GstRtspSink - Independent Stream Control
This wiki describes how to have advanced control over each independent stream by accessing the internal appsink. By doing so, synchronization, buffering, and other fine-grained control can be achieved.
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Internal GstAppSink
GstRtspSink allows the user to control each stream independently by setting properties on them. Internally, each stream is consumed by an appsink named rtspsinkpadX. The user can access the appsink properties using the child proxy notation, as in the following example:
gst-launch-1.0 videotestsrc ! x264enc ! video/x-h264, mapping=/stream1 ! rtspsink service=5000 rtspsinkpad0::sync=false
In the example above, the pipeline consists of a single video stream and, as such, a single AppSink is created. You can modify the properties of this appsink to control the behavior of the pipeline. For example, setting the sync property to FALSE (the default) will result in a CPU usage is 320% since no-one is limiting the rate of the videotestsrc. On the other hand, setting the sync to TRUE will decrease the CPU usage to 9,3%
If multiple streams are created, they can be accessed independently. In the following example two streams are created (video and audio). The video stream was configured to sync against the clock (sync=true) while the audio was configured to have a max buffering of 1000 (max-buffers=1000). The number in the appsink is dictated by the stream creation order.
gst-launch-1.0 rtspsink service=5000 name=sink rtspsinkpad0::sync=true rtspsinkpad1::max-buffers=1000 \ videotestsrc ! vp8enc ! capsfilter caps="video/x-vp8, mapping=/stream0" ! sink. \ audiotestsrc ! avenc_ac3 ! capsfilter caps="audio/x-ac3, mapping=/stream1" ! sink.
GstAppSink Properties
The following table summarizes the appsink properties that may be configured for each stream:
| Property | Description | Default |
|---|---|---|
| sync | Sync on the clock | true |
| max-lateness | Maximum number of nanoseconds that a buffer can be late before it is dropped | -1 |
| qos | Generate Quality-of-Service events upstream | false |
| async | Go asynchronously to PAUSED | true |
| ts-offset | Timestamp offset in nanoseconds | 0 |
| enable-last-sample | Enable the last-sample property | true |
| blocksize | Size in bytes to pull per buffer | 4096 |
| render-delay | Additional render delay of the sink in nanoseconds | 0 |
| throttle-time | The time to keep between rendered buffers | 0 |
| max-bitrate | The maximum bits per second to render | 0 |
| emit-signals | Emit new-preroll and new-sample signals | false |
| max-buffers | The maximum number of buffers to queue internally | 0 |
| drop | Drop old buffers when the buffer queue is filled | false |
| wait-on-eos | Wait for all buffers to be processed after receiving an EOS | true |
A more detailed list can always be retrieved by inspecting the appsink element.
gst-inspect-1.0 appsink