movenc: support cenc (common encryption)

support writing encrypted mp4 using aes-ctr, conforming to ISO/IEC
23001-7.

3 new parameters were added:
- encryption_scheme - allowed values are none (default) and cenc-aes-ctr
- encryption_key - 128 bit encryption key (hex)
- encryption_kid - 128 bit encryption key identifier (hex)

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

1 files changed, 86 insertions, 0 deletions

diff --git a/libavformat/movenccenc.h b/libavformat/movenccenc.h
new file mode 100644
index 0000000000..6f9e70e905
--- /dev/null
+++ b/libavformat/movenccenc.h
@@ -0,0 +1,86 @@
+/*
+ * MOV CENC (Common Encryption) writer
+ * Copyright (c) 2015 Eran Kornblau <erankor at gmail dot com>
+ *
+ * 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
+ */
+
+#ifndef AVFORMAT_MOVENCCENC_H
+#define AVFORMAT_MOVENCCENC_H
+
+#include "libavutil/aes_ctr.h"
+#include "avformat.h"
+#include "avio.h"
+
+#define CENC_KID_SIZE (16)
+
+struct MOVTrack;
+
+typedef struct {
+    struct AVAESCTR* aes_ctr;
+    uint8_t* auxiliary_info;
+    size_t auxiliary_info_size;
+    size_t auxiliary_info_alloc_size;
+    uint32_t auxiliary_info_entries;
+
+    /* subsample support */
+    int use_subsamples;
+    uint16_t subsample_count;
+    size_t auxiliary_info_subsample_start;
+    uint8_t* auxiliary_info_sizes;
+    size_t  auxiliary_info_sizes_alloc_size;
+} MOVMuxCencContext;
+
+/**
+ * Initialize a CENC context
+ * @param key encryption key, must have a length of AES_CTR_KEY_SIZE
+ * @param use_subsamples when enabled parts of a packet can be encrypted, otherwise the whole packet is encrypted
+ */
+int ff_mov_cenc_init(MOVMuxCencContext* ctx, uint8_t* encryption_key, int use_subsamples, int bitexact);
+
+/**
+ * Free a CENC context
+ */
+void ff_mov_cenc_free(MOVMuxCencContext* ctx);
+
+/**
+ * Write a fully encrypted packet
+ */
+int ff_mov_cenc_write_packet(MOVMuxCencContext* ctx, AVIOContext *pb, const uint8_t *buf_in, int size);
+
+/**
+ * Parse AVC NAL units from annex B format, the nal size and type are written in the clear while the body is encrypted
+ */
+int ff_mov_cenc_avc_parse_nal_units(MOVMuxCencContext* ctx, AVIOContext *pb, const uint8_t *buf_in, int size);
+
+/**
+ * Write AVC NAL units that are in MP4 format, the nal size and type are written in the clear while the body is encrypted
+ */
+int ff_mov_cenc_avc_write_nal_units(AVFormatContext *s, MOVMuxCencContext* ctx, int nal_length_size,
+    AVIOContext *pb, const uint8_t *buf_in, int size);
+
+/**
+ * Write the cenc atoms that should reside inside stbl
+ */
+void ff_mov_cenc_write_stbl_atoms(MOVMuxCencContext* ctx, AVIOContext *pb);
+
+/**
+ * Write the sinf atom, contained inside stsd
+ */
+int ff_mov_cenc_write_sinf_tag(struct MOVTrack* track, AVIOContext *pb, uint8_t* kid);
+
+#endif /* AVFORMAT_MOVENCCENC_H */