GstRTMPMetadata User Guide
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 | The GstRTMPMetadata documentation from RidgeRun is presently being developed. |
Adding FLV metadata support to your application involves two main tasks:
on the sending side, injecting metadata into the FLV stream using the muxer, and
on the receiving side, extracting metadata from the demuxer.
In this section, we will review how to achieve this using RidgeRun’s patched FLV muxer and demuxer elements.
To inject metadata it is possible to use the flvmux element patched by RidgeRun, which after applying the patches, is able to serialize and embed structured metadata (with keys starting with meta-*) into the FLV stream.
To extract metadata it is possible to use the flvdemux element patched by RidgeRun, which decodes the onMetaData message and makes the metadata available as GstMeta attached to the output buffers when the property attach-flvmeta is enabled.
FlvMux element
The expected output of running
gst-inspect-1.0 flvmux
is the following:
Factory Details:
Rank primary (256)
Long-name FLV muxer
Klass Codec/Muxer
Description Muxes video/audio streams into a FLV stream
Author Sebastian Dröge <sebastian.droege@collabora.co.uk>
Plugin Details:
Name flv
Description FLV muxing and demuxing plugin
Filename /home/jsantamaria/work/rnd/1.20/001/gstreamer/builddir/subprojects/gst-plugins-good/gst/flv/libgstflv.so
Version 1.20.7.1
License LGPL
Source module gst-plugins-good
Binary package GStreamer Good Plug-ins git
Origin URL Unknown package origin
GObject
+----GInitiallyUnowned
+----GstObject
+----GstElement
+----GstAggregator
+----GstFlvMux
Implemented Interfaces:
GstTagSetter
Pad Templates:
SINK template: 'audio'
Availability: On request
Capabilities:
audio/x-adpcm
layout: swf
channels: { (int)1, (int)2 }
rate: { (int)5512, (int)11025, (int)22050, (int)44100 }
audio/mpeg
mpegversion: 1
layer: 3
channels: { (int)1, (int)2 }
rate: { (int)5512, (int)8000, (int)11025, (int)22050, (int)44100 }
parsed: true
audio/mpeg
mpegversion: { (int)4, (int)2 }
stream-format: raw
audio/x-nellymoser
channels: { (int)1, (int)2 }
rate: { (int)5512, (int)8000, (int)11025, (int)16000, (int)22050, (in
t)44100 }
audio/x-raw
format: { (string)U8, (string)S16LE }
layout: interleaved
channels: { (int)1, (int)2 }
rate: { (int)5512, (int)11025, (int)22050, (int)44100 }
audio/x-alaw
channels: { (int)1, (int)2 }
rate: 8000
audio/x-mulaw
channels: { (int)1, (int)2 }
rate: 8000
audio/x-speex
channels: 1
rate: 16000
Type: GstFlvMuxPad
Pad Properties:
emit-signals : Send signals to signal data consumption
flags: readable, writable
Boolean. Default: false
SRC template: 'src'
Availability: Always
Capabilities:
video/x-flv
Type: GstAggregatorPad
Pad Properties:
emit-signals : Send signals to signal data consumption
flags: readable, writable
Boolean. Default: false
SINK template: 'video'
Availability: On request
Capabilities:
video/x-flash-video
video/x-flash-screen
video/x-vp6-flash
video/x-vp6-alpha
video/x-h264
stream-format: avc
Type: GstFlvMuxPad
Pad Properties:
emit-signals : Send signals to signal data consumption
flags: readable, writable
Boolean. Default: false
Element has no clocking capabilities.
Element has no URI handling capabilities.
Pads:
SRC: 'src'
Pad Template: 'src'
Element Properties:
emit-signals : Send signals
flags: readable, writable
Boolean. Default: false
encoder : The value of encoder in the meta packet.
flags: readable, writable
String. Default: "GStreamer 1.20.7.1 FLV muxer"
latency : Additional latency in live mode to allow upstream to take longer
to produce buffers for the current position (in nanoseconds)
flags: readable, writable
Unsigned Integer64. Range: 0 - 18446744073709551615 Default: 0
meta-binary : Binary metadata (GBytes)
flags: readable, writable
Boxed pointer of type "GBytes"
meta-string : Custom string to include as metadata
flags: readable, writable
String. Default: null
metadatacreator : The value of metadatacreator in the meta packet.
flags: readable, writable
String. Default: "GStreamer 1.20.7.1 FLV muxer"
min-upstream-latency: When sources with a higher latency are expected to be plugged in
dynamically after the aggregator has started playing, this allows overriding the minimu
m latency reported by the initial source(s). This is only taken into account when larger
than the actually reported minimum latency. (nanoseconds)
flags: readable, writable
Unsigned Integer64. Range: 0 - 18446744073709551615 Default: 0
name : The name of the object
flags: readable, writable, 0x2000
String. Default: "flvmux0"
parent : The parent of the object
flags: readable, writable, 0x2000
Object of type "GstObject"
skip-backwards-streams: If set to true, streams that go backwards related to the other
stream will have buffers dropped until they reach the correct timestamp
flags: readable, writable
Boolean. Default: false
start-time : Start time to use if start-time-selection=set
flags: readable, writable
Unsigned Integer64. Range: 0 - 18446744073709551615 Default: 184
46744073709551615
start-time-selection: Decides which start time is output
flags: readable, writable
Enum "GstAggregatorStartTimeSelection" Default: 0, "zero"
(0): zero - GST_AGGREGATOR_START_TIME_SELECTION_Z
ERO
(1): first - GST_AGGREGATOR_START_TIME_SELECTION_F
IRST
(2): set - GST_AGGREGATOR_START_TIME_SELECTION_S
ET
streamable : If set to true, the output should be as if it is to be streamed
and hence no indexes written or duration written.
