iana/www.ietf.org/rfc/rfc4587.txt: Therefore, the MB is taken as the unit of fragmentation. Packets iana/www.ietf.org/rfc/rfc4587.txt: bit stream cannot be fragmented between a GOB header and MB 1 of that iana/www.ietf.org/rfc/rfc4587.txt: cannot be fragmented between a GOB header and MB 1, the predictor iana/www.ietf.org/rfc/rfc4587.txt: large, the packetizer has to parse it to do MB fragmentation. (Note iana/www.ietf.org/rfc/rfc4587.txt: recommended that MB level fragmentation be used when feasible in iana/www.ietf.org/rfc/rfc4587.txt: fragmentation scheme reduces the output packet rate and therefore iana/www.ietf.org/rfc/rfc4598.txt: data fragmentation. iana/www.ietf.org/rfc/rfc4598.txt: contains the final fragment of an E-AC-3 frame. iana/www.ietf.org/rfc/rfc4598.txt: fragments of the same frame MUST have the same timestamp. The iana/www.ietf.org/rfc/rfc4598.txt: fragment of an E-AC-3 frame. iana/www.ietf.org/rfc/rfc4598.txt: fragmented for transmission within an RTP packet. Section 4.2 iana/www.ietf.org/rfc/rfc4598.txt: provides guidelines for creating frame fragments. iana/www.ietf.org/rfc/rfc4598.txt: bit in the RTP header is set for the final fragment.) iana/www.ietf.org/rfc/rfc4598.txt: o Number of frames/fragments (NF): An 8-bit field whose meaning iana/www.ietf.org/rfc/rfc4598.txt: frames in the RTP payload. For frame fragments (F of 1), it is iana/www.ietf.org/rfc/rfc4598.txt: used to indicate the number of fragments (and therefore packets) iana/www.ietf.org/rfc/rfc4598.txt: containing fragments of the same frame. iana/www.ietf.org/rfc/rfc4598.txt: E-AC-3 frame exceeds the MTU size, the frame SHOULD be fragmented at iana/www.ietf.org/rfc/rfc4598.txt: the RTP level. The fragmentation MAY be performed at any byte iana/www.ietf.org/rfc/rfc4598.txt: boundary in the frame. RTP packets containing fragments of the same iana/www.ietf.org/rfc/rfc4598.txt: fragment. This enables a receiver to assemble the fragments in the iana/www.rfc-editor.org/rfc/rfc2046.txt: RFC 822 messages, to permit the fragmented transmission iana/www.rfc-editor.org/rfc/rfc2046.txt: fragmentation and reassembly in the basic Internet Protocols.) This iana/www.rfc-editor.org/rfc/rfc2046.txt: "message/partial" thus indicates that the body contains a fragment of iana/www.rfc-editor.org/rfc/rfc2046.txt: them for the 7bit world, aside from waiting for all of the fragments, iana/www.rfc-editor.org/rfc/rfc2046.txt: different fragments might go through different gateways, even this is iana/www.rfc-editor.org/rfc/rfc2046.txt: fragment large messages, and because such agents may use very iana/www.rfc-editor.org/rfc/rfc2046.txt: different fragmentation thresholds, it is possible that the pieces of iana/www.rfc-editor.org/rfc/rfc2046.txt: fragments together. (In general, the identifier is essentially a iana/www.rfc-editor.org/rfc/rfc2046.txt: second, "number", an integer, is the fragment number, which indicates iana/www.rfc-editor.org/rfc/rfc2046.txt: where this fragment fits into the sequence of fragments. The third, iana/www.rfc-editor.org/rfc/rfc2046.txt: "total", another integer, is the total number of fragments. This iana/www.rfc-editor.org/rfc/rfc2046.txt: third subfield is required on the final fragment, and is optional iana/www.rfc-editor.org/rfc/rfc2046.txt: (though encouraged) on the earlier fragments. Note also that these iana/www.rfc-editor.org/rfc/rfc2046.txt: But the third piece MUST specify the total number of fragments: iana/www.rfc-editor.org/rfc/rfc2046.txt: Note that fragment numbering begins with 1, not 0. iana/www.rfc-editor.org/rfc/rfc2046.txt: When the fragments of an entity broken up in this manner are put iana/www.rfc-editor.org/rfc/rfc2046.txt: Then, when the fragmented message is reassembled, the resulting iana/www.rfc-editor.org/rfc/rfc2046.txt: and subsequent pieces of a fragmented message that references the iana/www.rfc-editor.org/rfc/rfc2046.txt: in the context of conversion to and from "message/partial" fragments. iana/www.rfc-editor.org/rfc/rfc3016.txt: fragmentation rules. It also provides specifications for iana/www.rfc-editor.org/rfc/rfc3016.txt: Audio [3][5] and MPEG-4 Visual streams [2][4] are to be fragmented iana/www.rfc-editor.org/rfc/rfc3016.txt: elements. In addition, it is beneficial to define the fragmentation iana/www.rfc-editor.org/rfc/rfc3016.txt: With respect to the fragmentation rules for an MPEG-4 Visual iana/www.rfc-editor.org/rfc/rfc3016.txt: restriction on fragmentation, and a fragmentation rule such as "a iana/www.rfc-editor.org/rfc/rfc3016.txt: fragmentation may cause degradation in error resiliency and bandwidth iana/www.rfc-editor.org/rfc/rfc3016.txt: efficiency. The fragmentation rules described in this document are