|
|
|
GStreamer Base Plugins 0.10 Library Reference Manual | |
|---|---|---|---|---|
#include <gst/app/appsrc.h>
GstAppSrc;
enum GstAppStreamType;
void gst_app_src_set_caps (GstAppSrc *appsrc,
const GstCaps *caps);
GstCaps* gst_app_src_get_caps (GstAppSrc *appsrc);
void gst_app_src_get_latency (GstAppSrc *appsrc,
guint64 *min,
guint64 *max);
void gst_app_src_set_latency (GstAppSrc *appsrc,
guint64 min,
guint64 max);
void gst_app_src_set_size (GstAppSrc *appsrc,
gint64 size);
gint64 gst_app_src_get_size (GstAppSrc *appsrc);
void gst_app_src_set_stream_type (GstAppSrc *appsrc,
GstAppStreamType type);
GstAppStreamType gst_app_src_get_stream_type (GstAppSrc *appsrc);
void gst_app_src_set_max_bytes (GstAppSrc *appsrc,
guint64 max);
guint64 gst_app_src_get_max_bytes (GstAppSrc *appsrc);
gboolean gst_app_src_get_emit_signals (GstAppSrc *appsrc);
void gst_app_src_set_emit_signals (GstAppSrc *appsrc,
gboolean emit);
GstAppSrcCallbacks;
void gst_app_src_set_callbacks (GstAppSrc *appsrc,
GstAppSrcCallbacks *callbacks,
gpointer user_data,
GDestroyNotify notify);
GstFlowReturn gst_app_src_push_buffer (GstAppSrc *appsrc,
GstBuffer *buffer);
GstFlowReturn gst_app_src_end_of_stream (GstAppSrc *appsrc);
The appsrc element can be used by applications to insert data into a GStreamer pipeline. Unlike most GStreamer elements, Appsrc provides external API functions.
appsrc can be used by linking to the gstappsrc.h header file to access the methods or by using the appsrc action signals. For the API documentation, see the documentation for libgstapp in the GStreamer Base Plugins Library reference...
Before operating appsrc, the caps property must be set to a fixed caps describing the format of the data that will be pushed with appsrc.
The main way of handing data to the appsrc element is by calling the
gst_app_src_push_buffer() method or by emiting the push-buffer action signal.
This will put the buffer onto a queue from which appsrc will read from in its
streaming thread. It is important to note that data transport will not happen
from the thread that performed the push-buffer call.
The "max-bytes" property controls how much data can be queued in appsrc before appsrc considers the queue full. A filled internal queue will always signal the "enough-data" signal, which signals the application that it should stop pushing data into appsrc. The "block" property will cause appsrc to block the push-buffer method until free data becomes available again.
When the internal queue is running out of data, the "need-data" signal is emited, which signals the application that it should start pushing more data into appsrc.
In addition to the "need-data" and "enough-data" signals, appsrc can emit the "seek-data" signal when the "stream-mode" property is set to "seekable" or "random-access". The signal argument will contain the new desired position in the stream expressed in the unit set with the "format" property. After receiving the seek-data signal, the application should push-buffers from the new position.
These signals allow the application to operate the appsrc in two different ways:
The push model, in which the application repeadedly calls the push-buffer method with a new buffer. Optionally, the queue size in the appsrc can be controlled with the enough-data and need-data signals by respectively stopping/starting the push-buffer calls. This is a typical mode of operation for the stream-type "stream" and "seekable". Use this model when implementing various network protocols or hardware devices.
The pull model where the need-data signal triggers the next push-buffer call. This mode is typically used in the "random-access" stream-type. Use this model for file access or other randomly accessable sources. In this mode, a buffer of exactly the amount of bytes given by the need-data signal should be pushed into appsrc.
In all modes, the size property on appsrc should contain the total stream size in bytes. Setting this property is mandatory in the random-access mode. For the stream and seekable modes, setting this property is optional but recommended.
When the application is finished pushing data into appsrc, it should call
gst_app_src_end_of_stream() or emit the end-of-stream action signal. After
this call, no more buffers can be pushed into appsrc until a flushing seek
happened or the state of the appsrc has gone through READY.
Last reviewed on 2008-12-17 (0.10.10)
typedef enum
{
GST_APP_STREAM_TYPE_STREAM,
GST_APP_STREAM_TYPE_SEEKABLE,
GST_APP_STREAM_TYPE_RANDOM_ACCESS
} GstAppStreamType;
The stream type.
| No seeking is supported in the stream, such as a live stream. | |
| The stream is seekable but seeking might not be very fast, such as data from a webserver. | |
| The stream is seekable and seeking is fast, such as in a local file. |
void gst_app_src_set_caps (GstAppSrc *appsrc, const GstCaps *caps);
Set the capabilities on the appsrc element. This function takes
a copy of the caps structure. After calling this method, the source will
only produce caps that match caps. caps must be fixed and the caps on the
buffers must match the caps or left NULL.
|
a GstAppSrc |
|
caps to set |
Since 0.10.22
GstCaps* gst_app_src_get_caps (GstAppSrc *appsrc);
Get the configured caps on appsrc.
|
a GstAppSrc |
Returns : |
the GstCaps produced by the source. gst_caps_unref() after usage.
