(per RFC6185)

Type name: video

Subtype name: H264-RCDO

Required parameters:

rate:  Indicates the RTP timestamp clock rate.  The rate value MUST
   be 90000.

Optional parameters:

profile-level-id:  A base16 RFC 4648 [9] (hexadecimal) representation
   of the following three bytes in the sequence parameter set NAL
   unit is specified in H.264 [2]: 1) profile_idc, 2) a byte herein
   referred to as profile-iop, composed of the values of
   constraint_set0_flag, constraint_set1_flag, constraint_set2_flag,
   constraint_set3_flag, constraint_set4_flag, constraint_set5_flag,
   and reserved_zero_2bits in bit-significance order, starting from
   the most-significant bit, and 3) level_idc.  Note that
   reserved_zero_2bits is required to be equal to 0 in H.264 [2], but
   other values for it may be specified in the future by ITU-T or
   ISO/IEC.

   The profile-level-id parameter indicates the default sub-profile
   (i.e., the subset of coding tools that may have been used to
   generate the stream or that the receiver supports) and the default
   level of the stream or the receiver supports.

   RCDO is distinct from any profile; this implies that the profile
   value 0 (no profile) and the profile_idc byte of the profile-
   level-id parameter are equal to 0.  An RCDO bitstream MUST obey
   all the constraints of the Baseline profile.  Therefore, only
   constraint_set0_flag is equal to 1 in the profile-iop part of the
   profile-level-id parameter; the remaining bits are set to 0.

   If the profile-level-id parameter is used to indicate properties
   of a NAL unit stream, it indicates that, to decode the stream, the
   minimum subset of coding tools a decoder has to support is the
   default sub-profile, and the lowest level the decoder has to
   support is the default level.

   If the profile-level-id parameter is used for capability exchange
   or session setup, it indicates the subset of coding tools, which
   is equal to the default sub-profile, that the codec supports for
   both receiving and sending.  If max-recv-level is not present, the
   default level from profile-level-id indicates the highest level
   the codec wishes to support.  If max-recv-level is present, it
   indicates the highest level the codec supports for receiving.  For
   either receiving or sending, all levels that are lower than the
   highest level supported MUST also be supported.

   For example, if a codec supports level 1.3, the profile-level-id
   becomes 00800d, in which 00 indicates the "no profile" value, 80
   indicates the constraints of the Baseline profile, and 0d
   indicates level 1.3.  When level 2.1 is supported, the profile-
   level-id becomes 008015.

   If no profile-level-id is present, level 1 (i.e., equivalent to
   profile-level-id 00800a) MUST be implied.

      Informative note: The definitions of the remaining optional
      parameters below are copied verbatim from Section 8.1 of RFC
      6184 [1].  Only the references are updated to match the
      numbering used in this document.

max-recv-level:  This parameter MAY be used to indicate the highest
   level a receiver supports when the highest level is higher than
   the default level (the level indicated by profile-level-id).  The
   value of max-recv-level is a base16 (hexadecimal) representation
   of the two bytes after the syntax element profile_idc in the
   sequence parameter set NAL unit specified in H.264 [2]: profile-
   iop (as defined above) and level_idc.  If the level_idc byte of
   max-recv-level is equal to 11 and bit 4 of the profile-iop byte of
   max-recv-level is equal to 1 or if the level_idc byte of max-recv-
   level is equal to 9 and bit 4 of the profile-iop byte of max-recv-
   level is equal to 0, the highest level the receiver supports is
   Level 1b.  Otherwise, the highest level the receiver supports is
   equal to the level_idc byte of max-recv-level divided by 10.

   max-recv-level MUST NOT be present if the highest level the
   receiver supports is not higher than the default level.

max-mbps, max-smbps, max-fs, max-cpb, max-dpb, and max-br:  These
   parameters MAY be used to signal the capabilities of a receiver
   implementation.  These parameters MUST NOT be used for any other
   purpose.  The highest level conveyed in the value of the profile-
   level-id parameter or the max-recv-level parameter MUST be such
   that the receiver is fully capable of supporting. max-mbps, max-
   smbps, max-fs, max-cpb, max-dpb, and max-br MAY be used to
   indicate capabilities of the receiver that extend the required
   capabilities of the signaled highest level, as specified below.

