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<div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span>&#160;<span class="comment">// Copyright (c) 2012 The Chromium Authors. All rights reserved.</span></div>
<div class="line"><a name="l00002"></a><span class="lineno"> 2</span>&#160;<span class="comment">// Use of this source code is governed by a BSD-style license that can be</span></div>
<div class="line"><a name="l00003"></a><span class="lineno"> 3</span>&#160;<span class="comment">// found in the LICENSE file.</span></div>
<div class="line"><a name="l00004"></a><span class="lineno"> 4</span>&#160; </div>
<div class="line"><a name="l00005"></a><span class="lineno"> 5</span>&#160;<span class="preprocessor">#include &quot;packager/media/base/audio_timestamp_helper.h&quot;</span></div>
<div class="line"><a name="l00006"></a><span class="lineno"> 6</span>&#160; </div>
<div class="line"><a name="l00007"></a><span class="lineno"> 7</span>&#160;<span class="preprocessor">#include &quot;packager/base/logging.h&quot;</span></div>
<div class="line"><a name="l00008"></a><span class="lineno"> 8</span>&#160;<span class="preprocessor">#include &quot;packager/media/base/timestamp.h&quot;</span></div>
<div class="line"><a name="l00009"></a><span class="lineno"> 9</span>&#160; </div>
<div class="line"><a name="l00010"></a><span class="lineno"> 10</span>&#160;<span class="keyword">namespace </span><a class="code" href="../../d8/daf/namespaceshaka.html">shaka</a> {</div>
<div class="line"><a name="l00011"></a><span class="lineno"> 11</span>&#160;<span class="keyword">namespace </span>media {</div>
<div class="line"><a name="l00012"></a><span class="lineno"> 12</span>&#160; </div>
<div class="line"><a name="l00013"></a><span class="lineno"> 13</span>&#160;AudioTimestampHelper::AudioTimestampHelper(uint32_t timescale,</div>
<div class="line"><a name="l00014"></a><span class="lineno"> 14</span>&#160; uint32_t samples_per_second)</div>
<div class="line"><a name="l00015"></a><span class="lineno"> 15</span>&#160; : base_timestamp_(kNoTimestamp), frame_count_(0) {</div>
<div class="line"><a name="l00016"></a><span class="lineno"> 16</span>&#160; DCHECK_GT(samples_per_second, 0u);</div>
<div class="line"><a name="l00017"></a><span class="lineno"> 17</span>&#160; <span class="keywordtype">double</span> fps = samples_per_second;</div>
<div class="line"><a name="l00018"></a><span class="lineno"> 18</span>&#160; ticks_per_frame_ = timescale / fps;</div>
<div class="line"><a name="l00019"></a><span class="lineno"> 19</span>&#160;}</div>
<div class="line"><a name="l00020"></a><span class="lineno"> 20</span>&#160; </div>
<div class="line"><a name="l00021"></a><span class="lineno"> 21</span>&#160;<span class="keywordtype">void</span> AudioTimestampHelper::SetBaseTimestamp(int64_t base_timestamp) {</div>
<div class="line"><a name="l00022"></a><span class="lineno"> 22</span>&#160; base_timestamp_ = base_timestamp;</div>
<div class="line"><a name="l00023"></a><span class="lineno"> 23</span>&#160; frame_count_ = 0;</div>
<div class="line"><a name="l00024"></a><span class="lineno"> 24</span>&#160;}</div>
<div class="line"><a name="l00025"></a><span class="lineno"> 25</span>&#160; </div>
<div class="line"><a name="l00026"></a><span class="lineno"> 26</span>&#160;int64_t AudioTimestampHelper::base_timestamp()<span class="keyword"> const </span>{</div>
<div class="line"><a name="l00027"></a><span class="lineno"> 27</span>&#160; <span class="keywordflow">return</span> base_timestamp_;</div>
<div class="line"><a name="l00028"></a><span class="lineno"> 28</span>&#160;}</div>
<div class="line"><a name="l00029"></a><span class="lineno"> 29</span>&#160; </div>
<div class="line"><a name="l00030"></a><span class="lineno"> 30</span>&#160;<span class="keywordtype">void</span> AudioTimestampHelper::AddFrames(int64_t frame_count) {</div>
<div class="line"><a name="l00031"></a><span class="lineno"> 31</span>&#160; DCHECK_GE(frame_count, 0);</div>
<div class="line"><a name="l00032"></a><span class="lineno"> 32</span>&#160; DCHECK(base_timestamp_ != kNoTimestamp);</div>
<div class="line"><a name="l00033"></a><span class="lineno"> 33</span>&#160; frame_count_ += frame_count;</div>
<div class="line"><a name="l00034"></a><span class="lineno"> 34</span>&#160;}</div>
<div class="line"><a name="l00035"></a><span class="lineno"> 35</span>&#160; </div>
<div class="line"><a name="l00036"></a><span class="lineno"> 36</span>&#160;int64_t AudioTimestampHelper::GetTimestamp()<span class="keyword"> const </span>{</div>
<div class="line"><a name="l00037"></a><span class="lineno"> 37</span>&#160; <span class="keywordflow">return</span> ComputeTimestamp(frame_count_);</div>
<div class="line"><a name="l00038"></a><span class="lineno"> 38</span>&#160;}</div>
<div class="line"><a name="l00039"></a><span class="lineno"> 39</span>&#160; </div>
<div class="line"><a name="l00040"></a><span class="lineno"> 40</span>&#160;int64_t AudioTimestampHelper::GetFrameDuration(int64_t frame_count)<span class="keyword"> const </span>{</div>
