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niandeng
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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package org.mangui.hls.flv {
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import flash.utils.ByteArray;
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/** Metadata needed to build an FLV tag. **/
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public class FLVTag {
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/** AAC Header Type ID. **/
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public static const AAC_HEADER : int = 0;
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/** AAC Data Type ID. **/
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public static const AAC_RAW : int = 1;
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/** AVC Header Type ID. **/
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public static const AVC_HEADER : int = 2;
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/** AVC Data Type ID. **/
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public static const AVC_NALU : int = 3;
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/** MP3 Data Type ID. **/
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public static const MP3_RAW : int = 4;
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/** Discontinuity Data Type ID. **/
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public static const DISCONTINUITY : int = 5;
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/** metadata Type ID. **/
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public static const METADATA : int = 6;
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/* FLV TAG TYPE */
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private static const TAG_TYPE_AUDIO : int = 8;
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private static const TAG_TYPE_VIDEO : int = 9;
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private static const TAG_TYPE_SCRIPT : int = 18;
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/** Is this a keyframe. **/
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public var keyframe : Boolean;
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/** Array with data pointers. **/
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protected var pointers : Vector.<TagData> = new Vector.<TagData>();
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/** PTS of this frame. **/
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public var pts : Number;
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/** DTS of this frame. **/
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public var dts : Number;
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/** Type of FLV tag.**/
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public var type : int;
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/* built data */
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protected var builtData : ByteArray;
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/* payload length */
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protected var length : int;
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/** Get the FLV file header. **/
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public static function getHeader() : ByteArray {
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var flv : ByteArray = new ByteArray();
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flv.length = 13;
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// "F" + "L" + "V".
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flv.writeByte(0x46);
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flv.writeByte(0x4C);
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flv.writeByte(0x56);
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// File version (1)
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flv.writeByte(1);
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/*
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Signal that both Audio and Video tags are present. this is needed as getHeader() is used when injecting discontinuity
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if we don't signal both, there will be issues while switching between AV stream to Video Only or vice versa
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*/
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flv.writeByte(5);
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// Length of the header.
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flv.writeUnsignedInt(9);
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// PreviousTagSize0
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flv.writeUnsignedInt(0);
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return flv;
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}
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/** Get an FLV Tag header (11 bytes). **/
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private static function updateTagHeader(tag: ByteArray, type : int, length : int, stamp : int) : void {
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if(tag.length == 0) {
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// set exact length only if not specified already
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tag.length = 11+length+4;
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}
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tag.writeByte(type);
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// Size of the tag in bytes after StreamID.
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tag.writeByte(length >> 16);
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tag.writeByte(length >> 8);
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tag.writeByte(length);
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// Timestamp (lower 24 plus upper 8)
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tag.writeByte(stamp >> 16);
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tag.writeByte(stamp >> 8);
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tag.writeByte(stamp);
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tag.writeByte(stamp >> 24);
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// StreamID (3 empty bytes)
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tag.writeByte(0);
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tag.writeByte(0);
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tag.writeByte(0);
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// All done
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return;
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}
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/** Save the frame data and parameters. **/
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public function FLVTag(typ : int, stp_p : Number, stp_d : Number, key : Boolean) {
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type = typ;
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pts = stp_p;
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dts = stp_d;
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keyframe = key;
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length = 0;
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}
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/** Returns the tag data. **/
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public function get data() : ByteArray {
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if(builtData) {
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// update header (PTS/DTS may have changed because of keyframe/accurate seeking)
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buildHeader(builtData);
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} else {
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build();
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}
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return builtData;
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}
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/** Build tag data (including header) **/
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public function build() : void {
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if(!builtData) {
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var array : ByteArray = new ByteArray();
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buildHeader(array);
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if(pointers) {
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for each(var pointer : TagData in pointers) {
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if (type == AVC_NALU) {
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array.writeUnsignedInt(pointer.length);
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}
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array.writeBytes(pointer.array, pointer.start, pointer.length);
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}
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// save memory, free pointers (PES payload)
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pointers = null;
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}
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// Write previousTagSize and return data.
