pipeio: add fallback for generating audio info from caps

added for gstreamer 1.20+ compatibility

gstlal/python/pipeio.py

@@ -109,8 +109,12 @@ def get_unit_size(caps):
 	struct = caps[0]
 	name = struct.get_name()
 	if name == "audio/x-raw":
-		info = GstAudio.AudioInfo()
-		info.from_caps(caps)
+		try:
+			info = GstAudio.AudioInfo()
+			info.from_caps(caps)
+		except NotImplementedError: # removed since gstreamer 1.22
+			success, info = GstAudio.audio_info_from_caps(caps)
+			assert success
 		return info.bpf
 	elif name == "video/x-raw" and struct["format"] in ("RGB", "RGBA", "ARGB", "ABGR"):
 		return struct["width"] * struct["height"] * (3 if struct["format"] == "RGB" else 4)
@@ -134,8 +138,12 @@ def numpy_dtype_from_caps(caps):
 		"Z128LE": numpy.dtype("complex128")
 	}
 
-	info = GstAudio.AudioInfo()
-	info.from_caps(caps)
+	try:
+		info = GstAudio.AudioInfo()
+		info.from_caps(caps)
+	except NotImplementedError: # removed since gstreamer 1.22
+		success, info = GstAudio.audio_info_from_caps(caps)
+		assert success
 
 	if info.finfo.format in formats_dict:
 		return formats_dict[info.finfo.format]