Interface CmcdBeta

Buffer length

The buffer length associated with the media object being requested. This value MUST be rounded to the nearest 100 ms. This key SHOULD only be sent with an object type of ‘a’, ‘v’ or ‘av’.

Integer milliseconds

Encoded bitrate

The encoded bitrate of the audio or video object being requested. This may not be known precisely by the player; however, it MAY be estimated based upon playlist/manifest declarations. If the playlist declares both peak and average bitrate values, the peak value should be transmitted.

Integer kbps

Buffer starvation

Key is included without a value if the buffer was starved at some point between the prior request and this object request, resulting in the player being in a rebuffering state and the video or audio playback being stalled. This key MUST NOT be sent if the buffer was not starved since the prior request.

If the object type ot key is sent along with this key, then the bs key refers to the buffer associated with the particular object type. If no object type is communicated, then the buffer state applies to the current session.

Boolean

Content ID

A unique string identifying the current content. Maximum length is 64 characters. This value is consistent across multiple different sessions and devices and is defined and updated at the discretion of the service provider.

String

Object duration

The playback duration in milliseconds of the object being requested. If a partial segment is being requested, then this value MUST indicate the playback duration of that part and not that of its parent segment. This value can be an approximation of the estimated duration if the explicit value is not known.

Integer milliseconds

Deadline

Deadline from the request time until the first sample of this Segment/Object needs to be available in order to not create a buffer underrun or any other playback problems. This value MUST be rounded to the nearest 100ms. For a playback rate of 1, this may be equivalent to the player’s remaining buffer length.

Integer milliseconds

Measured mtp CMCD throughput

The throughput between client and server, as measured by the client and MUST be rounded to the nearest 100 kbps. This value, however derived, SHOULD be the value that the client is using to make its next Adaptive Bitrate switching decision. If the client is connected to multiple servers concurrently, it must take care to report only the throughput measured against the receiving server. If the client has multiple concurrent connections to the server, then the intent is that this value communicates the aggregate throughput the client sees across all those connections.

Integer kbps

Next object request

Relative path of the next object to be requested. This can be used to trigger pre-fetching by the CDN. This MUST be a path relative to the current request. This string MUST be URLEncoded. The client SHOULD NOT depend upon any pre-fetch action being taken - it is merely a request for such a pre-fetch to take place.

String

Next range request

If the next request will be a partial object request, then this string denotes the byte range to be requested. If the ‘nor’ field is not set, then the object is assumed to match the object currently being requested. The client SHOULD NOT depend upon any pre-fetch action being taken – it is merely a request for such a pre-fetch to take place. Formatting is similar to the HTTP Range header, except that the unit MUST be ‘byte’, the ‘Range:’ prefix is NOT required and specifying multiple ranges is NOT allowed. Valid combinations are:

• "\<range-start\>-"
• "\<range-start\>-\<range-end\>"
• "-\<suffix-length\>"

String

Object type

The media type of the current object being requested:

• m = text file, such as a manifest or playlist
• a = audio only
• v = video only
• av = muxed audio and video
• i = init segment
• c = caption or subtitle
• tt = ISOBMFF timed text track
• k = cryptographic key, license or certificate.
• o = other

If the object type being requested is unknown, then this key MUST NOT be used.

Playback rate

1 if real-time, 2 if double speed, 0 if not playing. SHOULD only be sent if not equal to 1.

Decimal

Requested maximum throughput

The requested maximum throughput that the client considers sufficient for delivery of the asset. Values MUST be rounded to the nearest 100kbps. For example, a client would indicate that the current segment, encoded at 2Mbps, is to be delivered at no more than 10Mbps, by using rtp=10000.

Note: This can benefit clients by preventing buffer saturation through over-delivery and can also deliver a community benefit through fair-share delivery. The concept is that each client receives the throughput necessary for great performance, but no more. The CDN may not support the rtp feature.

Integer kbps

Streaming format

The streaming format that defines the current request.

• d = MPEG DASH
• h = HTTP Live Streaming (HLS)
• s = Smooth Streaming
• o = other

If the streaming format being requested is unknown, then this key MUST NOT be used.

Session ID

A GUID identifying the current playback session. A playback session typically ties together segments belonging to a single media asset. Maximum length is 64 characters. It is RECOMMENDED to conform to the UUID specification.

String

Stream type

• v = all segments are available – e.g., VOD
• l = segments become available over time – e.g., LIVE

Startup

Key is included without a value if the object is needed urgently due to startup, seeking or recovery after a buffer-empty event. The media SHOULD not be rendering when this request is made. This key MUST not be sent if it is FALSE.

Boolean

Top bitrate

The highest bitrate rendition in the manifest or playlist that the client is allowed to play, given current codec, licensing and sizing constraints.

Integer Kbps

CMCD version

The version of this specification used for interpreting the defined key names and values. If this key is omitted, the client and server MUST interpret the values as being defined by version 1. Client SHOULD omit this field if the version is 1.

Integer