/**
   * Copies the content of the most recently received packet into <tt>data</tt>.
   *
   * @param buffer an optional <tt>Buffer</tt> instance associated with the specified <tt>data</tt>,
   *     <tt>offset</tt> and <tt>length</tt> and provided to the method in case the implementation
   *     would like to provide additional <tt>Buffer</tt> properties such as <tt>flags</tt>
   * @param data the <tt>byte[]</tt> that we'd like to copy the content of the packet to.
   * @param offset the position where we are supposed to start writing in <tt>data</tt>.
   * @param length the number of <tt>byte</tt>s available for writing in <tt>data</tt>.
   * @return the number of bytes read
   * @throws IOException if <tt>length</tt> is less than the size of the packet.
   */
  protected int read(Buffer buffer, byte[] data, int offset, int length) throws IOException {
    if (data == null) throw new NullPointerException("data");

    if (ioError) return -1;

    RawPacket pkt;

    synchronized (pktSyncRoot) {
      pkt = this.pkt;
      this.pkt = null;
    }

    int pktLength;

    if (pkt == null) {
      pktLength = 0;
    } else {
      // By default, pkt will be returned to the pool after it was read.
      boolean poolPkt = true;

      try {
        pktLength = pkt.getLength();
        if (length < pktLength) {
          /*
           * If pkt is still the latest RawPacket made available to
           * reading, reinstate it for the next invocation of read;
           * otherwise, return it to the pool.
           */
          poolPkt = false;
          throw new IOException("Input buffer not big enough for " + pktLength);
        } else {
          byte[] pktBuffer = pkt.getBuffer();

          if (pktBuffer == null) {
            throw new NullPointerException(
                "pkt.buffer null, pkt.length " + pktLength + ", pkt.offset " + pkt.getOffset());
          } else {
            System.arraycopy(pkt.getBuffer(), pkt.getOffset(), data, offset, pktLength);
            if (buffer != null) buffer.setFlags(pkt.getFlags());
          }
        }
      } finally {
        if (!poolPkt) {
          synchronized (pktSyncRoot) {
            if (this.pkt == null) this.pkt = pkt;
            else poolPkt = true;
          }
        }
        if (poolPkt) {
          // Return pkt to the pool because it was successfully read.
          poolRawPacket(pkt);
        }
      }
    }

    return pktLength;
  }
    public VideoTrack(PullSourceStream stream) throws ResourceUnavailableException {
      super();

      this.stream = stream;
      // set format

      // read first frame to determine format
      final Buffer buffer = new Buffer();
      readFrame(buffer);
      if (buffer.isDiscard() || buffer.isEOM())
        throw new ResourceUnavailableException("Unable to read first frame");
      // TODO: catch runtime exception too?

      // parse jpeg
      final java.awt.Image image;
      try {
        image =
            ImageIO.read(
                new ByteArrayInputStream(
                    (byte[]) buffer.getData(), buffer.getOffset(), buffer.getLength()));
      } catch (IOException e) {
        logger.log(Level.WARNING, "" + e, e);
        throw new ResourceUnavailableException("Error reading image: " + e);
      }

      if (image == null) {
        logger.log(Level.WARNING, "Failed to read image (ImageIO.read returned null).");
        throw new ResourceUnavailableException();
      }

      if (frameContentType.equals("image/jpeg"))
        format =
            new JPEGFormat(
                new Dimension(image.getWidth(null), image.getHeight(null)),
                Format.NOT_SPECIFIED,
                Format.byteArray,
                -1.f,
                Format.NOT_SPECIFIED,
                Format.NOT_SPECIFIED);
      else if (frameContentType.equals("image/gif"))
        format =
            new GIFFormat(
                new Dimension(image.getWidth(null), image.getHeight(null)),
                Format.NOT_SPECIFIED,
                Format.byteArray,
                -1.f);
      else if (frameContentType.equals("image/png"))
        format =
            new PNGFormat(
                new Dimension(image.getWidth(null), image.getHeight(null)),
                Format.NOT_SPECIFIED,
                Format.byteArray,
                -1.f);
      else
        throw new ResourceUnavailableException(
            "Unsupported frame content type: " + frameContentType);
      // TODO: this discards first image. save and return first time
      // readFrame is called.