   When more than one parameter from the set (max-mbps, max-smbps,
   max-fs, max-cpb, max-dpb, max-br) is present, the receiver MUST
   support all signaled capabilities simultaneously.  For example, if
   both max-mbps and max-br are present, the signaled highest level
   with the extension of both the frame rate and bitrate is
   supported.  That is, the receiver is able to decode NAL unit
   streams in which the macroblock processing rate is up to max-mbps
   (inclusive), the bitrate is up to max-br (inclusive), the coded
   picture buffer size is derived as specified in the semantics of
   the max-br parameter below, and the other properties comply with
   the highest level specified in the value of the profile-level-id
   parameter or the max-recv-level parameter.

   If a receiver can support all the properties of Level A, the
   highest level specified in the value of the profile-level-id
   parameter or the max-recv-level parameter MUST be Level A (i.e.,
   MUST NOT be lower than Level A).  In other words, a receiver MUST
   NOT signal values of max-mbps, max-fs, max-cpb, max-dpb, and
   max-br that taken together meet the requirements of a higher level
   compared to the highest level specified in the value of the
   profile-level-id parameter or the max-recv-level parameter.

      Informative note: When the OPTIONAL media type parameters are
      used to signal the properties of a NAL unit stream, max-mbps,
      max-smbps, max-fs, max-cpb, max-dpb, and max-br are not
      present, and the value of profile-level-id must always be such
      that the NAL unit stream complies fully with the specified
      profile and level.

max-mbps:  The value of max-mbps is an integer indicating the maximum
   macroblock processing rate in units of macroblocks per second.
   The max-mbps parameter signals that the receiver is capable of
   decoding video at a higher rate than is required by the signaled
   highest level conveyed in the value of the profile-level-id
   parameter or the max-recv-level parameter.  When max-mbps is
   signaled, the receiver MUST be able to decode NAL unit streams
   that conform to the signaled highest level, with the exception
   that the MaxMBPS value in Table A-1 of H.264 [2] for the signaled
   highest level is replaced with the value of max-mbps.  The value
   of max-mbps MUST be greater than or equal to the value of MaxMBPS
   given in Table A-1 of H.264 [2] for the highest level.  Senders
   MAY use this knowledge to send pictures of a given size at a
   higher picture rate than is indicated in the signaled highest
   level.

max-smbps:  The value of max-smbps is an integer indicating the
   maximum static macroblock processing rate in units of static
   macroblocks per second, under the hypothetical assumption that all
   macroblocks are static macroblocks.  When max-smbps is signaled,
   the MaxMBPS value in Table A-1 of H.264 [2] should be replaced
   with the result of the following computation:

   o If the parameter max-mbps is signaled, set a variable
     MaxMacroblocksPerSecond to the value of max-mbps.  Otherwise,
     set MaxMacroblocksPerSecond equal to the value of MaxMBPS in
     Table A-1 of H.264 [2] for the signaled highest level conveyed
     in the value of the profile-level-id parameter or the
     max-recv-level parameter.

   o Set a variable P_non-static to the proportion of non-static
     macroblocks in picture n.

   o Set a variable P_static to the proportion of static macroblocks
     in picture n.

   o The value of MaxMBPS in Table A-1 of H.264 [2] should be
     considered by the encoder to be equal to:

      MaxMacroblocksPerSecond * max-smbps / (P_non-static * max-smbps
      + P_static * MaxMacroblocksPerSecond)

   The encoder should recompute this value for each picture.  The
   value of max-smbps MUST be greater than or equal to the value of
   MaxMBPS given explicitly as the value of the max-mbps parameter or
   implicitly in Table A-1 of H.264 [2] for the signaled highest
   level.  Senders MAY use this knowledge to send pictures of a given
   size at a higher picture rate than is indicated in the signaled
   highest level.

max-fs:  The value of max-fs is an integer indicating the maximum
   frame size in units of macroblocks.  The max-fs parameter signals
   that the receiver is capable of decoding larger picture sizes than
   are required by the signaled highest level conveyed in the value
   of the profile-level-id parameter or the max-recv-level parameter.
   When max-fs is signaled, the receiver MUST be able to decode NAL
   unit streams that conform to the signaled highest level, with the
   exception that the MaxFS value in Table A-1 of H.264 [2] for the
   signaled highest level is replaced with the value of max-fs.  The
   value of max-fs MUST be greater than or equal to the value of
   MaxFS given in Table A-1 of H.264 [2] for the highest level.
   Senders MAY use this knowledge to send larger pictures at a
   proportionally lower frame rate than is indicated in the signaled
   highest level.

