What Is MPEG PS ? Working Of MPEG PS Or Program Stream ?

mpeg ps

Introduction

In Digital Video Broadcasting industry MPEG Transport Streams are used to send the audio, video and data efficiently. Where these Transport Streams can be Multi Program Transport Streams and Single Program Transport Streams. Where Each PES packet is divided into fixed size TS packet referenced to independent time base.

So this kind of transmission is suitable if losses in packets happened during transmission.

While scenario in case of MPEG PS is different. Before understanding MPEG PS lets first understand Overview of ES PES. Which will make more easy for us to understand MPEG PS.

Overview Of ES PES

ES is known for Elementary Stream while PES is known for Packetized Elementary Stream.

Now suppose there is a MPEG 2 Encoder. We provides audio and video input to encoder separately. Now audio goes into the one elementary encoder and video goes into the other elementary encoder.

Now output of these two separate elementary encoder produces separate ES or Elementary Stream. One ES for video and One ES for audio.

Now each individual ES goes into the individual Packetizer which produces PES. Where PES is known for Packetized Elementary Stream.

While in case of Data, input Data goes into the packetizer to provide PES.

Elementary Stream bitrate can be fixed and variable too. Now finally, Multiplexing of one or more PES is the final output of a MPEG2 Encoder.

What Is MPEG PS ?

MPEG PS is acronym for Moving Picture Expert Group – Program Stream. A Program Stream contains Audio, Video and Data in a format for multiplexing. So it is multiplexing scheme for Audio, Video and Data in a format.

In other words,

A MPEG PS is a combination of one or more than one Packetized Elementary Streams (PES) reference to Common Time Base into a single stream.

So a Program Stream is a multiplexed output of video, audio and data.

MPEG Program Streams are good for transmission in error free medium. These Program Streams are used for recording or playback in DVD. It is not good transmission purpose in contrast with Transport Streams. Program Streams are also used in some network applications.

So MPEG2 PS contains only one channel for easily delivery in error free medium. It is good for storage medium like you download a video file from a network. So it is widely used for Digital Video Disc in VOB format while for HD-Digital Video Disc in EVO format.

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Working Of MPEG PS ?

mpeg ps working

As shown above in the figure audio and video is inserted into the MPEG2 Compressors. where audio and video are compressed separately. After compression its output goes into the MPEG 2 System Processor. Which gives the multiplexed output of audio and video is known as MPEG Program Stream.

This MPEG Program Stream goes into the Decoder. Now this decoder de-multiplex it and then decode it to play.

Conclusion

A MPEG program stream is multiplexed output of audio video and data. It is used for storage purpose only because it not so good for transmission. Whenever we needs to store a media file somewhere like in DVDs then program streams are used.

Suggested Articles

What Is Transport Stream ?

Different Between MPEG1 MPEG2 MPEG3 ?

What Is Transcoding ?

reference : rfc mime

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