iana/www.rfc-editor.org/rfc/rfc3016.txt: meaningless fragmentation while utilizing the error resilience iana/www.rfc-editor.org/rfc/rfc3016.txt: The fragmentation rule recommends not to map more than one VOP in an iana/www.rfc-editor.org/rfc/rfc3016.txt: blocks. To reduce the overhead for such cases, the fragmentation iana/www.rfc-editor.org/rfc/rfc3016.txt: fragmentation rule (4) in section 3.2 and marker bit and timestamp in iana/www.rfc-editor.org/rfc/rfc3016.txt: A fragmented MPEG-4 Visual bitstream is mapped directly onto the RTP iana/www.rfc-editor.org/rfc/rfc3016.txt: fragmentation. iana/www.rfc-editor.org/rfc/rfc3016.txt: (4) Different VOPs SHOULD be fragmented into different RTP packets so iana/www.rfc-editor.org/rfc/rfc3016.txt: Header(VO header, VOL header). Since the fragmentation rule defined iana/www.rfc-editor.org/rfc/rfc3016.txt: packet fragmentation may be used when the underlying network is iana/www.rfc-editor.org/rfc/rfc3016.txt:(f) | RTP | VOP |VOP fragment| | RTP |VOP fragment| iana/www.rfc-editor.org/rfc/rfc3016.txt: audioMuxElement or the last fragment of an audioMuxElement. iana/www.rfc-editor.org/rfc/rfc3016.txt: MAY be fragmented and spread across multiple packets. iana/www.rfc-editor.org/rfc/rfc3497.txt: video (EAV+LN+CRC) signals MUST NOT be fragmented across packets, as iana/www.rfc-editor.org/rfc/rfc3497.txt: the ALF principle translates into not fragmenting related luminance iana/www.rfc-editor.org/rfc/rfc3497.txt: values are not fragmented across 2 packets. However, with 10 bit iana/www.rfc-editor.org/rfc/rfc3497.txt: The contents of the Digital Active Line SHOULD NOT be fragmented iana/www.rfc-editor.org/rfc/rfc3497.txt: fragmented. iana/www.rfc-editor.org/rfc/rfc3640.txt: fragmentation of an Access Unit over multiple RTP packets. Hence, iana/www.rfc-editor.org/rfc/rfc3640.txt: when an IP packet is lost after IP-level fragmentation, only an AU iana/www.rfc-editor.org/rfc/rfc3640.txt: fragment may get lost instead of the entire AU. To simplify the iana/www.rfc-editor.org/rfc/rfc3640.txt: or more complete Access Units or a single fragment of one AU, i.e., iana/www.rfc-editor.org/rfc/rfc3640.txt: packets MUST NOT contain fragments of multiple Access Units. iana/www.rfc-editor.org/rfc/rfc3640.txt: (fragment) in the RTP packet. When multiple AUs are carried within iana/www.rfc-editor.org/rfc/rfc3640.txt: conveyed for the first AU (fragment), as the time stamp for the first iana/www.rfc-editor.org/rfc/rfc3640.txt: Access Unit Data Section, containing either a single fragment of one iana/www.rfc-editor.org/rfc/rfc3640.txt: payload contains either the final fragment of a fragmented Access iana/www.rfc-editor.org/rfc/rfc3640.txt: identical only if the RTP time stamp refers to fragments of the same iana/www.rfc-editor.org/rfc/rfc3640.txt: Each AU-header is associated with a single Access Unit (fragment) iana/www.rfc-editor.org/rfc/rfc3640.txt: For each contained Access Unit (fragment), there is exactly one AU- iana/www.rfc-editor.org/rfc/rfc3640.txt: the n-th AU (fragment). If the concatenated AU-headers consume a iana/www.rfc-editor.org/rfc/rfc3640.txt: AU-size is associated with an AU fragment, the AU size indicates iana/www.rfc-editor.org/rfc/rfc3640.txt: the size of the entire AU and not the size of the fragment. In iana/www.rfc-editor.org/rfc/rfc3640.txt: this case, the size of the fragment is known from the size of the iana/www.rfc-editor.org/rfc/rfc3640.txt: packet contains an entire AU or a fragment, which is particularly iana/www.rfc-editor.org/rfc/rfc3640.txt: useful after losing a packet carrying the last fragment of an AU. iana/www.rfc-editor.org/rfc/rfc3640.txt: (fragment). For each (in decoding order) consecutive AU or AU iana/www.rfc-editor.org/rfc/rfc3640.txt: fragment, the serial number is incremented by 1. When present, iana/www.rfc-editor.org/rfc/rfc3640.txt: The CTS-flag field SHOULD be 0 for any non-first fragment of an iana/www.rfc-editor.org/rfc/rfc3640.txt: DTS-flag field MUST have the same value for all fragments of an iana/www.rfc-editor.org/rfc/rfc3640.txt: same value for all fragments of an Access Unit. iana/www.rfc-editor.org/rfc/rfc3640.txt: an Access Unit is fragmented, the RAP flag, if present, MUST be iana/www.rfc-editor.org/rfc/rfc3640.txt: set to 0 for each non-first fragment of the AU. iana/www.rfc-editor.org/rfc/rfc3640.txt: Access Units or a single fragment of one AU. The Access Unit Data iana/www.rfc-editor.org/rfc/rfc3640.txt: fragmentation, which may result in reduced performance. iana/www.rfc-editor.org/rfc/rfc3640.txt: (fragment), i.e., that a single Access Unit (fragment) is transported iana/www.rfc-editor.org/rfc/rfc3640.txt: single fragment of an Access Unit. Fragments of