Bugfix: Seek on SRT external track

o Need to return closest upcoming subtitle when seeking time is within
gap ranges.
o Manually cherry-picked from GTV change.
(commit e026a83dc88888b42da77eca739b8f09a0cd6dae)

related-to-bug: 6796228
Change-Id: I02b7718a432d6b2f5575fa1a1a42bda6f04aa25b

4 files changed, 298 insertions, 26 deletions

diff --git a/media/libstagefright/timedtext/TimedTextSRTSource.cpp b/media/libstagefright/timedtext/TimedTextSRTSource.cpp
index 1f5d037..eac23ba 100644
--- a/media/libstagefright/timedtext/TimedTextSRTSource.cpp
+++ b/media/libstagefright/timedtext/TimedTextSRTSource.cpp
@@ -79,6 +79,10 @@ status_t TimedTextSRTSource::read(
     return OK;
 }
 
+sp<MetaData> TimedTextSRTSource::getFormat() {
+    return mMetaData;
+}
+
 status_t TimedTextSRTSource::scanFile() {
     off64_t offset = 0;
     int64_t startTimeUs;
@@ -155,18 +159,16 @@ status_t TimedTextSRTSource::getNextSubtitleInfo(
     while (needMoreData) {
         if ((err = readNextLine(offset, &data)) != OK) {
             if (err == ERROR_END_OF_STREAM) {
-                needMoreData = false;
+                break;
             } else {
                 return err;
             }
         }
 
-        if (needMoreData) {
-            data.trim();
-            if (data.empty()) {
-                // it's an empty line used to separate two subtitles
-                needMoreData = false;
-            }
+        data.trim();
+        if (data.empty()) {
+            // it's an empty line used to separate two subtitles
+            needMoreData = false;
         }
     }
     info->textLen = *offset - info->offset;
@@ -221,35 +223,24 @@ status_t TimedTextSRTSource::getText(
     if (options != NULL && options->getSeekTo(&seekTimeUs, &mode)) {
         int64_t lastEndTimeUs =
                 mTextVector.valueAt(mTextVector.size() - 1).endTimeUs;
-        int64_t firstStartTimeUs = mTextVector.keyAt(0);
-        if (seekTimeUs < 0 || seekTimeUs > lastEndTimeUs) {
+        if (seekTimeUs < 0) {
             return ERROR_OUT_OF_RANGE;
-        } else if (seekTimeUs < firstStartTimeUs) {
-            mIndex = 0;
+        } else if (seekTimeUs >= lastEndTimeUs) {
+            return ERROR_END_OF_STREAM;
         } else {
             // binary search
             size_t low = 0;
             size_t high = mTextVector.size() - 1;
             size_t mid = 0;
-            int64_t currTimeUs;
 
             while (low <= high) {
                 mid = low + (high - low)/2;
-                currTimeUs = mTextVector.keyAt(mid);
-                const int64_t diffTime = currTimeUs - seekTimeUs;
-
-                if (diffTime == 0) {
+                int diff = compareExtendedRangeAndTime(mid, seekTimeUs);
+                if (diff == 0) {
                     break;
-                } else if (diffTime < 0) {
+                } else if (diff < 0) {
                     low = mid + 1;
                 } else {
-                    if ((high == mid + 1)
-                        && (seekTimeUs < mTextVector.keyAt(high))) {
-                        break;
-                    }
-                    if (mid < 1) {
-                        break;
-                    }
                     high = mid - 1;
                 }
             }
@@ -260,6 +251,7 @@ status_t TimedTextSRTSource::getText(
     if (mIndex >= mTextVector.size()) {
         return ERROR_END_OF_STREAM;
     }
+
     const TextInfo &info = mTextVector.valueAt(mIndex);
     *startTimeUs = mTextVector.keyAt(mIndex);
     *endTimeUs = info.endTimeUs;
@@ -289,8 +281,18 @@ status_t TimedTextSRTSource::extractAndAppendLocalDescriptions(
     return OK;
 }
 
-sp<MetaData> TimedTextSRTSource::getFormat() {
-    return mMetaData;
+int TimedTextSRTSource::compareExtendedRangeAndTime(size_t index, int64_t timeUs) {
+    CHECK_LT(index, mTextVector.size());
+    int64_t endTimeUs = mTextVector.valueAt(index).endTimeUs;
+    int64_t startTimeUs = (index > 0) ?
+            mTextVector.valueAt(index - 1).endTimeUs : 0;
+    if (timeUs >= startTimeUs && timeUs < endTimeUs) {
+        return 0;
+    } else if (endTimeUs <= timeUs) {
+        return -1;
+    } else {
+        return 1;
+    }
 }
 
