Access unit queue for MediaCodecPlayer

media/base/android/access_unit_queue.cc

+// Copyright 2015 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.
+
+#include "media/base/android/access_unit_queue.h"
+
+#include "base/logging.h"
+#include "media/base/demuxer_stream.h"
+
+namespace media {
+
+namespace {
+// Amount of history chunks we keep by default. The zero size means we do not
+// keep chunks before the current one and the history is limited by the size
+// of one chunk.
+const int kDefaultHistoryChunksAmount = 0;
+}
+
+AccessUnitQueue::AccessUnitQueue()
+    : index_in_chunk_(0),
+      history_chunks_amount_(kDefaultHistoryChunksAmount),

[wolenetz, 2015/06/11 19:21:20]

aside: Do we ever need this? If not, always 0? If just being generic, I'm fine
(have no strong feeling). My suspicion is that caching lookback prior to current
chunk is doubly-caching what chunk_demuxer does.
ANyway, just an aside, no need for this to change here, though watch out for
double-caching (BrowserSeek already does the necessary for us).

+      has_eos_(false) {
+  current_chunk_ = chunks_.end();
+}
+
+AccessUnitQueue::~AccessUnitQueue() {
+}
+
+void AccessUnitQueue::PushBack(const DemuxerData& data) {
+  // Media thread
+  DCHECK(!data.access_units.empty());
+
+#if DCHECK_IS_ON()
+  // If there is an AU with  |kConfigChanged| status, it must me the last

[wolenetz, 2015/06/11 19:21:20]

nits: s/  / / and s/me/be/

[Tima Vaisburd, 2015/06/11 20:54:08]

Done.

+  // AU in the chunk and the data should have exactly one correslonging

[wolenetz, 2015/06/11 19:21:20]

nit: correslonging :)

[Tima Vaisburd, 2015/06/11 20:54:08]

Done.

+  // DemuxerConfigs.
+  for (size_t i = 0; i < data.access_units.size(); ++i) {
+    const AccessUnit& unit = data.access_units[i];
+
+    // EOS must be the last unit in the chunk
+    if (unit.is_end_of_stream) {
+      DCHECK(i == data.access_units.size() - 1);
+    }
+
+    // kConfigChanged must be the last unit in the chunk.
+    if (unit.status == DemuxerStream::kConfigChanged) {
+      DCHECK(i == data.access_units.size() - 1);
+      DCHECK(data.demuxer_configs.size() == 1);
+    }
+  }
+#endif
+
+  // Create the next chunk and copy data to it.
+  scoped_ptr<DemuxerData> chunk(new DemuxerData(data));
+
+  // EOS flag can only be in the last access unit.
+  bool has_eos = chunk->access_units.back().is_end_of_stream;
+
+  // Append this chunk to the queue.
+  base::AutoLock lock(lock_);
+
+  bool was_empty = (current_chunk_ == chunks_.end());
+
+  chunks_.push_back(chunk.Pass());
+
+  // Position the current chunk.
+  if (was_empty) {
+    current_chunk_ = --chunks_.end();
+    index_in_chunk_ = 0;
+  }
+
+  // We expect that the chunk containing EOS is the last chunk.
+  DCHECK(!has_eos_);
+  has_eos_ = has_eos;
+}
+
+void AccessUnitQueue::Advance() {
+  // Decoder thread
+  base::AutoLock lock(lock_);
+
+  if (current_chunk_ == chunks_.end())
+    return;
+
+  ++index_in_chunk_;
+  if ((*current_chunk_)->access_units.size() <= index_in_chunk_) {

[wolenetz, 2015/06/11 19:21:20]

nit: change the condition and return early if we're still in the middle of the
current_chunk_

[Tima Vaisburd, 2015/06/11 20:54:09]

Done.

+    index_in_chunk_ = 0;
+    ++current_chunk_;
+  }
+
+  // Keep only |history_chunks_amount_| before the current one.
+
+  // std::distance() and std::advance() do not work efficiently with std::list,

[wolenetz, 2015/06/11 19:21:21]

aside: I suppose we could cache the queue size ourselves if we needed perf gain.

[Tima Vaisburd, 2015/06/11 20:54:08]

Acknowledged.

+  // but the history_size should be small (default is 0).
+  size_t num_consumed_chunks = std::distance(chunks_.begin(), current_chunk_);
+  if (num_consumed_chunks > history_chunks_amount_) {
+    DataChunkQueue::iterator first_to_keep = chunks_.begin();
+    std::advance(first_to_keep, num_consumed_chunks - history_chunks_amount_);
+    chunks_.erase(chunks_.begin(), first_to_keep);
+  }
+}
+
+void AccessUnitQueue::Flush() {
+  // Media thread
+  base::AutoLock lock(lock_);
+
+  chunks_.clear();
+
+  current_chunk_ = chunks_.end();
+  index_in_chunk_ = 0;
+  has_eos_ = false;
+}
+
+bool AccessUnitQueue::RewindToLastKeyFrame() {
+  // Media thread
+  base::AutoLock lock(lock_);
+
+  // Search for the key frame backwards. Start with the current AU.
+
+  // Start with current chunk.
+  if (current_chunk_ != chunks_.end()) {
+    for (int i = (int)index_in_chunk_; i >= 0; --i) {
+      if ((*current_chunk_)->access_units[i].is_key_frame) {
+        index_in_chunk_ = i;
+        return true;
+      }
+    }
+  }
+
+  // Position reverse iterator before the current chunk.
+  DataChunkQueue::reverse_iterator rchunk(current_chunk_);
+
+  for (; rchunk != chunks_.rend(); ++rchunk) {
+    int i = (int)(*rchunk)->access_units.size() - 1;
+    for (; i >= 0; --i) {
+      if ((*rchunk)->access_units[i].is_key_frame) {
+        index_in_chunk_ = i;
+        current_chunk_ = --rchunk.base();

[wolenetz, 2015/06/11 19:21:20]

would be good to test this.

[Tima Vaisburd, 2015/06/11 20:54:08]

I added a new test KeyFrameWithLongHistory just because of this code. It should
cover.

[wolenetz, 2015/06/12 22:05:19]

Acknowledged.

+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
+AccessUnitQueue::Info AccessUnitQueue::GetInfo() const {
+  // Media thread, Decoder thread
+
+  Info info;
+  base::AutoLock lock(lock_);
+
+  info.length = GetUnconsumedAccessUnitLength();
+  info.has_eos = has_eos_;
+  info.front_unit = nullptr;
+  info.configs = nullptr;
+
+  if (info.length > 0) {
+    DCHECK(current_chunk_ != chunks_.end());
+    DCHECK(index_in_chunk_ < (*current_chunk_)->access_units.size());
+    info.front_unit = &(*current_chunk_)->access_units[index_in_chunk_];
+
+    if (info.front_unit->status == DemuxerStream::kConfigChanged) {
+      DCHECK((*current_chunk_)->demuxer_configs.size() == 1);
+      info.configs = &(*current_chunk_)->demuxer_configs[0];
+    }
+  }
+  return info;
+}
+
+void AccessUnitQueue::SetHistorySizeForTesting(size_t history_chunks_amount) {
+  history_chunks_amount_ = history_chunks_amount;
+}
+
+int AccessUnitQueue::GetUnconsumedAccessUnitLength() const {
+  int result = 0;
+  DataChunkQueue::const_iterator chunk;
+  for (chunk = current_chunk_; chunk != chunks_.end(); ++chunk)
+    result += (*chunk)->access_units.size();
+
+  result -= index_in_chunk_;
+  return result;
+}
+
+}  // namespace media