avcodec: add dca core extraction bsf

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

Changelog

@@ -17,6 +17,7 @@ version <next>:
 - AudioToolbox audio encoders
 - coreimage filter (GPU based image filtering on OSX)
 - libdcadec removed
+- bitstream filter for extracting DTS core
 
 version 3.0:
 - Common Encryption (CENC) MP4 encoding and decoding support

doc/bitstream_filters.texi

@@ -67,6 +67,10 @@ the header stored in extradata to the key packets:
 ffmpeg -i INPUT -map 0 -flags:v +global_header -c:v libx264 -bsf:v dump_extra out.ts
 @end example
 
+@section dca_core
+
+Extract DCA core from DTS-HD streams.
+
 @section h264_mp4toannexb
 
 Convert an H.264 bitstream from length prefixed mode to start code

libavcodec/Makefile

@@ -924,6 +924,7 @@ OBJS-$(CONFIG_AAC_ADTSTOASC_BSF)          += aac_adtstoasc_bsf.o aacadtsdec.o \
                                              mpeg4audio.o
 OBJS-$(CONFIG_CHOMP_BSF)                  += chomp_bsf.o
 OBJS-$(CONFIG_DUMP_EXTRADATA_BSF)         += dump_extradata_bsf.o
+OBJS-$(CONFIG_DCA_CORE_BSF)               += dca_core_bsf.o
 OBJS-$(CONFIG_H264_MP4TOANNEXB_BSF)       += h264_mp4toannexb_bsf.o
 OBJS-$(CONFIG_HEVC_MP4TOANNEXB_BSF)       += hevc_mp4toannexb_bsf.o
 OBJS-$(CONFIG_IMX_DUMP_HEADER_BSF)        += imx_dump_header_bsf.o

libavcodec/allcodecs.c

@@ -670,6 +670,7 @@ void avcodec_register_all(void)
     REGISTER_BSF(AAC_ADTSTOASC,         aac_adtstoasc);
     REGISTER_BSF(CHOMP,                 chomp);
     REGISTER_BSF(DUMP_EXTRADATA,        dump_extradata);
+    REGISTER_BSF(DCA_CORE,              dca_core);
     REGISTER_BSF(H264_MP4TOANNEXB,      h264_mp4toannexb);
     REGISTER_BSF(HEVC_MP4TOANNEXB,      hevc_mp4toannexb);
     REGISTER_BSF(IMX_DUMP_HEADER,       imx_dump_header);

libavcodec/dca_core_bsf.c

+/*
+ * 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,
+};

libavcodec/version.h

@@ -28,7 +28,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVCODEC_VERSION_MAJOR  57
-#define LIBAVCODEC_VERSION_MINOR  31
+#define LIBAVCODEC_VERSION_MINOR  32
 #define LIBAVCODEC_VERSION_MICRO 100
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \