From 11cbbd86fb5ffb80fdb21c70ee174618407ac393 Mon Sep 17 00:00:00 2001
From: KongQun Yang <kqyang@google.com>
Date: Thu, 8 Feb 2018 23:40:46 -0800
Subject: [PATCH] Fix fMP4 'cbcs' playback issue in Safari

Looks like Safari does not like v0 tenc box.

- Use v1 tenc box for cbcs and cens protection_scheme as required by
  CENCv3 spec.
- Set crypt_byte_block and skip_byte_block to 0 for full sample
  encryption cbcs and cens.

Fixes #326

Change-Id: I5581cd856fffc4ff104d950f3ca19b9337d57a78
---
 .../testdata/bear-640x360-a-cbcs-golden.mp4   | Bin 43947 -> 43947 bytes
 .../testdata/bear-640x360-a-cens-golden.mp4   | Bin 44620 -> 44620 bytes
 packager/media/formats/mp4/mp4_muxer.cc       |  27 ++++++++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/packager/app/test/testdata/bear-640x360-a-cbcs-golden.mp4 b/packager/app/test/testdata/bear-640x360-a-cbcs-golden.mp4
index 2c07174911386c2bfd59a139e737b3cfc1249f75..07afa6a80c44a23a938b731d388dbc083fa1c60b 100644
GIT binary patch
delta 21
acmZ2|ooV%TrVR_3*ccf=VDoY&mX!cg*amC>

delta 21
acmZ2|ooV%TrVR_3*cd=SVDoY&mX!chEe3l4

diff --git a/packager/app/test/testdata/bear-640x360-a-cens-golden.mp4 b/packager/app/test/testdata/bear-640x360-a-cens-golden.mp4
index 067799fab63dc54968f90808739992b6692bef0c..36c049aa3ab1933d5e2d8c19f49e28be263aa42a 100644
GIT binary patch
delta 21
acmX?ehw026rVR_3*ccf=VDoaOrK<s2+y`3#

delta 21
acmX?ehw026rVR_3*cd=SVDoaOrK<s3F$Zb@

diff --git a/packager/media/formats/mp4/mp4_muxer.cc b/packager/media/formats/mp4/mp4_muxer.cc
index 42ed5acc00..155a19d158 100644
--- a/packager/media/formats/mp4/mp4_muxer.cc
+++ b/packager/media/formats/mp4/mp4_muxer.cc
@@ -94,9 +94,36 @@ void GenerateSinf(FourCC old_type,
 
   auto& track_encryption = sinf->info.track_encryption;
   track_encryption.default_is_protected = 1;
+
   track_encryption.default_crypt_byte_block =
       encryption_config.crypt_byte_block;
   track_encryption.default_skip_byte_block = encryption_config.skip_byte_block;
+  switch (encryption_config.protection_scheme) {
+    case FOURCC_cenc:
+    case FOURCC_cbc1:
+      DCHECK_EQ(track_encryption.default_crypt_byte_block, 0u);
+      DCHECK_EQ(track_encryption.default_skip_byte_block, 0u);
+      // CENCv3 10.1 ‘cenc’ AES-CTR scheme and 10.2 ‘cbc1’ AES-CBC scheme:
+      // The version of the Track Encryption Box (‘tenc’) SHALL be 0.
+      track_encryption.version = 0;
+      break;
+    case FOURCC_cbcs:
+    case FOURCC_cens:
+      if (track_encryption.default_skip_byte_block == 0) {
+        // Some clients, e.g. Safari v11.0.3 does not like having
+        // crypt_byte_block as a non-zero value when skip_byte_block is zero.
+        track_encryption.default_crypt_byte_block = 0;
+      }
+      // CENCv3 10.3 ‘cens’ AES-CTR subsample pattern encryption scheme and
+      //        10.4 ‘cbcs’ AES-CBC subsample pattern encryption scheme:
+      // The version of the Track Encryption Box (‘tenc’) SHALL be 1.
+      track_encryption.version = 1;
+      break;
+    default:
+      NOTREACHED() << "Unexpected protection scheme "
+                   << encryption_config.protection_scheme;
+  }
+
   track_encryption.default_per_sample_iv_size =
       encryption_config.per_sample_iv_size;
   track_encryption.default_constant_iv = encryption_config.constant_iv;