avcodec: add dca core extraction bsf

Signed-off-by: Paul B Mahol <onemda@gmail.com>

1 files changed, 60 insertions, 0 deletions

diff --git a/libavcodec/dca_core_bsf.c b/libavcodec/dca_core_bsf.c
new file mode 100644
index 0000000000..7d372369ef
--- /dev/null
+++ b/libavcodec/dca_core_bsf.c
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2016 Paul B Mahol
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avcodec.h"
+#include "bytestream.h"
+#include "dca_syncwords.h"
+#include "libavutil/mem.h"
+
+static int dca_core(AVBitStreamFilterContext *bsfc,
+                    AVCodecContext *avctx, const char *args,
+                    uint8_t **poutbuf, int *poutbuf_size,
+                    const uint8_t *buf, int buf_size,
+                    int keyframe)
+{
+    GetByteContext gb;
+    uint32_t syncword;
+    int core_size = 0;
+
+    bytestream2_init(&gb, buf, buf_size);
+    syncword = bytestream2_get_be32(&gb);
+    bytestream2_skip(&gb, 1);
+
+    switch (syncword) {
+    case DCA_SYNCWORD_CORE_BE:
+        core_size = ((bytestream2_get_be24(&gb) >> 4) & 0x3fff) + 1;
+        break;
+    }
+
+    *poutbuf = (uint8_t *)buf;
+
+    if (core_size > 0 && core_size <= buf_size) {
+        *poutbuf_size = core_size;
+    } else {
+        *poutbuf_size = buf_size;
+    }
+
+    return 0;
+}
+
+AVBitStreamFilter ff_dca_core_bsf = {
+    .name   = "dca_core",
+    .filter = dca_core,
+};