the same Access Unit iana/www.rfc-editor.org/rfc/rfc3640.txt: marker bit in the RTP header is 1 on the last fragment of an Access iana/www.rfc-editor.org/rfc/rfc3640.txt: Unit, and 0 on all other fragments. iana/www.rfc-editor.org/rfc/rfc3640.txt: equal size. CELP frames MUST NOT be fragmented when using this mode. iana/www.rfc-editor.org/rfc/rfc3640.txt: fragmentation of CELP frames. Hence, CELP frames MUST NOT be iana/www.rfc-editor.org/rfc/rfc3640.txt: fragmented when using this mode. iana/www.rfc-editor.org/rfc/rfc3640.txt: frame in this mode is 63 octets. AAC frames MUST NOT be fragmented iana/www.rfc-editor.org/rfc/rfc3640.txt: fragment of an AAC frame is carried. In this mode, the AAC frames iana/www.rfc-editor.org/rfc/rfc3640.txt: one fragmented AAC frame. The Auxiliary Section MUST be empty. For iana/www.rfc-editor.org/rfc/rfc3984.txt: fragmentation units are specified in sections 5.7 and 5.8, iana/www.rfc-editor.org/rfc/rfc3984.txt: Fragmentation unit: Used to fragment a single NAL unit over multiple iana/www.rfc-editor.org/rfc/rfc3984.txt: fragmentation units. The maximum size of a NAL unit encapsulated iana/www.rfc-editor.org/rfc/rfc3984.txt: and a series of fragmentation units starting with an FU-B is iana/www.rfc-editor.org/rfc/rfc3984.txt: a series of fragmentation units starting with an FU-B is determined iana/www.rfc-editor.org/rfc/rfc3984.txt: aggregation packet nor a fragmentation unit can be used within a iana/www.rfc-editor.org/rfc/rfc3984.txt: fragmentation units specified in section 5.8. Aggregation packets iana/www.rfc-editor.org/rfc/rfc3984.txt: This payload type allows fragmenting a NAL unit into several RTP iana/www.rfc-editor.org/rfc/rfc3984.txt: lower layer fragmentation (e.g., by IP) has the following advantages: iana/www.rfc-editor.org/rfc/rfc3984.txt: o The fragmentation mechanism allows fragmenting a single picture iana/www.rfc-editor.org/rfc/rfc3984.txt: aggregation packets. A fragment of a NAL unit consists of an integer iana/www.rfc-editor.org/rfc/rfc3984.txt: unit MUST be part of exactly one fragment of that NAL unit. iana/www.rfc-editor.org/rfc/rfc3984.txt: fragment). Similarly, a NAL unit MUST be reassembled in RTP sequence iana/www.rfc-editor.org/rfc/rfc3984.txt: When a NAL unit is fragmented and conveyed within fragmentation units iana/www.rfc-editor.org/rfc/rfc3984.txt: (FUs), it is referred to as a fragmented NAL unit. STAPs and MTAPs iana/www.rfc-editor.org/rfc/rfc3984.txt: MUST NOT be fragmented. FUs MUST NOT be nested; i.e., an FU MUST NOT iana/www.rfc-editor.org/rfc/rfc3984.txt: time of the fragmented NAL unit. iana/www.rfc-editor.org/rfc/rfc3984.txt: consists of a fragmentation unit indicator of one octet, a iana/www.rfc-editor.org/rfc/rfc3984.txt: fragmentation unit header of one octet, and a fragmentation unit iana/www.rfc-editor.org/rfc/rfc3984.txt: consists of a fragmentation unit indicator of one octet, a iana/www.rfc-editor.org/rfc/rfc3984.txt: fragmentation unit header of one octet, a decoding order number (DON) iana/www.rfc-editor.org/rfc/rfc3984.txt: (in network byte order), and a fragmentation unit payload. In other iana/www.rfc-editor.org/rfc/rfc3984.txt: for the first fragmentation unit of a fragmented NAL unit. NAL unit iana/www.rfc-editor.org/rfc/rfc3984.txt: interleaved packetization mode, each NALU that is fragmented has an iana/www.rfc-editor.org/rfc/rfc3984.txt: FU-B as the first fragment, followed by one or more FU-A fragments. iana/www.rfc-editor.org/rfc/rfc3984.txt: according to the value of the NRI field in the fragmented NAL unit. iana/www.rfc-editor.org/rfc/rfc3984.txt: When set to one, the Start bit indicates the start of a fragmented iana/www.rfc-editor.org/rfc/rfc3984.txt: fragmented NAL unit payload, the Start bit is set to zero. iana/www.rfc-editor.org/rfc/rfc3984.txt: When set to one, the End bit indicates the end of a fragmented NAL iana/www.rfc-editor.org/rfc/rfc3984.txt: the fragmented NAL unit. When the following FU payload is not the iana/www.rfc-editor.org/rfc/rfc3984.txt: last fragment of a fragmented NAL unit, the End bit is set to iana/www.rfc-editor.org/rfc/rfc3984.txt: fragment NAL units to FU-Bs without organizing the incoming NAL iana/www.rfc-editor.org/rfc/rfc3984.txt: A fragmented NAL unit MUST NOT be transmitted in one FU; i.e., the iana/www.rfc-editor.org/rfc/rfc3984.txt: The FU payload consists of fragments of the payload of the fragmented iana/www.rfc-editor.org/rfc/rfc3984.txt: NAL unit so that if the fragmentation unit payloads of consecutive iana/www.rfc-editor.org/rfc/rfc3984.txt: FUs are sequentially concatenated, the payload of the fragmented NAL iana/www.rfc-editor.org/rfc/rfc3984.txt: unit can be reconstructed. The NAL unit type octet