rfc6184_h264.pdf

Internet Engineering Task Force (IETF) Y.-K. Wang

Request for Comments: 6184 R. Even

Obsoletes:

3984 Huawei Technologies

Category: Standards Track T. Kristensen

ISSN: 2070-1721 Tandberg

R. Jesup

WorldGate Communications

May 2011

extension, for which the RTP payload formats are defined elsewhere.

The RTP payload format allows for packetization of one or more

Network Abstraction Layer Units (NALUs), produced by an H.264 video

encoder, in each RTP payload. The payload format has wide

applicability, as it supports applications from simple low bitrate

conversational usage, to Internet video streaming with interleaved

transmission, to high bitrate video-on-demand.

This memo obsoletes

RFC 3984. Changes from RFC 3984 are summarized

in

(IETF). It represents the consensus of the IETF community. It has

received public review and has been approved for publication by the

Internet Engineering Steering Group (IESG). Further information on

Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of this document, any errata,

and how to provide feedback on it may be obtained at

http://www.rfc-editor.org/info/rfc6184.

Wang, et al. Standards Track [Page 1]

RFC 6184

RTP Payload Format for H.264 Video May 2011

(

http://trustee.ietf.org/license-info) in effect on the date of

publication of this document. Please review these documents

carefully, as they describe your rights and restrictions with respect

to this document. Code Components extracted from this document must

include Simplified BSD License text as described in Section 4.e of

the Trust Legal Provisions and are provided without warranty as

described in the Simplified BSD License.

Table of Contents

3. Scope ...........................................................7

5. RTP Payload Format .............................................10

5.1. RTP Header Usage ..........................................10

5.2. Payload Structures ........................................12

5.3. NAL Unit Header Usage .....................................13

5.4. Packetization Modes .......................................16

5.5. Decoding Order Number (DON) ...............................17

5.6. Single NAL Unit Packet ....................................19

5.7. Aggregation Packets .......................................20

5.7.1. Single-Time Aggregation Packet (STAP) ..............22

5.7.2. Multi-Time Aggregation Packets (MTAPs) .............25

5.8. Fragmentation Units (FUs) .................................29

6.1. Common Packetization Rules ................................33

7.2. Interleaved Mode ..........................................35

7.2.1. Size of the De-Interleaving Buffer .................36

7.2.2. De-Interleaving Process ............................36

7.3. Additional De-Packetization Guidelines ....................38

Wang, et al. Standards Track [Page 2]

RFC 6184

RTP Payload Format for H.264 Video May 2011

8. Payload Format Parameters ......................................39

8.1. Media Type Registration ...................................39

8.2.1. Mapping of Payload Type Parameters to SDP ..........57

8.2.2. Usage with the SDP Offer/Answer Model ..............58

8.3. Examples ..................................................68

8.4. Parameter Set Considerations ..............................75

8.5.2. Gradual Recovery Procedure to Respond to

a Request for a Decoder Refresh Point ..............

9. Security Considerations ........................................79

10. Congestion Control ............................................80

11. IANA Considerations ...........................................81

Recommendation H.241 .....................................

NAL Unit Aggregation .....................................

12.3. Video Telephony, Interleaved Packetization Using

NAL Unit Aggregation .....................................

Error Correction .........................................

12.6. Low Bitrate Streaming ....................................86

12.7. Robust Packet Scheduling in Video Streaming ..............86

13. Informative Appendix: Rationale for Decoding Order Number .....87

13.1. Introduction .............................................87

13.2. Example of Multi-Picture Slice Interleaving ..............88

13.3. Example of Robust Packet Scheduling ......................89

13.4. Robust Transmission Scheduling of Redundant Coded

Slices ...................................................

13.5. Remarks on Other Design Possibilities ....................94

14. Changes from RFC 3984 .........................................94

16. Acknowledgements ..............................................98

Wang, et al. Standards Track [Page 3]

RFC 6184

RTP Payload Format for H.264 Video May 2011

1. Introduction

This memo obsoletes

in

The H.264 video codec has a very broad application range that covers

all forms of digital compressed video, from low bitrate Internet

streaming applications to HDTV broadcast and Digital Cinema

applications with nearly lossless coding. Compared to the current

state of technology, the overall performance of H.264 is such that

bitrate savings of 50% or more are reported. Digital Satellite TV

quality, for example, was reported to be achievable at 1.5 Mbit/s,

compared to the current operation point of MPEG 2 video at around 3.5

The codec specification [

a Video Coding Layer (VCL) and a Network Abstraction Layer (NAL).

The VCL contains the signal processing functionality of the codec;

mechanisms such as transform, quantization, and motion-compensated

prediction; and a loop filter. It follows the general concept of

most of today’s video codecs, a macroblock-based coder that uses

inter picture prediction with motion compensation and transform

coding of the residual signal. The VCL encoder outputs slices: a bit

spatial address of the first macroblock in the slice, the initial

in [

The NAL encoder encapsulates the slice output of the VCL encoder into

Network Abstraction Layer Units (NALUs), which are suitable for

transmission over packet networks or for use in packet-oriented

Wang, et al. Standards Track [Page 4]

RFC 6184

RTP Payload Format for H.264 Video May 2011

process to transmit such NALUs over bytestream-oriented networks. In

Internally, the NAL uses NAL units. A NAL unit consists of a one-

type of the NAL unit, the (potential) presence of bit errors or

syntax violations in the NAL unit payload, and information regarding

the relative importance of the NAL unit for the decoding process.

One of the main properties of H.264 is the complete decoupling of the

transmission time, the decoding time, and the sampling or

standards). Also, there are NAL units that affect many pictures and

that are, therefore, inherently timeless. For this reason, the

handling of the RTP timestamp requires some special considerations

for NAL units for which the sampling or presentation time is not

defined or, at transmission time, is unknown.

contained packets, to make mechanisms such as the header duplication

RFC 4629 [11] or MPEG-4 Visual’s Header Extension Code (HEC) [12]

unnecessary. This was achieved by decoupling information relevant to

more than one slice from the media stream. This higher-layer meta

information should be sent reliably, asynchronously, and in advance

from the RTP packet stream that contains the slice packets.

(Provisions for sending this information in-band are also available

picture parameter sets. An active sequence parameter set remains