Add hardware accelerated VP8 encoder

Using libva.

pkg/codec/vaapi/vaapi.go

@@ -0,0 +1,58 @@
+// Package vaapi implements hardware accelerated codecs.
+// This package requires libva headers and libraries to be built.
+// libva requires supported graphic card and its driver.
+package vaapi
+
+import (
+	"fmt"
+	"unsafe"
+)
+
+// #include <stdlib.h>
+// #include <fcntl.h>
+// #include <unistd.h>
+// #include <va/va.h>
+// #include <va/va_drm.h>
+// #include "helper.h"
+import "C"
+
+const (
+	bufferCoded = iota
+	bufferSeqParam
+	bufferPicParam
+	bufferHRDParam
+	bufferQMatrix
+	bufferFRParam
+	bufferRCParam
+	bufferNum
+)
+
+type hrdParam struct {
+	hdr  C.VAEncMiscParameterBuffer
+	data C.VAEncMiscParameterHRD
+}
+type frParam struct {
+	hdr  C.VAEncMiscParameterBuffer
+	data C.VAEncMiscParameterFrameRate
+}
+type rcParam struct {
+	hdr  C.VAEncMiscParameterBuffer
+	data C.VAEncMiscParameterRateControl
+}
+
+func openDisplay(devPath string) (C.VADisplay, C.int, error) {
+	// Try using dri
+	path := C.CString(devPath)
+	defer C.free(unsafe.Pointer(path))
+	fdDRI := C.open2(path, C.O_RDWR)
+	if fdDRI < 0 {
+		C.close(fdDRI)
+		return nil, 0, fmt.Errorf("failed to open %s", devPath)
+	}
+	return C.vaGetDisplayDRM(fdDRI), fdDRI, nil
+}
+
+func closeDisplay(d C.VADisplay, fd C.int) {
+	C.vaTerminate(d)
+	C.close(fd)
+}