Tag Archives: P2P

Download VS. stream

Downloading and streaming are several basic technologies to distribute media over the Internet. Streaming evolved from downloading and makes it possible to consume media regardless of the point at which it starts receiving.

Download

  • Classical downloading – bringing in a database in its entirety before it can be played;
  • Progressive downloading – where a data file can be played before it is fully obtained;

Stream

  • Livestreaming – where the sender steers and the receiver can start consuming at any moment. Also known as webcast;
  • On-demand streaming – where the sender sends as soon as the recipient asks (as with video on demand and web videos).

Pros and cons

Every technique has advantages. The trade-off for a technique is mainly about the preference between the continuity of reception or the quality of the file transfer. The classic way of downloading only occurs when collecting files for which it is necessary that they are received without defects. Communication often takes place through the TCP protocol, which is designed for high reliability in poor connections. Sometimes continuity is more important than quality. For listening to conversations, online multiplayer games, or viewing footage, therefore, streaming is often chosen, often communicated via the UDP protocol. Some protocols even dynamically adjust quality based on continuity during the connection. Thanks to streaming, the receiver (a) can start consuming immediately and (b) start at any point.

Other benefits of streaming include:

  • More efficient use of server capacity
  • Data traffic is only generated when it is really necessary.
  • Better analysis of viewing behaviour
  • Because the receiver consumes at the time it downloads, the viewing behavior can be tracked very accurately. The information in these logs is essential for analysis of viewing behavior, trends and technical usage data for programme makers, advertisers, broadcasters, Internet providers, digital video stores and helpdesks.
  • Virtual assembly
  • Using a technique called bursting, it is possible to virtually assemble fragments from files in succession. For end users, the advantages are that one does not have to wait (actual on demand) and can use the file as if it is stored locally.
  • Better source protection
  • Because no complete files are stored with the recipient, it is less easy to illegally store copies.

Downloading is especially efficient if the file is consumed frequently, or with an Internet connection that is too slow to stream.

Network peer to peer

Peer-to-Peer

Peer-to-peer (P2) makes it possible to receive data (which belongs together) from different shippers via the Point-2-Point protocol. This is possible with both downloading and streaming. The big advantage is that the central server is relieved and data transfer is more efficient via fast (or more nearby) routes than those from the server. A disadvantage is that front and reverse coils become more unreliable. Another disadvantage is that distribution is no longer controlable or measureable.

Future

The general expectation was that around 2015 virtually all audiovisual content will be distributed via IP: as a download, VOD stream or as an IPTV stream. Analogue distribution over the air and cable will disappear first. The different DVB variants will migrate to IP. For example, DVB-IP is an MPEG-4 stream, but with a DVB naming to accelerate adoption in the cable industry. Television distribution with peer-to-peer technology is also seen as a possible contender, although current trials show that lesser-known titles are poorly distributed and in particular that the quality and reliability of the signals is far below par.

Few Internet service providers support multicasting and unicasting is used instead. Despite the larger data volumes of unicasting, livestreams – as opposed to p2p solutions – can be distributed well thanks to decentralized distribution and even QoS (quality guarantees) can be designed on availability and reliability.