@@ -61,6 +61,7 @@ typedef struct OutputStream {

     AVFormatContext *ctx;

     int ctx_inited, as_idx;

     AVIOContext *out;

+    char format_name[8];

     int packets_written;

     char initfile[1024];

     int64_t init_start_pos, pos;

@@ -101,12 +102,32 @@ typedef struct DASHContext {

     const char *utc_timing_url;

 } DASHContext;

-// RFC 6381

+static struct codec_string {

+    int id;

+    const char *str;

+} codecs[] = {

+    { AV_CODEC_ID_VP8, "vp8" },

+    { AV_CODEC_ID_VP9, "vp9" },

+    { AV_CODEC_ID_VORBIS, "vorbis" },

+    { AV_CODEC_ID_OPUS, "opus" },

+    { 0, NULL }

+};

+

 static void set_codec_str(AVFormatContext *s, AVCodecParameters *par,

                           char *str, int size)

 {

     const AVCodecTag *tags[2] = { NULL, NULL };

     uint32_t tag;

+    int i;

+

+    // common Webm codecs are not part of RFC 6381

+    for (i = 0; codecs[i].id; i++)

+        if (codecs[i].id == par->codec_id) {

+            av_strlcpy(str, codecs[i].str, size);

+            return;

+        }

+

+    // for codecs part of RFC 6381

     if (par->codec_type == AVMEDIA_TYPE_VIDEO)

         tags[0] = ff_codec_movvideo_tags;

     else if (par->codec_type == AVMEDIA_TYPE_AUDIO)

@@ -189,6 +210,21 @@ static int flush_dynbuf(OutputStream *os, int *range_length)

     return avio_open_dyn_buf(&os->ctx->pb);

 }

+static int flush_init_segment(AVFormatContext *s, OutputStream *os)

+{

+    DASHContext *c = s->priv_data;

+    int ret, range_length;

+

+    ret = flush_dynbuf(os, &range_length);

+    if (ret < 0)

+        return ret;

+

+    os->pos = os->init_range_length = range_length;

+    if (!c->single_file)

+        ff_format_io_close(s, &os->out);

+    return 0;

+}

+

 static void dash_free(AVFormatContext *s)

 {

     DASHContext *c = s->priv_data;

@@ -376,14 +412,14 @@ static int write_adaptation_set(AVFormatContext *s, AVIOContext *out, int as_ind

         if (as->media_type == AVMEDIA_TYPE_VIDEO) {

             AVStream *st = s->streams[i];

-            avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"video/mp4\" codecs=\"%s\"%s width=\"%d\" height=\"%d\"",

-                i, os->codec_str, os->bandwidth_str, s->streams[i]->codecpar->width, s->streams[i]->codecpar->height);

+            avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"video/%s\" codecs=\"%s\"%s width=\"%d\" height=\"%d\"",

+                i, os->format_name, os->codec_str, os->bandwidth_str, s->streams[i]->codecpar->width, s->streams[i]->codecpar->height);

             if (st->avg_frame_rate.num)

                 avio_printf(out, " frameRate=\"%d/%d\"", st->avg_frame_rate.num, st->avg_frame_rate.den);

             avio_printf(out, ">\n");

         } else {

-            avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"audio/mp4\" codecs=\"%s\"%s audioSamplingRate=\"%d\">\n",

-                i, os->codec_str, os->bandwidth_str, s->streams[i]->codecpar->sample_rate);

+            avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"audio/%s\" codecs=\"%s\"%s audioSamplingRate=\"%d\">\n",

+                i, os->format_name, os->codec_str, os->bandwidth_str, s->streams[i]->codecpar->sample_rate);

             avio_printf(out, "\t\t\t\t<AudioChannelConfiguration schemeIdUri=\"urn:mpeg:dash:23003:3:audio_channel_configuration:2011\" value=\"%d\" />\n",

                 s->streams[i]->codecpar->channels);

         }

@@ -628,11 +664,18 @@ static int dict_copy_entry(AVDictionary **dst, const AVDictionary *src, const ch

     return 0;

 }

+static int dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags)

+{

+    char valuestr[22];

+    snprintf(valuestr, sizeof(valuestr), "%"PRId64, value);

+    flags &= ~AV_DICT_DONT_STRDUP_VAL;

+    return av_dict_set(pm, key, valuestr, flags);

+}

+

 static int dash_init(AVFormatContext *s)

 {

     DASHContext *c = s->priv_data;

     int ret = 0, i;

-    AVOutputFormat *oformat;

     char *ptr;

     char basename[1024];

@@ -656,10 +699,6 @@ static int dash_init(AVFormatContext *s)

     if (ptr)