max-cpb:  The value of max-cpb is an integer indicating the maximum
   coded picture buffer size in units of 1000 bits for the VCL HRD
   parameters and in units of 1200 bits for the NAL HRD parameters.
   Note that this parameter does not use units of cpbBrVclFactor and
   cpbBrNALFactor (see Table A-1 of H.264 [2]).  The max-cpb
   parameter signals that the receiver has more memory than the
   minimum amount of coded picture buffer memory required by the
   signaled highest level conveyed in the value of the
   profile-level-id parameter or the max-recv-level parameter.  When
   max-cpb is signaled, the receiver MUST be able to decode NAL unit
   streams that conform to the signaled highest level, with the
   exception that the MaxCPB value in Table A-1 of H.264 [2] for the
   signaled highest level is replaced with the value of max-cpb
   (after taking cpbBrVclFactor and cpbBrNALFactor into consideration
   when needed).  The value of max-cpb (after taking cpbBrVclFactor
   and cpbBrNALFactor into consideration when needed) MUST be greater
   than or equal to the value of MaxCPB given in Table A-1 of H.264
   [2] for the highest level.  Senders MAY use this knowledge to
   construct coded video streams with greater variation of bitrate
   than can be achieved with the MaxCPB value in Table A-1 of H.264
   [2].

      Informative note: The coded picture buffer is used in the
      hypothetical reference decoder (Annex C of H.264).  The use of
      the hypothetical reference decoder is recommended in H.264
      encoders to verify that the produced bitstream conforms to the
      standard and to control the output bitrate.  Thus, the coded
      picture buffer is conceptually independent of any other
      potential buffers in the receiver, including de-interleaving
      and de-jitter buffers.  The coded picture buffer need not be
      implemented in decoders as specified in Annex C of H.264, but
      rather standard-compliant decoders can have any buffering
      arrangements provided that they can decode standard-compliant
      bitstreams.  Thus, in practice, the input buffer for a video
      decoder can be integrated with de-interleaving and de-jitter
      buffers of the receiver.

max-dpb:  The value of max-dpb is an integer indicating the maximum
   decoded picture buffer size in units of 8/3 macroblocks.  The max-
   dpb parameter signals that the receiver has more memory than the
   minimum amount of decoded picture buffer memory required by the
   signaled highest level conveyed in the value of the
   profile-level-id parameter or the max-recv-level parameter.  When
   max-dpb is signaled, the receiver MUST be able to decode NAL unit
   streams that conform to the signaled highest level, with the
   exception that the MaxDpbMbs value in Table A-1 of H.264 [2] for
   the signaled highest level is replaced with the value of max-dpb *
   3 / 8.  Consequently, a receiver that signals max-dpb MUST be
   capable of storing the following number of decoded frames,
   complementary field pairs, and non-paired fields in its decoded
   picture buffer:

      Min(max-dpb * 3 / 8 / ( PicWidthInMbs * FrameHeightInMbs), 16)

   Wherein PicWidthInMbs and FrameHeightInMbs are defined in H.264
   [2].

   The value of max-dpb MUST be greater than or equal to the value of
   MaxDpbMbs * 3 / 8, wherein the value of MaxDpbMbs is given in
   Table A-1 of H.264 [2] for the highest level.  Senders MAY use
   this knowledge to construct coded video streams with improved
   compression.

      Informative note: This parameter was added primarily to
      complement a similar codepoint in the ITU-T Recommendation
      H.245, so as to facilitate signaling gateway designs.  The
      decoded picture buffer stores reconstructed samples.  There is
      no relationship between the size of the decoded picture buffer
      and the buffers used in RTP, especially de-interleaving and
      de-jitter buffers.

      Informative note: In RFC 3984, which is obsoleted by RFC 6184,
      the unit of this parameter was 1024 bytes.  The unit has been
      changed to 8/3 macroblocks in this document.  The reason for
      this change was due to the changes from the 2003 version of the
      H.264 specification referenced by RFC 3984 to the 2010 version
      of the H.264 specification referenced by this document,
      particularly the changes to Table A-1 in the H.264
      specification due to addition of color formats and bit depths
      not supported earlier.  The changed semantics of this parameter
      keeps backward compatibility to RFC 3984 and supports all
      profiles defined in the 2010 version of the H.264
      specification.

max-br:  The value of max-br is an integer indicating the maximum
   video bitrate in units of 1000 bits per second for the VCL HRD
   parameters and in units of 1200 bits per second for the NAL HRD
   parameters.  Note that this parameter does not use units of
   cpbBrVclFactor and cpbBrNALFactor (see Table A-1 of H.264 [2]).