flags: readable, writable
Boolean. Default: false
Element Signals:
"samples-selected" : void user_function (GstElement* object,
GstSegment* arg0,
guint64 arg1,
guint64 arg2,
guint64 arg3,
GstStructure* arg4,
gpointer user_data);
Important Notes
- The flvmux element supports embedding metadata fields with meta-* keys into the output FLV file or stream.
- This metadata is later recognized by the demuxer for automatic extraction.
FlvDemux element
The expected output of running
gst-inspect-1.0 flvdemux
is the following:
Factory Details:
Rank primary (256)
Long-name FLV Demuxer
Klass Codec/Demuxer
Description Demux FLV feeds into digital streams
Author Julien Moutte <julien@moutte.net>
Plugin Details:
Name flv
Description FLV muxing and demuxing plugin
Filename /home/jsantamaria/work/rnd/1.20/001/gstreamer/builddir/subprojects/gst-plugins-good/gst/flv/libgstflv.so
Version 1.20.7.1
License LGPL
Source module gst-plugins-good
Binary package GStreamer Good Plug-ins git
Origin URL Unknown package origin
GObject
+----GInitiallyUnowned
+----GstObject
+----GstElement
+----GstFlvDemux
Pad Templates:
SRC template: 'audio'
Availability: Sometimes
Capabilities:
audio/x-adpcm
layout: swf
channels: { (int)1, (int)2 }
rate: { (int)5512, (int)11025, (int)22050, (int)44100 }
audio/mpeg
mpegversion: 1
layer: 3
channels: { (int)1, (int)2 }
rate: { (int)5512, (int)8000, (int)11025, (int)22050, (int)44100 }
parsed: true
audio/mpeg
mpegversion: 4
stream-format: raw
framed: true
audio/x-nellymoser
channels: { (int)1, (int)2 }
rate: { (int)5512, (int)8000, (int)11025, (int)16000, (int)22050, (in
t)44100 }
audio/x-raw
format: { (string)U8, (string)S16LE }
layout: interleaved
channels: { (int)1, (int)2 }
rate: { (int)5512, (int)11025, (int)22050, (int)44100 }
audio/x-alaw
channels: { (int)1, (int)2 }
rate: 8000
audio/x-mulaw
channels: { (int)1, (int)2 }
rate: 8000
audio/x-speex
channels: 1
rate: 16000
SINK template: 'sink'
Availability: Always
Capabilities:
video/x-flv
SRC template: 'video'
Availability: Sometimes
Capabilities:
video/x-flash-video
flvversion: 1
video/x-flash-screen
video/x-vp6-flash
video/x-vp6-alpha
video/x-h264
stream-format: avc
Element has no clocking capabilities.
Element has no URI handling capabilities.
Pads:
SINK: 'sink'
Pad Template: 'sink'
Element Properties:
attach-flvmeta : Attach custom onMetaData (meta-*) as GstFlvMeta to first audio a
nd video buffers
flags: readable, writable
Boolean. Default: false
flv-meta-signal : Emit a signal carrying custom onMetaData (meta-*) payload as GBy
tes
flags: readable, writable
Boolean. Default: false
name : The name of the object
flags: readable, writable, 0x2000
String. Default: "flvdemux0"
parent : The parent of the object
flags: readable, writable, 0x2000
Object of type "GstObject"
Element Signals:
"pad-added" : void user_function (GstElement* object,
GstPad* arg0,
gpointer user_data);
"pad-removed" : void user_function (GstElement* object,
GstPad* arg0,
gpointer user_data);
"no-more-pads" : void user_function (GstElement* object,
gpointer user_data);
"flv-meta" : void user_function (GstElement* object,
GBytes* arg0,
gpointer user_data);
Important Properties
Injecting metadata
- meta-string:
- Use this property on flvmux to insert metadata as a UTF-8 string into the outgoing stream.
- meta-binary:
- Use this property onflvmuxto insert metadata as binary data (GBytes).
- GstFlvMeta (injection):
- You can attach aGstFlvMetato an upstream buffer, andflvmuxwill serialize and embed that metadata into the FLV stream.
Extracting metadata
- attach-flvmeta:
- If set to TRUE,flvdemuxattaches the extracted metadata from theonMetaDatamessage asGstFlvMetaon outgoing buffers. - This makes the metadata available downstream in the pipeline.
- flv-meta signal:
- Ifflv-meta-signalis enabled,flvdemuxemits theflv-metasignal with the metadata payload asGBytes. - This allows applications to listen for metadata events without inspecting buffers directly.
Summary
- Muxing side (flvmux): add meta-* fields to inject metadata into FLV streams.
- Demuxing side (flvdemux): enable the property attach-flvmeta to have the metadata automatically attached to buffers as GstMeta.