|
Since 0.10.22
void gst_app_src_get_latency (GstAppSrc *appsrc, guint64 *min, guint64 *max);
Retrieve the min and max latencies in min and max respectively.
|
a GstAppSrc |
|
the min latency |
|
the min latency |
Since 0.10.22
void gst_app_src_set_latency (GstAppSrc *appsrc, guint64 min, guint64 max);
Configure the min and max latency in src. If min is set to -1, the
default latency calculations for pseudo-live sources will be used.
|
a GstAppSrc |
|
the min latency |
|
the min latency |
Since 0.10.22
void gst_app_src_set_size (GstAppSrc *appsrc, gint64 size);
Set the size of the stream in bytes. A value of -1 means that the size is not known.
|
a GstAppSrc |
|
the size to set |
Since 0.10.22
gint64 gst_app_src_get_size (GstAppSrc *appsrc);
Get the size of the stream in bytes. A value of -1 means that the size is not known.
|
a GstAppSrc |
Returns : |
the size of the stream previously set with gst_app_src_set_size();
|
Since 0.10.22
void gst_app_src_set_stream_type (GstAppSrc *appsrc, GstAppStreamType type);
Set the stream type on appsrc. For seekable streams, the "seek" signal must
be connected to.
A stream_type stream
|
a GstAppSrc |
|
the new state |
Since 0.10.22
GstAppStreamType gst_app_src_get_stream_type (GstAppSrc *appsrc);
Get the stream type. Control the stream type of appsrc
with gst_app_src_set_stream_type().
|
a GstAppSrc |
Returns : |
the stream type. |
Since 0.10.22
void gst_app_src_set_max_bytes (GstAppSrc *appsrc, guint64 max);
Set the maximum amount of bytes that can be queued in appsrc.
After the maximum amount of bytes are queued, appsrc will emit the
"enough-data" signal.
|
a GstAppSrc |
|
the maximum number of bytes to queue |
Since 0.10.22
guint64 gst_app_src_get_max_bytes (GstAppSrc *appsrc);
Get the maximum amount of bytes that can be queued in appsrc.
|
a GstAppSrc |
Returns : |
The maximum amount of bytes that can be queued. |
Since 0.10.22
gboolean gst_app_src_get_emit_signals (GstAppSrc *appsrc);
Check if appsrc will emit the "new-preroll" and "new-buffer" signals.
|
a GstAppSrc |
Returns : |
TRUE if appsrc is emiting the "new-preroll" and "new-buffer"
signals.
|
Since 0.10.23
void gst_app_src_set_emit_signals (GstAppSrc *appsrc, gboolean emit);
Make appsrc emit the "new-preroll" and "new-buffer" signals. This option is by default disabled because signal emission is expensive and unneeded when the application prefers to operate in pull mode.
|
a GstAppSrc |
|
the new state |
Since 0.10.23
typedef struct {
void (*need_data) (GstAppSrc *src, guint length, gpointer user_data);
void (*enough_data) (GstAppSrc *src, gpointer user_data);
gboolean (*seek_data) (GstAppSrc *src, guint64 offset, gpointer user_data);
} GstAppSrcCallbacks;
A set of callbacks that can be installed on the appsrc with
gst_app_src_set_callbacks().
|
Called when the appsrc needs more data. A buffer or EOS should be
pushed to appsrc from this thread or another thread. length is just a hint
and when it is set to -1, any number of bytes can be pushed into appsrc.
|
|
Called when appsrc has enough data. It is recommended that the application stops calling push-buffer until the need_data callback is emited again to avoid excessive buffer queueing. |
|
Called when a seek should be performed to the offset.
The next push-buffer should produce buffers from the new offset.
This callback is only called for seekable stream types.
|
Since 0.10.23
void gst_app_src_set_callbacks (GstAppSrc *appsrc, GstAppSrcCallbacks *callbacks, gpointer user_data, GDestroyNotify notify);
Set callbacks which will be executed when data is needed, enough data has been collected or when a seek should be performed. This is an alternative to using the signals, it has lower overhead and is thus less expensive, but also less flexible.
If callbacks are installed, no signals will be emited for performance reasons.
|
a GstAppSrc |
|
the callbacks |
|
a user_data argument for the callbacks |
|
a destroy notify function |
Since 0.10.23
GstFlowReturn gst_app_src_push_buffer (GstAppSrc *appsrc, GstBuffer *buffer);
Adds a buffer to the queue of buffers that the appsrc element will push to its source pad. This function takes ownership of the buffer.
When the block property is TRUE, this function can block until free space becomes available in the queue.
|
a GstAppSrc |
|
a GstBuffer to push |
Returns : |
GST_FLOW_OK when the buffer was successfuly queued.
GST_FLOW_WRONG_STATE when appsrc is not PAUSED or PLAYING.
GST_FLOW_UNEXPECTED when EOS occured.
|
Since 0.10.22
GstFlowReturn gst_app_src_end_of_stream (GstAppSrc *appsrc);
Indicates to the appsrc element that the last buffer queued in the element is the last buffer of the stream.
|
a GstAppSrc |
Returns : |
GST_FLOW_OK when the EOS was successfuly queued.
GST_FLOW_WRONG_STATE when appsrc is not PAUSED or PLAYING.
|
Since 0.10.22