android-34/com/google/android/exoplayer2/text/ssa/SsaDecoder.java - platform/prebuilts/fullsdk/sources - Git at Google

 /*
  * Copyright (C) 2017 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.
  */
 package com.google.android.exoplayer2.text.ssa;

 import static com.google.android.exoplayer2.text.Cue.LINE_TYPE_FRACTION;
 import static com.google.android.exoplayer2.util.Util.castNonNull;

 import android.graphics.Typeface;
 import android.text.Layout;
 import android.text.SpannableString;
 import android.text.style.ForegroundColorSpan;
 import android.text.style.StrikethroughSpan;
 import android.text.style.StyleSpan;
 import android.text.style.UnderlineSpan;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.text.Cue;
 import com.google.android.exoplayer2.text.SimpleSubtitleDecoder;
 import com.google.android.exoplayer2.text.Subtitle;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Log;
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import com.google.android.exoplayer2.util.Util;
 import com.google.common.base.Ascii;
 import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;

 /** A {@link SimpleSubtitleDecoder} for SSA/ASS. */
 public final class SsaDecoder extends SimpleSubtitleDecoder {

   private static final String TAG = "SsaDecoder";

   private static final Pattern SSA_TIMECODE_PATTERN =
       Pattern.compile("(?:(\\d+):)?(\\d+):(\\d+)[:.](\\d+)");

   /* package */ static final String FORMAT_LINE_PREFIX = "Format:";
   /* package */ static final String STYLE_LINE_PREFIX = "Style:";
   private static final String DIALOGUE_LINE_PREFIX = "Dialogue:";

   private static final float DEFAULT_MARGIN = 0.05f;

   private final boolean haveInitializationData;
   @Nullable private final SsaDialogueFormat dialogueFormatFromInitializationData;

   private @MonotonicNonNull Map<String, SsaStyle> styles;

   /**
    * The horizontal resolution used by the subtitle author - all cue positions are relative to this.
    *
    * <p>Parsed from the {@code PlayResX} value in the {@code [Script Info]} section.
    */
   private float screenWidth;
   /**
    * The vertical resolution used by the subtitle author - all cue positions are relative to this.
    *
    * <p>Parsed from the {@code PlayResY} value in the {@code [Script Info]} section.
    */
   private float screenHeight;

   public SsaDecoder() {
     this(/* initializationData= */ null);
   }

   /**
    * Constructs an SsaDecoder with optional format and header info.
    *
    * @param initializationData Optional initialization data for the decoder. If not null or empty,
    *     the initialization data must consist of two byte arrays. The first must contain an SSA
    *     format line. The second must contain an SSA header that will be assumed common to all
    *     samples. The header is everything in an SSA file before the {@code [Events]} section (i.e.
    *     {@code [Script Info]} and optional {@code [V4+ Styles]} section.
    */
   public SsaDecoder(@Nullable List<byte[]> initializationData) {
     super("SsaDecoder");
     screenWidth = Cue.DIMEN_UNSET;
     screenHeight = Cue.DIMEN_UNSET;

     if (initializationData != null && !initializationData.isEmpty()) {
       haveInitializationData = true;
       String formatLine = Util.fromUtf8Bytes(initializationData.get(0));
       Assertions.checkArgument(formatLine.startsWith(FORMAT_LINE_PREFIX));
       dialogueFormatFromInitializationData =
           Assertions.checkNotNull(SsaDialogueFormat.fromFormatLine(formatLine));
       parseHeader(new ParsableByteArray(initializationData.get(1)));
     } else {
       haveInitializationData = false;
       dialogueFormatFromInitializationData = null;
     }
   }

   @Override
   protected Subtitle decode(byte[] bytes, int length, boolean reset) {
     List<List<Cue>> cues = new ArrayList<>();
     List<Long> cueTimesUs = new ArrayList<>();

     ParsableByteArray data = new ParsableByteArray(bytes, length);
     if (!haveInitializationData) {
       parseHeader(data);
     }
     parseEventBody(data, cues, cueTimesUs);
     return new SsaSubtitle(cues, cueTimesUs);
   }

   /**
    * Parses the header of the subtitle.
    *
    * @param data A {@link ParsableByteArray} from which the header should be read.
    */
   private void parseHeader(ParsableByteArray data) {
     @Nullable String currentLine;
     while ((currentLine = data.readLine()) != null) {
       if ("[Script Info]".equalsIgnoreCase(currentLine)) {
         parseScriptInfo(data);
       } else if ("[V4+ Styles]".equalsIgnoreCase(currentLine)) {
         styles = parseStyles(data);
       } else if ("[V4 Styles]".equalsIgnoreCase(currentLine)) {
         Log.i(TAG, "[V4 Styles] are not supported");
       } else if ("[Events]".equalsIgnoreCase(currentLine)) {
         // We've reached the [Events] section, so the header is over.
         return;
       }
     }
   }

