initial commit

gst/c_util.go

@@ -0,0 +1,97 @@
+package gst
+
+/*
+#cgo pkg-config: gstreamer-1.0
+#cgo CFLAGS: -Wno-deprecated-declarations -g -Wall
+#include <gst/gst.h>
+*/
+import "C"
+import (
+	"errors"
+	"unsafe"
+)
+
+// Init runs `gst_init`. It currently does not support arguments. This should
+// be called before building any pipelines.
+func Init() {
+	C.gst_init(nil, nil)
+}
+
+// gobool provides an easy type conversion between C.gboolean and a go bool.
+func gobool(b C.gboolean) bool {
+	return b != 0
+}
+
+// gboolean converts a go bool to a C.gboolean.
+func gboolean(b bool) C.gboolean {
+	if b {
+		return C.gboolean(1)
+	}
+	return C.gboolean(0)
+}
+
+// structureToGoMap converts a GstStructure into a Go map of strings.
+func structureToGoMap(st *C.GstStructure) map[string]string {
+	goDetails := make(map[string]string)
+	numFields := int(C.gst_structure_n_fields((*C.GstStructure)(st)))
+	for i := 0; i < numFields-1; i++ {
+		fieldName := C.gst_structure_nth_field_name((*C.GstStructure)(st), (C.guint)(i))
+		fieldValue := C.gst_structure_get_value((*C.GstStructure)(st), (*C.gchar)(fieldName))
+		strValueDup := C.g_strdup_value_contents((*C.GValue)(fieldValue))
+		goDetails[C.GoString(fieldName)] = C.GoString(strValueDup)
+	}
+	return goDetails
+}
+
+// MessageType is an alias to the C equivalent of GstMessageType.
+type MessageType C.GstMessageType
+
+// Type casting of GstMessageTypes
+const (
+	MessageAny          MessageType = C.GST_MESSAGE_ANY
+	MessageStreamStart              = C.GST_MESSAGE_STREAM_START
+	MessageEOS                      = C.GST_MESSAGE_EOS
+	MessageInfo                     = C.GST_MESSAGE_INFO
+	MessageWarning                  = C.GST_MESSAGE_WARNING
+	MessageError                    = C.GST_MESSAGE_ERROR
+	MessageStateChanged             = C.GST_MESSAGE_STATE_CHANGED
+	MessageElement                  = C.GST_MESSAGE_ELEMENT
+	MessageStreamStatus             = C.GST_MESSAGE_STREAM_STATUS
+	MessageBuffering                = C.GST_MESSAGE_BUFFERING
+	MessageLatency                  = C.GST_MESSAGE_LATENCY
+	MessageNewClock                 = C.GST_MESSAGE_NEW_CLOCK
+	MessageAsyncDone                = C.GST_MESSAGE_ASYNC_DONE
+	MessageTag                      = C.GST_MESSAGE_TAG
+)
+
+func iteratorToElementSlice(iterator *C.GstIterator) ([]*Element, error) {
+	elems := make([]*Element, 0)
+	gval := new(C.GValue)
+
+	for {
+		switch C.gst_iterator_next((*C.GstIterator)(iterator), (*C.GValue)(unsafe.Pointer(gval))) {
+		case C.GST_ITERATOR_DONE:
+			C.gst_iterator_free((*C.GstIterator)(iterator))
+			return elems, nil
+		case C.GST_ITERATOR_RESYNC:
+			C.gst_iterator_resync((*C.GstIterator)(iterator))
+		case C.GST_ITERATOR_OK:
+			cElemVoid := C.g_value_get_object((*C.GValue)(gval))
+			cElem := (*C.GstElement)(cElemVoid)
+			elems = append(elems, wrapElement(cElem))
+			C.g_value_reset((*C.GValue)(gval))
+		default:
+			return nil, errors.New("Element iterator failed")
+		}
+	}
+}
+
+func goStrings(argc C.int, argv **C.gchar) []string {
+	length := int(argc)
+	tmpslice := (*[1 << 30]*C.gchar)(unsafe.Pointer(argv))[:length:length]
+	gostrings := make([]string, length)
+	for i, s := range tmpslice {
+		gostrings[i] = C.GoString(s)
+	}
+	return gostrings
+}