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design: probes: fix subsection breakdown
Additionally, add missing markup while at it.
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@ -3,7 +3,7 @@
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Probes are callbacks that can be installed by the application and will notify
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the application about the states of the dataflow.
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# Requirements
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## Requirements
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Applications should be able to monitor and control the dataflow on pads.
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We identify the following types:
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@ -22,9 +22,9 @@ We identify the following types:
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performed by the application
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thread.
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# Overview
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## Overview
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The function gst_pad_add_probe() is used to add a probe to a pad. It accepts a
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The function `gst_pad_add_probe()` is used to add a probe to a pad. It accepts a
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probe type mask and a callback.
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``` c
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@ -36,7 +36,7 @@ probe type mask and a callback.
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```
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The function returns a gulong that uniquely identifies the probe and that can
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be used to remove the probe with gst_pad_remove_probe():
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be used to remove the probe with `gst_pad_remove_probe()`:
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``` c
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void gst_pad_remove_probe (GstPad *pad, gulong id);
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@ -101,13 +101,13 @@ typedef enum
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```
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`GST_PAD_PROBE_OK` is the normal return value. DROP will drop the item that is
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currently being probed. GST_PAD_PROBE_REMOVE the currently executing probe from the
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currently being probed. `GST_PAD_PROBE_REMOVE` the currently executing probe from the
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list of probes.
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`GST_PAD_PROBE_PASS` is relevant for blocking probes and will temporarily unblock the
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pad and let the item trough, it will then block again on the next item.
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# Blocking probes
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## Blocking probes
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Blocking probes are probes with BLOCK or IDLE flags set. They will always
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block the dataflow and trigger the callback according to the following rules:
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@ -127,19 +127,19 @@ When the BLOCK flag is set, the probe callback will be called when new data
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arrives on the pad and right before the pad goes into the blocking state. This
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callback is thus only called when there is new data on the pad.
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The blocking probe is removed with gst_pad_remove_probe() or when the probe
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callback return GST_PAD_PROBE_REMOVE. In both cases, and if this was the last
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The blocking probe is removed with `gst_pad_remove_probe()` or when the probe
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callback return `GST_PAD_PROBE_REMOVE`. In both cases, and if this was the last
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blocking probe on the pad, the pad is unblocked and dataflow can continue.
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# Non-Blocking probes
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## Non-Blocking probes
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Non-blocking probes or DATA probes are probes triggered when data is flowing
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over the pad. The are called after the blocking probes are run and always with
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data.
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# Push dataflow
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## Push dataflow
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Push probes have the GST\_PAD\_PROBE\_TYPE\_PUSH flag set in the
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Push probes have the `GST_PAD_PROBE_TYPE_PUSH` flag set in the
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callbacks.
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In push based scheduling, the blocking probe is called first with the
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@ -194,7 +194,7 @@ gst_pad_push_event() | |
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```
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# Pull dataflow
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## Pull dataflow
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Pull probes have the `GST_PAD_PROBE_TYPE_PULL` flag set in the
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callbacks.
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@ -250,9 +250,9 @@ do BLOCK probes <-O O
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```
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# Queries
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## Queries
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Query probes have the GST_PAD_PROBE_TYPE_QUERY_* flag set in the
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Query probes have the `GST_PAD_PROBE_TYPE_QUERY_*` flag set in the
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callbacks.
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```
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@ -290,9 +290,9 @@ For queries, the PUSH ProbeType is set when the query is traveling to
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the object that will answer the query and the PULL type is set when the
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query contains the answer.
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# Use-cases
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## Use-cases
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## Prerolling a partial pipeline
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### Prerolling a partial pipeline
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```
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.---------. .---------. .----------.
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@ -325,7 +325,7 @@ prerolled pipeline:
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- connect other elements and unblock the blocked pads.
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## dynamically switching an element in a PLAYING pipeline
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### dynamically switching an element in a PLAYING pipeline
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```
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.----------. .----------. .----------.
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