   /**
    * Parse the {@code [Script Info]} section.
    *
    * <p>When this returns, {@code data.position} will be set to the beginning of the first line that
    * starts with {@code [} (i.e. the title of the next section).
    *
    * @param data A {@link ParsableByteArray} with {@link ParsableByteArray#getPosition() position}
    *     set to the beginning of the first line after {@code [Script Info]}.
    */
   private void parseScriptInfo(ParsableByteArray data) {
     @Nullable String currentLine;
     while ((currentLine = data.readLine()) != null
         && (data.bytesLeft() == 0 || data.peekUnsignedByte() != '[')) {
       String[] infoNameAndValue = currentLine.split(":");
       if (infoNameAndValue.length != 2) {
         continue;
       }
       switch (Ascii.toLowerCase(infoNameAndValue[0].trim())) {
         case "playresx":
           try {
             screenWidth = Float.parseFloat(infoNameAndValue[1].trim());
           } catch (NumberFormatException e) {
             // Ignore invalid PlayResX value.
           }
           break;
         case "playresy":
           try {
             screenHeight = Float.parseFloat(infoNameAndValue[1].trim());
           } catch (NumberFormatException e) {
             // Ignore invalid PlayResY value.
           }
           break;
       }
     }
   }

   /**
    * Parse the {@code [V4+ Styles]} section.
    *
    * <p>When this returns, {@code data.position} will be set to the beginning of the first line that
    * starts with {@code [} (i.e. the title of the next section).
    *
    * @param data A {@link ParsableByteArray} with {@link ParsableByteArray#getPosition()} pointing
    *     at the beginning of the first line after {@code [V4+ Styles]}.
    */
   private static Map<String, SsaStyle> parseStyles(ParsableByteArray data) {
     Map<String, SsaStyle> styles = new LinkedHashMap<>();
     @Nullable SsaStyle.Format formatInfo = null;
     @Nullable String currentLine;
     while ((currentLine = data.readLine()) != null
         && (data.bytesLeft() == 0 || data.peekUnsignedByte() != '[')) {
       if (currentLine.startsWith(FORMAT_LINE_PREFIX)) {
         formatInfo = SsaStyle.Format.fromFormatLine(currentLine);
       } else if (currentLine.startsWith(STYLE_LINE_PREFIX)) {
         if (formatInfo == null) {
           Log.w(TAG, "Skipping 'Style:' line before 'Format:' line: " + currentLine);
           continue;
         }
         @Nullable SsaStyle style = SsaStyle.fromStyleLine(currentLine, formatInfo);
         if (style != null) {
           styles.put(style.name, style);
         }
       }
     }
     return styles;
   }

   /**
    * Parses the event body of the subtitle.
    *
    * @param data A {@link ParsableByteArray} from which the body should be read.
    * @param cues A list to which parsed cues will be added.
    * @param cueTimesUs A sorted list to which parsed cue timestamps will be added.
    */
   private void parseEventBody(ParsableByteArray data, List<List<Cue>> cues, List<Long> cueTimesUs) {
     @Nullable
     SsaDialogueFormat format = haveInitializationData ? dialogueFormatFromInitializationData : null;
     @Nullable String currentLine;
     while ((currentLine = data.readLine()) != null) {
       if (currentLine.startsWith(FORMAT_LINE_PREFIX)) {
         format = SsaDialogueFormat.fromFormatLine(currentLine);
       } else if (currentLine.startsWith(DIALOGUE_LINE_PREFIX)) {
         if (format == null) {
           Log.w(TAG, "Skipping dialogue line before complete format: " + currentLine);
           continue;
         }
         parseDialogueLine(currentLine, format, cues, cueTimesUs);
       }
     }
   }

   /**
    * Parses a dialogue line.
    *
    * @param dialogueLine The dialogue values (i.e. everything after {@code Dialogue:}).
    * @param format The dialogue format to use when parsing {@code dialogueLine}.
    * @param cues A list to which parsed cues will be added.
    * @param cueTimesUs A sorted list to which parsed cue timestamps will be added.
    */
   private void parseDialogueLine(
       String dialogueLine, SsaDialogueFormat format, List<List<Cue>> cues, List<Long> cueTimesUs) {
     Assertions.checkArgument(dialogueLine.startsWith(DIALOGUE_LINE_PREFIX));
     String[] lineValues =
         dialogueLine.substring(DIALOGUE_LINE_PREFIX.length()).split(",", format.length);
     if (lineValues.length != format.length) {
       Log.w(TAG, "Skipping dialogue line with fewer columns than format: " + dialogueLine);
       return;
     }

     long startTimeUs = parseTimecodeUs(lineValues[format.startTimeIndex]);
     if (startTimeUs == C.TIME_UNSET) {
       Log.w(TAG, "Skipping invalid timing: " + dialogueLine);
       return;
     }

     long endTimeUs = parseTimecodeUs(lineValues[format.endTimeIndex]);
     if (endTimeUs == C.TIME_UNSET) {
       Log.w(TAG, "Skipping invalid timing: " + dialogueLine);
       return;
     }