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array.writeUnsignedInt(array.length);
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builtData = array;
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}
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}
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/** build/update FLV tag header **/
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private function buildHeader(array : ByteArray) : void {
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/* following specification http://download.macromedia.com/f4v/video_file_format_spec_v10_1.pdf */
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// Render header data
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// ensure that we are at the beginning , for update case
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array.position = 0;
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if (type == FLVTag.MP3_RAW) {
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updateTagHeader(array,TAG_TYPE_AUDIO, length + 1, pts);
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// Presume MP3 is 44.1 stereo.
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array.writeByte(0x2F);
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} else if (type == AVC_HEADER || type == AVC_NALU) {
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updateTagHeader(array,TAG_TYPE_VIDEO, length + 5, dts);
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// keyframe/interframe switch (0x10 / 0x20) + AVC (0x07)
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keyframe ? array.writeByte(0x17) : array.writeByte(0x27);
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/* AVC Packet Type :
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0 = AVC sequence header
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1 = AVC NALU
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2 = AVC end of sequence (lower level NALU sequence ender is
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not required or supported) */
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type == AVC_HEADER ? array.writeByte(0x00) : array.writeByte(0x01);
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// CompositionTime (in ms)
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// CONFIG::LOGGING {
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// Log.info("pts:"+pts+",dts:"+dts+",delta:"+compositionTime);
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// }
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var compositionTime : Number = (pts - dts);
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array.writeByte(compositionTime >> 16);
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array.writeByte(compositionTime >> 8);
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array.writeByte(compositionTime);
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} else if (type == DISCONTINUITY || type == METADATA) {
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updateTagHeader(array,FLVTag.TAG_TYPE_SCRIPT, length, pts);
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} else {
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updateTagHeader(array,TAG_TYPE_AUDIO, length + 2, pts);
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// SoundFormat, -Rate, -Size, Type and Header/Raw switch.
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array.writeByte(0xAF);
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type == AAC_HEADER ? array.writeByte(0x00) : array.writeByte(0x01);
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}
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return;
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}
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CONFIG::LOGGING {
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public function get typeString() : String {
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switch(type) {
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case AAC_HEADER:
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return "AAC_HEADER";
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case AAC_RAW :
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return "AAC_RAW";
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case AVC_HEADER:
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return "AVC_HEADER";
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case AVC_NALU:
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if(keyframe) {
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return "AVC_NALU_K";
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} else {
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return "AVC_NALU";
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}
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case MP3_RAW:
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return "MP3_RAW";
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case DISCONTINUITY:
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return "DISCONTINUITY";
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case METADATA:
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return "METADATA";
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default:
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return "";
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}
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}
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}
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/** push a data pointer into the frame. **/
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public function push(array : ByteArray, start : int, len : int) : void {
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if(len) {
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pointers.push(new TagData(array, start, len));
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length += len;
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if (type == AVC_NALU) {
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length += 4;
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}
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}
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}
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/** Trace the contents of this tag. **/
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public function toString() : String {
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return "TAG (type: " + type + ", pts:" + pts + ", dts:" + dts + ", length:" + length + ")";
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}
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public function clone() : FLVTag {
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var cloned : FLVTag = new FLVTag(this.type, this.pts, this.dts, this.keyframe);
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cloned.builtData = this.builtData;
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cloned.pointers = this.pointers;
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cloned.length = this.length;
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return cloned;
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}
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}
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}
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/** Tag Content **/
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class TagData {
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import flash.utils.ByteArray;
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public var array : ByteArray;
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public var start : int;
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public var length : int;
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public function TagData(array : ByteArray, start : int, length : int) {
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this.array = array;
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this.start = start;
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this.length = length;
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}
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}
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