   The max-br parameter signals that the video decoder of the
   receiver is capable of decoding video at a higher bitrate than is
   required by the signaled highest level conveyed in the value of
   the profile-level-id parameter or the max-recv-level parameter.

   When max-br is signaled, the video codec of the receiver MUST be
   able to decode NAL unit streams that conform to the signaled
   highest level, with the following exceptions in the limits
   specified by the highest level:

   o The value of max-br (after taking cpbBrVclFactor and
     cpbBrNALFactor into consideration when needed) replaces the
     MaxBR value in Table A-1 of H.264 [2] for the highest level.

   o When the max-cpb parameter is not present, the result of the
     following formula replaces the value of MaxCPB in Table A-1 of
     H.264 [2]: (MaxCPB of the signaled level) * max-br / (MaxBR of
     the signaled highest level).

   For example, if a receiver signals capability for Main profile
   Level 1.2 with max-br equal to 1550, this indicates a maximum
   video bitrate of 1550 kbits/sec for VCL HRD parameters, a maximum
   video bitrate of 1860 kbits/sec for NAL HRD parameters, and a CPB
   size of 4036458 bits (1550000 / 384000 * 1000 * 1000).

   The value of max-br (after taking cpbBrVclFactor and
   cpbBrNALFactor into consideration when needed) MUST be greater
   than or equal to the value MaxBR given in Table A-1 of H.264 [2]
   for the signaled highest level.

   Senders MAY use this knowledge to send higher bitrate video as
   allowed in the level definition of Annex A of H.264 to achieve
   improved video quality.

      Informative note: This parameter was added primarily to
      complement a similar codepoint in the ITU-T Recommendation
      H.245, so as to facilitate signaling gateway designs.  The
      assumption that the network is capable of handling such
      bitrates at any given time cannot be made from the value of
      this parameter.  In particular, no conclusion can be drawn that
      the signaled bitrate is possible under congestion control
      constraints.

redundant-pic-cap:  This parameter signals the capabilities of a
   receiver implementation.  When equal to 0, the parameter indicates
   that the receiver makes no attempt to use redundant coded pictures
   to correct incorrectly decoded primary coded pictures.  When equal
   to 0, the receiver is not capable of using redundant slices;
   therefore, a sender SHOULD avoid sending redundant slices to save
   bandwidth.  When equal to 1, the receiver is capable of decoding
   any such redundant slice that covers a corrupted area in a primary
   decoded picture (at least partly), and therefore a sender MAY send
   redundant slices.  When the parameter is not present, a value of 0
   MUST be used for redundant-pic-cap.  When present, the value of
   redundant-pic-cap MUST be either 0 or 1.

   When the profile-level-id parameter is present in the same
   signaling as the redundant-pic-cap parameter and the profile
   indicated in profile-level-id is such that it disallows the use of
   redundant coded pictures (e.g., Main profile), the value of
   redundant-pic-cap MUST be equal to 0.  When a receiver indicates
   redundant-pic-cap equal to 0, the received stream SHOULD NOT
   contain redundant coded pictures.

      Informative note: Even if redundant-pic-cap is equal to 0, the
      decoder is able to ignore redundant codec pictures provided
      that the decoder supports a profile (Baseline, Extended) in
      which redundant coded pictures are allowed.

      Informative note: Even if redundant-pic-cap is equal to 1, the
      receiver may also choose other error concealment strategies to
      replace or complement decoding of redundant slices.

sprop-parameter-sets:  This parameter MAY be used to convey any
   sequence and picture parameter set NAL units (herein referred to
   as the initial parameter set NAL units) that can be placed in the
   NAL unit stream to precede any other NAL units in decoding order.
   The parameter MUST NOT be used to indicate codec capability in any
   capability exchange procedure.  The value of the parameter is a
   comma-separated (',') list of base64 RFC 4648 [9] representations
   of parameter set NAL units as specified in Sections 7.3.2.1 and
   7.3.2.2 of H.264 [2].  Note that the number of bytes in a
   parameter set NAL unit is typically less than 10, but a picture
   parameter set NAL unit can contain several hundred bytes.

