23rd 13, 02:54 PM posted to uk.tech.digital-tv
Neil[_5_]
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Posts: 4
Default Avtex L236DRS USB port won't reliably read camera jpeg files

On Mon, 23 Sep 2013 10:36:30 +0100, David Woolley
wrote:

On 23/09/13 08:32, Paul D Smith wrote:

Or to put this into English, your product should obey all the
appropriate standards to the letter (in so much much as it is possible
to do), but don't expect others to - and if you want your product to
survive in the real world, you'll just have to suck this up and find a
way to work with these "might not be perfect" products.

So take the TV back as "unfit for purpose" and get one that does what
you want.


Unless they specifically told the salesman of their intent to use that
camera, or the camera draws less than 100mA, or the current sourcing
capabilities of the TV are specified, you would be depending on the
goodwill of the seller.

Compliant USB ports don't have to source more than 100mA, although
devices can demand up to 500mA; on non-PC devices, it is common to rely
on this. There would be a fault in the host if it accepted a connection
from a device which specified a higher current than it could source, but
that would not affect whether or not it would work with the device;
refusing to up the power above 100mA would just as much prevent the use
of the camera.

It is also possible that the camera is sinking more current than it
claims to use, and other hosts have less efficient current limiting.

An actual fault specific to reading from mass storage class devices
would be a firmware bug, and, as everyone probably gets this code from a
very limited range of sources, seems an unlikely fault. The SD card
should not be distinguishable from other mass storage devices to the
firmware on the TV.


Paul and David

I think I may have said further back in this thread somewhere, that
the camera has to be powered ON in order to be read by ANY device as a
USB Mass Storage Device, so I doubt that USB power drain will be an
issue here.

Secondly, my belief that there is an intrinsic flaw in the
software/firmware/whatever, in these new models, is now further
supported by the fact that upon trying the same procedures with a
different set of the same model, i.e. the display set where I bought
it, I get exactly the same results!

This despite Avtex's firm belief that this model is designed to read
jpg and other media files from a USB connected storage device.

They've just suggested again, that the TV is not compatible with my
camera. OK I said, so why then if I remove the SD card from the
camera and insert it into a USB card reader, does it still not work as
it is claimed to?

I'm expecting another call back from Avtex this afternoon - fingers
crossed!

As an aside, as far fitness for purpose is concerned, the product
description includes these two sentences which are applicable to my
model:-

"All Avtex TV's that carry this symbol have a USB socket allowing them
to be connected to an external memory device to view still pictures
etc."

"Products that carry this record symbol are able to record to a (USB
memory stick or an external Hard Drive)."

That's exactly how it is worded.

Neil

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