Hello, i want to know if udpcast will be able to transmit different files to different multicast addresses at the same time.
Also if it is plausible to make a web interface to handle scheduling of the files that are going to be sent over udpcast, so remote recievers are able to get the files they where requested, this will be like on demand content delivery.
to do this all clocks from the remote sides have to be in sync with the master content node, and the remote content node or client should be able to parse a file to see the content that udpcast will transmit.
Also i need to know what is the best fec algorithm for one way satellite comunicacion.
Fernando Rodriguez frod@aitelecom.net
Fernando Rodriguez wrote:
Hello, i want to know if udpcast will be able to transmit different files to different multicast addresses at the same time.
Yes, you can start several instances of udpcast simultaneously. You only need to make sure that each instance uses a different port base (-P parameter).
Also if it is plausible to make a web interface to handle scheduling of the files that are going to be sent over udpcast, so remote recievers are able to get the files they where requested, this will be like on demand content delivery.
You could make a cgi script that would start udpcast in the background as requested.
to do this all clocks from the remote sides have to be in sync with the master content node, and the remote content node or client should be able to parse a file to see the content that udpcast will transmit.
You could have one udpcast responsible for transmitting the announcement, which would be saved to a file on the receiver, to be parsed by the GUI frontend. Then, the actual content would be transmitted by separate instances, either on-demand, or continuously as a carousel.
Also i need to know what is the best fec algorithm for one way satellite comunicacion.
It all depends on the quality of the link, and the power of your receivers. You want to play with the 3 parameters stripes x redundancy / stripesize .
A higher ratio redundancy / stripesize can protect against higher loss rates. However, it also makes the transmission larger.
Larger number of stripes protects against clustered losses (so, if your link is likely to lose many packets in a row, use a high number of stripes). However, a higher number of stripes leads to higher memory requirements.
A bigger stripesize also helps against clustered losses, at the cost of memory and computation time.
You need to play a little bit with the parameters to find the best fit for your transmission link and receiver hardware.
The way it works is that each stripe is an independant FEC group. Each stripe is made up of stripesize (n) data packets plus a number of redundancy packets (k). As long as at least n packets are received (i.e. less than k packets lost), no matter whether they are original data packets, or redundancy packets, everything in the FEC group (stripe) can be reconstructed.
During transmission, s stripes (FEC groups) are active simultaneously, a packet of each being transmitted in a round-robin fashion (i.e. first a packet of stripe 1, then one stripe 2, etc. until the last stripe is reached, after which the second packet of stripe 1 will be transmitted). This interleaving is meant to protect against clustered losses, so that if for instance 10 packets in a row are lost, they won't all fall within the same FEC group.
Fernando Rodriguez frod@aitelecom.net
Alain
Alain,
I also wanted to know because on your satellite example you set the interface to dvb0 i have some cards dvb cards and lnb.
Im going to get a php programer to make the scheduling.
Thanks
On Sep 18, 2008, at 3:16 PM, Alain Knaff wrote:
Fernando Rodriguez wrote:
Hello, i want to know if udpcast will be able to transmit different files to different multicast addresses at the same time.
Yes, you can start several instances of udpcast simultaneously. You only need to make sure that each instance uses a different port base (-P parameter).
Also if it is plausible to make a web interface to handle scheduling of the files that are going to be sent over udpcast, so remote recievers are able to get the files they where requested, this will be like on demand content delivery.
You could make a cgi script that would start udpcast in the background as requested.
to do this all clocks from the remote sides have to be in sync with the master content node, and the remote content node or client should be able to parse a file to see the content that udpcast will transmit.
You could have one udpcast responsible for transmitting the announcement, which would be saved to a file on the receiver, to be parsed by the GUI frontend. Then, the actual content would be transmitted by separate instances, either on-demand, or continuously as a carousel.
Also i need to know what is the best fec algorithm for one way satellite comunicacion.
It all depends on the quality of the link, and the power of your receivers. You want to play with the 3 parameters stripes x redundancy / stripesize .
A higher ratio redundancy / stripesize can protect against higher loss rates. However, it also makes the transmission larger.
Larger number of stripes protects against clustered losses (so, if your link is likely to lose many packets in a row, use a high number of stripes). However, a higher number of stripes leads to higher memory requirements.
A bigger stripesize also helps against clustered losses, at the cost of memory and computation time.
You need to play a little bit with the parameters to find the best fit for your transmission link and receiver hardware.
The way it works is that each stripe is an independant FEC group. Each stripe is made up of stripesize (n) data packets plus a number of redundancy packets (k). As long as at least n packets are received (i.e. less than k packets lost), no matter whether they are original data packets, or redundancy packets, everything in the FEC group (stripe) can be reconstructed.
During transmission, s stripes (FEC groups) are active simultaneously, a packet of each being transmitted in a round-robin fashion (i.e. first a packet of stripe 1, then one stripe 2, etc. until the last stripe is reached, after which the second packet of stripe 1 will be transmitted). This interleaving is meant to protect against clustered losses, so that if for instance 10 packets in a row are lost, they won't all fall within the same FEC group.
Fernando Rodriguez frod@aitelecom.net
Alain
Fernando Rodriguez frod@aitelecom.net
-
Alain Knaff -
Fernando Rodriguez