      Informative note: When several payload types are offered in the
      SDP Offer/Answer model, each with its own sprop-parameter-sets
      parameter, the receiver cannot assume that those parameter sets
      do not use conflicting storage locations (i.e., identical
      values of parameter set identifiers).  Therefore, a receiver
      should buffer all sprop-parameter-sets and make them available
      to the decoder instance that decodes a certain payload type.

   The sprop-parameter-sets parameter MUST only contain parameter
   sets that are conforming to the profile-level-id, i.e., the subset
   of coding tools indicated by any of the parameter sets MUST be
   equal to the default sub-profile, and the level indicated by any
   of the parameter sets MUST be equal to the default level.

sprop-level-parameter-sets:  This parameter MAY be used to convey any
   sequence and picture parameter set NAL units (herein referred to
   as the initial parameter set NAL units) that can be placed in the
   NAL unit stream to precede any other NAL units in decoding order
   and that are associated with one or more levels different than the
   default level.  The parameter MUST NOT be used to indicate codec
   capability in any capability exchange procedure.

   The sprop-level-parameter-sets parameter contains parameter sets
   for one or more levels that are different than the default level.
   All parameter sets associated with one level are clustered and
   prefixed with a three-byte field that has the same syntax as
   profile-level-id.  This enables the receiver to install the
   parameter sets for one level and discard the rest.  The three-byte
   field is named PLId, and all parameter sets associated with one
   level are named PSL, which has the same syntax as sprop-parameter-
   sets.  Parameter sets for each level are represented in the form
   of PLId:PSL, i.e., PLId followed by a colon (':') and the base64
   RFC 4648 [9] representation of the initial parameter set NAL units
   for the level.  Each pair of PLId:PSLs is also separated by a
   colon.  Note that a PSL can contain multiple parameter sets for
   that level, separated with commas (',').

   The subset of coding tools indicated by each PLId field MUST be
   equal to the default sub-profile, and the level indicated by each
   PLId field MUST be different than the default level.  All sequence
   parameter sets contained in each PSL MUST have the three bytes
   from profile_idc to level_idc, inclusive, equal to the preceding
   PLId.

      Informative note: This parameter allows for efficient level
      downgrade or upgrade in SDP Offer/Answer and out-of-band
      transport of parameter sets simultaneously.

use-level-src-parameter-sets:  This parameter MAY be used to indicate
   a receiver capability.  The value MAY be equal to either 0 or 1.
   When the parameter is not present, the value MUST be inferred to
   be equal to 0.  The value 0 indicates that the receiver does not
   understand the sprop-level-parameter-sets parameter, does not
   understand the "fmtp" source attribute as specified in Section 6.3
   of RFC 5576 [14], will ignore sprop-level-parameter-sets when
   present, and will ignore sprop-parameter-sets when conveyed using
   the "fmtp" source attribute.  The value 1 indicates that the
   receiver understands the sprop-level-parameter-sets parameter,
   understands the "fmtp" source attribute as specified in Section
   6.3 of RFC 5576 [14], and is capable of using parameter sets
   contained in the sprop-level-parameter-sets or contained in the
   sprop-parameter-sets that is conveyed using the "fmtp" source
   attribute.

      Informative note: An RFC 3984 receiver does not understand
      sprop-level-parameter-sets, use-level-src-parameter-sets, or
      the "fmtp" source attribute as specified in Section 6.3 of RFC
      5576 [14].  Therefore, during SDP Offer/Answer, an RFC 3984
      receiver as the answerer will simply ignore sprop-level-
      parameter-sets when present in an offer and sprop-parameter-
      sets conveyed using the "fmtp" source attribute, as specified
      in Section 6.3 of RFC 5576 [14].  Assume that the offered
      payload type was accepted at a level lower than the default
      level.  If the offered payload type included sprop-level-
      parameter-sets or included sprop-parameter-sets conveyed using
      the "fmtp" source attribute and if the offerer sees that the
      answerer has not included use-level-src-parameter-sets equal to
      1 in the answer, the offerer knows that in-band transport of
      parameter sets is needed.