of the fragmented iana/www.rfc-editor.org/rfc/rfc3984.txt: NAL unit is not included as such in the fragmentation unit payload, iana/www.rfc-editor.org/rfc/rfc3984.txt: fragmented NAL unit is conveyed in F and NRI fields of the FU iana/www.rfc-editor.org/rfc/rfc3984.txt: indicator octet of the fragmentation unit and in the type field of iana/www.rfc-editor.org/rfc/rfc3984.txt: senders can be characterized in that they packetize NALU fragments iana/www.rfc-editor.org/rfc/rfc3984.txt: NALU size is known. If zero-length NALU fragments were not iana/www.rfc-editor.org/rfc/rfc3984.txt: data of the following fragment before the current fragment could iana/www.rfc-editor.org/rfc/rfc3984.txt: If a fragmentation unit is lost, the receiver SHOULD discard all iana/www.rfc-editor.org/rfc/rfc3984.txt: following fragmentation units in transmission order corresponding to iana/www.rfc-editor.org/rfc/rfc3984.txt: the same fragmented NAL unit. iana/www.rfc-editor.org/rfc/rfc3984.txt: fragments of a NAL unit to an (incomplete) NAL unit, even if fragment iana/www.rfc-editor.org/rfc/rfc3984.txt: decapsulated packet is an FU-A, all the fragments of the fragmented iana/www.rfc-editor.org/rfc/rfc3984.txt: following FUs of the same fragmented NAL unit, as their iana/www.rfc-editor.org/rfc/rfc3984.txt: that unless all created fragments can be recovered, the whole slice iana/www.rfc-editor.org/rfc/rfc4060.txt: fragmentation and SHOULD follow the recommendations given in Section iana/www.rfc-editor.org/rfc/rfc4175.txt: MTU, the scan line SHOULD be fragmented into multiple RTP packets, iana/www.rfc-editor.org/rfc/rfc4175.txt: samples relating to a single pixel are not fragmented across multiple iana/www.rfc-editor.org/rfc/rfc4175.txt: digital active line content, video data MUST NOT be fragmented within iana/www.rfc-editor.org/rfc/rfc4175.txt: fragment) of video is included in each RTP packet. iana/www.rfc-editor.org/rfc/rfc4175.txt: if it is necessary to fragment a line. iana/www.rfc-editor.org/rfc/rfc4175.txt: single complete scan line, a single fragment of a scan line, or one iana/www.rfc-editor.org/rfc/rfc4175.txt: (or more) complete scan lines and scan line fragments. The length of iana/www.rfc-editor.org/rfc/rfc4175.txt: each scan line or scan line fragment MUST be an integer multiple of iana/www.rfc-editor.org/rfc/rfc4175.txt: the pgroup size in octets. Scan lines SHOULD be fragmented so that iana/www.rfc-editor.org/rfc/rfc4184.txt: support for data fragmentation. iana/www.rfc-editor.org/rfc/rfc4184.txt: contains the final fragment of an AC-3 frame. iana/www.rfc-editor.org/rfc/rfc4184.txt: fragments of the same frame MUST have the same time stamp. The iana/www.rfc-editor.org/rfc/rfc4184.txt: an integral number of complete AC-3 frames or by a single fragment of iana/www.rfc-editor.org/rfc/rfc4184.txt: fragmented for transmission within an RTP packet. Section 4.2 iana/www.rfc-editor.org/rfc/rfc4184.txt: provides guidelines for creating frame fragments. iana/www.rfc-editor.org/rfc/rfc4184.txt: 1 - Initial fragment of frame which includes the first 5/8ths of iana/www.rfc-editor.org/rfc/rfc4184.txt: 2 - Initial fragment of frame, which does not include the first iana/www.rfc-editor.org/rfc/rfc4184.txt: 3 - Fragment of frame other than initial fragment. (Note that M iana/www.rfc-editor.org/rfc/rfc4184.txt: bit in RTP header is set for final fragment). iana/www.rfc-editor.org/rfc/rfc4184.txt: o NF (Number of frames/fragments): An 8-bit field whose meaning iana/www.rfc-editor.org/rfc/rfc4184.txt: in the RTP payload. For frame fragments (FT of 1, 2, or 3), it is iana/www.rfc-editor.org/rfc/rfc4184.txt: used to indicate the number fragments (and therefore packets) that iana/www.rfc-editor.org/rfc/rfc4184.txt: containing fragments of the same frame. iana/www.rfc-editor.org/rfc/rfc4184.txt: SHOULD be fragmented at the RTP level. The fragmentation MAY be iana/www.rfc-editor.org/rfc/rfc4184.txt: fragments of the same AC-3 frame SHALL be sent in consecutive order, iana/www.rfc-editor.org/rfc/rfc4184.txt: from first to last fragment. This enables a receiver to assemble the iana/www.rfc-editor.org/rfc/rfc4184.txt: fragments in correct order. iana/www.rfc-editor.org/rfc/rfc4184.txt: When an AC-3 frame is fragmented, it MAY be fragmented such that at iana/www.rfc-editor.org/rfc/rfc4184.txt: least the first 5/8ths of the frame data is in the first fragment. iana/www.rfc-editor.org/rfc/rfc4184.txt: decode the first two blocks of the frame. Any frame fragments other iana/www.rfc-editor.org/rfc/rfc4396.txt: payload headers, the fragmentation and re-assembly rules for text iana/www.rfc-editor.org/rfc/rfc4396.txt: b. Enable the fragmentation of a text sample into several RTP