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docs: update qos design doc

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Fix some typos.
change the definition of the quality field for video decoders to something that
makes more sense.
This commit is contained in:
Wim Taymans 2010-10-07 19:18:03 +02:00
parent dedb7adce9
commit 8b61681cff
1 changed files with 8 additions and 7 deletions
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15
docs/design/part-qos.txt
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@ -107,7 +107,7 @@ The GST_MESSAGE_QOS contains at least the following info:
will likely use GST_FORMAT_DEFAULT (samples). will likely use GST_FORMAT_DEFAULT (samples).
- processed: G_TYPE_UINT64: - processed: G_TYPE_UINT64:
Total number of units correctly precessed since the last state change to Total number of units correctly processed since the last state change to
READY or a flushing operation. READY or a flushing operation.
- dropped: G_TYPE_UINT64: - dropped: G_TYPE_UINT64:
@ -117,7 +117,7 @@ The GST_MESSAGE_QOS contains at least the following info:
The 'running-time' and 'processed' fields can be used to estimate the average The 'running-time' and 'processed' fields can be used to estimate the average
processing rate (framerate for video). processing rate (framerate for video).
Elements might add additional fields in the message which are documents in the Elements might add additional fields in the message which are documented in the
relevant elements or baseclasses. relevant elements or baseclasses.
@ -350,14 +350,15 @@ proportion member be used to permanently skip frames.
It is suggested to adjust the quality field of the QoS message with the expected It is suggested to adjust the quality field of the QoS message with the expected
amount of dropped frames (skipping B and/or P frames). This depends on the amount of dropped frames (skipping B and/or P frames). This depends on the
particulat spacing of B and P frames in the stream. If the quality control would particular spacing of B and P frames in the stream. If the quality control would
result in half of the frames to be dropped (typical B frame skipping), the result in half of the frames to be dropped (typical B frame skipping), the
quality field would be set to 1000000/2 = 500000. If a typical I frame spacing quality field would be set to 1000000 * 1/2 = 500000. If a typical I frame spacing
of 18 frames is used, skipping B and P frames would result in 17 dropped frames, of 18 frames is used, skipping B and P frames would result in 17 dropped frames
and the quality member should be set to 1000000/17 = 58824. or 1 decoded frame every 18 frames. The quality member should be set to
1000000 * 1/18 = 55555.
- skipping B frames: quality = 500000 - skipping B frames: quality = 500000
- skipping P/B frames: quality = 58824 (for I-frame spacing of 18 frames) - skipping P/B frames: quality = 55555 (for I-frame spacing of 18 frames)
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