Add Common Encryption support to BMFF, including subsample decryption.

media/mp4/track_run_iterator.h

Index: media/mp4/track_run_iterator.h
diff --git a/media/mp4/track_run_iterator.h b/media/mp4/track_run_iterator.h
index c1f61c3a2425d4cbd034ec7a9104e2f17b2f00e5..6923970830c9d4c1abd096925b9b97b4defc4b85 100644
--- a/media/mp4/track_run_iterator.h
+++ b/media/mp4/track_run_iterator.h
@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "base/time.h"
+#include "media/base/decrypt_config.h"
 #include "media/mp4/box_definitions.h"
 #include "media/mp4/cenc.h"
 
@@ -31,13 +32,12 @@ struct TrackRunInfo {
   TimeDelta start_dts;
   int64 sample_start_offset;
 
-  bool is_encrypted;
-  int64 cenc_start_offset;
-  int cenc_total_size;
-  uint8 default_cenc_size;
-  // Only valid if default_cenc_size == 0. (In this case, infer the sample count
-  // from the 'samples' parameter; they shall be the same.)
-  std::vector<uint8> cenc_sizes;
+  int64 aux_info_start_offset;
+  int aux_info_default_size;
+  std::vector<uint8> aux_info_sizes;  // Present if default_size == 0.
+  int aux_info_total_size;
+
+  TrackEncryption track_encryption;
 
   TrackRunInfo();
   ~TrackRunInfo();
@@ -62,12 +62,14 @@ class TrackRunIterator {
   void AdvanceRun();
   void AdvanceSample();
 
-  // Returns true iff the track is encrypted and the common encryption sample
-  // auxiliary information has not yet been cached for the current track.
-  bool NeedsCENC();
+  // Returns true if this track run has auxiliary information and has not yet
+  // been cached. Requires |RunValid()|.

[ddorwin, 2012/06/26 06:09:19]

Did you see || around function names somewhere? I thought we only did that for
parameters/variables.

[strobe_, 2012/06/27 02:01:21]

I thought so, but I could be mistaken, and if it looks weird to you then it
probably does to other people too, so removed.

+  bool AuxInfoRequired();

[ddorwin, 2012/06/26 06:09:19]

Is*

[strobe_, 2012/06/27 02:01:21]

Okay, I renamed this to AuxInfoNeedsToBeCached() based on this and the comment
below, which might possibly be the clunkiest name of the year, but should
resolve the confusion about the meaning of AuxInfoRequired(). WDYT?

 
-  // Cache the CENC data from the given buffer.
-  bool CacheCENC(const uint8* buf, int size);
+  // Cache the CENC data from the given buffer. |buf| must be a buffer starting

[ddorwin, 2012/06/26 06:09:19]

Is AuxInfo CENC data? If so, the function name should specify this, as should
the code that was calling it.

[strobe_, 2012/06/27 02:01:21]

"Auxiliary information" is a generic mechanism in the amended ISO spec. Here we
only use it when CENC is signaled elsewhere in the spec (or, rather, we will,
once the flux between CENC, PIFF, and WideVine settles down and I can provide
some reasonable assurance of correct behavior across the spectrum of files which
users are likely to see), but there's no guarantee that any aux info we read is
in fact CENC info, so I felt it best to separate the two names. If you feel
otherwise, I'm happy to switch.

[ddorwin, 2012/07/03 21:03:46]

As long as the code is not making assumptions about it being CENC data. There is
other code assuming AuxInfo == CENC, and I seem to remember it being related to
this (or similar) function.

+  // at the offset given by |cenc_offset()|, with a |size| of at least
+  // |cenc_size()|. Returns true on success, false on error.
+  bool CacheAuxInfo(const uint8* buf, int size);
 
   // Returns the maximum buffer location at which no data earlier in the stream
   // will be required in order to read the current or any subsequent sample. You
@@ -79,37 +81,36 @@ class TrackRunIterator {
   // Returns the minimum timestamp (or kInfiniteDuration if no runs present).
   TimeDelta GetMinDecodeTimestamp();
 
-  // Property of the current run. Reqiures RunValid().
+  // Property of the current run. Reqiures |RunValid()|.
   uint32 track_id() const;
+  int64 aux_info_offset() const;
+  int aux_info_size() const;
   bool is_encrypted() const;
-  // Only valid if is_encrypted() is true.
-  int64 cenc_offset() const;
-  int cenc_size() const;
 
-  // Properties of the current sample. Requires SampleValid().
+  // Properties of the current sample. Requires |SampleValid()|.

[ddorwin, 2012/06/26 06:09:19]

What does requires mean? Maybe "Only valid if SampleValid()."

[strobe_, 2012/06/27 02:01:21]

Done.

   int64 offset() const;
   int size() const;
   TimeDelta dts() const;
   TimeDelta cts() const;
   TimeDelta duration() const;
   bool is_keyframe() const;
-  // Only valid if is_encrypted() is true and NeedsCENC() is false.
-  const FrameCENCInfo& frame_cenc_info();
+
+  // Requires |is_encrypted()| and |!AuxInfoRequired()|.

[ddorwin, 2012/06/26 06:09:19]

Same comment as above.
Also, why is this only valid if auxinfo not required?

[strobe_, 2012/06/27 02:01:21]

Done.

+  scoped_ptr<DecryptConfig> GetDecryptConfig();
 
  private:
   void ResetRun();
   std::vector<TrackRunInfo> runs_;
   std::vector<TrackRunInfo>::const_iterator run_itr_;
-
   std::vector<SampleInfo>::const_iterator sample_itr_;
-  std::vector<uint8> cenc_cache_;
 
   std::vector<int64> min_clear_offsets_;
   std::vector<int64>::const_iterator min_clear_offset_itr_;
 
+  std::vector<FrameCENCInfo> cenc_info_;
+
   TimeDelta sample_dts_;
   int64 sample_offset_;
-  FrameCENCInfo frame_cenc_info_;
 };
 
 }  // namespace mp4