         *ptr = '\0';

-    oformat = av_guess_format("mp4", NULL, NULL);

-    if (!oformat)

-        return AVERROR_MUXER_NOT_FOUND;

-

     c->streams = av_mallocz(sizeof(*c->streams) * s->nb_streams);

     if (!c->streams)

         return AVERROR(ENOMEM);

@@ -694,8 +733,22 @@ static int dash_init(AVFormatContext *s)

         ctx = avformat_alloc_context();

         if (!ctx)

             return AVERROR(ENOMEM);

+

+        // choose muxer based on codec: webm for VP8/9 and opus, mp4 otherwise

+        // note: os->format_name is also used as part of the mimetype of the

+        //       representation, e.g. video/<format_name>

+        if (s->streams[i]->codecpar->codec_id == AV_CODEC_ID_VP8 ||

+            s->streams[i]->codecpar->codec_id == AV_CODEC_ID_VP9 ||

+            s->streams[i]->codecpar->codec_id == AV_CODEC_ID_OPUS ||

+            s->streams[i]->codecpar->codec_id == AV_CODEC_ID_VORBIS) {

+            snprintf(os->format_name, sizeof(os->format_name), "webm");

+        } else {

+            snprintf(os->format_name, sizeof(os->format_name), "mp4");

+        }

+        ctx->oformat = av_guess_format(os->format_name, NULL, NULL);

+        if (!ctx->oformat)

+            return AVERROR_MUXER_NOT_FOUND;

         os->ctx = ctx;

-        ctx->oformat = oformat;

         ctx->interrupt_callback = s->interrupt_callback;

         ctx->opaque             = s->opaque;

         ctx->io_close           = s->io_close;

@@ -726,8 +779,13 @@ static int dash_init(AVFormatContext *s)

             return ret;

         os->init_start_pos = 0;

-        av_dict_set(&opts, "movflags", "frag_custom+dash+delay_moov", 0);

-        if ((ret = avformat_init_output(ctx, &opts)) < 0)

+        if (!strcmp(os->format_name, "mp4")) {

+            av_dict_set(&opts, "movflags", "frag_custom+dash+delay_moov", 0);

+        } else {

+            dict_set_int(&opts, "cluster_time_limit", c->min_seg_duration / 1000, 0);

+            dict_set_int(&opts, "cluster_size_limit", 5 * 1024 * 1024, 0); // set a large cluster size limit

+        }

+        if ((ret = avformat_write_header(ctx, &opts)) < 0)

             return ret;

         os->ctx_inited = 1;

         avio_flush(ctx->pb);

@@ -735,6 +793,13 @@ static int dash_init(AVFormatContext *s)

         av_log(s, AV_LOG_VERBOSE, "Representation %d init segment will be written to: %s\n", i, filename);

+        // Flush init segment

+        // except for mp4, since delay_moov is set and the init segment

+        // is then flushed after the first packets

+        if (strcmp(os->format_name, "mp4")) {

+            flush_init_segment(s, os);

+        }

+

         s->streams[i]->time_base = st->time_base;

         // If the muxer wants to shift timestamps, request to have them shifted

         // already before being handed to this muxer, so we don't have mismatches

@@ -907,12 +972,7 @@ static int dash_flush(AVFormatContext *s, int final, int stream)

         }

         if (!os->init_range_length) {

-            ret = flush_dynbuf(os, &range_length);

-            if (ret < 0)

-                break;

-            os->pos = os->init_range_length = range_length;

-            if (!c->single_file)

-                ff_format_io_close(s, &os->out);

+            flush_init_segment(s, os);

         }

         if (!c->single_file) {

@@ -922,7 +982,8 @@ static int dash_flush(AVFormatContext *s, int final, int stream)

             ret = s->io_open(s, &os->out, temp_path, AVIO_FLAG_WRITE, NULL);

             if (ret < 0)

                 break;

-            write_styp(os->ctx->pb);

+            if (!strcmp(os->format_name, "mp4"))

+                write_styp(os->ctx->pb);

         } else {

             snprintf(full_path, sizeof(full_path), "%s%s", c->dirname, os->initfile);

         }

@@ -33,7 +33,7 @@

 // Also please add any ticket numbers that you believe might be affected here

 #define LIBAVFORMAT_VERSION_MAJOR  57

 #define LIBAVFORMAT_VERSION_MINOR  82

-#define LIBAVFORMAT_VERSION_MICRO 101

+#define LIBAVFORMAT_VERSION_MICRO 102

 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \

                                                LIBAVFORMAT_VERSION_MINOR, \