USB Backup on AVC 761

[todd2 0]

Having problems with USB backup on the 761. Recorded several

events and played them back without problem; I see them in the

event list. However, when I insert the USB key and try to do

the backup, nothing is put on the USB drive even though the 761 tells

me the backup was successful.

 

USB drive is a FAT32 formated OCZ Rally 2gb drive, which is not on the

list of approved USB drives--but the user manual says that if the drive

is not approved, it won't be recognized at all. My drive is recognized

"USB inserted" and the backup menu shows me the free space (1809mb).

 

I bump the year for 'start' back to 2007, select channels 1 & 2, and

hit "start" and a bunch of stuff shoots by too fast to read, though I can

see "cannot find file CH01,"cannot find file CH02", etc. for each channel

I selected. At the end it says something like "backup succesful 1-1-2000".

(I.e., a wacko date is shown even though the current date is set on the

DVR.)

 

Is it a USB drive brand issue, or something else?

[scorpion 0]

I bump the year for 'start' back to 2007

 

What size hard drive do you have?

 

If you have been using this DVR recently, then I cannot see how you can go all the way back to 2007. I doubt that you can store that much video on your hard drive.

 

Is this a DVR that has not been used for a while, and it has the last footage recorded that is from 2007??

 

What is the time/date frame for the start, and end times?

 

I was just curious.

[todd2 0]

Dude, it's a brand new machine. What's more, I wiped the hard drive,

and recorded a single "event" before trying to back up. I selected

2007 just because it was an easy way to select all the events. I actually

was a little confused by the fact that I'm supposed to select "start" and

"end" times rather than selecting the events to backup, but I assume if

I start at 2007 and run to the current time, I'll get them all. (With one

event, probably < 50mb.)

[todd2 0]

Ok, I finally figured this out. I thought it might be a usb stick compatibility

issue but it wasn't (OCZ Rally 2gb stick). Apparently, the issue is that

the "start time" you configure in the USB Backup menu must *exactly*

match a labeled event time listed in the list of playable events. (The

stop time apparently doesn't matter.)

 

I was originally just trying to bound the events I wanted with a pair

of times, but that would always generate a bunch of "not found" errors

and the final "Backup Successful" would have the date 1-1-2000. When

finally, I put the exact time (down to the second) of one of my events,

then the backup didn't exit in a few seconds, and instead started displaying

a status bar. When it finally exited, the correct date was displayed, rather

than 1-1-2000. So apparently, the backup is only successful if you see

the correct date (regardless of whether it says "backup successful".)

 

A few comments:

 

* The API I just described is horrendous. It's non intuitive and gives no

feedback as to what the problem is.

 

* The backup process takes a very long time, perhaps as long as it

took to record the segments. I can't believe the I/O takes that long,

so it must be running a format conversion algorithm. I wonder how

long a flash stick will last under such brutal conditions. (Flash drives

have limited write cycle capability; I once burned one out with 2 weeks

of continous writing. That's only 336 hours.)

 

* I was very impressed by the quality of the video format VSE that's

produced on your PC when you click on the USB backup file. It almost

seems to be higher quality than what you get when you press "play"

on the DVR, which is unusual because you usually lose fidelity during

format conversions. I was not impressed by the AVI quality if you

convert it to an AVI, but the VSE quality is impressive--little blocking.

[cachecreekcctv 0]

Not sure of the Avtech models, but on my Avermedia with USB backup, I have used 4 different USB drives with no problems. The display screen should display the first and the last times/dates you can access, correct? I also have always downloaded several minutes of video, never downloaded "events", though.

[todd2 0]

Yeah, I used the term "events" since I wasn't sure what to call them. Say

your motion detection goes off 4 times giving you 4 clips of video that

show up as 4 events or entries when you hit the left play button "play list".

By backing up "events" I meant clips but maybe that term is not clear.

 

I stand by my claim that it's non intuitive; when you don't select the *exact*

time of one of the "events" or "clips" then you get nothing for your backup.

Bounding them is not sufficient.

[cachecreekcctv 0]

This is the one big reason I carry my Plextor Hardware Encoder. I can take the video output from just about anything, VCR,DVR, camcorder, etc.and input it into this encoder, and encode a video into any of several different formats. A quicker process, especially when it comes to customers who have antiquated time-lapse VCR systems. Just use my laptop/PC then to write this AVI file ( or MPEG1, Mpeg2) to either a CDR or DVD disk. Once I encode this digital video file, can then even upload to Youtube if need be.

[Kiwi 0]

Products such as these lower-cost DVR's are not highly-developed, high-volume consumer products. Probably only one or two engineers designed the firmware and so you're not going to find a refined UI that can second guess your intentions and tolerate your mistakes. However, with a bit of patience and experimentation you will find that you can do just about everything you need to do for the purpose these were designed for.