     @Nullable
     SsaStyle style =
         styles != null && format.styleIndex != C.INDEX_UNSET
             ? styles.get(lineValues[format.styleIndex].trim())
             : null;
     String rawText = lineValues[format.textIndex];
     SsaStyle.Overrides styleOverrides = SsaStyle.Overrides.parseFromDialogue(rawText);
     String text =
         SsaStyle.Overrides.stripStyleOverrides(rawText)
             .replace("\\N", "\n")
             .replace("\\n", "\n")
             .replace("\\h", "\u00A0");
     Cue cue = createCue(text, style, styleOverrides, screenWidth, screenHeight);

     int startTimeIndex = addCuePlacerholderByTime(startTimeUs, cueTimesUs, cues);
     int endTimeIndex = addCuePlacerholderByTime(endTimeUs, cueTimesUs, cues);
     // Iterate on cues from startTimeIndex until endTimeIndex, adding the current cue.
     for (int i = startTimeIndex; i < endTimeIndex; i++) {
       cues.get(i).add(cue);
     }
   }

   /**
    * Parses an SSA timecode string.
    *
    * @param timeString The string to parse.
    * @return The parsed timestamp in microseconds.
    */
   private static long parseTimecodeUs(String timeString) {
     Matcher matcher = SSA_TIMECODE_PATTERN.matcher(timeString.trim());
     if (!matcher.matches()) {
       return C.TIME_UNSET;
     }
     long timestampUs =
         Long.parseLong(castNonNull(matcher.group(1))) * 60 * 60 * C.MICROS_PER_SECOND;
     timestampUs += Long.parseLong(castNonNull(matcher.group(2))) * 60 * C.MICROS_PER_SECOND;
     timestampUs += Long.parseLong(castNonNull(matcher.group(3))) * C.MICROS_PER_SECOND;
     timestampUs += Long.parseLong(castNonNull(matcher.group(4))) * 10000; // 100ths of a second.
     return timestampUs;
   }

   private static Cue createCue(
       String text,
       @Nullable SsaStyle style,
       SsaStyle.Overrides styleOverrides,
       float screenWidth,
       float screenHeight) {
     SpannableString spannableText = new SpannableString(text);
     Cue.Builder cue = new Cue.Builder().setText(spannableText);

     if (style != null) {
       if (style.primaryColor != null) {
         spannableText.setSpan(
             new ForegroundColorSpan(style.primaryColor),
             /* start= */ 0,
             /* end= */ spannableText.length(),
             SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
       }
       if (style.fontSize != Cue.DIMEN_UNSET && screenHeight != Cue.DIMEN_UNSET) {
         cue.setTextSize(
             style.fontSize / screenHeight, Cue.TEXT_SIZE_TYPE_FRACTIONAL_IGNORE_PADDING);
       }
       if (style.bold && style.italic) {
         spannableText.setSpan(
             new StyleSpan(Typeface.BOLD_ITALIC),
             /* start= */ 0,
             /* end= */ spannableText.length(),
             SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
       } else if (style.bold) {
         spannableText.setSpan(
             new StyleSpan(Typeface.BOLD),
             /* start= */ 0,
             /* end= */ spannableText.length(),
             SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
       } else if (style.italic) {
         spannableText.setSpan(
             new StyleSpan(Typeface.ITALIC),
             /* start= */ 0,
             /* end= */ spannableText.length(),
             SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
       }
       if (style.underline) {
         spannableText.setSpan(
             new UnderlineSpan(),
             /* start= */ 0,
             /* end= */ spannableText.length(),
             SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
       }
       if (style.strikeout) {
         spannableText.setSpan(
             new StrikethroughSpan(),
             /* start= */ 0,
             /* end= */ spannableText.length(),
             SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
       }
     }

     @SsaStyle.SsaAlignment int alignment;
     if (styleOverrides.alignment != SsaStyle.SSA_ALIGNMENT_UNKNOWN) {
       alignment = styleOverrides.alignment;
     } else if (style != null) {
       alignment = style.alignment;
     } else {
       alignment = SsaStyle.SSA_ALIGNMENT_UNKNOWN;
     }
     cue.setTextAlignment(toTextAlignment(alignment))
         .setPositionAnchor(toPositionAnchor(alignment))
         .setLineAnchor(toLineAnchor(alignment));

     if (styleOverrides.position != null
         && screenHeight != Cue.DIMEN_UNSET
         && screenWidth != Cue.DIMEN_UNSET) {
       cue.setPosition(styleOverrides.position.x / screenWidth);
       cue.setLine(styleOverrides.position.y / screenHeight, LINE_TYPE_FRACTION);
     } else {
       // TODO: Read the MarginL, MarginR and MarginV values from the Style & Dialogue lines.
       cue.setPosition(computeDefaultLineOrPosition(cue.getPositionAnchor()));
       cue.setLine(computeDefaultLineOrPosition(cue.getLineAnchor()), LINE_TYPE_FRACTION);
     }

     return cue.build();
   }

   @Nullable
   private static Layout.Alignment toTextAlignment(@SsaStyle.SsaAlignment int alignment) {
     switch (alignment) {
       case SsaStyle.SSA_ALIGNMENT_BOTTOM_LEFT:
       case SsaStyle.SSA_ALIGNMENT_MIDDLE_LEFT:
       case SsaStyle.SSA_ALIGNMENT_TOP_LEFT:
         return Layout.Alignment.ALIGN_NORMAL;
       case SsaStyle.SSA_ALIGNMENT_BOTTOM_CENTER:
       case SsaStyle.SSA_ALIGNMENT_MIDDLE_CENTER:
       case SsaStyle.SSA_ALIGNMENT_TOP_CENTER:
         return Layout.Alignment.ALIGN_CENTER;
       case SsaStyle.SSA_ALIGNMENT_BOTTOM_RIGHT:
       case SsaStyle.SSA_ALIGNMENT_MIDDLE_RIGHT:
       case SsaStyle.SSA_ALIGNMENT_TOP_RIGHT:
         return Layout.Alignment.ALIGN_OPPOSITE;
       case SsaStyle.SSA_ALIGNMENT_UNKNOWN:
         return null;
       default:
         Log.w(TAG, "Unknown alignment: " + alignment);
         return null;
     }
   }

