Draft: draft-jholland-mops-taxonomy

Commentary: Some initial changes and additions .
Paragraph (version A):
Height and width are in pixels, and frame rate in frames per second.
The actual bit-rate required for a specific video will also depend on
the codec used and some other characteristics of the video itself,
such as the frequency of high-detail motion, which may influence the
compressability of the content, but this equation provides a rough
estimate.
Paragraph (version A):
TBD: Reference and/or adapt content from expired work-in-progress I-
D.han-iccrg-arvr-transport-problem.
Paragraph (version A):
The punchline is that it starts at a bare minimum of 22 Mbps mean
with a 130 Mbps peak rate, up to 3.3 Gbps mean with 38 Gbps peak for
high-end technology.
Paragraph (version A):
The bit-rate requirements in scaling are per end-user actively
consuming a media feed, so in the worst case, the bit-rate demands
can be multiplied by the number of simultaneous users to find the
bandwidth requirements for a router on the delivery path with that
number of users downstream.  For example, at a node with 10,000
downstream users simultaneously consuming video streams,
approximately up to 180 Gbps would be necessary in order for all of
them to get 1080p resolution at 60 fps.
Paragraph (version B):
Height and width are in pixels, and frame rate is in frames per
second.  The actual bitrate required for a specific video will also
depend on the codec used, fidelity desired and some other
characteristics of the video itself, such as the amount and frequency
of high-detail motion, which may influence the compressability of the
content, but this equation provides a rough estimate.
Paragraph (version B):
Even the basic virtual reality (360-degree) videos (that allow users
to look around freely, referred to as three degrees of freedom -
3DoF) require substantially larger bitrates when they are captured
and encoded as such videos require multiple fields of view of the
scene.  The typical multiplication factor is 8 to 10.  Yet, due to
smart delivery methods such as viewport-based or tiled-based
streaming, we do not need to send the whole scene to the user.
Instead, the user needs only the portion corresponding to its
viewpoint at any given time.
Paragraph (version B):
In more immersive applications, where basic user movement (3DoF+) or
full user movement (6DoF) is allowed, the required bitrate grows even
further.  In this case, the immersive content is typically referred
to as volumetric media.  One way to represent the volumetric media is
to use point clouds, where streaming a single object may easily
require a bitrate of 30 Mbps or higher.  Refer to PCC for more
details.
Paragraph (version B):
The bitrate requirements in scaling are per end-user actively
consuming a media feed, so in the worst case, the bitrate demands can
be multiplied by the number of simultaneous users to find the
bandwidth requirements for a router on the delivery path with that
number of users downstream.  For example, at a node with 10,000
downstream users simultaneously consuming video streams,
approximately up to 80 Gbps would be necessary in order for all of
them to get 1080p resolution at 60 fps.
Paragraph (version B):
Historical data shows that users consume more video and videos at
higher bitrates than they did in the past on their connected devices.
Improvements in the codecs that help with reducing the encoding
bitrates with better compression algorithms could not have offset the
increase in the demand for the higher quality video (higher
resolution, higher frame rate, better color gamut, better dynamic
range, etc.).  In particular, mobile data usage has shown a large
jump over the years due to increased consumption of entertainement as
well as conversational video.
Paragraph (version A):
Adaptive Bit-Rate (ABR) is a sort of application-level congestion
response strategy in which the receiving media player attempts to
detect the available bandwidth of the network path by experiment or
by observing the successful application-layer download speed, then
chooses a video bitrate that fits within that bandwidth, typically
adjusting as changes in available bandwidth occur in the network.
Paragraph (version A):
The choice of bit-rate occurs within the context of optimizing for
some metric monitored by the video player, such as highest achievable
video quality, or lowest rate of expected rebuffering events.
Paragraph (version A):
ABR strategies are commonly implemented by video players using HLS
RFC8216 or DASH DASH to perform a reliable segment delivery of video
data over HTTP.  Different player implementations and receiving
devices use different strategies, often proprietary algorithms, to
perform the bit-rate selection and available bandwidth estimation.
Paragraph (version A):
This kind of bandwidth-detection system can experience trouble in
several ways that can be affected by networking design choices.
Paragraph (version A):
When the bit-rate selection is successfully chosen below the
available capacity of the network path, the response to a segment
request will complete in less absolute time than the video bit-rate
speed.
Paragraph (version B):
Adaptive BitRate (ABR) is a sort of application-level response
strategy in which the receiving media player attempts to detect the
available bandwidth of the network path by experiment or by observing
the successful application-layer download speed, then chooses a video
bitrate (among the limited number of available options) that fits
within that bandwidth, typically adjusting as changes in available
bandwidth occur in the network or changes in capabilities occur in
the player (such as available memory, CPU, display size, etc.).
Paragraph (version B):
The choice of bitrate occurs within the context of optimizing for
some metric monitored by the video player, such as highest achievable
video quality, or lowest rate of expected rebuffering events.
Paragraph (version B):
ABR playback is commonly implemented by video players using HLS
RFC8216 or DASH DASH to perform a reliable segmented delivery of
video data over HTTP.  Different player implementations and receiving
devices use different strategies, often proprietary algorithms
(called rate adaptation or bitrate selection algorithms), to perform
available bandwidth estimation/prediction and the bitrate selection.
Most players only use passive observations, i.e., they do not
generate probe traffic to measure the available bandwidth.
Paragraph (version B):
This kind of bandwidth-measurement systems can experience trouble in
several ways that can be affected by networking design choices.
Paragraph (version B):
A detailed investigation of this phenomenon is available in
NOSSDAV12.
Paragraph (version A):
Under congestion and loss, this approach generally experiences more
video artifacts with fewer delay or head of line blocking effects.
Often one of the key goals is to reduce latency, to better support
applications like video conferencing, or for other live-action video
with interactive components, such as some sporting events.
Paragraph (version B):
Under congestion and loss, this approach generally experiences more
video artifacts with fewer delay or head-of-line blocking effects.
Often one of the key goals is to reduce latency, to better support
applications like videoconferencing, or for other live-action video
with interactive components, such as some sporting events.