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docs: merge QoS message fields
There was already a section about QoS messages that is now merged with the new information.
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Wim Taymans
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1 changed files with 49 additions and 79 deletions
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@ -53,40 +53,72 @@ operations.
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QoS message
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-----------
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Whenever QoS discards a piece of data or affects the quality of the stream, a
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message must be posted by the element that performed the QoS. We assume that
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the time gained by dropping the data outweighs the time spend in creating and
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posting the QoS message so that posting the message should not cause more
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performance problems.
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A QOS message is posted on the bus whenever an element decides to:
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- drop a buffer because of QoS reasons
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- change its processing strategy because of QoS reasons (quality)
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It should be expected that creating and posting the QoS message is reasonably
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fast and does not significantly contribute to the QoS problems. Options to
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disable this feature could also be presented on elements.
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This message can be posted by a sink/src that performs synchronisation against the
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clock or it could be dropped by an upstream element that performs QoS because of
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QOS events received from a downstream element.
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clock (live) or it could be dropped by an upstream element that performs QoS
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because of QOS events received from a downstream element (!live).
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The GST_MESSAGE_QOS contains at least the following info:
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- live: G_TYPE_BOOLEAN:
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If the QoS message was dropped by a live element such as a sink or a live
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source. If the live property is FALSE, the QoS message was generated as a
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response to a QoS event in a non-live element.
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- running-time, G_TYPE_UINT64:
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The running_time of the buffer that generated the QoS message.
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- stream-time, G_TYPE_UINT64:
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The stream_time of the buffer that generated the QoS message.
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- timestamp, G_TYPE_UINT64:
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Running_time of the data that is dropped.
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The timestamp of the buffer that generated the QoS message.
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- duration, G_TYPE_UINT64:
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The duration of the buffer that generated the QoS message.
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- jitter, G_TYPE_INT64:
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The lateness of the buffer.
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The difference of the running-time against the deadline. Negative
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values mean the timestamp was on time. Positive values indicate the
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timestamp was late (and dropped) by that amount. The deadline can be
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a realtime running_time or an estimated running_time.
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- proportion, G_TYPE_DOUBLE:
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Long term prediction of the ideal rate.
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Long term prediction of the ideal rate relative to normal rate to get
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optimal quality.
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Optional stats:
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- quality, G_TYPE_INT:
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An element dependent integer value that specifies the current quality
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level of the element. The default maximum quality is 1000000.
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- dropped, G_TYPE_INT64:
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The total number of dropped buffers since the element went to READY
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last. -1 if unknown.
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- handled, G_TYPE_INT64:
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The total number of processed buffers since the element went to READY
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last. -1 if unknown.
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- format, GST_TYPE_FORMAT
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Units of the 'processed' and 'dropped' fields. Video sinks and video
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filters will use GST_FORMAT_BUFFERS (frames). Audio sinks and audio filters
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will likely use GST_FORMAT_DEFAULT (samples).
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- processed: G_TYPE_UINT64:
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Total number of units correctly precessed since the last state change to
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READY or a flushing operation.
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- dropped: G_TYPE_UINT64:
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Total number of units dropped since the last state change to READY or a
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flushing operation.
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The 'running-time' and 'processed' fields can be used to estimate the average
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processing rate (framerate for video).
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Elements might add additional fields in the message which are documents in the
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relevant elements or baseclasses.
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Collecting statistics
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@ -244,68 +276,6 @@ real time performance.
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- assign more CPU(s) to critical pipeline parts
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QoS Messages
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------------
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A QOS message is posted on the bus whenever an element decides to:
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- drop a buffer because of QoS reasons
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- change its processing strategy because of QoS reasons (quality)
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It should be expected that creating and posting the QoS message is reasonably
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fast and does not significantly contribute to the QoS problems. Options to
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disable this feature could also be presented on elements.
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The GST_MESSAGE_QOS contains at least the following info:
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- running-time, G_TYPE_UINT64:
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The running_time of the buffer that generated the QoS message.
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- stream-time, G_TYPE_UINT64:
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The stream_time of the buffer that generated the QoS message.
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- timestamp, G_TYPE_UINT64:
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The timestamp of the buffer that generated the QoS message.
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- duration, G_TYPE_UINT64:
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The duration of the buffer that generated the QoS message.
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- jitter, G_TYPE_INT64:
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The difference of the running-time against the deadline. Negative
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values mean the timestamp was on time. Positive values indicate the
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timestamp was late (and dropped) by that amount. The deadline can be
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a realtime running_time or an estimated running_time.
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- proportion, G_TYPE_DOUBLE:
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Long term prediction of the ideal rate relative to normal rate to get
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optimal quality.
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- quality, G_TYPE_INT:
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An element dependent integer value that specifies the current quality
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level of the element. The default maximum quality is 1000000.
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- format, GST_TYPE_FORMAT
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Units of the 'processed' and 'dropped' fields. Video sinks and video
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filters will use GST_FORMAT_BUFFERS (frames). Audio sinks and audio filters
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will likely use GST_FORMAT_DEFAULT (samples).
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- processed: G_TYPE_UINT64:
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Total number of units correctly precessed since the last state change to
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READY or a flushing operation.
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- dropped: G_TYPE_UINT64:
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Total number of units dropped since the last state change to READY or a
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flushing operation.
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The 'running-time' and 'processed' fields can be used to estimate the average
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processing rate (framerate for video).
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Elements might add additional fields in the message which are documents in the
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relevant elements or baseclasses.
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QoS implementations
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-------------------
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