   @Cue.AnchorType
   private static int toLineAnchor(@SsaStyle.SsaAlignment int alignment) {
     switch (alignment) {
       case SsaStyle.SSA_ALIGNMENT_BOTTOM_LEFT:
       case SsaStyle.SSA_ALIGNMENT_BOTTOM_CENTER:
       case SsaStyle.SSA_ALIGNMENT_BOTTOM_RIGHT:
         return Cue.ANCHOR_TYPE_END;
       case SsaStyle.SSA_ALIGNMENT_MIDDLE_LEFT:
       case SsaStyle.SSA_ALIGNMENT_MIDDLE_CENTER:
       case SsaStyle.SSA_ALIGNMENT_MIDDLE_RIGHT:
         return Cue.ANCHOR_TYPE_MIDDLE;
       case SsaStyle.SSA_ALIGNMENT_TOP_LEFT:
       case SsaStyle.SSA_ALIGNMENT_TOP_CENTER:
       case SsaStyle.SSA_ALIGNMENT_TOP_RIGHT:
         return Cue.ANCHOR_TYPE_START;
       case SsaStyle.SSA_ALIGNMENT_UNKNOWN:
         return Cue.TYPE_UNSET;
       default:
         Log.w(TAG, "Unknown alignment: " + alignment);
         return Cue.TYPE_UNSET;
     }
   }

   @Cue.AnchorType
   private static int toPositionAnchor(@SsaStyle.SsaAlignment int alignment) {
     switch (alignment) {
       case SsaStyle.SSA_ALIGNMENT_BOTTOM_LEFT:
       case SsaStyle.SSA_ALIGNMENT_MIDDLE_LEFT:
       case SsaStyle.SSA_ALIGNMENT_TOP_LEFT:
         return Cue.ANCHOR_TYPE_START;
       case SsaStyle.SSA_ALIGNMENT_BOTTOM_CENTER:
       case SsaStyle.SSA_ALIGNMENT_MIDDLE_CENTER:
       case SsaStyle.SSA_ALIGNMENT_TOP_CENTER:
         return Cue.ANCHOR_TYPE_MIDDLE;
       case SsaStyle.SSA_ALIGNMENT_BOTTOM_RIGHT:
       case SsaStyle.SSA_ALIGNMENT_MIDDLE_RIGHT:
       case SsaStyle.SSA_ALIGNMENT_TOP_RIGHT:
         return Cue.ANCHOR_TYPE_END;
       case SsaStyle.SSA_ALIGNMENT_UNKNOWN:
         return Cue.TYPE_UNSET;
       default:
         Log.w(TAG, "Unknown alignment: " + alignment);
         return Cue.TYPE_UNSET;
     }
   }

   private static float computeDefaultLineOrPosition(@Cue.AnchorType int anchor) {
     switch (anchor) {
       case Cue.ANCHOR_TYPE_START:
         return DEFAULT_MARGIN;
       case Cue.ANCHOR_TYPE_MIDDLE:
         return 0.5f;
       case Cue.ANCHOR_TYPE_END:
         return 1.0f - DEFAULT_MARGIN;
       case Cue.TYPE_UNSET:
       default:
         return Cue.DIMEN_UNSET;
     }
   }

   /**
    * Searches for {@code timeUs} in {@code sortedCueTimesUs}, inserting it if it's not found, and
    * returns the index.
    *
    * <p>If it's inserted, we also insert a matching entry to {@code cues}.
    */
   private static int addCuePlacerholderByTime(
       long timeUs, List<Long> sortedCueTimesUs, List<List<Cue>> cues) {
     int insertionIndex = 0;
     for (int i = sortedCueTimesUs.size() - 1; i >= 0; i--) {
       if (sortedCueTimesUs.get(i) == timeUs) {
         return i;
       }

       if (sortedCueTimesUs.get(i) < timeUs) {
         insertionIndex = i + 1;
         break;
       }
     }
     sortedCueTimesUs.add(insertionIndex, timeUs);
     // Copy over cues from left, or use an empty list if we're inserting at the beginning.
     cues.add(
         insertionIndex,
         insertionIndex == 0 ? new ArrayList<>() : new ArrayList<>(cues.get(insertionIndex - 1)));
     return insertionIndex;
   }
 }
	/*
	* Copyright (C) 2017 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.
	*/
	package com.google.android.exoplayer2.text.ssa;

	import static com.google.android.exoplayer2.text.Cue.LINE_TYPE_FRACTION;
	import static com.google.android.exoplayer2.util.Util.castNonNull;