    }
    @Override
    public void readFrame(Buffer buffer) {
      // example data:
      // --ssBoundary8345
      // Content-Type: image/jpeg
      // Content-Length: 114587

      try {
        String line;
        // eat leading blank lines
        while (true) {
          line = readLine(MAX_LINE_LENGTH);
          if (line == null) {
            buffer.setEOM(true);
            buffer.setLength(0);
            return;
          }

          if (!line.trim().equals("")) break; // end of header
        }

        if (boundary == null) {
          boundary = line.trim(); // TODO: we should be able to get
          // this from the content type, but
          // the content type has this
          // stripped out. So we'll just take
          // the first nonblank line to be the
          // boundary.
          // System.out.println("boundary: " + boundary);
        } else {
          if (!line.trim().equals(boundary)) {
            // throw new IOException("Expected boundary: " +
            // toPrintable(line));
            // TODO: why do we seem to get these when playing back
            // mmr files recorded using FmjTranscode?
            logger.warning("Expected boundary (frame " + framesRead + "): " + toPrintable(line));

            // handle streams that are truncated in the middle of a
            // frame:
            final int eatResult = eatUntil(boundary); // TODO: no
            // need to
            // store the
            // data

            logger.info(
                "Ignored bytes (eom after="
                    + (eatResult < 0)
                    + "): "
                    + (eatResult < 0 ? (-1 * eatResult - 1) : eatResult));
            if (eatResult < 0) {
              buffer.setEOM(true);
              buffer.setLength(0);
              return;
            }

            // now read boundary
            line = readLine(MAX_LINE_LENGTH);
            if (!line.trim().equals(boundary)) {
              throw new RuntimeException("No boundary found after eatUntil(boundary)"); // should
              // never
              // happen
            }
          }
        }

        final Properties properties = new Properties();

        while (true) {
          line = readLine(MAX_LINE_LENGTH);
          if (line == null) {
            buffer.setEOM(true);
            buffer.setLength(0);
            return;
          }

          if (line.trim().equals("")) break; // end of header

          if (!parseProperty(line, properties))
            throw new IOException("Expected property: " + toPrintable(line));
        }

        final String contentType = properties.getProperty("Content-Type".toUpperCase());
        if (contentType == null) {
          logger.warning("Header properties: " + properties);
          throw new IOException("Expected Content-Type in header");
        }

        // check supported content types:
        if (!isSupportedFrameContentType(contentType)) {
          throw new IOException("Unsupported Content-Type: " + contentType);
        }

        if (frameContentType == null) {
          frameContentType = contentType;
        } else {
          if (!contentType.equals(frameContentType))
            throw new IOException(
                "Content type changed during stream from "
                    + frameContentType
                    + " to "
                    + contentType);
        }

        // TODO: check that size doesn't change throughout

        final byte[] data;

        final String contentLenStr = properties.getProperty("Content-Length".toUpperCase());
        if (contentLenStr != null) { // if we know the content length, use it
          final int contentLen;
          try {
            contentLen = Integer.parseInt(contentLenStr);
          } catch (NumberFormatException e) {
            throw new IOException("Invalid content length: " + contentLenStr);
          }

          // now, read the content-length bytes
          data = readFully(contentLen); // TODO: don't realloc each
          // time
        } else {
          // if we don't know the content length, just read until we
          // find the boundary.
          // Some IP cameras don't specify it, like
          // http://webcam-1.duesseldorf.it-on.net/cgi-bin/nph-update.cgi
          data = readUntil(boundary);
        }

        // ext
        final String timestampStr = properties.getProperty(TIMESTAMP_KEY.toUpperCase());
        if (timestampStr != null) {
          try {
            final long timestamp = Long.parseLong(timestampStr);
            buffer.setTimeStamp(timestamp);

          } catch (NumberFormatException e) {
            logger.log(Level.WARNING, "" + e, e);
          }
        }

        if (data == null) {
          buffer.setEOM(true);
          buffer.setLength(0);
          return;
        }

        buffer.setData(data);
        buffer.setOffset(0);
        buffer.setLength(data.length);
        ++framesRead;

      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
    @Override
    public void read(Buffer buffer) throws IOException {
      pbs.read(buffer);

      // Remap the time stamps so it won't wrap around
      // while changing to a new file.
      if (buffer.getTimeStamp() != Buffer.TIME_UNKNOWN) {
        long diff = buffer.getTimeStamp() - lastTS;
        lastTS = buffer.getTimeStamp();
        if (diff > 0) timeStamp += diff;
        buffer.setTimeStamp(timeStamp);
      }

      // If this track is to be used as the master time base,
      // we'll need to compute the master time based on this track.
      if (useAsMaster) {
        if (buffer.getFormat() instanceof AudioFormat) {
          AudioFormat af = (AudioFormat) buffer.getFormat();
          masterAudioLen += buffer.getLength();
          long t = af.computeDuration(masterAudioLen);
          if (t > 0) {
            masterTime = t;
          } else {
            masterTime = buffer.getTimeStamp();
          }
        } else {
          masterTime = buffer.getTimeStamp();
        }
      }

      if (buffer.isEOM()) {
        tInfo.done = true;
        if (!ds.handleEOM(tInfo)) {
          // This is not the last processor to be done.
          // We'll need to un-set the EOM flag.
          buffer.setEOM(false);
          buffer.setDiscard(true);
        }
      }
    }