Elementary stream, packetized elementary stream, transport stream, and Program Stream

Elementary stream
In the MPEG-2, bit streams that contain encoded images, sounds, or data are called the basic stream ES (elementary stream ), it only contains one type of data (audio, video, or subtitle). What we call "audio", "video", or "bit stream" is elementary stream, the format is generally determined only by the data contained (such as the video codec ).

Packetized elementary stream
After packaging, es becomes the package's basic stream PES (packetized elementary stream). It can synthesize one transport stream TS with the other PES. Each PES is packaged into an 188byte long TS packet. It should be pointed out that the transmission stream ts is not composed of Program Stream ps, but is re-connected by PES. One ts can contain several independent programs, each of which has a packet identifier PID (packetized identifier, all ts packages of a specific program can be extracted from the transmission stream by the PID. You can also add new programs to an existing transmission stream.

Transport Stream
A container format defined by ISO/IEC Standard 13818-1. It is designed for audio and video replay and synchronous output. TS provides fault recovery capabilities for data transmission on unreliable media (networks) and is widely used in broadcast and television systems such as DVB and ATSC.

Program Stream
A container format defined by ISO/IEC Standard 13818-1 is generally used for data transmission on reliable media (such as a DVD disc.

Http://www.vbrick.net/the article details the features of transport stream and program stream, as well as the applicable occasions. I posted it (modified and removed the advertisement :)).

We are talking about how MPEG-2 is delivered, not how it is encoded. so whether a video is transport stream or program stream has nothing to do with the quality of the video encoding or the MPEG-2 GOP structure. in other words, a beautiful woman can arrive at a party via a car, truck, or bus and she wowould still be a beautiful woman. so the format for delivery is independent of the content.

Why are there two formats? Well, because there are conflicting applications. if you want to save MPEG-2 to a file on your computer, you are not very concerned about transmission. if you want to transmit MPEG-2, you are not very concerned with file format. happily, the MPEG-2 standards address both.

Unfortunately, we have some trouble with language. the word "program" cocould mean "what I'm watching on TV", or it cocould mean "a channel", or it cocould mean "a specific format ". we are talking about the format, and to avoid confusion, I'll try to use the word "content" when talking about the MPEG-2 audio/video. but you need to be aware that different industries use the term "program" in different way S!

It is very important to point out that "Program Stream" has a very specific meaning. the MPEG-2 has two different multiplexing schemes: Program Stream and transport stream. the program streams are mostly used in storage applications. broadcast usage commonly uses the transport stream format. if you have one content channel (one program), it does not imply that the stream that carries the program wocould be a program stream. in broadcast usage it wocould be a so-called single program transport stream (as defined by ISO 13818-1): A multiplexed collection of Concatenated program streams without beginning or end.

• An MPEG-2 Program Stream contains one, and only one, content channel. A program stream is like a single-passenger car without shock absorbers: drive it on a smooth road.
• An MPEG-2 transport stream can contain one or more content channels. A transport stream is like a high end car or bus: it can carry one or more passengers and has a good suspension system that can handle the bumps in the road.
• Authoring tools, such as Adobe, avid, Ulead, media100, can produce MPEG-2 program streams (usually with 3rd party plug-ins ). this is because the intended applications are the creation of files for distribution on disk, including DVD. some vendors like to stream program streams directly... but this is not a good solution because it is not compliant with the broadcast industry, set top boxes, and is error prone.
• In the DVB (Satellite TV) World, a satellite needs to deliver, via radio, one stream to subscribers. that one stream needs to carry sans TV channels. to do this, the specified channels are multiplexed into a transport stream. the specified er actually es all of the channels at once (it has no choice !), But it only demultiplexes and then decodes the selected content, one at a time, from the delivered transport stream.
• When sending MPEG over IP, there is less value in having one transport stream that contains multiple content channels. it is more useful, flexible, and uses less bandwidth when each content channel has its own IP multicast address.
• Commercial Broadcasters and cable companies use transport stream format for delivery of content to set top boxes. in a mixed, streaming-to-the-desktop, and STB world, it is better to use only one format which takes you to transport stream.

 

So, which is "better", transport stream or Program Stream? The answer is transport stream if you are talking about streaming, and program if you are talking about authoring.