	import android.graphics.Typeface;
	import android.text.Layout;
	import android.text.SpannableString;
	import android.text.style.ForegroundColorSpan;
	import android.text.style.StrikethroughSpan;
	import android.text.style.StyleSpan;
	import android.text.style.UnderlineSpan;
	import androidx.annotation.Nullable;
	import com.google.android.exoplayer2.C;
	import com.google.android.exoplayer2.text.Cue;
	import com.google.android.exoplayer2.text.SimpleSubtitleDecoder;
	import com.google.android.exoplayer2.text.Subtitle;
	import com.google.android.exoplayer2.util.Assertions;
	import com.google.android.exoplayer2.util.Log;
	import com.google.android.exoplayer2.util.ParsableByteArray;
	import com.google.android.exoplayer2.util.Util;
	import com.google.common.base.Ascii;
	import java.util.ArrayList;
	import java.util.LinkedHashMap;
	import java.util.List;
	import java.util.Map;
	import java.util.regex.Matcher;
	import java.util.regex.Pattern;
	import org.checkerframework.checker.nullness.qual.MonotonicNonNull;

	/** A {@link SimpleSubtitleDecoder} for SSA/ASS. */
	public final class SsaDecoder extends SimpleSubtitleDecoder {

	private static final String TAG = "SsaDecoder";

	private static final Pattern SSA_TIMECODE_PATTERN =
	Pattern.compile("(?:(\\d+):)?(\\d+):(\\d+)[:.](\\d+)");

	/* package */ static final String FORMAT_LINE_PREFIX = "Format:";
	/* package */ static final String STYLE_LINE_PREFIX = "Style:";
	private static final String DIALOGUE_LINE_PREFIX = "Dialogue:";

	private static final float DEFAULT_MARGIN = 0.05f;

	private final boolean haveInitializationData;
	@Nullable private final SsaDialogueFormat dialogueFormatFromInitializationData;

	private @MonotonicNonNull Map<String, SsaStyle> styles;

	/**
	* The horizontal resolution used by the subtitle author - all cue positions are relative to this.
	*
	* <p>Parsed from the {@code PlayResX} value in the {@code [Script Info]} section.
	*/
	private float screenWidth;
	/**
	* The vertical resolution used by the subtitle author - all cue positions are relative to this.
	*
	* <p>Parsed from the {@code PlayResY} value in the {@code [Script Info]} section.
	*/
	private float screenHeight;

	public SsaDecoder() {
	this(/* initializationData= */ null);
	}

	/**
	* Constructs an SsaDecoder with optional format and header info.
	*
	* @param initializationData Optional initialization data for the decoder. If not null or empty,
	* the initialization data must consist of two byte arrays. The first must contain an SSA
	* format line. The second must contain an SSA header that will be assumed common to all
	* samples. The header is everything in an SSA file before the {@code [Events]} section (i.e.
	* {@code [Script Info]} and optional {@code [V4+ Styles]} section.
	*/
	public SsaDecoder(@Nullable List<byte[]> initializationData) {
	super("SsaDecoder");
	screenWidth = Cue.DIMEN_UNSET;
	screenHeight = Cue.DIMEN_UNSET;

	if (initializationData != null && !initializationData.isEmpty()) {
	haveInitializationData = true;
	String formatLine = Util.fromUtf8Bytes(initializationData.get(0));
	Assertions.checkArgument(formatLine.startsWith(FORMAT_LINE_PREFIX));
	dialogueFormatFromInitializationData =
	Assertions.checkNotNull(SsaDialogueFormat.fromFormatLine(formatLine));
	parseHeader(new ParsableByteArray(initializationData.get(1)));
	} else {
	haveInitializationData = false;
	dialogueFormatFromInitializationData = null;
	}
	}

	@Override
	protected Subtitle decode(byte[] bytes, int length, boolean reset) {
	List<List<Cue>> cues = new ArrayList<>();
	List<Long> cueTimesUs = new ArrayList<>();

	ParsableByteArray data = new ParsableByteArray(bytes, length);
	if (!haveInitializationData) {
	parseHeader(data);
	}
	parseEventBody(data, cues, cueTimesUs);
	return new SsaSubtitle(cues, cueTimesUs);
	}

	/**
	* Parses the header of the subtitle.
	*
	* @param data A {@link ParsableByteArray} from which the header should be read.
	*/
	private void parseHeader(ParsableByteArray data) {
	@Nullable String currentLine;
	while ((currentLine = data.readLine()) != null) {
	if ("[Script Info]".equalsIgnoreCase(currentLine)) {
	parseScriptInfo(data);
	} else if ("[V4+ Styles]".equalsIgnoreCase(currentLine)) {
	styles = parseStyles(data);
	} else if ("[V4 Styles]".equalsIgnoreCase(currentLine)) {
	Log.i(TAG, "[V4 Styles] are not supported");
	} else if ("[Events]".equalsIgnoreCase(currentLine)) {
	// We've reached the [Events] section, so the header is over.
	return;
	}
	}
	}

