TT#14008 move avpkt alloc to encoder_new

If encoder_config errors out for some reason, avpkt may end up
uninitialised. Make sure there is an avpkt when flushing/closing the
encoder. Also make the encoder input more resilient against
half-initialised encoders for the same reason.

closes #1312

Change-Id: I44ebcf6e35f1c383aa5c8202b5d9bbf968b0d5f1
(cherry picked from commit 6e160da497)

lib/codeclib.c

@@ -1231,6 +1231,7 @@ encoder_t *encoder_new(void) {
 	encoder_t *ret = g_slice_alloc0(sizeof(*ret));
 	format_init(&ret->requested_format);
 	format_init(&ret->actual_format);
+	ret->avpkt = av_packet_alloc();
 	return ret;
 }
 
@@ -1312,8 +1313,6 @@ int encoder_config_fmtp(encoder_t *enc, const codec_def_t *def, int bitrate, int
 	if (err)
 		goto err;
 
-	enc->avpkt = av_packet_alloc();
-
 // output frame and fifo
 	enc->frame = av_frame_alloc();
 
@@ -1455,6 +1454,8 @@ int encoder_input_data(encoder_t *enc, AVFrame *frame,
 	enc->avpkt->size = 0;
 
 	while (1) {
+		if (!enc->def || !enc->def->codec_type)
+			break;
 		if (!enc->def->codec_type->encoder_input)
 			break;