iana/www.rfc-editor.org/rfc/rfc4396.txt: network environments. In general, fragmentation should be iana/www.rfc-editor.org/rfc/rfc4396.txt: means for coping with fragmentation and reassembly. Section iana/www.rfc-editor.org/rfc/rfc4396.txt: 4.4 deals with fragmentation. iana/www.rfc-editor.org/rfc/rfc4396.txt: (fragment) type. Following these headers, the text sample iana/www.rfc-editor.org/rfc/rfc4396.txt: fragment thereof, iana/www.rfc-editor.org/rfc/rfc4396.txt: the first fragment thereof, iana/www.rfc-editor.org/rfc/rfc4396.txt: d. A TYPE 4 unit that contains one modifier fragment other iana/www.rfc-editor.org/rfc/rfc4396.txt: text sample fragments that can be conveyed by the iana/www.rfc-editor.org/rfc/rfc4396.txt: detect lost text samples fragments, but it does not enable an iana/www.rfc-editor.org/rfc/rfc4396.txt: lost. In fact, the fragment size included in the payload iana/www.rfc-editor.org/rfc/rfc4396.txt: offset) upon fragmentation would be required. This would iana/www.rfc-editor.org/rfc/rfc4396.txt: additionally require that the entity performing fragmentation iana/www.rfc-editor.org/rfc/rfc4396.txt: count the characters included in each text fragment. iana/www.rfc-editor.org/rfc/rfc4396.txt: fragments using the measures outlined in Section 5. iana/www.rfc-editor.org/rfc/rfc4396.txt: indicate the total number and current index of fragments of a iana/www.rfc-editor.org/rfc/rfc4396.txt: field in each fragment. Details in Section 4.1.3. iana/www.rfc-editor.org/rfc/rfc4396.txt: fragment or text sample fragment iana/www.rfc-editor.org/rfc/rfc4396.txt: A fraction of a text sample. A fragment may contain either text iana/www.rfc-editor.org/rfc/rfc4396.txt: samples, sample descriptions, and sample fragments (note that, iana/www.rfc-editor.org/rfc/rfc4396.txt: one fragment may be included in a payload). iana/www.rfc-editor.org/rfc/rfc4396.txt: samples, fragments thereof, and sample descriptions by placing a iana/www.rfc-editor.org/rfc/rfc4396.txt: includes one or more whole text samples or the last fragment of a iana/www.rfc-editor.org/rfc/rfc4396.txt: fragments of the same text sample. The details of the timestamp iana/www.rfc-editor.org/rfc/rfc4396.txt: the second contains one text sample fragment. After each unit header iana/www.rfc-editor.org/rfc/rfc4396.txt: - TYPE 2, for a text string fragment (without modifiers). iana/www.rfc-editor.org/rfc/rfc4396.txt: - TYPE 3, for a whole modifier box or the first fragment of a iana/www.rfc-editor.org/rfc/rfc4396.txt: - TYPE 4, for a modifier fragment other than first. iana/www.rfc-editor.org/rfc/rfc4396.txt: fragment (see Section 2.5). In order to guarantee backwards- iana/www.rfc-editor.org/rfc/rfc4396.txt: current fragment MUST be calculated during the sampling process or iana/www.rfc-editor.org/rfc/rfc4396.txt: during fragmentation. iana/www.rfc-editor.org/rfc/rfc4396.txt: text string fragments (TYPE 2) since it can be deductively iana/www.rfc-editor.org/rfc/rfc4396.txt: calculated from the LEN values of each fragment. iana/www.rfc-editor.org/rfc/rfc4396.txt: fragment of it. TYPE 2 units SHALL NOT contain modifiers. In iana/www.rfc-editor.org/rfc/rfc4396.txt: fragment plus nine (9) bytes of headers. Its value is calculated iana/www.rfc-editor.org/rfc/rfc4396.txt: upon fragmentation. LEN MUST always be greater than nine (0x0009). iana/www.rfc-editor.org/rfc/rfc4396.txt: fragments. Therefore, a text fragment MUST contain at least one iana/www.rfc-editor.org/rfc/rfc4396.txt: formalism since by observing the guidelines, much larger fragments iana/www.rfc-editor.org/rfc/rfc4396.txt: original (whole) text sample to which this fragment belongs. This iana/www.rfc-editor.org/rfc/rfc4396.txt: Depending on the packet length, fragmentation may be needed. iana/www.rfc-editor.org/rfc/rfc4396.txt: remaining fragments of a text sample. iana/www.rfc-editor.org/rfc/rfc4396.txt: number of fragments in which the original text sample (i.e., the iana/www.rfc-editor.org/rfc/rfc4396.txt: text string and its modifiers) has been fragmented and which order iana/www.rfc-editor.org/rfc/rfc4396.txt: occupies the current fragment in that sequence, respectively. Note iana/www.rfc-editor.org/rfc/rfc4396.txt: the THIS field, since packets (and fragments) may be repeated, iana/www.rfc-editor.org/rfc/rfc4396.txt: indication for "fragment offset" is needed. iana/www.rfc-editor.org/rfc/rfc4396.txt: the fragments. iana/www.rfc-editor.org/rfc/rfc4396.txt: than TOTAL or if TOTAL equals zero (0x0), the fragment SHALL be iana/www.rfc-editor.org/rfc/rfc4396.txt: fragment of the UTF-8/UTF-16 character string; no modifiers follow. iana/www.rfc-editor.org/rfc/rfc4396.txt: contents present in a text sample or just the first fragment of