schrodec: optimize parse logic

Header will be read each and everytime parse function will be called
which is not necessary since until we have complete data,
we need not parse the header again.

https://bugzilla.gnome.org/show_bug.cgi?id=737984

1 files changed, 53 insertions, 41 deletions

diff --git a/ext/schroedinger/gstschrodec.c b/ext/schroedinger/gstschrodec.c
index 0a273faea..15065af1e 100644
--- a/ext/schroedinger/gstschrodec.c
+++ b/ext/schroedinger/gstschrodec.c
@@ -58,6 +58,10 @@ struct _GstSchroDec
   SchroDecoder *decoder;
 
   gboolean seq_header_buffer_seen;
+  gint next;
+  gint prev;
+  gint parse_code;
+  gboolean header_read;
 };
 
 struct _GstSchroDecClass
@@ -151,6 +155,7 @@ gst_schro_dec_init (GstSchroDec * schro_dec)
 
   schro_dec->decoder = schro_decoder_new ();
   gst_video_decoder_set_packetized (GST_VIDEO_DECODER (schro_dec), FALSE);
+  schro_dec->header_read = FALSE;
 }
 
 static gboolean
@@ -163,7 +168,11 @@ gst_schro_dec_start (GstVideoDecoder * dec)
 static gboolean
 gst_schro_dec_stop (GstVideoDecoder * dec)
 {
+  GstSchroDec *schro_dec;
+
+  schro_dec = GST_SCHRO_DEC (dec);
 
+  schro_dec->header_read = FALSE;
   return TRUE;
 }
 
@@ -178,7 +187,7 @@ gst_schro_dec_flush (GstVideoDecoder * dec)
 
   if (schro_dec->decoder)
     schro_decoder_reset (schro_dec->decoder);
-
+  schro_dec->header_read = FALSE;
   return TRUE;
 }
 
@@ -278,9 +287,6 @@ gst_schro_dec_parse (GstVideoDecoder * base_video_decoder,
 {
   GstSchroDec *schro_decoder;
   unsigned char header[SCHRO_PARSE_HEADER_SIZE];
-  int next;
-  int prev;
-  int parse_code;
   int av, loc;
 
   GST_DEBUG_OBJECT (base_video_decoder, "parse");
@@ -295,58 +301,65 @@ gst_schro_dec_parse (GstVideoDecoder * base_video_decoder,
   GST_DEBUG ("available %d", av);
 
   /* Check for header */
-  loc =
-      gst_adapter_masked_scan_uint32 (adapter, 0xffffffff, 0x42424344, 0,
-      av - 3);
-  if (G_UNLIKELY (loc == -1)) {
-    GST_DEBUG_OBJECT (schro_decoder, "No header");
-    gst_adapter_flush (adapter, av - 3);
-    return GST_VIDEO_DECODER_FLOW_NEED_DATA;
-  }
+  if (schro_decoder->header_read == FALSE) {
+    /* Check for header */
+    loc =
+        gst_adapter_masked_scan_uint32 (adapter, 0xffffffff, 0x42424344, 0,
+        av - (SCHRO_PARSE_HEADER_SIZE - 1));
+    if (G_UNLIKELY (loc == -1)) {
+      GST_DEBUG_OBJECT (schro_decoder, "No header");
+      gst_adapter_flush (adapter, av - (SCHRO_PARSE_HEADER_SIZE - 1));
+      return GST_VIDEO_DECODER_FLOW_NEED_DATA;
+    }
 
-  /* Skip data until header */
-  if (loc > 0)
-    gst_adapter_flush (adapter, loc);
+    /* Skip data until header */
+    if (loc > 0)
+      gst_adapter_flush (adapter, loc);
 
-  gst_adapter_copy (adapter, header, 0, SCHRO_PARSE_HEADER_SIZE);
+    gst_adapter_copy (adapter, header, 0, SCHRO_PARSE_HEADER_SIZE);
 
-  parse_code = header[4];
-  next = GST_READ_UINT32_BE (header + 5);
-  prev = GST_READ_UINT32_BE (header + 9);
+    schro_decoder->parse_code = header[4];
+    schro_decoder->next = GST_READ_UINT32_BE (header + 5);
+    schro_decoder->prev = GST_READ_UINT32_BE (header + 9);
 