 }  // namespace android
diff --git a/media/libstagefright/timedtext/TimedTextSRTSource.h b/media/libstagefright/timedtext/TimedTextSRTSource.h
index 9eeab39..598c200 100644
--- a/media/libstagefright/timedtext/TimedTextSRTSource.h
+++ b/media/libstagefright/timedtext/TimedTextSRTSource.h
@@ -70,6 +70,25 @@ private:
     status_t extractAndAppendLocalDescriptions(
             int64_t timeUs, const AString &text, Parcel *parcel);
 
+    // Compares the time range of the subtitle at index to the given timeUs.
+    // The time range of the subtitle to match with given timeUs is extended to
+    // [endTimeUs of the previous subtitle, endTimeUs of current subtitle).
+    //
+    // This compare function is used to find a next subtitle when read() is
+    // called with seek options. Note that timeUs within gap ranges, such as
+    // [200, 300) in the below example, will be matched to the closest future
+    // subtitle, [300, 400).
+    //
+    // For instance, assuming there are 3 subtitles in mTextVector,
+    // 0: [100, 200)      ----> [0, 200)
+    // 1: [300, 400)      ----> [200, 400)
+    // 2: [500, 600)      ----> [400, 600)
+    // If the 'index' parameter contains 1, this function
+    // returns 0, if timeUs is in [200, 400)
+    // returns -1, if timeUs >= 400,
+    // returns 1, if timeUs < 200.
+    int compareExtendedRangeAndTime(size_t index, int64_t timeUs);
+
     DISALLOW_EVIL_CONSTRUCTORS(TimedTextSRTSource);
 };
 
