diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 50c34db..6f54495 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -1358,6 +1358,14 @@ enum AVPacketSideDataType {
     AV_PKT_DATA_ENCRYPTION_INFO,
 
     /**
+     * This side data contains timeline entries for a given stream. This type
+     * will only apear as stream side data.
+     *
+     * The format is not part of the ABI, use av_timeline_* method to access.
+     */
+    AV_PKT_DATA_TIMELINE,
+
+    /**
      * The number of side data types.
      * This is not part of the public API/ABI in the sense that it may
      * change when new side data types are added.
diff --git a/libavutil/timeline.h b/libavutil/timeline.h
new file mode 100644
index 0000000..f1f3e1b
--- /dev/null
+++ b/libavutil/timeline.h
@@ -0,0 +1,160 @@
+/*
+ * Copyright (C) 2018 Derek Buitenhuis
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVUTIL_TIMELINE_H
+#define AVUTIL_TIMELINE_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "rational.h"
+
+typedef struct AVTimelineEntry {
+    /**
+     * The start time of the given timeline entry, in stream timebase units.
+     * If this value is AV_NOPTS_VALUE, you must display black for the duration
+     * of the entry. For audio, silence must be played.
+     */
+    int64_t start;
+
+    /**
+     * The duration of the given timeline entry, in steam timebase units.
+     */
+    int64_t duration;
+
+    /**
+     * The rate at which this entry should be played back. The value is a multipier
+     * of the stream's rate, for example: 1.2 means play back this entry at 1.2x speed.
+     * If this value is 0, then the first sample (located at 'start') must be displayed
+     * for the duration of the entry.
+     */
+    AVRational media_rate;
+} AVTimelineEntry;
+
+/**
+ * Describes a timeline for a stream in terms of edits/entries. Each entry must be
+ * played back in order, according to the information in each. Each stream may have
+ * multiple timelines which need to be correlated between different streams.
+ */
+typedef struct AVTimeline {
+    /**
+     * The ID of a given timeline. Since each stream may have multiple timelines
+     * defined, this value is used to correlated different streams' timelines
+     * which should be used together. For example, if one has two streams,
+     * one video, and one audio, with two timelines each, the timelines
+     * with matching IDs should be used in conjuction, to assure everything
+     * is in sync and matches. The concept is similar to that of EditionUID
+     * in Matroska.
+     */
+    uint32_t id;
+
+    /**
+     * An in-order array of entries for the given timeline.
+     * Each entry contains information on which samples to display for a
+     * particular edit.
+     */
+    AVTimelineEntry *entries;
+
+    /**
+     * Number of entries in the timeline.
+     */
+    size_t entry_count;
+} AVTimeline;
+
+typedef struct AVTimelineList {
+    /**
+     * An array of timelines associated with the stream.
+     */
+    AVTimeline *timelines;
+
+    /**
+     * Then number of timelines associated with the stream.
+     */
+    size_t timeline_count;
+} AVTimelineList;
+
+/**
+ * Allocates an AVTimeline strcture with the requested number of entires.
+ *
+ * @param entry_count The number of entries in the timeline.
+ *
+ * @return The new AVTimeline structure, or NULL on error.
+ */
+AVTimeline *av_timeline_alloc(size_t entry_count);
+
+
+/**
+ * Frees an AVTimeline structure and its members.
+ *
+ * @param timeline The AVTimeline structure to free.
+ */
+void av_timeline_free(AVTimeline *timeline);
+
+/**
+ * Allocates an AVTimeline strcture with room for the request number of timelines.
+ *
+ * @param timeline_count The number of entries in the timeline.
+ *
+ * @return The new AVTimelineList structure, or NULL on error.
+ */
+AVTimelineList *av_timeline_list_alloc(size_t timeline_count);
+
+
+/**
+ * Frees an AVTimelineList structure and its timelines, and their entries.
+ *
+ * @param timeline_list The AVTimelineList structure to free.
+ */
+void av_timeline_list_free(AVTimeline *timeline_list);
+
+/**
+ * Allocates a new AVTimelineList structure and copies the data from an
+ * existing structure, allocating new members.
+ *
+ * @param timeline_list The existing AVTimelineList structure to copy data from.
+ *
+ * @return The new AVTimelineList structure, or NULL on error.
+ */
+AVTimelineList *av_timeline_list_clone(const AVTimelineList *timeline_list);
+
+/**
+ * Creates a copy of the AVTimelineList that is contained in the given side
+ * data. The resulting struct should be passed to av_timeline_list_free()
+ * when done.
+ *
+ * @param side_data The side data array.
+ * @param side_data_size The size of the side data array.
+ *
+ * @return The new AVTimelineList structure, or NULL on error.
+ */
+AVTimelineList *av_timeline_list_get_side_data(const uint8_t *side_data, size_t side_data_size);
+
+/**
+ * Allocates and initializes side data that holds a copy of the given timeline
+ * list. The resulting pointer should be either freed using av_free() or given
+ * to av_packet_add_side_data().
+ *
+ * @param timeline_list The AVTimelineList to put into side data.
+ * @param side_data_size A pointer to where the size can be filled in.
+ *
+ * @return The new side-data pointer, or NULL.
+ */
+uint8_t *av_timeline_list_add_side_data(const AVTimelineList *timeline_list, size_t *side_data_size);
+