	/**
	* Parse the {@code [Script Info]} section.
	*
	* <p>When this returns, {@code data.position} will be set to the beginning of the first line that
	* starts with {@code [} (i.e. the title of the next section).
	*
	* @param data A {@link ParsableByteArray} with {@link ParsableByteArray#getPosition() position}
	* set to the beginning of the first line after {@code [Script Info]}.
	*/
	private void parseScriptInfo(ParsableByteArray data) {
	@Nullable String currentLine;
	while ((currentLine = data.readLine()) != null
	&& (data.bytesLeft() == 0 \|\| data.peekUnsignedByte() != '[')) {
	String[] infoNameAndValue = currentLine.split(":");
	if (infoNameAndValue.length != 2) {
	continue;
	}
	switch (Ascii.toLowerCase(infoNameAndValue[0].trim())) {
	case "playresx":
	try {
	screenWidth = Float.parseFloat(infoNameAndValue[1].trim());
	} catch (NumberFormatException e) {
	// Ignore invalid PlayResX value.
	}
	break;
	case "playresy":
	try {
	screenHeight = Float.parseFloat(infoNameAndValue[1].trim());
	} catch (NumberFormatException e) {
	// Ignore invalid PlayResY value.
	}
	break;
	}
	}
	}

	/**
	* Parse the {@code [V4+ Styles]} section.
	*
	* <p>When this returns, {@code data.position} will be set to the beginning of the first line that
	* starts with {@code [} (i.e. the title of the next section).
	*
	* @param data A {@link ParsableByteArray} with {@link ParsableByteArray#getPosition()} pointing
	* at the beginning of the first line after {@code [V4+ Styles]}.
	*/
	private static Map<String, SsaStyle> parseStyles(ParsableByteArray data) {
	Map<String, SsaStyle> styles = new LinkedHashMap<>();
	@Nullable SsaStyle.Format formatInfo = null;
	@Nullable String currentLine;
	while ((currentLine = data.readLine()) != null
	&& (data.bytesLeft() == 0 \|\| data.peekUnsignedByte() != '[')) {
	if (currentLine.startsWith(FORMAT_LINE_PREFIX)) {
	formatInfo = SsaStyle.Format.fromFormatLine(currentLine);
	} else if (currentLine.startsWith(STYLE_LINE_PREFIX)) {
	if (formatInfo == null) {
	Log.w(TAG, "Skipping 'Style:' line before 'Format:' line: " + currentLine);
	continue;
	}
	@Nullable SsaStyle style = SsaStyle.fromStyleLine(currentLine, formatInfo);
	if (style != null) {
	styles.put(style.name, style);
	}
	}
	}
	return styles;
	}

	/**
	* Parses the event body of the subtitle.
	*
	* @param data A {@link ParsableByteArray} from which the body should be read.
	* @param cues A list to which parsed cues will be added.
	* @param cueTimesUs A sorted list to which parsed cue timestamps will be added.
	*/
	private void parseEventBody(ParsableByteArray data, List<List<Cue>> cues, List<Long> cueTimesUs) {
	@Nullable
	SsaDialogueFormat format = haveInitializationData ? dialogueFormatFromInitializationData : null;
	@Nullable String currentLine;
	while ((currentLine = data.readLine()) != null) {
	if (currentLine.startsWith(FORMAT_LINE_PREFIX)) {
	format = SsaDialogueFormat.fromFormatLine(currentLine);
	} else if (currentLine.startsWith(DIALOGUE_LINE_PREFIX)) {
	if (format == null) {
	Log.w(TAG, "Skipping dialogue line before complete format: " + currentLine);
	continue;
	}
	parseDialogueLine(currentLine, format, cues, cueTimesUs);
	}
	}
	}

	/**
	* Parses a dialogue line.
	*
	* @param dialogueLine The dialogue values (i.e. everything after {@code Dialogue:}).
	* @param format The dialogue format to use when parsing {@code dialogueLine}.
	* @param cues A list to which parsed cues will be added.
	* @param cueTimesUs A sorted list to which parsed cue timestamps will be added.
	*/
	private void parseDialogueLine(
	String dialogueLine, SsaDialogueFormat format, List<List<Cue>> cues, List<Long> cueTimesUs) {
	Assertions.checkArgument(dialogueLine.startsWith(DIALOGUE_LINE_PREFIX));
	String[] lineValues =
	dialogueLine.substring(DIALOGUE_LINE_PREFIX.length()).split(",", format.length);
	if (lineValues.length != format.length) {
	Log.w(TAG, "Skipping dialogue line with fewer columns than format: " + dialogueLine);
	return;
	}

	long startTimeUs = parseTimecodeUs(lineValues[format.startTimeIndex]);
	if (startTimeUs == C.TIME_UNSET) {
	Log.w(TAG, "Skipping invalid timing: " + dialogueLine);
	return;
	}

	long endTimeUs = parseTimecodeUs(lineValues[format.endTimeIndex]);
	if (endTimeUs == C.TIME_UNSET) {
	Log.w(TAG, "Skipping invalid timing: " + dialogueLine);
	return;
	}

