media/libstagefright/timedtext/TimedTextSRTSource.h

/*
 * 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.
 */

#ifndef TIMED_TEXT_SRT_SOURCE_H_
#define TIMED_TEXT_SRT_SOURCE_H_

#include <media/stagefright/MediaErrors.h>
#include <media/stagefright/MediaSource.h>
#include <utils/Compat.h>  // off64_t

#include "TimedTextSource.h"

namespace android {

class AString;
class DataSource;
class MediaBuffer;
class Parcel;

class TimedTextSRTSource : public TimedTextSource {
public:
    TimedTextSRTSource(const sp<DataSource>& dataSource);
    virtual status_t start();
    virtual status_t stop();
    virtual status_t read(
            int64_t *startTimeUs,
            int64_t *endTimeUs,
            Parcel *parcel,
            const MediaSource::ReadOptions *options = NULL);
    virtual sp<MetaData> getFormat();

protected:
    virtual ~TimedTextSRTSource();

private:
    sp<DataSource> mSource;
    sp<MetaData> mMetaData;

    struct TextInfo {
        int64_t endTimeUs;
        // The offset of the text in the original file.
        off64_t offset;
        int textLen;
    };

    size_t mIndex;
    KeyedVector<int64_t, TextInfo> mTextVector;

    void reset();
    status_t scanFile();
    status_t getNextSubtitleInfo(
            off64_t *offset, int64_t *startTimeUs, TextInfo *info);
    status_t readNextLine(off64_t *offset, AString *data);
    status_t getText(
            const MediaSource::ReadOptions *options,
            AString *text, int64_t *startTimeUs, int64_t *endTimeUs);
    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);
};

}  // namespace android

#endif  // TIMED_TEXT_SRT_SOURCE_H_