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I am trying to understand the MPEG streaming over network. I have couple of questions specific to MPEG-2 and MPEG-4 streaming.

1) As I understood MPEG-2 uses a Transport Stream (TS) which is encapsulated within RTP/UDP or directly in UDP/TCP packets for transmission. My question is which one is actually implemented by broadcast operators these days?

2) I read that broadcast operators are supporting MPEG-4 for spectral efficiency these days. Now, MPEG-4 transmission can be done in various ways. As per RFC3640 the Elementary Streams with Access Units can be transmitted over RTP; Or, encapsulated NAL unit in RTP packet in case of H.264 (RFC 3984); Or, MPEG-4 encoded data can also be transmitted using a Transport Stream (which is actually designed for MPEG-2). Now, in context of current days broadcasting which transport mechanism is used for MPEG-4?

CompNet
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    For broadcast do you mean "over the air"? If so do you mean US, Europe, etc? And finally do not confuse codecs and containers. MPEG-2, MPEG-4 are neither. There is a MPEG2 codec and there is an MPEG2 container (TS) But you can put an mpeg4 codec (there are several) in an MPEG2 container, and vice versa. – szatmary Sep 22 '15 at 16:28
  • Hi szatmary, thank you very much for answering. Yes, I meant ‘over the air’ broadcast in USA. Sorry for confusion between codec and container. I wanted to ask that in context of broadcasting in USA, is the mpeg4 codec put in an mpeg2 container (TS) for transport or, mpeg4 codec is transported differently? – CompNet Sep 22 '15 at 17:04

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The standard is called ATSC. Over the air is NOT the internet. There is no IP hence no UDP/TCP/RTP/etc. Its just an MPEG transport stream with FEC. In the case of mpeg-4 codec, specifically AVC is multiplexed within the transport stream.

https://en.wikipedia.org/wiki/Advanced_Television_Systems_Committee_standards

szatmary
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  • Hi szatmary, thanks again. Although I didn’t ask in the original post, could you please tell the scenario of mpeg4 codec transport over Internet? I found some streaming protocols for mpeg AVC e.g. HTTP Live Streaming (HLS) , DASH. But popular applications are mostly moving towards DASH and trying to get rid of mpeg2 TS as they are trying to encapsulate fragmented mp4 directly over HLS or DASH. Could you please tell if mpeg2 TS is still used for mpeg AVC streaming over Internet these days? Is RTP used underneath HLS or DASH before packets transported over UDP/TCP? – CompNet Sep 22 '15 at 20:39
  • HLS is AVC (mpeg4 family) in TS (mpeg2 family) delivered over HTTP. DASH is AVC in ISO-14496-12 (mpeg4 family) over HTTP. neither use RTP. – szatmary Sep 22 '15 at 22:19
  • Hi szatmary, thanks. As there are several ways of transporting mpeg4 AVC/H.264 over Internet e.g. packetizing NAL units or byte stream of NAL units, could you please tell what is most commonly used for multimedia streaming? For example, which protocols are used by Netflix or some other popular applications for transporting H.264 high profile videos? – CompNet Sep 25 '15 at 00:44
  • HLS and DASH is probably 95% of all video on the internet. The rest is RTMP/RTSP/RTP – szatmary Sep 25 '15 at 00:52
  • I should mention MP4 and webm for VOD are most common. But these don't support live streaming so I tend to forget about them. – szatmary Sep 25 '15 at 15:39