Mpeg2 TS parser: Es parsing using an ES byte queue.

media/formats/mp2t/es_parser.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_FORMATS_MP2T_ES_PARSER_H_
 #define MEDIA_FORMATS_MP2T_ES_PARSER_H_
 
+#include <list>
+
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/time/time.h"
 #include "media/base/media_export.h"
 #include "media/base/stream_parser_buffer.h"
 
 namespace media {
 
+class OffsetByteQueue;
 class StreamParserBuffer;
 
 namespace mp2t {
 
 class MEDIA_EXPORT EsParser {
  public:
   typedef base::Callback<void(scoped_refptr<StreamParserBuffer>)> EmitBufferCB;
 
-  EsParser() {}
-  virtual ~EsParser() {}
+  EsParser();
+  virtual ~EsParser();
 
   // ES parsing.
   // Should use kNoTimestamp when a timestamp is not valid.
-  virtual bool Parse(const uint8* buf, int size,
-                     base::TimeDelta pts,
-                     DecodeTimestamp dts) = 0;
+  bool Parse(const uint8* buf, int size,
+             base::TimeDelta pts,
+             DecodeTimestamp dts);
 
   // Flush any pending buffer.
   virtual void Flush() = 0;
 
   // Reset the state of the ES parser.
-  virtual void Reset() = 0;
+  virtual void Reset();
+
+ protected:
+  struct TimingDesc {
+    TimingDesc();
+    TimingDesc(DecodeTimestamp dts, base::TimeDelta pts);
+
+    DecodeTimestamp dts;
+    base::TimeDelta pts;
+  };
+
+  // Parse ES data from |es_queue_|.
+  // Return true when successful.
+  virtual bool ParseFromEsQueue() = 0;
+
+  // Get the timing descriptor that applies to position |es_byte_count| inside

[wolenetz, 2014/08/26 23:01:44]

nit: Can there be a position in |es_queue_| for which there is no applicable
timing descriptor, though there might be a prior or later (or both) position in
|es_queue_| for which there is an applicable timing descriptor? I'm trying to
understand the comment here and for |timing_desc_list_|. The latter scopes the
applicability to "the first access unit [at or after this position]", so does
this mean that if the position is not at or within an access unit, there is not
an applicable timing descriptor?

[damienv1, 2014/08/27 16:23:43]

There is not necessarily a timing descriptor associated with each access unit
(that's why in ADTS we have an AudioTimestampHelper).
I re-phrased the explanation and added some comments on the relationship with
the Mpeg2TS spec.

+  // the ES byte queue. This timing descriptor and all the ones that come before
+  // (in stream order) are removed from list |timing_desc_list_|.
+  // If no timing descriptor is found, then the default TimingDesc is returned.
+  TimingDesc GetTimingDescriptor(int64 es_byte_count);
+
+  // Bytes of the ES stream that have not been emitted yet.
+  scoped_ptr<media::OffsetByteQueue> es_queue_;
+
+ private:
+  // Anchor some timing information into the ES queue.
+  // A timing descriptor associated with a given ES position applies to the
+  // first access unit that comes at or after this ES position in the queue.
+  std::list<std::pair<int64, TimingDesc> > timing_desc_list_;

[wolenetz, 2014/08/26 23:01:44]

lint nit: add #include for pair<>

[damienv1, 2014/08/27 16:23:43]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(EsParser);
 };
 
 }  // namespace mp2t
 }  // namespace media
 
 #endif