webmdashenc: Support for live stream manifests

This patch adds support for creating DASH manifests for WebM Live
Streams. It also updates the documentation and adds a fate test to
verify the behavior of the new muxer flag.
Signed-off-by: Vignesh Venkatasubramanian <vigneshv@google.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

doc/muxers.texi

@@ -1210,7 +1210,17 @@ is the @option{global_header} flag.
 
 WebM DASH Manifest muxer.
 
-This muxer implements the WebM DASH Manifest specification to generate the DASH manifest XML.
+This muxer implements the WebM DASH Manifest specification to generate the DASH
+manifest XML. It also supports manifest generation for DASH live streams.
+
+For more information see:
+
+@itemize @bullet
+@item
+WebM DASH Specification: @url{https://sites.google.com/a/webmproject.org/wiki/adaptive-streaming/webm-dash-specification}
+@item
+ISO DASH Specification: @url{http://standards.iso.org/ittf/PubliclyAvailableStandards/c065274_ISO_IEC_23009-1_2014.zip}
+@end itemize
 
 @subsection Options
 
@@ -1221,6 +1231,28 @@ This muxer supports the following options:
 This option has the following syntax: "id=x,streams=a,b,c id=y,streams=d,e" where x and y are the
 unique identifiers of the adaptation sets and a,b,c,d and e are the indices of the corresponding
 audio and video streams. Any number of adaptation sets can be added using this option.
+
+@item live
+Set this to 1 to create a live stream DASH Manifest. Default: 0.
+
+@item chunk_start_index
+Start index of the first chunk. This will go in the @samp{startNumber} attribute
+of the @samp{SegmentTemplate} element in the manifest. Default: 0.
+
+@item chunk_duration_ms
+Duration of each chunk in milliseconds. This will go in the @samp{duration}
+attribute of the @samp{SegmentTemplate} element in the manifest. Default: 1000.
+
+@item utc_timing_url
+URL of the page that will return the UTC timestamp in ISO format. This will go
+in the @samp{value} attribute of the @samp{UTCTiming} element in the manifest.
+Default: None.
+
+@item time_shift_buffer_depth
+Smallest time (in seconds) shifting buffer for which any Representation is
+guaranteed to be available. This will go in the @samp{timeShiftBufferDepth}
+attribute of the @samp{MPD} element. Default: 60.
+
 @end table
 
 @subsection Example

libavformat/webmdashenc.c

@@ -22,8 +22,11 @@
 /*
  * WebM DASH Specification:
  * https://sites.google.com/a/webmproject.org/wiki/adaptive-streaming/webm-dash-specification
+ * ISO DASH Specification:
+ * http://standards.iso.org/ittf/PubliclyAvailableStandards/c065274_ISO_IEC_23009-1_2014.zip
  */
 
+#include <float.h>
 #include <stdint.h>
 #include <string.h>
 
@@ -34,6 +37,7 @@
 #include "libavutil/avstring.h"
 #include "libavutil/dict.h"
 #include "libavutil/opt.h"
+#include "libavutil/time_internal.h"
 
 typedef struct AdaptationSet {
     char id[10];
@@ -47,6 +51,12 @@ typedef struct WebMDashMuxContext {
     AdaptationSet *as;
     int nb_as;
     int representation_id;
+    int is_live;
+    int chunk_start_index;
+    int chunk_duration;
+    char *utc_timing_url;
+    double time_shift_buffer_depth;
+    int debug_mode;
 } WebMDashMuxContext;
 
 static const char *get_codec_name(int codec_id)
@@ -79,19 +89,42 @@ static double get_duration(AVFormatContext *s)
 
