As per Relevance of the word document, we have this rfc below:
Network Working Group K.
Request for Comments: 3189 CommunicationResearch
Category: Standards Track A.
Keio
S.
Packet
C.
Universitaet Bremen
January 2002
This documentspecifies the packetization scheme for
the compressed digital video data streams commonly known as "DV"
a payload format for the Real-Time TransportProtocol (RTP).
RFC 3189 RTP Payload Format for DV (IEC 61834) Video January 2002
extended for professional use were published by SMPTE as 306M
314M, for differentsampling systems, higher color resolution,
faster bit rates [4,5].
There are two kinds of DV, one for consumer use and the other
professional. The original "DV" specification designed consumer-use digital VCRs is approved as the IEC 61834 standard set
The specifications for professional DV are published as SMPTE 306
and 314M. Both encoding formats are based on consumer DV and used
SMPTE D-7 and D-9 video systems. The RTP payload format specified
this documentsupports IEC 61834 consumer DV and professional
306M and 314M (DV-Based) formats
IEC 61834 also includes magnetic tape recording for digital
broadcasting systems (such as DVB and ATV) that use MPEG2 encoding
The payload format for encapsulating MPEG2 into RTP has already
defined in RFC 2250 [7] and others
Consequently, the payload specified in this document will support
video formats of the IEC standard: SD-VCR (525/60, 625/50), HD-
(1125/60, 1250/50) and SDL-VCR (525/60, 625/50), and six of the standards: 306M (525/60, 625/50), 314M 25Mbps (525/60, 625/50)
314M 50Mbps (525/60, 625/50). In the future it can be extended
other high-definition formats
The DV format only uses the DCT compressiontechnique within
frame, contrasted with the interframe compression of the MPEG standards [9,10]. All video data, including audio and other
data, are managed within the picture frame unit of video
The DV video encoding is composed of a three-level structure. A picture frame is divided into rectangle- or clipped
rectangle-shaped DCT super blocks. DCT super blocks are divided
27 rectangle- or square-shaped DCT macro blocks
RFC 3189 RTP Payload Format for DV (IEC 61834) Video January 2002
Audio data is encoded with PCM format. The samplingfrequency is 32
kHz, 44.1 kHz or 48 kHz and the quantization is 12-bit non-linear
16-bit linear or 20-bit linear. The number of channels may be up
8. Only certain combinations of these parameters are
depending upon the video format; the restrictions are specified
each document
A frame of data in the DV format stream is divided into several "
sequences". A DIF sequence is composed of an integral number of 80-
byte DIF blocks. A DIF block is the primitive unit for all
of DV streams. Each DIF block contains a 3-byte ID header specifies the type of the DIF block and its position in the sequence. Five types of DIF blocks are defined: DIF sequence header
Subcode, Video Auxiliary information (VAUX), Audio, and Video.
DIF blocks are composed of 5 bytes of Audio Auxiliary data (AAUX)
72 bytes of audio data
Each RTP packet starts with the RTP header as defined in RFC 1889
[6]. No additional payload-format-specific header is required
this payload format
2.1 RTP header
The RTP header fields that have a meaning specific to the DV
are described as follows
Payload type (PT): The payload type is dynamically assigned by
outside the scope of this document. If multiple DV encoding
are to be used within one RTP session, then multiple dynamic
types MUST be assigned, one for each DV encoding format. The
MUST change to the corresponding payload type whenever the
format is changed
RFC 3189 RTP Payload Format for DV (IEC 61834) Video January 2002
When the DV stream is obtained from an IEEE 1394 interface,
progress of video frame times MAY be monitored using the timestamp carried in the CIP header as specified in IEC 61883 [2].
Marker bit (M): The marker bit of the RTP fixed header is set to
on the last packet of a video frame, and otherwise, must be zero
The M bit allows the receiver to know that it has received the
packet of a frame so it can display the image without waiting for
first packet of the next frame to arrive to detect the frame change
However, detection of a frame change MUST NOT rely on the marker
since the last packet of the frame might be lost. Detection of
frame change MUST be based on a difference in the RTP timestamp
Integral DIF blocks are placed into the RTP payload immediately after the RTP header. Any number of DIF blocks may
packed into one RTP packet, except that all DIF blocks in one
packet must be from the same video frame. DIF blocks from the
video frame MUST NOT be packed into the same RTP packet even if
payload space remains. This requirement stems from the fact that transition from one video frame to the next is indicated by a
in the RTP timestamp. It also reduces the processing complexity
the receiver. Since the RTP payload contains an integral number
DIF blocks, the length of the RTP payload will be a multiple of 80
bytes
Audio and video data may be transmitted as one bundled RTP stream
in separate RTP streams (unbundled). The choice MUST be indicated
part of the assignment of the dynamic payload type and MUST
unchanged for the duration of the RTP session to avoid procedures of sequence number synchronization. The RTP sender
omit DIF-sequence header and subcode DIF blocks from a stream
the information is either known out-of-band or may not be
for RTP transport. When sending DIF-sequence header and subcode
blocks, both types of blocks MUST be included in the video stream
RFC 3189 RTP Payload Format for DV (IEC 61834) Video January 2002
In the case of one bundled stream, DIF blocks for both audio
video are packed into RTP packets in the same order as they
encoded
In the case of an unbundled stream, only the header, subcode,
and VAUX DIF blocks are sent within the video stream. Audio is
in a different stream if desired, using a different RTP payload type
It is also possible to send audio duplicated in a separate stream, addition to bundling it in with the video stream
When using unbundled mode, it is RECOMMENDED that the audio
data be extracted from the DIF blocks and repackaged into corresponding RTP payload format for the audio encoding (DAT12, L16,
L20) [11,12] in order to maximize interoperability with non-DV
capable receivers while maintaining the original source quality
In the case of unbundled transmission where both audio and video
sent in the DV format, the same timestamp SHOULD be used for
audio and video data within the same frame to simplify the synchronization effort on the receiver. Lip synchronization may
be achieved using reference timestamps passed in RTCP as described
RFC 1889 [6].
The sender MAY reduce the video frame rate by discarding the
data and VAUX DIF blocks for some of the video frames. The timestamp must still be incremented to account for the
frames. The sender MAY alternatively reduce bandwidth by
video data DIF blocks for portions of the image which are
from the previous image. To enable this bandwidth reduction
receivers SHOULD implement an error concealment strategy
accommodate lost or missing DIF blocks, e.g., repeating corresponding DIF block from the previous image
RFC 3189 RTP Payload Format for DV (IEC 61834) Video January 2002
"DV" is the encoding name for the DV video payload format defined
this document. The "90000" specifies the RTP timestamp clock rate
which for the payload format defined in this document is a 90
clock
