7.1. Mapping Media Type Parameters into SDP . . . . . . . . . . 20
7.1.1. SDP Example . . . . . . . . . . . . . . . . . . . . . 21
7.2. Usage with the SDP Offer/Answer Model . . . . . . . . . . 21
- 8. Congestion Control . . . . . . . . . . . . . . . . . . . . . . 21
- 9. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
- 9.1. Stream Radio . . . . . . . . . . . . . . . . . . . . . . . 22
- 10. Security Considerations . . . . . . . . . . . . . . . . . . . 22
- 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23
- 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
- 12.1. Normative References . . . . . . . . . . . . . . . . . . . 23
- 12.2. Informative References . . . . . . . . . . . . . . . . . . 24
+ 8. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
+ 8.1. Stream Radio . . . . . . . . . . . . . . . . . . . . . . . 22
+ 9. Security Considerations . . . . . . . . . . . . . . . . . . . 22
+ 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23
+ 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
+ 11.1. Normative References . . . . . . . . . . . . . . . . . . . 23
+ 11.2. Informative References . . . . . . . . . . . . . . . . . . 24
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 24
Intellectual Property and Copyright Statements . . . . . . . . . . 25
+
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The Packed Configuration (Section 3.1.1) Payload is sent in-band with
the packet type bits set to match the Vorbis Data Type. Clients MUST
be capable of dealing with fragmentation and periodic re-transmission
- of [14] the configuration headers.
+ of [14] the configuration headers. The RTP timestamp value MUST
+ reflect the transmission time of the next data packet.
3.1.1. Packed Configuration
-
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3.3. Loss of Configuration Headers
Unlike the loss of raw Vorbis payload data, loss of a configuration
- header can lead to a situation where it will not be possible to
- successfully decode the stream.
-
- Loss of Configuration Packets results in the halting of stream
- decoding.
+ header lead to a situation where it will not be possible to
+ successfully decode the stream. Implementations MAY try to recover
+ from error requesting again the missing Configuration, the baseline
+ reaction SHOULD be either reset or end the connection.
4. Comment Headers
+
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A fragmented packet has a zero in the last four bits of the payload
header. The first fragment will set the Fragment type to 1. Each
fragment after the first will set the Fragment type to 2 in the
- payload header. The RTP payload containing the last fragment of the
- Vorbis packet will have the Fragment type set to 3. To maintain the
- correct sequence for fragmented packet reception the timestamp field
- of fragmented packets MUST be the same as the first packet sent, with
- the sequence number incremented as normal for the subsequent RTP
+ payload header. The consecutive fragments MUST be sent without any
+ other payloads being sent between the first and the last fragment.
+ The RTP payload containing the last fragment of the Vorbis packet
+ will have the Fragment type set to 3. To maintain the correct
+ sequence for fragmented packet reception the timestamp field of
Internet-Draft draft-ietf-avt-rtp-vorbis-08 Oct 2007
- payloads. The length field shows the fragment length.
+ fragmented packets MUST be the same as the first packet sent, with
+ the sequence number incremented as normal for the subsequent RTP
+ payloads, this will affect the RTCP jitter measurement. The length
+ field shows the fragment length.
5.1. Example Fragmented Vorbis Packet
-
-
-
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Control. [3]
delivery-method: indicates the delivery methods in use, the
- possible values are: inline, in_band, out_band, MAY be included
- multiple times
+ possible values are: inline, in_band, out_band. The parameter
+ MAY be included multiple time, followed by the configuration or
+ configuration-uri parameter associated.
configuration: the base64 [9] representation of the Packed
Headers (Section 3.2.1). It MUST follow the associated
-
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6.1. Packed Headers IANA Considerations
- The following IANA considerations MUST only be applied to the packed
- headers.
+ The following IANA considerations MUST only be applied to the Packed
+ Headers (Section 3.2.1).
parameters MUST not be altered on answer otherwise.
-8. Congestion Control
+8. Examples
+
+ The following examples are common usage patterns that MAY be applied
+ in such situations, the main scope of this section is to explain
+ better usage of the transmission vectors.
- Vorbis clients SHOULD send regular receiver reports detailing
- congestion. A mechanism for dynamically downgrading the stream,
- known as bitrate peeling, will allow for a graceful backing off of
- the stream bitrate. This feature is not available at present so an
Internet-Draft draft-ietf-avt-rtp-vorbis-08 Oct 2007
- alternative would be to redirect the client to a lower bitrate stream
- if one is available.
-
-
-9. Examples
-
- The following examples are common usage patterns that MAY be applied
- in such situations, the main scope of this section is to explain
- better usage of the transmission vectors.
-
-9.1. Stream Radio
+8.1. Stream Radio
This is one of the most common situation: one single server streaming
content in multicast, the clients may start a session at random time.
already known.
-10. Security Considerations
+9. Security Considerations
RTP packets using this payload format are subject to the security
- considerations discussed in the RTP specification [2]. This implies
+ considerations discussed in the RTP specification [2], the base64
+ specification [9] and the URI Generic syntax specification [4].
+ Among other considerations, this implies that the confidentiality of
+ the media stream is archieved by using encryption. Because the data
+ compression used with this payload format is applied end-to-end,
+ encryption may be performed on the compressed data. Additional care
+ MAY be needed for delivery methods that point to external resources,
+ using secure protocols to fetch the configuration payloads. Where
+ the size of a data block is set, care MUST be taken to prevent buffer
+ overflows in the client applications.
+
Internet-Draft draft-ietf-avt-rtp-vorbis-08 Oct 2007
- that the confidentiality of the media stream is archieved by using
- encryption. Because the data compression used with this payload
- format is applied end-to-end, encryption may be performed on the
- compressed data. Additional care MAY be needed for delivery methods
- that point to external resources, using secure protocols to fetch the
- configuration payloads. Where the size of a data block is set, care
- MUST be taken to prevent buffer overflows in the client applications.
-
-
-11. Acknowledgments
+10. Acknowledgments
This document is a continuation of draft-moffitt-vorbis-rtp-00.txt
and draft-kerr-avt-vorbis-rtp-04.txt. The Media Type declaration is
Carlos De Martin.
-12. References
+11. References
-12.1. Normative References
+11.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", RFC 2119.
[6] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
November 1990.
-
-
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-
-
[7] McCann et al., J., "Path MTU Discovery for IP version 6",
RFC 1981.
[9] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings",
RFC 3548.
+
+
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+
+
[10] "Ogg Vorbis I specification: Codec setup and packet decode.
- Available from the Xiph website, http://www.xiph.org".
+ Available from the Xiph website,
+ http://xiph.org/vorbis/doc/Vorbis_I_spec.html".
-12.2. Informative References
+11.2. Informative References
[11] Pfeiffer, S., "The Ogg Encapsulation Format Version 0",
RFC 3533.
- [12] "libvorbis: Available from the Xiph website,
- http://www.xiph.org".
+ [12] "libvorbis: Available from the dedicated website,
+ http://www.vorbis.com".
[13] Friedman, T., Caceres, R., and A. Clark, "RTP Control Protocol
Extended Reports (RTCP XR)", RFC 3611, November 2003.
+
+
+
+
+
+
+
+
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projects / platform / upstream / libvorbis.git / commitdiff