 

I was very impressed by the quality of the video format VSE that's

produced on your PC when you click on the USB backup file. It almost

seems to be higher quality than what you get when you press "play"

on the DVR

 

Yes, I almost returned my DVR before I discovered this. If I understand it correctly, that's because the playback (on my 782) comes from MJPEG while the "backup" is MPEG4. Not sure about the 761.

[cachecreekcctv 0]

Forgot to mention that if go to Youtube , and search for "Plextor Personal video Recorder Convertx" , you can find information on this Encoder. A big help to me anyway. Especially when there is no source of CD/DVD backup, or when I am trying to capture video from an ancient VHS recorder.

[todd2 0]

Yes, I almost returned my DVR before I discovered this. If I understand it correctly, that's because the playback (on my 782) comes from MJPEG while the "backup" is MPEG4. Not sure about the 761.

 

The compression happens when the video is stored on the HDD; that's

why the hard drive space is consumed at a low rate--compared with

the equivalent uncompressed raw video frame rate. So the compression

algorithm type is determined when you hit record. You don't have a

choice when you play back--you must decompress with whatever

algorithm type was used to encode it--MJPEG, MPEG1, MPEG4, etc.

 

That's why I have a little trouble with your statement that you're using

two different codec types to play back the same video segment from your

DVR--both MJPEG and MPEG4. The video could be decompressed--using

whatever algorithm compressed it when it was originally recorded--and

then recompressed for web transmission, but that usually degrades

quality. (I.e. passing something through a series of algorithms usually

degrades it, or at best leaves it the same.)

 

Therefore, it's puzzling how the VSE file can end up looking better. The

only thing I can think of is that it's perhaps using a better implementation

of the same algorithm that the DVR uses--one that's more processor

intensive but generates better quality. (I.e., we must decompress with

the same algorithm MJPEG, MPEG1, MPEG4, etc. that we compressed with,

but the decompression algorithm can be implemented in various ways,

leaning more towards speed or more towards quality.)

[scorpion 0]

I was thinking "that's news to me"!

 

Interesting if it did!

[Kiwi 0]

Yes, I see your point todd2, but if you look at numerous DVR specs you will find it is quite common for an "MPEG4" DVR to use MJPEG or similar when sending video over the network interface in real time.

 

In my case the resulting MJPEG quality on the 782 is much poorer that I experience on my older generation DVR that uses only MJPEG and has no network viewing.

 

Perhaps it is re-compressing the decoded MPEG4 into MJPEG just for the network such that compression quality can be adjusted as required to suit the bit rate obtained and maintain real time viewing?

 

The 761 brochure states:

 

"MPEG4/MJPEG DVR Technology

Compression format providing crystal clear images with real time performance."

 

To confuse it further, it specifies MPEG4 for CIF setting and MJPEG for frame setting, and that I believe would refer to the backup file.

[scorpion 0]

The manual on page 3 does state

 

Web Transmitting Compression Format: Motion JPEG.

 

KIWI wins the prize!

 

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To confuse it further, it specifies MPEG4 for CIF setting and MJPEG for frame setting, and that I believe would refer to the backup file.

 

This is for model 3, and 4.

 

Models 1, and 2 are:

 

MPEG4 for FRAME, and MPEG4 for CIF!

 

_____________________________________________________________

 

 

The AVTech AVC 760, CPCam 560, and the Nubix 4BC is a model 3. This is the only one that cannot be backed up with a USB, it has to be backed up by the remote software.

Model 3 does not have the USB feature. Models 1,2, 4, and 5 do.

http://211.75.84.102/web/manu/760.pdf

 

 

AVC 761, and the CPD 561 is a model 4 MJPEG at frame, MPEG4 at CIF, 1 audio in, with IR.

http://211.75.84.102/web/manu/761.pdf

 

 

AVC 781, and CPD 501 is a model 2 MPEG4 at frame, MPEG4 at CIF, 2 audio in, no IR.

 

http://211.75.84.102/web/manu/781.pdf

 

 

AVC 782A, and CPD 502 is a model 1 MPEG4 at frame. Model 1 is the only one

with the CD back up, and it has 2 audio inputs.

Model 5 does not have the power/data bus, but it has 2 audio inputs, CD back

up, and it has IR.

http://211.75.84.102/web/manu/782.pdf

 

 

A/V Support:

 

Support 2 audio-in, 1 audio-out to record sounds (Model 1 and Model 2)

Support 1 audio-in, 1 audio-out to record sounds (Model 3 and Model 4)

Support VGA output to monitor (optional)

_____________________________________________________________

 

OK! Now my head is hurting trying to figure this all out!