Handle interlaced formats (two coding units together make one full frame)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/dnxhd_parser.c

@@ -26,21 +26,32 @@
 
 #include "parser.h"
 
-#define DNXHD_HEADER_PREFIX 0x0000028001
+#define DNXHD_HEADER_PREFIX 0x000002800100
 
-static int dnxhd_find_frame_end(ParseContext *pc,
+typedef struct {
+    ParseContext pc;
+    int interlaced;
+    int cur_field; /* first field is 0, second is 1 */
+} DNXHDParserContext;
+
+static int dnxhd_find_frame_end(DNXHDParserContext *dctx,
                                 const uint8_t *buf, int buf_size)
 {
+    ParseContext *pc = &dctx->pc;
     uint64_t state = pc->state64;
     int pic_found = pc->frame_start_found;
     int i = 0;
+    int interlaced = dctx->interlaced;
+    int cur_field = dctx->cur_field;
 
     if (!pic_found) {
         for (i = 0; i < buf_size; i++) {
             state = (state<<8) | buf[i];
-            if ((state & 0xffffffffffLL) == DNXHD_HEADER_PREFIX) {
+            if ((state & 0xffffffffff00LL) == DNXHD_HEADER_PREFIX) {
                 i++;
                 pic_found = 1;
+                interlaced = (state&2)>>1; /* byte following the 5-byte header prefix */
+                cur_field = state&1;
                 break;
             }
         }
@@ -51,15 +62,25 @@ static int dnxhd_find_frame_end(ParseContext *pc,
             return 0;
         for (; i < buf_size; i++) {
             state = (state<<8) | buf[i];
-            if ((state & 0xffffffffffLL) == DNXHD_HEADER_PREFIX) {
-                pc->frame_start_found = 0;
-                pc->state64 = -1;
-                return i-4;
+            if ((state & 0xffffffffff00LL) == DNXHD_HEADER_PREFIX) {
+                if (!interlaced || dctx->cur_field) {
+                    pc->frame_start_found = 0;
+                    pc->state64 = -1;
+                    dctx->interlaced = interlaced;
+                    dctx->cur_field = 0;
+                    return i-5;
+                } else {
+                    /* continue, to get the second field */
+                    dctx->interlaced = interlaced = (state&2)>>1;
+                    dctx->cur_field = cur_field = state&1;
+                }
             }
         }
     }
     pc->frame_start_found = pic_found;
     pc->state64 = state;
+    dctx->interlaced = interlaced;
+    dctx->cur_field = cur_field;
     return END_NOT_FOUND;
 }
 
@@ -68,13 +89,14 @@ static int dnxhd_parse(AVCodecParserContext *s,
                        const uint8_t **poutbuf, int *poutbuf_size,
                        const uint8_t *buf, int buf_size)
 {
-    ParseContext *pc = s->priv_data;
+    DNXHDParserContext *dctx = s->priv_data;
+    ParseContext *pc = &dctx->pc;
     int next;
 
     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
         next = buf_size;
     } else {
-        next = dnxhd_find_frame_end(pc, buf, buf_size);
+        next = dnxhd_find_frame_end(dctx, buf, buf_size);
         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
             *poutbuf = NULL;
             *poutbuf_size = 0;
@@ -88,7 +110,7 @@ static int dnxhd_parse(AVCodecParserContext *s,
 
 AVCodecParser ff_dnxhd_parser = {
     .codec_ids      = { CODEC_ID_DNXHD },
-    .priv_data_size = sizeof(ParseContext),
+    .priv_data_size = sizeof(DNXHDParserContext),
     .parser_parse   = dnxhd_parse,
     .parser_close   = ff_parse_close,
 };