lavc: Move start code finding to utils.c

This allows dropping the mpegvideo dependency from a number of
components.

This also fixes standalone building of the h264 parser, which
was broken in 64e438697.

Signed-off-by: Martin Storsjö <martin@martin.st>

1 files changed, 34 insertions, 0 deletions

diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index e18f42d99a..d8ebda61dc 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -39,6 +39,7 @@
 #include "avcodec.h"
 #include "dsputil.h"
 #include "libavutil/opt.h"
+#include "mpegvideo.h"
 #include "thread.h"
 #include "internal.h"
 #include "bytestream.h"
@@ -2197,3 +2198,36 @@ int avcodec_is_open(AVCodecContext *s)
 {
     return !!s->internal;
 }
+
+const uint8_t *avpriv_mpv_find_start_code(const uint8_t *restrict p,
+                                          const uint8_t *end,
+                                          uint32_t * restrict state)
+{
+    int i;
+
+    assert(p <= end);
+    if (p >= end)
+        return end;
+
+    for (i = 0; i < 3; i++) {
+        uint32_t tmp = *state << 8;
+        *state = tmp + *(p++);
+        if (tmp == 0x100 || p == end)
+            return p;
+    }
+
+    while (p < end) {
+        if      (p[-1] > 1      ) p += 3;
+        else if (p[-2]          ) p += 2;
+        else if (p[-3]|(p[-1]-1)) p++;
+        else {
+            p++;
+            break;
+        }
+    }
+
+    p = FFMIN(p, end) - 4;
+    *state = AV_RB32(p);
+
+    return p + 4;
+}