them. iana/www.rfc-editor.org/rfc/rfc4396.txt: If a text sample containing modifiers is fragmented, this header MUST iana/www.rfc-editor.org/rfc/rfc4396.txt: be used to transport the first fragment or, if possible, the complete iana/www.rfc-editor.org/rfc/rfc4396.txt: obtained upon fragmentation. Additionally, the LEN field MUST be iana/www.rfc-editor.org/rfc/rfc4396.txt: For TYPE 3 units containing the last (trailing) modifier fragment, iana/www.rfc-editor.org/rfc/rfc4396.txt: number of fragments of a text sample is logically always larger iana/www.rfc-editor.org/rfc/rfc4396.txt: means that the unit contains the first fragment of the modifiers. iana/www.rfc-editor.org/rfc/rfc4396.txt: o The SDUR has the same definition for TYPE 1. Since the fragments iana/www.rfc-editor.org/rfc/rfc4396.txt: needed to know how long this fragment is valid. This may, e.g., be iana/www.rfc-editor.org/rfc/rfc4396.txt: headers. This is because a) these fragments do not contain text iana/www.rfc-editor.org/rfc/rfc4396.txt: strings and b) these types of fragments are applied over text string iana/www.rfc-editor.org/rfc/rfc4396.txt: fragments, which already contain this information. iana/www.rfc-editor.org/rfc/rfc4396.txt: This header type is placed before modifier fragments, other than the iana/www.rfc-editor.org/rfc/rfc4396.txt: SHALL also be obtained upon fragmentation. The LEN field MUST be iana/www.rfc-editor.org/rfc/rfc4396.txt: since fragmentation of sample descriptions is not defined iana/www.rfc-editor.org/rfc/rfc4396.txt: This section explains why text samples may have to be fragmented and iana/www.rfc-editor.org/rfc/rfc4396.txt: proposed together with rules and recommendations for fragmenting and iana/www.rfc-editor.org/rfc/rfc4396.txt: one or two hundred bytes) makes fragmentation of text samples a rare iana/www.rfc-editor.org/rfc/rfc4396.txt: way that fragmentation is avoided. If it is, this is preferred to iana/www.rfc-editor.org/rfc/rfc4396.txt: fragmentation and SHOULD be done. iana/www.rfc-editor.org/rfc/rfc4396.txt: fragmentation MAY be used, and the basic guidelines given in this iana/www.rfc-editor.org/rfc/rfc4396.txt: o It is RECOMMENDED that text samples be fragmented as seldom as iana/www.rfc-editor.org/rfc/rfc4396.txt: possible, i.e., the least possible number of fragments is created iana/www.rfc-editor.org/rfc/rfc4396.txt: fragment if a previous fragment was lost. As a consequence, text iana/www.rfc-editor.org/rfc/rfc4396.txt: string fragmentation requires knowledge of the UTF-8/UTF-16 iana/www.rfc-editor.org/rfc/rfc4396.txt: and for all fragment loss constellations) would place additional iana/www.rfc-editor.org/rfc/rfc4396.txt: modifier boxes and b) specific fragment headers for each of the iana/www.rfc-editor.org/rfc/rfc4396.txt: fragments are affected, which modifiers may or may not be split, iana/www.rfc-editor.org/rfc/rfc4396.txt: split the modifiers in such a way that each fragment can be iana/www.rfc-editor.org/rfc/rfc4396.txt: require a more intelligent fragmentation entity and more complex iana/www.rfc-editor.org/rfc/rfc4396.txt: headers. Given the low probability of fragmentation and the iana/www.rfc-editor.org/rfc/rfc4396.txt: o Modifier and text string fragments SHOULD be protected against iana/www.rfc-editor.org/rfc/rfc4396.txt: o An additional requirement when fragmenting text samples is that the iana/www.rfc-editor.org/rfc/rfc4396.txt: o Finally, sample descriptions SHALL NOT be fragmented because they iana/www.rfc-editor.org/rfc/rfc4396.txt: fragmented text samples. For this purpose, the standard RTP iana/www.rfc-editor.org/rfc/rfc4396.txt: The process for collecting the different fragments (units) of a text iana/www.rfc-editor.org/rfc/rfc4396.txt: fields; the TOTAL field indicates how many fragments were iana/www.rfc-editor.org/rfc/rfc4396.txt: position of this fragment in the text sample. As result of this iana/www.rfc-editor.org/rfc/rfc4396.txt: a. No fragment is missing. Then, the THIS field SHALL be used iana/www.rfc-editor.org/rfc/rfc4396.txt: to order the fragments and reassemble the text sample iana/www.rfc-editor.org/rfc/rfc4396.txt: b. One or more fragments are missing: Check whether this iana/www.rfc-editor.org/rfc/rfc4396.txt: fragment belongs to the text string or to the modifiers. iana/www.rfc-editor.org/rfc/rfc4396.txt: TYPE 2 units identify text string fragments, and TYPE 3 and iana/www.rfc-editor.org/rfc/rfc4396.txt: 4 identify modifier fragments: iana/www.rfc-editor.org/rfc/rfc4396.txt: i. If the fragment or fragments missing belong to the text iana/www.rfc-editor.org/rfc/rfc4396.txt: fragment is lost. This is the case for modifiers iana/www.rfc-editor.org/rfc/rfc4396.txt: ii. If the fragment missing belongs to the