in-band-parameter-sets:  This parameter MAY be used to indicate a
   receiver capability.  The value MAY be equal to either 0 or 1.
   The value 1 indicates that the receiver discards out-of-band
   parameter sets in sprop-parameter-sets and sprop-level-parameter-
   sets; therefore, the sender MUST transmit all parameter sets in-
   band.  The value 0 indicates that the receiver utilizes out-of-
   band parameter sets included in sprop-parameter-sets and/or sprop-
   level-parameter-sets.  However, in this case, the sender MAY still
   choose to send parameter sets in-band.  When in-band-parameter-
   sets is equal to 1, use-level-src-parameter-sets MUST NOT be
   present or MUST be equal to 0.  When the parameter is not present,
   this receiver capability is not specified, and therefore the
   sender MAY send out-of-band parameter sets only, it MAY send in-
   band-parameter-sets only, or it MAY send both.

level-asymmetry-allowed:  This parameter MAY be used in SDP Offer/
   Answer to indicate whether level asymmetry, i.e., sending media
   encoded at a different level in the offerer-to-answerer direction
   than the level in the answerer-to-offerer direction, is allowed.
   The value MAY be equal to either 0 or 1.  When the parameter is
   not present, the value MUST be inferred to be equal to 0.  The
   value 1 in both the offer and the answer indicates that level
   asymmetry is allowed.  The value of 0 in either the offer or the
   answer indicates that level asymmetry is not allowed.

   If level-asymmetry-allowed is equal to 0 (or not present) in
   either the offer or the answer, level asymmetry is not allowed.
   In this case, the level to use in the direction from the offerer
   to the answerer MUST be the same as the level to use in the
   opposite direction.

packetization-mode:  This parameter signals the properties of an RTP
   payload type or the capabilities of a receiver implementation.
   Only a single configuration point can be indicated; thus, when
   capabilities to support more than one packetization-mode are
   declared, multiple configuration points (RTP payload types) must
   be used.

   When the value of packetization-mode is equal to 0 or
   packetization-mode is not present, the single NAL mode MUST be
   used.  This mode is in use in standards using ITU-T Recommendation
   H.241 [3] (see Section 12.1).  When the value of packetization-
   mode is equal to 1, the non-interleaved mode MUST be used.  When
   the value of packetization-mode is equal to 2, the interleaved
   mode MUST be used.  The value of packetization-mode MUST be an
   integer in the range of 0 to 2, inclusive.

sprop-interleaving-depth:  This parameter MUST NOT be present when
   packetization-mode is not present or the value of packetization-
   mode is equal to 0 or 1.  This parameter MUST be present when the
   value of packetization-mode is equal to 2.

   This parameter signals the properties of an RTP packet stream.  It
   specifies the maximum number of VCL NAL units that precede any VCL
   NAL unit in the RTP packet stream in transmission order and that
   follow the VCL NAL unit in decoding order.  Consequently, it is
   guaranteed that receivers can reconstruct NAL unit decoding order
   when the buffer size for NAL unit decoding order recovery is at
   least the value of sprop-interleaving-depth + 1 in terms of VCL
   NAL units.

   The value of sprop-interleaving-depth MUST be an integer in the
   range of 0 to 32767, inclusive.

sprop-deint-buf-req:  This parameter MUST NOT be present when
   packetization-mode is not present or the value of packetization-
   mode is equal to 0 or 1.  It MUST be present when the value of
   packetization-mode is equal to 2.

   sprop-deint-buf-req signals the required size of the
   de-interleaving buffer for the RTP packet stream.  The value of
   the parameter MUST be greater than or equal to the maximum buffer
   occupancy (in units of bytes) required in such a de-interleaving
   buffer that is specified in Section 7.2 of RFC 6184 [1].  It is
   guaranteed that receivers can perform the de-interleaving of
   interleaved NAL units into NAL unit decoding order, when the
   de-interleaving buffer size is at least the value of
   sprop-deint-buf-req in terms of bytes.

   The value of sprop-deint-buf-req MUST be an integer in the range
   of 0 to 4294967295, inclusive.

      Informative note: sprop-deint-buf-req indicates the required
      size of the de-interleaving buffer only.  When network jitter
      can occur, an appropriately sized jitter buffer has to be
      provisioned for as well.

deint-buf-cap:  This parameter signals the capabilities of a receiver
   implementation and indicates the amount of de-interleaving buffer
   space in units of bytes that the receiver has available for
   reconstructing the NAL unit decoding order.  A receiver is able to
   handle any stream for which the value of the sprop-deint-buf-req
   parameter is smaller than or equal to this parameter.

