AVI -> ASF conversion

Paul Kievits · Post by **Paul Kievits** » Sun Feb 15, 2004 4:29 am

The project is for a hospital. They want to stream pre-recorded catheterisation to go with their existing diagnostic tools. The thing I'm certain of is that they want to be able to start the video at a random point.

Searchability may not be the biggest problem, but I was just wondering why I was seeing what I was seeing... But you think that searchability may not be possible? In that case I'll just report that in my findings and see what my employers have to say.

kmv · Post by **kmv** » Sun Feb 15, 2004 6:22 am

Thanks for the information that helped a lot.

From my understanding I think you can quite happily forget about needing to stream the files:

You are on an internal network (presumably a LAN), meaning that the more interactive protocols (like NFS) are OK
You need random access, if a doctor wants to pause, go back etc., then they should be able to
Piracy and unauthorised retention of the video is not issue, although restricted access might be

Instead of streaming the video, I would recommend that you just serve file itself. Essentially you make it look like the video file is on a file server (although it could really be in a database or whatever) and the client just accesses the file.

There are lots of ways you could handle access control (both security and lookup) but one way would be to provide access to the patents files and diagnostic information via a portal (WebSphere or something similar), which would take care of access and authentication and allows the client to be a nothing more complex than a browser. Then link through to the video file, and play it in the browser using the QuickTime plug-in (although that assumes MPEG or MOV files). That would be one solution that has everything you wanted, including random access, but there are others.

BTW if you need my credentials email me, but in short I am a telecommunications solutions architect for large scale and huge scale telecommunications business support systems.

Paul Kievits · Post by **Paul Kievits** » Sun Feb 15, 2004 7:20 am

Wow...

Thanks a lot KMV, it's good to see there are still some helpful people on te .org. Anyway I had been playing around with file serving via a HTTP server (apache) and it seemed like a good solution but I was just also playing with RTSP to see if it was an alternative...

I still do have one question: Let's say I have a 15 minute video (a huge download) and the doctor only wants to see the last minute. Is there a way to actually send a message to the server (or the media file) which states it should start at a given point and thus reduces the download size/time? If it's not possible by a direct command is it possible to do a fast mux which eliminates the part of the video they don't want to see?

kmv · Post by **kmv** » Mon Feb 16, 2004 5:52 pm

In my example I was suggesting more immediate protocol like NFS (or NTFS), in other words a "file:" as opposed to an "http:", because if you use HTTP then the client is forced to download the entire file. When the file gets there you will have random access but you will have to wait for it - which you noted in your second paragraph.

RTSP is fine protocol, and would be another realistic option. Its random access though isn't as random as you might wish for - but it can do it through the proper use of the PAUSE and PLAY commands (but the client should take care of that).

I guess the key differentiator between NFS and RTSP in this case is access. In your original requirements you said that it was on a LAN - meaning that there is only one client for a video and they are inside the firewall. If the client is going to be outside the firewall (or if there is a future requirement for them to be outside it) or there will be multiple clients viewing the same video at the same time then NFS is unsuitable and you should go for something like RTSP. If you will always be inside the firewall then NFS should be OK - and I think the performance will be better.

I am reasonably sure that the QuickTime plug-in doesn't force the entire file to come down (and the small amount of testing I just did locally would seem to confirm that). Which means that in the case of your 15 minute file you shouldn't need to wait for the whole thing, once it has started playing you can skip to the end. Of course, you should confirm this for yourself.

One other point of note on the QuickTime plug-in - it seems to get upset when there are %20's in the URL and you are using "file:". I have no idea why.