modifiers and iana/www.rfc-editor.org/rfc/rfc4396.txt: fragment, either TYPE 3 or TYPE 4. At least one unit MUST be iana/www.rfc-editor.org/rfc/rfc4396.txt: string fragment (TYPE 2), followed by zero or one TYPE 3 unit. If iana/www.rfc-editor.org/rfc/rfc4396.txt: fragments of one (and only one) text sample. If it does, then iana/www.rfc-editor.org/rfc/rfc4396.txt: Section 2.4, which explicitly disallows combining fragments of iana/www.rfc-editor.org/rfc/rfc4396.txt: | text string fragment (no.bytes=TLEN) | iana/www.rfc-editor.org/rfc/rfc4396.txt: | text string fragment (no.bytes=LEN - 9) | iana/www.rfc-editor.org/rfc/rfc4396.txt: Figure 14. Payload with first text string fragment of a sample iana/www.rfc-editor.org/rfc/rfc4396.txt: fragments of the same text sample is represented (see configuration 3 iana/www.rfc-editor.org/rfc/rfc4396.txt: last modifier fragment, a TYPE 4. iana/www.rfc-editor.org/rfc/rfc4396.txt: | text string fragment (no.bytes=LEN - 9) | iana/www.rfc-editor.org/rfc/rfc4396.txt: Figure 16. An RTP packet carrying last modifiers fragment (TYPE 4) iana/www.rfc-editor.org/rfc/rfc4396.txt: Apart from the basic fragmentation guidelines described in the iana/www.rfc-editor.org/rfc/rfc4396.txt: fragmentation is needed, it SHALL be performed only once for each iana/www.rfc-editor.org/rfc/rfc4396.txt: the RTP timestamp is used to group together the fragments of a iana/www.rfc-editor.org/rfc/rfc4396.txt: non-fragmented text sample (one TYPE 1 unit), a repetition of iana/www.rfc-editor.org/rfc/rfc4396.txt: that sample MUST be sent also as a single non-fragmented text iana/www.rfc-editor.org/rfc/rfc4396.txt: fragmented and spread over several RTP packets (say, a total of iana/www.rfc-editor.org/rfc/rfc4396.txt: 3 units), then the repeated fragments SHALL also have the same iana/www.rfc-editor.org/rfc/rfc4396.txt: fragment. iana/www.rfc-editor.org/rfc/rfc4396.txt: re-assemble fragments with different sequence numbers). iana/www.rfc-editor.org/rfc/rfc4396.txt: Another form of attack may consist of sending redundant fragments, iana/www.rfc-editor.org/rfc/rfc4396.txt: (as indicated by LEN) or fragments that carry different sample iana/www.rfc-editor.org/rfc/rfc4425.txt: be fragmented across multiple AUs (see section 4.2). iana/www.rfc-editor.org/rfc/rfc4425.txt: payload contains a fragmented frame, in which case the rules in iana/www.rfc-editor.org/rfc/rfc4425.txt: fragmented frame. Section 4.2 describes how to handle fragmented iana/www.rfc-editor.org/rfc/rfc4425.txt: SHOULD be fragmented into multiple AUs to avoid IP-level iana/www.rfc-editor.org/rfc/rfc4425.txt: fragmentation. When an AU contains a fragmented frame, this MUST be iana/www.rfc-editor.org/rfc/rfc4425.txt: AU payloads that do not contain a fragmented frame or that contain iana/www.rfc-editor.org/rfc/rfc4425.txt: the first fragment of a frame MUST start at an EBDU boundary if iana/www.rfc-editor.org/rfc/rfc4425.txt: If Advanced profile is used, AU payloads that contain a fragment of a iana/www.rfc-editor.org/rfc/rfc4425.txt: frame other than the first fragment SHOULD start at an EBDU boundary, iana/www.rfc-editor.org/rfc/rfc4425.txt: possible to continue a fragmented frame at an EBDU boundary. One can iana/www.rfc-editor.org/rfc/rfc4425.txt: macroblocks are not byte-aligned, the fragmentation boundary may be iana/www.rfc-editor.org/rfc/rfc4425.txt: If an RTP packet contains an AU with the last fragment of a frame, iana/www.rfc-editor.org/rfc/rfc4425.txt: If the PTS Delta field in the AU header is present, each fragment of iana/www.rfc-editor.org/rfc/rfc4425.txt: in the AU header is present, each fragment of a frame MUST have the iana/www.rfc-editor.org/rfc/rfc4425.txt: or the first fragment of an AU, and the RA bit is set to 1 but the AU iana/www.rfc-editor.org/rfc/rfc4425.txt: containing a complete VC-1 frame or the last fragment of a VC-1 iana/www.rfc-editor.org/rfc/rfc4425.txt: When VC-1 frames have been fragmented across RTP packets, the iana/www.rfc-editor.org/rfc/rfc4425.txt: no fragment is missing. iana/www.rfc-editor.org/rfc/rfc4425.txt: payload contains a complete frame or a fragment of a frame. It iana/www.rfc-editor.org/rfc/rfc4425.txt: 0: The AU payload contains a fragment of a frame other than the iana/www.rfc-editor.org/rfc/rfc4425.txt: first or last fragment. iana/www.rfc-editor.org/rfc/rfc4425.txt: 1: The AU payload contains the first fragment of a frame. iana/www.rfc-editor.org/rfc/rfc4425.txt: 2: The AU payload contains the last fragment of a frame. iana/www.rfc-editor.org/rfc/rfc4425.txt: 3: The AU payload contains a complete frame (not fragmented.) iana/www.rfc-editor.org/rfc/rfc4629.txt: fragmentation at macroblock boundaries. iana/www.rfc-editor.org/rfc/rfc4629.txt: be fragmented across packet boundaries. The only reasonable need iana/www.rfc-editor.org/rfc/rfc4629.txt: for a slice to be fragmented across packet boundaries is when the iana/www.rfc-editor.org/rfc/rfc4695.txt: fragmenting and interleaving AUs MUST NOT be used with RTP MIDI. The iana/www.rfc-editor.org/rfc/rfc5109.txt: coincident with the independently decodable fragment boundaries. iana/www.rfc-editor.org/rfc/rfc5215.txt: following packet contains fragmented Vorbis data and/or the number of iana/www.rfc-editor.org/rfc/rfc5215.txt: the payload. If the payload contains fragmented data, the number of iana/www.rfc-editor.org/rfc/rfc5215.txt: fragmentation, the Vorbis data packet size SHOULD be kept iana/www.rfc-editor.org/rfc/rfc5215.txt: be capable of dealing with fragmentation and periodic re-transmission iana/www.rfc-editor.org/rfc/rfc5215.txt: fragmented. iana/www.rfc-editor.org/rfc/rfc5215.txt: Each RTP payload contains either one Vorbis packet fragment or an iana/www.rfc-editor.org/rfc/rfc5215.txt: A fragmented packet has a zero in the last four bits of the payload iana/www.rfc-editor.org/rfc/rfc5215.txt: header. The first fragment will set the Fragment type to 1. Each iana/www.rfc-editor.org/rfc/rfc5215.txt: fragment after the first will set the Fragment type to 2 in the iana/www.rfc-editor.org/rfc/rfc5215.txt: payload header. The consecutive fragments MUST be sent without any iana/www.rfc-editor.org/rfc/rfc5215.txt: other payload being sent between the first and the last fragment. iana/www.rfc-editor.org/rfc/rfc5215.txt: The RTP payload containing the last fragment of the Vorbis packet iana/www.rfc-editor.org/rfc/rfc5215.txt: sequence for fragmented packet reception, the timestamp field of iana/www.rfc-editor.org/rfc/rfc5215.txt: fragmented packets MUST be the same as the first packet sent, with iana/www.rfc-editor.org/rfc/rfc5215.txt: field shows the fragment length. iana/www.rfc-editor.org/rfc/rfc5215.txt: Here is an example of a fragmented Vorbis packet split over three RTP iana/www.rfc-editor.org/rfc/rfc5215.txt: is set to 0. For large Vorbis fragments, there can be several of iana/www.rfc-editor.org/rfc/rfc5215.txt: This is the last Vorbis fragment payload. The Fragment type is set iana/www.rfc-editor.org/rfc/rfc5215.txt: fragmented Vorbis packets as the client will have to cope with the iana/www.rfc-editor.org/rfc/rfc5215.txt: handling of the Fragment Type. In case of loss of fragments, the iana/www.rfc-editor.org/rfc/rfc5215.txt: client MUST discard all the remaining Vorbis fragments and decode the iana/www.rfc-editor.org/rfc/rfc5215.txt: incomplete packet. If we use the fragmented Vorbis packet example iana/www.rfc-editor.org/rfc/rfc5215.txt: final fragmented packet, MUST be dropped in the same manner. If the iana/www.rfc-editor.org/rfc/rfc5215.txt: missing RTP payload is the last, the two fragments received will be iana/www.rfc-editor.org/rfc/rfc5215.txt: Loss of any of the Configuration fragment will result in the loss of iana/www.rfc-editor.org/rfc/rfc5371.txt: * Special markers for the headers, fragments of headers, etc. iana/www.rfc-editor.org/rfc/rfc5371.txt: in each RTP packet carrying a fragment of a given frame. When a iana/www.rfc-editor.org/rfc/rfc5371.txt: |reserved | fragment offset | iana/www.rfc-editor.org/rfc/rfc5371.txt: part of a fragmented header, MHF has a value of 1. If there is iana/www.rfc-editor.org/rfc/rfc5371.txt: the last part of a fragmented header, MHF has value of 2. If the iana/www.rfc-editor.org/rfc/rfc5371.txt: | 1 | piece of fragmented header | iana/www.rfc-editor.org/rfc/rfc5371.txt: | 2 | last part of a fragmented header | iana/www.rfc-editor.org/rfc/rfc5371.txt: fragment offset: 24 bits iana/www.rfc-editor.org/rfc/rfc5371.txt: fragment offset. It is then possible to deliver layered video iana/www.rfc-editor.org/rfc/rfc5371.txt: using multiple RTP sessions; the fragment offset might not start iana/www.rfc-editor.org/rfc/rfc5371.txt: payload header) is larger than the MTU size, it MAY be fragmented. iana/www.rfc-editor.org/rfc/rfc5371.txt: To pack a fragmented packetization unit, the fragmented unit MUST NOT iana/www.rfc-editor.org/rfc/rfc5371.txt: |RTP |payload| packetization unit fragment | iana/www.rfc-editor.org/rfc/rfc5371.txt: |RTP |payload| packetization unit fragment | iana/www.rfc-editor.org/rfc/rfc5371.txt: |RTP |payload| end of packetization unit fragment | iana/www.rfc-editor.org/rfc/rfc5371.txt: Figure 5: An example with a fragmented packetization unit iana/www.rfc-editor.org/rfc/rfc5371.txt: |reserved | fragment offset | iana/www.rfc-editor.org/rfc/rfc5372.txt: |reserved | fragment offset | iana/www.rfc-editor.org/rfc/rfc5372.txt: |reserved | fragment offset |