diff --git a/media/libstagefright/timedtext/test/Android.mk b/media/libstagefright/timedtext/test/Android.mk
new file mode 100644
index 0000000..a5e7ba2
--- /dev/null
+++ b/media/libstagefright/timedtext/test/Android.mk
@@ -0,0 +1,27 @@
+LOCAL_PATH:= $(call my-dir)
+
+# ================================================================
+# Unit tests for libstagefright_timedtext
+# See also /development/testrunner/test_defs.xml
+# ================================================================
+
+# ================================================================
+# A test for TimedTextSRTSource
+# ================================================================
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := TimedTextSRTSource_test
+
+LOCAL_MODULE_TAGS := eng tests
+
+LOCAL_SRC_FILES := TimedTextSRTSource_test.cpp
+
+LOCAL_C_INCLUDES := \
+    $(TOP)/external/expat/lib \
+    $(TOP)/frameworks/base/media/libstagefright/timedtext
+
+LOCAL_SHARED_LIBRARIES := \
+    libexpat \
+    libstagefright
+
+include $(BUILD_NATIVE_TEST)
diff --git a/media/libstagefright/timedtext/test/TimedTextSRTSource_test.cpp b/media/libstagefright/timedtext/test/TimedTextSRTSource_test.cpp
new file mode 100644
index 0000000..40e93c7
--- /dev/null
+++ b/media/libstagefright/timedtext/test/TimedTextSRTSource_test.cpp
@@ -0,0 +1,224 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "TimedTextSRTSource_test"
+#include <utils/Log.h>
+
+#include <gtest/gtest.h>
+
+#include <binder/Parcel.h>
+#include <media/stagefright/foundation/AString.h>
+#include <media/stagefright/DataSource.h>
+#include <media/stagefright/MediaErrors.h>
+#include <utils/misc.h>
+
+#include <TimedTextSource.h>
+#include <TimedTextSRTSource.h>
+
+namespace android {
+namespace test {
+
+static const int kSecToUsec = 1000000;
+static const int kSecToMsec = 1000;
+static const int kMsecToUsec = 1000;
+
+/* SRT format (http://en.wikipedia.org/wiki/SubRip)
+ *   Subtitle number
+ *   Start time --> End time
+ *   Text of subtitle (one or more lines)
+ *   Blank lines
+ */
+static const char *kSRTString =
+    "1\n00:00:1,000 --> 00:00:1,500\n1\n\n"
+    "2\n00:00:2,000 --> 00:00:2,500\n2\n\n"
+    "3\n00:00:3,000 --> 00:00:3,500\n3\n\n"
+    "4\n00:00:4,000 --> 00:00:4,500\n4\n\n"
+    "5\n00:00:5,000 --> 00:00:5,500\n5\n\n"
+    // edge case : previos end time = next start time
+    "6\n00:00:5,500 --> 00:00:5,800\n6\n\n"
+    "7\n00:00:5,800 --> 00:00:6,000\n7\n\n"
+    "8\n00:00:6,000 --> 00:00:7,000\n8\n\n";
+
+class SRTDataSourceStub : public DataSource {
+public:
+    SRTDataSourceStub(const char *data, size_t size) :
+        mData(data), mSize(size) {}
+    virtual ~SRTDataSourceStub() {}
+
+    virtual status_t initCheck() const {
+        return OK;
+    }
+
+    virtual ssize_t readAt(off64_t offset, void *data, size_t size) {
+        if (offset >= mSize) return 0;
+
+        ssize_t avail = mSize - offset;
+        if (avail > size) {
+            avail = size;
+        }
+        memcpy(data, mData + offset, avail);
+        return avail;
+    }
+
+private:
+    const char *mData;
+    size_t mSize;
+};
+
+class TimedTextSRTSourceTest : public testing::Test {
+protected:
+    void SetUp() {
+        sp<DataSource> stub= new SRTDataSourceStub(
+                kSRTString,
+                strlen(kSRTString));
+        mSource = new TimedTextSRTSource(stub);
+        mSource->start();
+    }
+
+    void CheckStartTimeMs(const Parcel& parcel, int32_t timeMs) {
+        int32_t intval;
+        parcel.setDataPosition(8);
+        parcel.readInt32(&intval);
+        EXPECT_EQ(timeMs, intval);
+    }
+
+    void CheckDataEquals(const Parcel& parcel, const char* content) {
+        int32_t intval;
+        parcel.setDataPosition(16);
+        parcel.readInt32(&intval);
+        parcel.setDataPosition(24);
+        const char* data = (const char*) parcel.readInplace(intval);
+
+        int32_t content_len = strlen(content);
+        EXPECT_EQ(content_len, intval);
+        EXPECT_TRUE(strncmp(data, content, content_len) == 0);
+    }
+
+    sp<TimedTextSource> mSource;
+    int64_t startTimeUs;
+    int64_t endTimeUs;
+    Parcel parcel;
+    AString subtitle;
+    status_t err;
+};
+
+TEST_F(TimedTextSRTSourceTest, readAll) {
+    for (int i = 1; i <= 5; i++) {
