What is MPEG-PS?
MPEG-PS stands for Moving Picture Expert Group Program Stream. It is usually referred to as Program Stream or PS.
It is a container format.
It multiplexes (muxes) digital audio, video, and other digital data. In other words, it combines multiple digital signals into a single signal.
In MPEG-2, there are two information streams – Transport Stream (TS) and Program Stream (PS).
Layers in MPEG-PS Files
MPEG-PS files consist of 3 layers:
PS layer (Program Stream) – containing the needed information to identify and transmit data stream that is added to the PES layer
PES layer (Packet Elemental Stream) describes the data frame – for example, timestamps on the audio and video data
ES layer (Elementary Stream) consisting of audio and video data
Difference Between MPEG-PS and MPEG-TS
What’s the difference between MPEG – Program Stream and MPEG -Transport Stream?
The main difference between MPEG-PS and MPEG-TS is in the packet structure. The PS structure is of variable length whereas that of TS is of fixed length.
What is the Effect of the Packet Structure Difference ?
The difference is in the different ways they’re resistant to transmission errors.
TS’ fixed-length packet structure enables it to correct corruption of synchronization information and prevent information loss.
Hence it is more resistant to transmission errors.
PS’ variable-length packet structure makes it unable to recover the information when information synchronization of a particular PS packet is lost.
This is because the receiver can’t determine the synchronization position of the following packet.
As a result, there will be information loss.
So, generally, the TS stream is used in environments where transmission errors are high and the PS Stream where transmission errors are low.
Where are MPEG-PS and MPEG-TS Used?
Here’s another notable difference between MPEG-PS and MPEG-TS.
MPEG-PS is preferred for content that has a fixed duration like in DVD movies and HD DVD movies.
DVD movies use the VOB extension whereas HD DVDs use the EVO extension.
MPEG-TS is more suited for real-time content such a TV program broadcasts.
If the front part of a VOB file on a DVD is corrupted or damaged, you’ll not be able to read it.
In the case of a TV program transmission, in MPEG2-TS any part of the video stream can be independently decoded. So, you can turn your TV on at any time and watch a show.
So, MPEG-PS is used for playback and editing systems, and MPEG-TS is used for video data transmission as in TV broadcasts.