-  GST_DEBUG ("%08x %02x %08x %08x",
-      GST_READ_UINT32_BE (header), parse_code, next, prev);
+    GST_DEBUG ("%08x %02x %08x %08x",
+        GST_READ_UINT32_BE (header), schro_decoder->parse_code,
+        schro_decoder->next, schro_decoder->prev);
 
-  if (memcmp (header, "BBCD", 4) != 0 ||
-      (next & 0xf0000000) || (prev & 0xf0000000)) {
-    gst_adapter_flush (adapter, 1);
-    return GST_VIDEO_DECODER_FLOW_NEED_DATA;
+    if (memcmp (header, "BBCD", 4) != 0 || (schro_decoder->next & 0xf0000000)
+        || (schro_decoder->prev & 0xf0000000)) {
+      gst_adapter_flush (adapter, 1);
+      return GST_VIDEO_DECODER_FLOW_NEED_DATA;
+    }
+    schro_decoder->header_read = TRUE;
   }
-
-  if (SCHRO_PARSE_CODE_IS_END_OF_SEQUENCE (parse_code)) {
-    if (next != 0 && next != SCHRO_PARSE_HEADER_SIZE) {
-      GST_WARNING ("next is not 0 or 13 in EOS packet (%d)", next);
+  if (SCHRO_PARSE_CODE_IS_END_OF_SEQUENCE (schro_decoder->parse_code)) {
+    if (schro_decoder->next != 0
+        && schro_decoder->next != SCHRO_PARSE_HEADER_SIZE) {
+      GST_WARNING ("next is not 0 or 13 in EOS packet (%d)",
+          schro_decoder->next);
     }
 
     gst_video_decoder_add_to_frame (base_video_decoder,
         SCHRO_PARSE_HEADER_SIZE);
 
     SCHRO_DEBUG ("eos");
-
+    schro_decoder->header_read = FALSE;
     return gst_video_decoder_have_frame (base_video_decoder);
   }
 
-  if (gst_adapter_available (adapter) < next) {
+  if (gst_adapter_available (adapter) < schro_decoder->next) {
     return GST_VIDEO_DECODER_FLOW_NEED_DATA;
-  }
+  } else
+    schro_decoder->header_read = FALSE;
 
-  if (SCHRO_PARSE_CODE_IS_SEQ_HEADER (parse_code)) {
+  if (SCHRO_PARSE_CODE_IS_SEQ_HEADER (schro_decoder->parse_code)) {
     guint8 *data;
 
-    data = g_malloc (next);
+    data = g_malloc (schro_decoder->next);
 
-    gst_adapter_copy (adapter, data, 0, next);
-    parse_sequence_header (schro_decoder, data, next);
+    gst_adapter_copy (adapter, data, 0, schro_decoder->next);
+    parse_sequence_header (schro_decoder, data, schro_decoder->next);
 
     GST_VIDEO_CODEC_FRAME_SET_SYNC_POINT (frame);
 
@@ -395,11 +408,11 @@ gst_schro_dec_parse (GstVideoDecoder * base_video_decoder,
   }
 
   if (!schro_decoder->seq_header_buffer_seen) {
-    gst_adapter_flush (adapter, next);
+    gst_adapter_flush (adapter, schro_decoder->next);
     return GST_FLOW_OK;
   }
 
-  if (SCHRO_PARSE_CODE_IS_PICTURE (parse_code)) {
+  if (SCHRO_PARSE_CODE_IS_PICTURE (schro_decoder->parse_code)) {
     guint8 tmp[4];
 
     gst_adapter_copy (adapter, tmp, SCHRO_PARSE_HEADER_SIZE, 4);
@@ -408,11 +421,10 @@ gst_schro_dec_parse (GstVideoDecoder * base_video_decoder,
      * do anything with presentation_frame_number */
     frame->presentation_frame_number = GST_READ_UINT32_BE (tmp);
 
-    gst_video_decoder_add_to_frame (base_video_decoder, next);
-
+    gst_video_decoder_add_to_frame (base_video_decoder, schro_decoder->next);
     return gst_video_decoder_have_frame (base_video_decoder);
   } else {
-    gst_video_decoder_add_to_frame (base_video_decoder, next);
+    gst_video_decoder_add_to_frame (base_video_decoder, schro_decoder->next);
   }
 
   return GST_FLOW_OK;