	@Nullable
	SsaStyle style =
	styles != null && format.styleIndex != C.INDEX_UNSET
	? styles.get(lineValues[format.styleIndex].trim())
	: null;
	String rawText = lineValues[format.textIndex];
	SsaStyle.Overrides styleOverrides = SsaStyle.Overrides.parseFromDialogue(rawText);
	String text =
	SsaStyle.Overrides.stripStyleOverrides(rawText)
	.replace("\\N", "\n")
	.replace("\\n", "\n")
	.replace("\\h", "\u00A0");
	Cue cue = createCue(text, style, styleOverrides, screenWidth, screenHeight);

	int startTimeIndex = addCuePlacerholderByTime(startTimeUs, cueTimesUs, cues);
	int endTimeIndex = addCuePlacerholderByTime(endTimeUs, cueTimesUs, cues);
	// Iterate on cues from startTimeIndex until endTimeIndex, adding the current cue.
	for (int i = startTimeIndex; i < endTimeIndex; i++) {
	cues.get(i).add(cue);
	}
	}

	/**
	* Parses an SSA timecode string.
	*
	* @param timeString The string to parse.
	* @return The parsed timestamp in microseconds.
	*/
	private static long parseTimecodeUs(String timeString) {
	Matcher matcher = SSA_TIMECODE_PATTERN.matcher(timeString.trim());
	if (!matcher.matches()) {
	return C.TIME_UNSET;
	}
	long timestampUs =
	Long.parseLong(castNonNull(matcher.group(1))) * 60 * 60 * C.MICROS_PER_SECOND;
	timestampUs += Long.parseLong(castNonNull(matcher.group(2))) * 60 * C.MICROS_PER_SECOND;
	timestampUs += Long.parseLong(castNonNull(matcher.group(3))) * C.MICROS_PER_SECOND;
	timestampUs += Long.parseLong(castNonNull(matcher.group(4))) * 10000; // 100ths of a second.
	return timestampUs;
	}

	private static Cue createCue(
	String text,
	@Nullable SsaStyle style,
	SsaStyle.Overrides styleOverrides,
	float screenWidth,
	float screenHeight) {
	SpannableString spannableText = new SpannableString(text);
	Cue.Builder cue = new Cue.Builder().setText(spannableText);

	if (style != null) {
	if (style.primaryColor != null) {
	spannableText.setSpan(
	new ForegroundColorSpan(style.primaryColor),
	/* start= */ 0,
	/* end= */ spannableText.length(),
	SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
	}
	if (style.fontSize != Cue.DIMEN_UNSET && screenHeight != Cue.DIMEN_UNSET) {
	cue.setTextSize(
	style.fontSize / screenHeight, Cue.TEXT_SIZE_TYPE_FRACTIONAL_IGNORE_PADDING);
	}
	if (style.bold && style.italic) {
	spannableText.setSpan(
	new StyleSpan(Typeface.BOLD_ITALIC),
	/* start= */ 0,
	/* end= */ spannableText.length(),
	SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
	} else if (style.bold) {
	spannableText.setSpan(
	new StyleSpan(Typeface.BOLD),
	/* start= */ 0,
	/* end= */ spannableText.length(),
	SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
	} else if (style.italic) {
	spannableText.setSpan(
	new StyleSpan(Typeface.ITALIC),
	/* start= */ 0,
	/* end= */ spannableText.length(),
	SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
	}
	if (style.underline) {
	spannableText.setSpan(
	new UnderlineSpan(),
	/* start= */ 0,
	/* end= */ spannableText.length(),
	SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
	}
	if (style.strikeout) {
	spannableText.setSpan(
	new StrikethroughSpan(),
	/* start= */ 0,
	/* end= */ spannableText.length(),
	SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
	}
	}

	@SsaStyle.SsaAlignment int alignment;
	if (styleOverrides.alignment != SsaStyle.SSA_ALIGNMENT_UNKNOWN) {
	alignment = styleOverrides.alignment;
	} else if (style != null) {
	alignment = style.alignment;
	} else {
	alignment = SsaStyle.SSA_ALIGNMENT_UNKNOWN;
	}
	cue.setTextAlignment(toTextAlignment(alignment))
	.setPositionAnchor(toPositionAnchor(alignment))
	.setLineAnchor(toLineAnchor(alignment));

	if (styleOverrides.position != null
	&& screenHeight != Cue.DIMEN_UNSET
	&& screenWidth != Cue.DIMEN_UNSET) {
	cue.setPosition(styleOverrides.position.x / screenWidth);
	cue.setLine(styleOverrides.position.y / screenHeight, LINE_TYPE_FRACTION);
	} else {
	// TODO: Read the MarginL, MarginR and MarginV values from the Style & Dialogue lines.
	cue.setPosition(computeDefaultLineOrPosition(cue.getPositionAnchor()));
	cue.setLine(computeDefaultLineOrPosition(cue.getLineAnchor()), LINE_TYPE_FRACTION);
	}