   If the parameter is not present, then a value of 0 MUST be used
   for deint-buf-cap.  The value of deint-buf-cap MUST be an integer
   in the range of 0 to 4294967295, inclusive.

      Informative note: deint-buf-cap indicates the maximum possible
      size of the de-interleaving buffer of the receiver only.  When
      network jitter can occur, an appropriately sized jitter buffer
      has to be provisioned for as well.

sprop-init-buf-time:  This parameter MAY be used to signal the
   properties of an RTP packet stream.  The parameter MUST NOT be
   present if the value of packetization-mode is equal to 0 or 1.

   The parameter signals the initial buffering time that a receiver
   MUST wait before starting decoding to recover the NAL unit
   decoding order from the transmission order.  The parameter is the
   maximum value of (decoding time of the NAL unit - transmission
   time of a NAL unit), assuming reliable and instantaneous
   transmission, the same timeline for transmission and decoding, and
   commencement of decoding when the first packet arrives.

   An example of specifying the value of sprop-init-buf-time follows.
   A NAL unit stream is sent in the following interleaved order, in

   which the value corresponds to the decoding time and the
   transmission order is from left to right:

      0 2 1 3 5 4 6 8 7 ...

   Assuming a steady transmission rate of NAL units, the transmission
   times are:

      0 1 2 3 4 5 6 7 8 ...

   Subtracting the decoding time from the transmission time column-
   wise results in the following series:

      0 -1 1 0 -1 1 0 -1 1 ...

   Thus, in terms of intervals of NAL unit transmission times, the
   value of sprop-init-buf-time in this example is 1.  The parameter
   is coded as a non-negative base10 integer representation in clock
   ticks of a 90-kHz clock.  If the parameter is not present, then no
   initial buffering time value is defined.  Otherwise, the value of
   sprop-init-buf-time MUST be an integer in the range of 0 to
   4294967295, inclusive.

   In addition to the signaled sprop-init-buf-time, receivers SHOULD
   take into account the transmission delay jitter buffering,
   including buffering for the delay jitter caused by mixers,
   translators, gateways, proxies, traffic-shapers, and other network
   elements.

sprop-max-don-diff:  This parameter MAY be used to signal the
   properties of an RTP packet stream.  It MUST NOT be used to signal
   transmitter, receiver, or codec capabilities.  The parameter MUST
   NOT be present if the value of packetization-mode is equal to 0 or
   1. sprop-max-don-diff is an integer in the range of 0 to 32767,
   inclusive.  If sprop-max-don-diff is not present, the value of the
   parameter is unspecified. sprop-max-don-diff is calculated as
   follows:

      sprop-max-don-diff = max{AbsDON(i) - AbsDON(j)}, for any i and
      any j>i,

   where i and j indicate the index of the NAL unit in the
   transmission order and AbsDON denotes a decoding order number of
   the NAL unit that does not wrap around to 0 after 65535.  In other
   words, AbsDON is calculated as follows: let m and n be consecutive
   NAL units in transmission order.  For the very first NAL unit in
   transmission order (whose index is 0), AbsDON(0) = DON(0).  For
   other NAL units, AbsDON is calculated as follows:

   If DON(m) == DON(n), AbsDON(n) = AbsDON(m)

   If (DON(m) < DON(n) and DON(n) - DON(m) < 32768),

   AbsDON(n) = AbsDON(m) + DON(n) - DON(m)

   If (DON(m) > DON(n) and DON(m) - DON(n) >= 32768),

   AbsDON(n) = AbsDON(m) + 65536 - DON(m) + DON(n)

   If (DON(m) < DON(n) and DON(n) - DON(m) >= 32768),

   AbsDON(n) = AbsDON(m) - (DON(m) + 65536 - DON(n))

   If (DON(m) > DON(n) and DON(m) - DON(n) < 32768),

   AbsDON(n) = AbsDON(m) - (DON(m) - DON(n))

   where DON(i) is the decoding order number of the NAL unit having
   index i in the transmission order.  The decoding order number is
   specified in Section 5.5 of RFC 6184 [1].

      Informative note: Receivers may use sprop-max-don-diff to
      trigger which NAL units in the receiver buffer can be passed to
      the decoder.

max-rcmd-nalu-size:  This parameter MAY be used to signal the
   capabilities of a receiver.  The parameter MUST NOT be used for
   any other purposes.  The value of the parameter indicates the
   largest NALU size in bytes that the receiver can handle
   efficiently.  The parameter value is a recommendation, not a
   strict upper boundary.  The sender MAY create larger NALUs but
   must be aware that the handling of these may come at a higher cost
   than NALUs conforming to the limitation.