 static void write_header(AVFormatContext *s)
 {
+    WebMDashMuxContext *w = s->priv_data;
     double min_buffer_time = 1.0;
+    time_t local_time;
+    struct tm *gmt, gmt_buffer;
+    char *gmt_iso = av_malloc(21);
     avio_printf(s->pb, "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n");
     avio_printf(s->pb, "<MPD\n");
     avio_printf(s->pb, "  xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n");
     avio_printf(s->pb, "  xmlns=\"urn:mpeg:DASH:schema:MPD:2011\"\n");
     avio_printf(s->pb, "  xsi:schemaLocation=\"urn:mpeg:DASH:schema:MPD:2011\"\n");
-    avio_printf(s->pb, "  type=\"static\"\n");
-    avio_printf(s->pb, "  mediaPresentationDuration=\"PT%gS\"\n",
-                get_duration(s));
-    avio_printf(s->pb, "  minBufferTime=\"PT%gS\"\n",
-                min_buffer_time);
-    avio_printf(s->pb, "  profiles=\"urn:webm:dash:profile:webm-on-demand:2012\"");
-    avio_printf(s->pb, ">\n");
+    avio_printf(s->pb, "  type=\"%s\"\n", w->is_live ? "dynamic" : "static");
+    if (!w->is_live) {
+        avio_printf(s->pb, "  mediaPresentationDuration=\"PT%gS\"\n",
+                    get_duration(s));
+    }
+    avio_printf(s->pb, "  minBufferTime=\"PT%gS\"\n", min_buffer_time);
+    avio_printf(s->pb, "  profiles=\"%s\"%s",
+                w->is_live ? "urn:mpeg:dash:profile:isoff-live:2011" : "urn:webm:dash:profile:webm-on-demand:2012",
+                w->is_live ? "\n" : ">\n");
+    time(&local_time);
+    gmt = gmtime_r(&local_time, &gmt_buffer);
+    strftime(gmt_iso, 21, "%FT%TZ", gmt);
+    if (w->debug_mode) {
+        av_strlcpy(gmt_iso, "", 1);
+    }
+    if (w->is_live) {
+        avio_printf(s->pb, "  availabilityStartTime=\"%s\"\n", gmt_iso);
+        avio_printf(s->pb, "  timeShiftBufferDepth=\"PT%gS\"", w->time_shift_buffer_depth);
+        avio_printf(s->pb, ">\n");
+        avio_printf(s->pb, "<UTCTiming\n");
+        avio_printf(s->pb, "  schemeIdUri=\"%s\"\n",
+                    w->utc_timing_url ? "urn:mpeg:dash:utc:http-iso:2014" : "urn:mpeg:dash:utc:direct:2012");
+        avio_printf(s->pb, "  value=\"%s\"/>\n",
+                    w->utc_timing_url ? w->utc_timing_url : gmt_iso);
+    }
+    av_free(gmt_iso);
 }
 
 static void write_footer(AVFormatContext *s)
@@ -137,33 +170,47 @@ static int bitstream_switching(AVFormatContext *s, AdaptationSet *as) {
  * Writes a Representation within an Adaptation Set. Returns 0 on success and
  * < 0 on failure.
  */
-static int write_representation(AVFormatContext *s, AVStream *stream, int id,
+static int write_representation(AVFormatContext *s, AVStream *stream, char *id,
                                 int output_width, int output_height,
                                 int output_sample_rate) {
+    WebMDashMuxContext *w = s->priv_data;
     AVDictionaryEntry *irange = av_dict_get(stream->metadata, INITIALIZATION_RANGE, NULL, 0);
     AVDictionaryEntry *cues_start = av_dict_get(stream->metadata, CUES_START, NULL, 0);
     AVDictionaryEntry *cues_end = av_dict_get(stream->metadata, CUES_END, NULL, 0);
     AVDictionaryEntry *filename = av_dict_get(stream->metadata, FILENAME, NULL, 0);
     AVDictionaryEntry *bandwidth = av_dict_get(stream->metadata, BANDWIDTH, NULL, 0);
-    if (!irange || cues_start == NULL || cues_end == NULL || filename == NULL ||
-        !bandwidth) {
+    if ((w->is_live && (!filename)) ||
+        (!w->is_live && (!irange || !cues_start || !cues_end || !filename || !bandwidth))) {
         return -1;
     }
-    avio_printf(s->pb, "<Representation id=\"%d\"", id);
-    avio_printf(s->pb, " bandwidth=\"%s\"", bandwidth->value);
+    avio_printf(s->pb, "<Representation id=\"%s\"", id);
+    // FIXME: For live, This should be obtained from the input file or as an AVOption.
+    avio_printf(s->pb, " bandwidth=\"%s\"",
+                w->is_live ? (stream->codec->codec_type == AVMEDIA_TYPE_AUDIO ? "128000" : "1000000") : bandwidth->value);
     if (stream->codec->codec_type == AVMEDIA_TYPE_VIDEO && output_width)
         avio_printf(s->pb, " width=\"%d\"", stream->codec->width);
     if (stream->codec->codec_type == AVMEDIA_TYPE_VIDEO && output_height)
         avio_printf(s->pb, " height=\"%d\"", stream->codec->height);
     if (stream->codec->codec_type = AVMEDIA_TYPE_AUDIO && output_sample_rate)
         avio_printf(s->pb, " audioSamplingRate=\"%d\"", stream->codec->sample_rate);
-    avio_printf(s->pb, ">\n");
-    avio_printf(s->pb, "<BaseURL>%s</BaseURL>\n", filename->value);
-    avio_printf(s->pb, "<SegmentBase\n");
-    avio_printf(s->pb, "  indexRange=\"%s-%s\">\n", cues_start->value, cues_end->value);
-    avio_printf(s->pb, "<Initialization\n");
-    avio_printf(s->pb, "  range=\"0-%s\" />\n", irange->value);
-    avio_printf(s->pb, "</SegmentBase>\n");
+    if (w->is_live) {
+        // For live streams, Codec and Mime Type always go in the Representation tag.
+        avio_printf(s->pb, " codecs=\"%s\"", get_codec_name(stream->codec->codec_id));
+        avio_printf(s->pb, " mimeType=\"%s/webm\"",
+                    stream->codec->codec_type == AVMEDIA_TYPE_VIDEO ? "video" : "audio");
+        // For live streams, subsegments always start with key frames. So this
+        // is always 1.
+        avio_printf(s->pb, " startsWithSAP=\"1\"");
+        avio_printf(s->pb, ">");
+    } else {
+        avio_printf(s->pb, ">\n");
+        avio_printf(s->pb, "<BaseURL>%s</BaseURL>\n", filename->value);
+        avio_printf(s->pb, "<SegmentBase\n");
+        avio_printf(s->pb, "  indexRange=\"%s-%s\">\n", cues_start->value, cues_end->value);
+        avio_printf(s->pb, "<Initialization\n");
+        avio_printf(s->pb, "  range=\"0-%s\" />\n", irange->value);
+        avio_printf(s->pb, "</SegmentBase>\n");
+    }
     avio_printf(s->pb, "</Representation>\n");
     return 0;
 }
@@ -207,6 +254,51 @@ static int check_matching_sample_rate(AVFormatContext *s, AdaptationSet *as) {
     return 1;
 }
 