	return cue.build();
	}

	@Nullable
	private static Layout.Alignment toTextAlignment(@SsaStyle.SsaAlignment int alignment) {
	switch (alignment) {
	case SsaStyle.SSA_ALIGNMENT_BOTTOM_LEFT:
	case SsaStyle.SSA_ALIGNMENT_MIDDLE_LEFT:
	case SsaStyle.SSA_ALIGNMENT_TOP_LEFT:
	return Layout.Alignment.ALIGN_NORMAL;
	case SsaStyle.SSA_ALIGNMENT_BOTTOM_CENTER:
	case SsaStyle.SSA_ALIGNMENT_MIDDLE_CENTER:
	case SsaStyle.SSA_ALIGNMENT_TOP_CENTER:
	return Layout.Alignment.ALIGN_CENTER;
	case SsaStyle.SSA_ALIGNMENT_BOTTOM_RIGHT:
	case SsaStyle.SSA_ALIGNMENT_MIDDLE_RIGHT:
	case SsaStyle.SSA_ALIGNMENT_TOP_RIGHT:
	return Layout.Alignment.ALIGN_OPPOSITE;
	case SsaStyle.SSA_ALIGNMENT_UNKNOWN:
	return null;
	default:
	Log.w(TAG, "Unknown alignment: " + alignment);
	return null;
	}
	}

	@Cue.AnchorType
	private static int toLineAnchor(@SsaStyle.SsaAlignment int alignment) {
	switch (alignment) {
	case SsaStyle.SSA_ALIGNMENT_BOTTOM_LEFT:
	case SsaStyle.SSA_ALIGNMENT_BOTTOM_CENTER:
	case SsaStyle.SSA_ALIGNMENT_BOTTOM_RIGHT:
	return Cue.ANCHOR_TYPE_END;
	case SsaStyle.SSA_ALIGNMENT_MIDDLE_LEFT:
	case SsaStyle.SSA_ALIGNMENT_MIDDLE_CENTER:
	case SsaStyle.SSA_ALIGNMENT_MIDDLE_RIGHT:
	return Cue.ANCHOR_TYPE_MIDDLE;
	case SsaStyle.SSA_ALIGNMENT_TOP_LEFT:
	case SsaStyle.SSA_ALIGNMENT_TOP_CENTER:
	case SsaStyle.SSA_ALIGNMENT_TOP_RIGHT:
	return Cue.ANCHOR_TYPE_START;
	case SsaStyle.SSA_ALIGNMENT_UNKNOWN:
	return Cue.TYPE_UNSET;
	default:
	Log.w(TAG, "Unknown alignment: " + alignment);
	return Cue.TYPE_UNSET;
	}
	}

	@Cue.AnchorType
	private static int toPositionAnchor(@SsaStyle.SsaAlignment int alignment) {
	switch (alignment) {
	case SsaStyle.SSA_ALIGNMENT_BOTTOM_LEFT:
	case SsaStyle.SSA_ALIGNMENT_MIDDLE_LEFT:
	case SsaStyle.SSA_ALIGNMENT_TOP_LEFT:
	return Cue.ANCHOR_TYPE_START;
	case SsaStyle.SSA_ALIGNMENT_BOTTOM_CENTER:
	case SsaStyle.SSA_ALIGNMENT_MIDDLE_CENTER:
	case SsaStyle.SSA_ALIGNMENT_TOP_CENTER:
	return Cue.ANCHOR_TYPE_MIDDLE;
	case SsaStyle.SSA_ALIGNMENT_BOTTOM_RIGHT:
	case SsaStyle.SSA_ALIGNMENT_MIDDLE_RIGHT:
	case SsaStyle.SSA_ALIGNMENT_TOP_RIGHT:
	return Cue.ANCHOR_TYPE_END;
	case SsaStyle.SSA_ALIGNMENT_UNKNOWN:
	return Cue.TYPE_UNSET;
	default:
	Log.w(TAG, "Unknown alignment: " + alignment);
	return Cue.TYPE_UNSET;
	}
	}

	private static float computeDefaultLineOrPosition(@Cue.AnchorType int anchor) {
	switch (anchor) {
	case Cue.ANCHOR_TYPE_START:
	return DEFAULT_MARGIN;
	case Cue.ANCHOR_TYPE_MIDDLE:
	return 0.5f;
	case Cue.ANCHOR_TYPE_END:
	return 1.0f - DEFAULT_MARGIN;
	case Cue.TYPE_UNSET:
	default:
	return Cue.DIMEN_UNSET;
	}
	}

	/**
	* Searches for {@code timeUs} in {@code sortedCueTimesUs}, inserting it if it's not found, and
	* returns the index.
	*
	* <p>If it's inserted, we also insert a matching entry to {@code cues}.
	*/
	private static int addCuePlacerholderByTime(
	long timeUs, List<Long> sortedCueTimesUs, List<List<Cue>> cues) {
	int insertionIndex = 0;
	for (int i = sortedCueTimesUs.size() - 1; i >= 0; i--) {
	if (sortedCueTimesUs.get(i) == timeUs) {
	return i;
	}

	if (sortedCueTimesUs.get(i) < timeUs) {
	insertionIndex = i + 1;
	break;
	}
	}
	sortedCueTimesUs.add(insertionIndex, timeUs);
	// Copy over cues from left, or use an empty list if we're inserting at the beginning.
	cues.add(
	insertionIndex,
	insertionIndex == 0 ? new ArrayList<>() : new ArrayList<>(cues.get(insertionIndex - 1)));
	return insertionIndex;
	}
	}