Differences between true streaming and pseudo streaming
Let's compare two ways of streaming video files - true streaming and HTTP pseudo streaming.
True streaming is available with CDN Video, CDN Video Push and CDN Live services. On the other hand pseudo streaming is available with CDN Static and CDN Static Push services. In particular true streaming is available only in (Wowza based) streaming CDN Locations and pseudo streaming is available in all CDN Locations. It is because all our CDN Locations support (Nginx based) HTTP delivery. Please refer to the network page for more details and note that streaming CDN Locations are marked with a "play" icon.
Both true streaming and pseudo streaming work with Flash and HTML5 players such as JW Player or Flowplayer and work also natively on iOS and Android devices. However true streaming is more compatible since it is delivered over multiple protocols such as RTMP, HLS, RTSP, etc. Please refer to Supported CDN streaming protocols and formats for more details.
Both true streaming and pseudo streaming allow viewers to seek to not yet downloaded parts of a video file.
True streaming buffers only video chunks from the CDN that are requested by a viewer. On the other hand pseudo streaming buffers the whole remaining part of a video file as fast as viewer's connection speed.
For true streaming (CDN Video, CDN Video Push and CDN Live services) the CDN caching is fully under our control. For pseudo streaming (CDN Static and CDN Static Push services) you can control the CDN caching, namely you can purge and prefech (prepopulate) your video files and you can set their expiry time.
For true streaming a video file is not being cached to viewer's local cache (memory or disk in viewer's device) on the other hand for pseudo streaming a video file is being cached to viewer's local cache. In particular for true streaming if a viewer replays a video then it is not played from viewer's local cache but it is delivered from the CDN again, on the other hand for pseudo streaming if a viewer replays a video then it is played from viewer's local cache.
True streaming is delivered from our CDN edge servers with Wowza Media System. On the other hand pseudo streaming is delivered from our CDN edge servers with Nginx.
Advantages of true streaming
- Multiple protocols such as RTMP, HLS, RTSP, etc.
- Buffers only video chunks that are requested by a viewer. It can save traffic costs in some cases.
Advantages of pseudo streaming
- Pseudo streaming is available in all CDN Locations.
- Video files can be prefetched (prepopulated) to the CDN.
- Video files are cached to viewer's local cache. It saves traffic costs when viewers often replay your videos.
The biggest disadvantage of pseudo streaming
It is its name. It is true that true streaming sounds better than pseudo streaming but in all other aspects pseudo streaming is performing very well and very effectively and you should definitely consider it for your streaming.