+/*
+ * Parses a live header filename and computes the representation id,
+ * initialization pattern and the media pattern. Pass NULL if you don't want to
+ * compute any of those 3. Returns 0 on success and non-zero on failure.
+ *
+ * Name of the header file should conform to the following pattern:
+ * <file_description>_<representation_id>.hdr where <file_description> can be
+ * anything. The chunks should be named according to the following pattern:
+ * <file_description>_<representation_id>_<chunk_number>.chk
+ */
+static int parse_filename(char *filename, char **representation_id,
+                          char **initialization_pattern, char **media_pattern) {
+    char *underscore_pos = NULL;
+    char *period_pos = NULL;
+    char *temp_pos = NULL;
+    char *filename_str = av_strdup(filename);
+    if (!filename_str) return AVERROR(ENOMEM);
+    temp_pos = av_stristr(filename_str, "_");
+    while (temp_pos) {
+        underscore_pos = temp_pos + 1;
+        temp_pos = av_stristr(temp_pos + 1, "_");
+    }
+    if (!underscore_pos) return -1;
+    period_pos = av_stristr(underscore_pos, ".");
+    if (!period_pos) return -1;
+    *(underscore_pos - 1) = 0;
+    if (representation_id) {
+        *representation_id = av_malloc(period_pos - underscore_pos + 1);
+        if (!(*representation_id)) return AVERROR(ENOMEM);
+        av_strlcpy(*representation_id, underscore_pos, period_pos - underscore_pos + 1);
+    }
+    if (initialization_pattern) {
+        *initialization_pattern = av_asprintf("%s_$RepresentationID$.hdr",
+                                              filename_str);
+        if (!(*initialization_pattern)) return AVERROR(ENOMEM);
+    }
+    if (media_pattern) {
+        *media_pattern = av_asprintf("%s_$RepresentationID$_$Number$.chk",
+                                     filename_str);
+        if (!(*media_pattern)) return AVERROR(ENOMEM);
+    }
+    av_free(filename_str);
+    return 0;
+}
+
 /*
  * Writes an Adaptation Set. Returns 0 on success and < 0 on failure.
  */
@@ -222,13 +314,14 @@ static int write_adaptation_set(AVFormatContext *s, int as_index)
 