   The value of max-rcmd-nalu-size MUST be an integer in the range of
   0 to 4294967295, inclusive.  If this parameter is not specified,
   no known limitation to the NALU size exists.  Senders still have
   to consider the MTU size available between the sender and the
   receiver and SHOULD run MTU discovery for this purpose.

   This parameter is motivated by, for example, an IP to H.223 video
   telephony gateway, where NALUs smaller than the H.223 transport
   data unit will be more efficient.  A gateway may terminate IP;
   thus, MTU discovery will normally not work beyond the gateway.

      Informative note: Setting this parameter to a lower than
      necessary value may have a negative impact.

sar-understood:  This parameter MAY be used to indicate a receiver
   capability and nothing else.  The parameter indicates the maximum
   value of aspect_ratio_idc (specified in H.264 [2]) smaller than
   255 that the receiver understands.  Table E-1 of H.264 [2]
   specifies aspect_ratio_idc equal to 0 as "unspecified"; 1 to 16,
   inclusive, as specific Sample Aspect Ratios (SARs); 17 to 254,
   inclusive, as "reserved"; and 255 as the Extended SAR, for which
   SAR width and SAR height are explicitly signaled.  Therefore, a
   receiver with a decoder according to H.264 [2] understands
   aspect_ratio_idc in the range of 1 to 16, inclusive, and
   aspect_ratio_idc equal to 255, in the sense that the receiver
   knows exactly what the SAR is.  For such a receiver, the value of
   sar-understood is 16.  In the future, if Table E-1 of H.264 [2] is
   extended, e.g., such that the SAR for aspect_ratio_idc equal to 17
   is specified, then for a receiver with a decoder that understands
   the extension, the value of sar-understood is 17.  For a receiver
   with a decoder according to the 2003 version of H.264 [2], the
   value of sar-understood is 13, as the minimum reserved
   aspect_ratio_idc therein is 14.

   When sar-understood is not present, the value MUST be inferred to
   be equal to 13.

sar-supported:  This parameter MAY be used to indicate a receiver
   capability and nothing else.  The value of this parameter is an
   integer in the range of 1 to sar-understood, inclusive, equal to
   255.  The value of sar-supported equal to N smaller than 255
   indicates that the receiver supports all the SARs corresponding to
   H.264 aspect_ratio_idc values (see Table E-1 of H.264 [2]) in the
   range from 1 to N, inclusive, without geometric distortion.  The
   value of sar-supported equal to 255 indicates that the receiver
   supports all sample aspect ratios that are expressible using two
   16-bit integer values as the numerator and denominator, i.e.,
   those that are expressible using the H.264 aspect_ratio_idc value
   of 255 (Extended_SAR, see Table E-1 of H.264 [2]), without
   geometric distortion.

   H.264-compliant encoders SHOULD NOT send an aspect_ratio_idc equal
   to 0 or an aspect_ratio_idc larger than sar-understood and smaller
   than 255.  H.264-compliant encoders SHOULD send an
   aspect_ratio_idc that the receiver is able to display without
   geometrical distortion.  However, H.264-compliant encoders MAY
   choose to send pictures using any SAR.

   Note that the actual sample aspect ratio or extended sample aspect
   ratio, when present, of the stream is conveyed in the Video
   Usability Information (VUI) part of the sequence parameter set.

Encoding considerations:  This type is only defined for transfer via
   RTP (RFC 3550) and is framed and binary (see Section 4.8 in RFC
   4288).

Security considerations:  See Section 9 of RFC 6185.

Interoperability considerations:  None

Published specification:  RFC 6185 and its reference section

Applications that use this media type:  Video streaming and
   conferencing applications

Additional information:  None

   Magic number(s):

   File extension(s):

   Macintosh file type code(s):

Person & email address to contact for further information:

   Tom Kristensen <tom.kristensen&tandberg.com>, <tomkri&ifi.uio.no>

Intended usage:  COMMON

Restrictions on usage:  This type depends on RTP framing; hence, it
   is only defined for transfer via RTP (see RFC 3550).  Transport
   within other framing protocols is not defined at this time.

Author:  Tom Kristensen

Change controller:  IETF Audio/Video Transport Working Group
   delegated from the IESG