[FFmpeg-devel] [PATCH v3 1/3] lavf/dashdec: Prepare DASH decoder for multithreading

[Lukas Fellechner]

For adding multithreading to the DASH decoder initialization,
the open_demux_for_component() method must be split up into two parts:

begin_open_demux_for_component(): Opens the stream and does probing
and format detection. This can be run in parallel.

end_open_demux_for_component(): Creates the AVStreams and adds
them to the common parent AVFormatContext. This method must always be
run synchronously, after all threads are finished.
---
 libavformat/dashdec.c | 42 ++++++++++++++++++++++++++++++------------
 1 file changed, 30 insertions(+), 12 deletions(-)

diff --git a/libavformat/dashdec.c b/libavformat/dashdec.c
index 63bf7e96a5..e82da45e43 100644
--- a/libavformat/dashdec.c
+++ b/libavformat/dashdec.c
@@ -1918,10 +1918,9 @@ fail:
     return ret;
 }

-static int open_demux_for_component(AVFormatContext *s, struct representation *pls)
+static int begin_open_demux_for_component(AVFormatContext *s, struct representation *pls)
 {
     int ret = 0;
-    int i;

     pls->parent = s;
     pls->cur_seq_no  = calc_cur_seg_no(s, pls);
@@ -1931,9 +1930,15 @@ static int open_demux_for_component(AVFormatContext *s, struct representation *p
     }

     ret = reopen_demux_for_component(s, pls);
-    if (ret < 0) {
-        goto fail;
-    }
+
+    return ret;
+}
+
+static int end_open_demux_for_component(AVFormatContext *s, struct representation *pls)
+{
+    int ret = 0;
+    int i;
+
     for (i = 0; i < pls->ctx->nb_streams; i++) {
         AVStream *st = avformat_new_stream(s, NULL);
         AVStream *ist = pls->ctx->streams[i];
@@ -1965,6 +1970,19 @@ fail:
     return ret;
 }

+static int open_demux_for_component(AVFormatContext* s, struct representation* pls)
+{
+    int ret = 0;
+
+    ret = begin_open_demux_for_component(s, pls);
+    if (ret < 0)
+        return ret;
+
+    ret = end_open_demux_for_component(s, pls);
+
+    return ret;
+}
+
 static int is_common_init_section_exist(struct representation **pls, int n_pls)
 {
     struct fragment *first_init_section = pls[0]->init_section;
@@ -2040,9 +2058,15 @@ static int dash_read_header(AVFormatContext *s)
         av_dict_set(&c->avio_opts, "seekable", "0", 0);
     }

-    if(c->n_videos)
+    if (c->n_videos)
         c->is_init_section_common_video = is_common_init_section_exist(c->videos, c->n_videos);

+    if (c->n_audios)
+        c->is_init_section_common_audio = is_common_init_section_exist(c->audios, c->n_audios);
+
+    if (c->n_subtitles)
+        c->is_init_section_common_subtitle = is_common_init_section_exist(c->subtitles, c->n_subtitles);
+
     /* Open the demuxer for video and audio components if available */
     for (i = 0; i < c->n_videos; i++) {
         rep = c->videos[i];
@@ -2059,9 +2083,6 @@ static int dash_read_header(AVFormatContext *s)
         ++stream_index;
     }

-    if(c->n_audios)
-        c->is_init_section_common_audio = is_common_init_section_exist(c->audios, c->n_audios);
-
     for (i = 0; i < c->n_audios; i++) {
         rep = c->audios[i];
         if (i > 0 && c->is_init_section_common_audio) {
@@ -2077,9 +2098,6 @@ static int dash_read_header(AVFormatContext *s)
         ++stream_index;
     }

-    if (c->n_subtitles)
-        c->is_init_section_common_subtitle = is_common_init_section_exist(c->subtitles, c->n_subtitles);
-
     for (i = 0; i < c->n_subtitles; i++) {
         rep = c->subtitles[i];
         if (i > 0 && c->is_init_section_common_subtitle) {
--
2.31.1.windows.1