     // Width, Height and Sample Rate will go in the AdaptationSet tag if they
     // are the same for all contained Representations. otherwise, they will go
-    // on their respective Representation tag.
+    // on their respective Representation tag. For live streams, they always go
+    // in the Representation tag.
     int width_in_as = 1, height_in_as = 1, sample_rate_in_as = 1;
     if (codec->codec_type == AVMEDIA_TYPE_VIDEO) {
-      width_in_as = check_matching_width(s, as);
-      height_in_as = check_matching_height(s, as);
+      width_in_as = !w->is_live && check_matching_width(s, as);
+      height_in_as = !w->is_live && check_matching_height(s, as);
     } else {
-      sample_rate_in_as = check_matching_sample_rate(s, as);
+      sample_rate_in_as = !w->is_live && check_matching_sample_rate(s, as);
     }
 
     avio_printf(s->pb, "<AdaptationSet id=\"%s\"", as->id);
@@ -249,19 +342,53 @@ static int write_adaptation_set(AVFormatContext *s, int as_index)
     avio_printf(s->pb, " bitstreamSwitching=\"%s\"",
                 boolean[bitstream_switching(s, as)]);
     avio_printf(s->pb, " subsegmentAlignment=\"%s\"",
-                boolean[subsegment_alignment(s, as)]);
+                boolean[w->is_live || subsegment_alignment(s, as)]);
 
     for (i = 0; i < as->nb_streams; i++) {
         AVDictionaryEntry *kf = av_dict_get(s->streams[as->streams[i]]->metadata,
                                             CLUSTER_KEYFRAME, NULL, 0);
-        if (!kf || !strncmp(kf->value, "0", 1)) subsegmentStartsWithSAP = 0;
+        if (!w->is_live && (!kf || !strncmp(kf->value, "0", 1))) subsegmentStartsWithSAP = 0;
     }
     avio_printf(s->pb, " subsegmentStartsWithSAP=\"%d\"", subsegmentStartsWithSAP);
     avio_printf(s->pb, ">\n");
 
+    if (w->is_live) {
+        AVDictionaryEntry *filename =
+            av_dict_get(s->streams[as->streams[0]]->metadata, FILENAME, NULL, 0);
+        char *initialization_pattern = NULL;
+        char *media_pattern = NULL;
+        int ret = parse_filename(filename->value, NULL, &initialization_pattern,
+                                 &media_pattern);
+        if (ret) return ret;
+        avio_printf(s->pb, "<ContentComponent id=\"1\" type=\"%s\"/>\n",
+                    codec->codec_type == AVMEDIA_TYPE_VIDEO ? "video" : "audio");
+        avio_printf(s->pb, "<SegmentTemplate");
+        avio_printf(s->pb, " timescale=\"1000\"");
+        avio_printf(s->pb, " duration=\"%d\"", w->chunk_duration);
+        avio_printf(s->pb, " media=\"%s\"", media_pattern);
+        avio_printf(s->pb, " startNumber=\"%d\"", w->chunk_start_index);
+        avio_printf(s->pb, " initialization=\"%s\"", initialization_pattern);
+        avio_printf(s->pb, "/>\n");
+        av_free(initialization_pattern);
+        av_free(media_pattern);
+    }
+
     for (i = 0; i < as->nb_streams; i++) {
-        write_representation(s, s->streams[as->streams[i]], w->representation_id++,
+        char *representation_id = NULL;
+        if (w->is_live) {
+            AVDictionaryEntry *filename =
+                av_dict_get(s->streams[as->streams[i]]->metadata, FILENAME, NULL, 0);
+            if (!filename ||
+                parse_filename(filename->value, &representation_id, NULL, NULL)) {
+                return -1;
+            }
+        } else {
+            representation_id = av_asprintf("%d", w->representation_id++);
+            if (!representation_id) return -1;
+        }
+        write_representation(s, s->streams[as->streams[i]], representation_id,
                              !width_in_as, !height_in_as, !sample_rate_in_as);
+        av_free(representation_id);
     }
     avio_printf(s->pb, "</AdaptationSet>\n");
     return 0;
@@ -333,7 +460,9 @@ static int webm_dash_manifest_write_header(AVFormatContext *s)
     write_header(s);
     avio_printf(s->pb, "<Period id=\"0\"");
     avio_printf(s->pb, " start=\"PT%gS\"", start);
-    avio_printf(s->pb, " duration=\"PT%gS\"", get_duration(s));
+    if (!w->is_live) {
+        avio_printf(s->pb, " duration=\"PT%gS\"", get_duration(s));
+    }
     avio_printf(s->pb, " >\n");
 
