DemoVideoMulticast en
Multicast Hierarchical Video
Context
IP multicast is a group communication mechanism. When several users want to receive the same content, the multicast mechanism permits the server to send it only once. Then, the routeurs are in charge to duplicate the packets. Thereby, a minimal number of copies travel over the network links, which allows to reduce the bandwidth usage. In example, the multicast has democratized the IP-TV.
To generalize the deployment and the use of multicast, a congestion control mechanism is compulsory. Moreover, this mechanism must be fair with TCP. Several receiver-driven layered multicast congestion control scheme have been proposed. They are scalable to very large groups, but none of these are yet fully satisfying. The "Networking & Protocols" research team works on this problematic with the aim of improving:
- The fairness between multcast streams and TCP.
- The convergence quickness to the fair rate.
Principles
We want to show the possibilities given by the multicast associated with a congestion control. Thereby, we have designed a live time video streaming software, which allows several users to receive the same stream, but with an image quality fitted to the bandwidth available for each receiver.
Thus, the congestion control allows each receiver to calculate his own maximal rate and to receive the matching image quality. Therefore, when the received rate grows, each receiver improve its own the image quality.
Demonstration
Goal
This demonstration shows the capacity of each multicast client to auto-regulate his reception rate, depending on the network conditions. And consequently receive an optimal image quality.
Test bed
The test bed demonstration allows the dynamic rate modification of the congestioned link. That permits to highlight the relation between the image quality an the network bandwidth.
Scénario
Pour cette démonstration, nous avons mis en place en serveur de vidéo et un récepteur. Pendant la réception, nous changeons le débit du lien :
- Test 1 : Le débit permet de recevoir la première couche.
- Test 2 : Le débit permet de recevoir les 4 premières couches.
- Test 3 : Le débit permet de recevoir les 16 premières couches.
- Test 4 : Le débit permet de recevoir les 64 premières couches.
Résultats
| Test 1 - 1 couche :
<videoflash>K4VR1vCs63c|300</videoflash> |
Test 2 - 4 couches :
<videoflash>5_i5V9TKaB4|300</videoflash> |
|---|---|
| Test 3 - 16 couches :
<videoflash>2JYch0Fpieg|300</videoflash> |
Test 4 - 64 couches :
<videoflash>PM3PYnuahxc|300</videoflash> |
Sources de l'application
L'application est disponible sous licence GPLv2 à l'adresse suivante : MuVi-Channel