Half a croissant, on a plate, with a sign in front of it saying '50c'
h a l f b a k e r y
Professional croissant on closed course. Do not attempt.

idea: add, search, annotate, link, view, overview, recent, by name, random

meta: news, help, about, links, report a problem

account: browse anonymously, or get an account and write.

user:
pass:
register,


         

Non-streaming video transfer protocol

For captures
  (+3)
(+3)
  [vote for,
against]

Firewire cameras do a great job of playing back video in real time, but a problem arises when trying to transfer it to a computer. Since it utilizes a streaming transfer protocol, there is no room for error. If a frame is lost in transmission, it is lost forever. No going back to get it.

Instead, use a packet based transfer system. The camera sends out fram packets, waiting for the ACK from the computer. If it loses a frame, the camera simply sends it again, not losing a single frame. This may result in a total delay of a few seconds behind real-time, but for captures, who cares?

When connected to a non-capture device, it will stream normally.

Aq_Bi, Jun 29 2005

Please log in.
If you're not logged in, you can see what this page looks like, but you will not be able to add anything.
Short name, e.g., Bob's Coffee
Destination URL. E.g., https://www.coffee.com/
Description (displayed with the short name and URL.)






       The reason video transfer is done in real time is because a DV video camera records onto and plays back from a tape. Stopping and starting the tape at exactly the right frame when your computer glitches is not an efficient solution to the problem.   

       An easier way to stop computer glitches is to get a fast hard disk drive and plenty of RAM.
xaviergisz, Jun 29 2005
  

       It need not start and stop the tape. Simply give the camera a slightly larger buffer. How do you think computer tape drives work?   

       Even a high end machine will experience periodic frame loss, especially those running a certain unnamed operating system. I've even used dedecated mac workstations with an unsatisfactory number of lost frames. This will also allow the computer to perform other tasks simultaniously without risk of loss.
Aq_Bi, Jun 29 2005
  

       I can see where you're coming from, but I think creating a new protocol is a bit of overkill... whether you have a RAM buffer in the video camera or in the computer is (or rather should be) immaterial. It must be possible to optimize operating systems for tasks such as video transfer (or maybe I'm dreaming).
xaviergisz, Jun 29 2005
  

       Not having ever used a modern video camera, I had naïvely assumed that they already worked as Aq_Bi describes. [+].
st3f, Jun 29 2005
  


 

back: main index

business  computer  culture  fashion  food  halfbakery  home  other  product  public  science  sport  vehicle