     for (i = 0; i < w->nb_as; i++) {
@@ -364,6 +493,12 @@ static int webm_dash_manifest_write_trailer(AVFormatContext *s)
 #define OFFSET(x) offsetof(WebMDashMuxContext, x)
 static const AVOption options[] = {
     { "adaptation_sets", "Adaptation sets. Syntax: id=0,streams=0,1,2 id=1,streams=3,4 and so on", OFFSET(adaptation_sets), AV_OPT_TYPE_STRING, { 0 }, 0, 0, AV_OPT_FLAG_ENCODING_PARAM },
+    { "debug_mode", "[private option - users should never set this]. set this to 1 to create deterministic output", OFFSET(debug_mode), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
+    { "live", "set this to 1 to create a live stream manifest", OFFSET(is_live), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
+    { "chunk_start_index",  "start index of the chunk", OFFSET(chunk_start_index), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
+    { "chunk_duration_ms", "duration of each chunk (in milliseconds)", OFFSET(chunk_duration), AV_OPT_TYPE_INT, {.i64 = 1000}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
+    { "utc_timing_url", "URL of the page that will return the UTC timestamp in ISO format", OFFSET(utc_timing_url), AV_OPT_TYPE_STRING, { 0 }, 0, 0, AV_OPT_FLAG_ENCODING_PARAM },
+    { "time_shift_buffer_depth", "Smallest time (in seconds) shifting buffer for which any Representation is guaranteed to be available.", OFFSET(time_shift_buffer_depth), AV_OPT_TYPE_DOUBLE, { .dbl = 60.0 }, 1.0, DBL_MAX, AV_OPT_FLAG_ENCODING_PARAM },
     { NULL },
 };
 

tests/fate/vpx.mak

@@ -43,6 +43,9 @@ fate-webm-dash-manifest-unaligned-audio-streams: CMD = run ffmpeg -f webm_dash_m
 FATE_VP8-$(call DEMDEC, WEBM_DASH_MANIFEST, VP8) += fate-webm-dash-manifest-representations
 fate-webm-dash-manifest-representations: CMD = run ffmpeg -f webm_dash_manifest -i $(TARGET_SAMPLES)/vp8/dash_video1.webm -f webm_dash_manifest -i $(TARGET_SAMPLES)/vp8/dash_video4.webm -c copy -map 0 -map 1 -f webm_dash_manifest -adaptation_sets "id=0,streams=0,1" -
 
+FATE_VP8-$(call DEMDEC, WEBM_DASH_MANIFEST, VP8) += fate-webm-dash-manifest-live
+fate-webm-dash-manifest-live: CMD = run ffmpeg -f webm_dash_manifest -live 1 -i $(TARGET_SAMPLES)/vp8/dash_live_video_360.hdr -f webm_dash_manifest -live 1 -i $(TARGET_SAMPLES)/vp8/dash_live_audio_171.hdr -c copy -map 0 -map 1 -f webm_dash_manifest -live 1 -adaptation_sets "id=0,streams=0 id=1,streams=1" -chunk_start_index 1 -chunk_duration_ms 5000 -time_shift_buffer_depth 7200 -debug_mode 1 -
+
 FATE_SAMPLES_AVCONV += $(FATE_VP6-yes)
 fate-vp6: $(FATE_VP6-yes)
 

tests/ref/fate/webm-dash-manifest-live

+<?xml version="1.0" encoding="UTF-8"?>
+<MPD
+  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xmlns="urn:mpeg:DASH:schema:MPD:2011"
+  xsi:schemaLocation="urn:mpeg:DASH:schema:MPD:2011"
+  type="dynamic"
+  minBufferTime="PT1S"
+  profiles="urn:mpeg:dash:profile:isoff-live:2011"
+  availabilityStartTime=""
+  timeShiftBufferDepth="PT7200S">
+<UTCTiming
+  schemeIdUri="urn:mpeg:dash:utc:direct:2012"
+  value=""/>
+<Period id="0" start="PT0S" >
+<AdaptationSet id="0" mimeType="video/webm" codecs="vp9" bitstreamSwitching="true" subsegmentAlignment="true" subsegmentStartsWithSAP="1">
+<ContentComponent id="1" type="video"/>
+<SegmentTemplate timescale="1000" duration="5000" media="dash_live_video_$RepresentationID$_$Number$.chk" startNumber="1" initialization="dash_live_video_$RepresentationID$.hdr"/>
+<Representation id="360" bandwidth="1000000" width="640" height="360" codecs="vp9" mimeType="video/webm" startsWithSAP="1"></Representation>
+</AdaptationSet>
+<AdaptationSet id="1" mimeType="audio/webm" codecs="vorbis" bitstreamSwitching="true" subsegmentAlignment="true" subsegmentStartsWithSAP="1">
+<ContentComponent id="1" type="audio"/>
+<SegmentTemplate timescale="1000" duration="5000" media="dash_live_audio_$RepresentationID$_$Number$.chk" startNumber="1" initialization="dash_live_audio_$RepresentationID$.hdr"/>
+<Representation id="171" bandwidth="128000" audioSamplingRate="32000" codecs="vorbis" mimeType="audio/webm" startsWithSAP="1"></Representation>
+</AdaptationSet>
+</Period>
+</MPD>