<div class="line"><a name="l00041"></a><span class="lineno"> 41</span>&#160; DCHECK_GE(frame_count, 0);</div>
<div class="line"><a name="l00042"></a><span class="lineno"> 42</span>&#160; int64_t end_timestamp = ComputeTimestamp(frame_count_ + frame_count);</div>
<div class="line"><a name="l00043"></a><span class="lineno"> 43</span>&#160; <span class="keywordflow">return</span> end_timestamp - GetTimestamp();</div>
<div class="line"><a name="l00044"></a><span class="lineno"> 44</span>&#160;}</div>
<div class="line"><a name="l00045"></a><span class="lineno"> 45</span>&#160; </div>
<div class="line"><a name="l00046"></a><span class="lineno"> 46</span>&#160;int64_t AudioTimestampHelper::GetFramesToTarget(int64_t target)<span class="keyword"> const </span>{</div>
<div class="line"><a name="l00047"></a><span class="lineno"> 47</span>&#160; DCHECK(base_timestamp_ != kNoTimestamp);</div>
<div class="line"><a name="l00048"></a><span class="lineno"> 48</span>&#160; DCHECK(target &gt;= base_timestamp_);</div>
<div class="line"><a name="l00049"></a><span class="lineno"> 49</span>&#160; </div>
<div class="line"><a name="l00050"></a><span class="lineno"> 50</span>&#160; int64_t delta_in_ticks = (target - GetTimestamp());</div>
<div class="line"><a name="l00051"></a><span class="lineno"> 51</span>&#160; <span class="keywordflow">if</span> (delta_in_ticks == 0)</div>
<div class="line"><a name="l00052"></a><span class="lineno"> 52</span>&#160; <span class="keywordflow">return</span> 0;</div>
<div class="line"><a name="l00053"></a><span class="lineno"> 53</span>&#160; </div>
<div class="line"><a name="l00054"></a><span class="lineno"> 54</span>&#160; <span class="comment">// Compute a timestamp relative to |base_timestamp_| since timestamps</span></div>
<div class="line"><a name="l00055"></a><span class="lineno"> 55</span>&#160; <span class="comment">// created from |frame_count_| are computed relative to this base.</span></div>
<div class="line"><a name="l00056"></a><span class="lineno"> 56</span>&#160; <span class="comment">// This ensures that the time to frame computation here is the proper inverse</span></div>
<div class="line"><a name="l00057"></a><span class="lineno"> 57</span>&#160; <span class="comment">// of the frame to time computation in ComputeTimestamp().</span></div>
<div class="line"><a name="l00058"></a><span class="lineno"> 58</span>&#160; int64_t delta_from_base = target - base_timestamp_;</div>
<div class="line"><a name="l00059"></a><span class="lineno"> 59</span>&#160; </div>
<div class="line"><a name="l00060"></a><span class="lineno"> 60</span>&#160; <span class="comment">// Compute frame count for the time delta. This computation rounds to</span></div>
<div class="line"><a name="l00061"></a><span class="lineno"> 61</span>&#160; <span class="comment">// the nearest whole number of frames.</span></div>
<div class="line"><a name="l00062"></a><span class="lineno"> 62</span>&#160; <span class="keywordtype">double</span> threshold = ticks_per_frame_ / 2;</div>
<div class="line"><a name="l00063"></a><span class="lineno"> 63</span>&#160; int64_t target_frame_count = (delta_from_base + threshold) / ticks_per_frame_;</div>
<div class="line"><a name="l00064"></a><span class="lineno"> 64</span>&#160; <span class="keywordflow">return</span> target_frame_count - frame_count_;</div>
<div class="line"><a name="l00065"></a><span class="lineno"> 65</span>&#160;}</div>
<div class="line"><a name="l00066"></a><span class="lineno"> 66</span>&#160; </div>
<div class="line"><a name="l00067"></a><span class="lineno"> 67</span>&#160;int64_t AudioTimestampHelper::ComputeTimestamp(int64_t frame_count)<span class="keyword"> const </span>{</div>
<div class="line"><a name="l00068"></a><span class="lineno"> 68</span>&#160; DCHECK_GE(frame_count, 0);</div>
<div class="line"><a name="l00069"></a><span class="lineno"> 69</span>&#160; DCHECK(base_timestamp_ != kNoTimestamp);</div>
<div class="line"><a name="l00070"></a><span class="lineno"> 70</span>&#160; <span class="keywordtype">double</span> frames_ticks = ticks_per_frame_ * frame_count;</div>
<div class="line"><a name="l00071"></a><span class="lineno"> 71</span>&#160; <span class="keywordflow">return</span> base_timestamp_ + frames_ticks;</div>
<div class="line"><a name="l00072"></a><span class="lineno"> 72</span>&#160;}</div>
<div class="line"><a name="l00073"></a><span class="lineno"> 73</span>&#160; </div>
<div class="line"><a name="l00074"></a><span class="lineno"> 74</span>&#160;} <span class="comment">// namespace media</span></div>
<div class="line"><a name="l00075"></a><span class="lineno"> 75</span>&#160;} <span class="comment">// namespace shaka</span></div>
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<div class="ttc" id="anamespaceshaka_html"><div class="ttname"><a href="../../d8/daf/namespaceshaka.html">shaka</a></div><div class="ttdoc">All the methods that are virtual are virtual for mocking.</div><div class="ttdef"><b>Definition:</b> <a href="../../d4/d15/gflags__hex__bytes_8cc_source.html#l00011">gflags_hex_bytes.cc:11</a></div></div>
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