I am trying to playback encrypted content. I know that libavformat
handles decryption already when using clearkey, but I want to handle
the decryption myself. The encryption info is parsed in mov.c but not
exposed to the app.
This adds some structures to hold new side-data that will hold the
info needed to decrypt. I wanted to post this first before I
implemented the code in mov.c (and probably eventually matroskadec.c
for webm).
Also, can I use the flexible array member feature, it was introduced
in C99? Would a 0-length array be better?
From 608524d302bec8a8339e8389cfbdebfd573cf75b Mon Sep 17 00:00:00 2001
From: Jacob Trimble <modma...@google.com>
Date: Tue, 5 Dec 2017 14:52:22 -0800
Subject: [PATCH] avpacket: Add encryption info side data.
Signed-off-by: Jacob Trimble <modma...@google.com>
---
libavcodec/avcodec.h | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 65 insertions(+)
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 5db6a81320..7c9b071c48 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -1112,6 +1112,58 @@ typedef struct AVCPBProperties {
uint64_t vbv_delay;
} AVCPBProperties;
+/**
+ * This describes encryption info for a packet. This contains frame-specific
+ * info for how to decrypt the packet before passing it to the decoder. If this
+ * side-data is present, then the packet is encrypted.
+ *
+ * Since this uses a flexible array member, the size and layout of this type
+ * is part of the public API/ABI.
+ */
+typedef struct AVPacketEncryptionInfo {
+ /** The fourcc encryption scheme. */
+ char scheme[4];
+
+ /** The ID of the key used to encrypt the packet. */
+ uint8_t key_id[16];
+
+ /** The initialization vector. */
+ uint8_t iv[16];
+
+ /** The size of the IV, this will either be 8 or 16. */
+ int iv_size;
+
+ /**
+ * Only used for pattern encryption. This is the number of 16-byte blocks
+ * that are encrypted.
+ */
+ unsigned int crypt_byte_size;
+
+ /**
+ * Only used for pattern encryption. This is the number of 16-byte blocks
+ * that are clear.
+ */
+ unsigned int skip_byte_size;
+
+ /**
+ * The number of sub-samples in this packet. If 0, then the whole sample
+ * is encrypted.
+ */
+ unsigned int subsample_count;
+
+ struct {
+ /** The number of bytes that are clear. */
+ unsigned int bytes_of_clear_data;
+
+ /**
+ * The number of bytes that are protected. If using pattern encryption,
+ * the pattern applies to only the protected bytes; if not using pattern
+ * encryption, all these bytes are encrypted.
+ */
+ unsigned int bytes_of_protected_data;
+ } subsamples[];
+} AVPacketEncryptionInfo;
+
/**
* The decoder will keep a reference to the frame and may reuse it later.
*/
@@ -1327,6 +1379,19 @@ enum AVPacketSideDataType {
*/
AV_PKT_DATA_A53_CC,
+ /**
+ * This side data is encryption "initialization data".
+ * For MP4 this is the entire 'pssh' box.
+ * For WebM this is the key ID.
+ */
+ AV_PKT_DATA_ENCRYPTION_INIT_DATA,
+
+ /**
+ * This side data is an AVPacketEncryptionInfo structure and contains info
+ * about how the packet is encrypted.
+ */
+ AV_PKT_DATA_PACKET_ENCRYPTION_INFO,
+
/**
* The number of side data types.
* This is not part of the public API/ABI in the sense that it may
--
2.15.1.424.g9478a66081-goog
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