+        err = mSource->read(&startTimeUs, &endTimeUs, &parcel);
+        EXPECT_EQ(OK, err);
+        CheckStartTimeMs(parcel, i * kSecToMsec);
+        subtitle = StringPrintf("%d\n\n", i);
+        CheckDataEquals(parcel, subtitle.c_str());
+    }
+    // read edge cases
+    err = mSource->read(&startTimeUs, &endTimeUs, &parcel);
+    EXPECT_EQ(OK, err);
+    CheckStartTimeMs(parcel, 5500);
+    subtitle = StringPrintf("6\n\n");
+    CheckDataEquals(parcel, subtitle.c_str());
+
+    err = mSource->read(&startTimeUs, &endTimeUs, &parcel);
+    EXPECT_EQ(OK, err);
+    CheckStartTimeMs(parcel, 5800);
+    subtitle = StringPrintf("7\n\n");
+    CheckDataEquals(parcel, subtitle.c_str());
+
+    err = mSource->read(&startTimeUs, &endTimeUs, &parcel);
+    EXPECT_EQ(OK, err);
+    CheckStartTimeMs(parcel, 6000);
+    subtitle = StringPrintf("8\n\n");
+    CheckDataEquals(parcel, subtitle.c_str());
+
+    err = mSource->read(&startTimeUs, &endTimeUs, &parcel);
+    EXPECT_EQ(ERROR_END_OF_STREAM, err);
+}
+
+TEST_F(TimedTextSRTSourceTest, seekTimeIsEarlierThanFirst) {
+    MediaSource::ReadOptions options;
+    options.setSeekTo(500, MediaSource::ReadOptions::SEEK_PREVIOUS_SYNC);
+    err = mSource->read(&startTimeUs, &endTimeUs, &parcel, &options);
+    EXPECT_EQ(OK, err);
+    EXPECT_EQ(1 * kSecToUsec, startTimeUs);
+    CheckStartTimeMs(parcel, 1 * kSecToMsec);
+}
+
+TEST_F(TimedTextSRTSourceTest, seekTimeIsLaterThanLast) {
+    MediaSource::ReadOptions options;
+    options.setSeekTo(7 * kSecToUsec, MediaSource::ReadOptions::SEEK_PREVIOUS_SYNC);
+    err = mSource->read(&startTimeUs, &endTimeUs, &parcel, &options);
+    EXPECT_EQ(ERROR_END_OF_STREAM, err);
+
+    options.setSeekTo(8 * kSecToUsec, MediaSource::ReadOptions::SEEK_PREVIOUS_SYNC);
+    err = mSource->read(&startTimeUs, &endTimeUs, &parcel, &options);
+    EXPECT_EQ(ERROR_END_OF_STREAM, err);
+}
+
+TEST_F(TimedTextSRTSourceTest, seekTimeIsMatched) {
+    for (int i = 1; i <= 5; i++) {
+        MediaSource::ReadOptions options;
+        options.setSeekTo(i * kSecToUsec, MediaSource::ReadOptions::SEEK_PREVIOUS_SYNC);
+        err = mSource->read(&startTimeUs, &endTimeUs, &parcel, &options);
+        EXPECT_EQ(OK, err);
+        EXPECT_EQ(i * kSecToUsec, startTimeUs);
+
+        options.setSeekTo(i * kSecToUsec + 100, MediaSource::ReadOptions::SEEK_PREVIOUS_SYNC);
+        err = mSource->read(&startTimeUs, &endTimeUs, &parcel, &options);
+        EXPECT_EQ(OK, err);
+        EXPECT_EQ(i * kSecToUsec, startTimeUs);
+    }
+}
+
+TEST_F(TimedTextSRTSourceTest, seekTimeInBetweenTwo) {
+    for (int i = 1; i <= 4; i++) {
+        MediaSource::ReadOptions options;
+        options.setSeekTo(i * kSecToUsec + 500000, MediaSource::ReadOptions::SEEK_PREVIOUS_SYNC);
+        err = mSource->read(&startTimeUs, &endTimeUs, &parcel, &options);
+        EXPECT_EQ(OK, err);
+        EXPECT_EQ((i + 1) * kSecToUsec, startTimeUs);
+
+        options.setSeekTo(i * kSecToUsec + 600000, MediaSource::ReadOptions::SEEK_PREVIOUS_SYNC);
+        err = mSource->read(&startTimeUs, &endTimeUs, &parcel, &options);
+        EXPECT_EQ(OK, err);
+        EXPECT_EQ((i + 1) * kSecToUsec, startTimeUs);
+    }
+}
+
+TEST_F(TimedTextSRTSourceTest, checkEdgeCase) {
+    MediaSource::ReadOptions options;
+    options.setSeekTo(5500 * kMsecToUsec, MediaSource::ReadOptions::SEEK_PREVIOUS_SYNC);
+    err = mSource->read(&startTimeUs, &endTimeUs, &parcel, &options);
+    EXPECT_EQ(OK, err);
+    EXPECT_EQ(5500 * kMsecToUsec, startTimeUs);
+    subtitle = StringPrintf("6\n\n");
+    CheckDataEquals(parcel, subtitle.c_str());
+
+    options.setSeekTo(5800 * kMsecToUsec, MediaSource::ReadOptions::SEEK_PREVIOUS_SYNC);
+    err = mSource->read(&startTimeUs, &endTimeUs, &parcel, &options);
+    EXPECT_EQ(OK, err);
+    EXPECT_EQ(5800 * kMsecToUsec, startTimeUs);
+    subtitle = StringPrintf("7\n\n");
+    CheckDataEquals(parcel, subtitle.c_str());
+
+    options.setSeekTo(6000 * kMsecToUsec, MediaSource::ReadOptions::SEEK_PREVIOUS_SYNC);
+    err = mSource->read(&startTimeUs, &endTimeUs, &parcel, &options);
+    EXPECT_EQ(OK, err);
+    EXPECT_EQ(6000 * kMsecToUsec, startTimeUs);
+    subtitle = StringPrintf("8\n\n");
+    CheckDataEquals(parcel, subtitle.c_str());
+}
+
+}  // namespace test
+}  // namespace android