[FFmpeg-devel] [PATCH]lavf/matroskaenc: Do not unecessarily consume memory for cuepoints

[Carl Eugen Hoyos]

Hi!

Matroska streaming currently consumes memory for 
cuepoints that are never used if the output stream 
is no seekable. This can lead to oom.
Attached patch fixes ticket #4690.

Please comment, Carl Eugen
-------------- next part --------------
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 3b525ad..f07851e 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -1047,9 +1047,11 @@ static int mkv_write_tracks(AVFormatContext *s)
     ebml_master tracks;
     int i, ret, default_stream_exists = 0;
 
+    if (s->pb->seekable) {
     ret = mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_TRACKS, avio_tell(pb));
     if (ret < 0)
         return ret;
+    }
 
     tracks = start_ebml_master(pb, MATROSKA_ID_TRACKS, 0);
     for (i = 0; i < s->nb_streams; i++) {
@@ -1076,8 +1078,10 @@ static int mkv_write_chapters(AVFormatContext *s)
     if (!s->nb_chapters || mkv->wrote_chapters)
         return 0;
 
+    if (s->pb->seekable) {
     ret = mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_CHAPTERS, avio_tell(pb));
     if (ret < 0) return ret;
+    }
 
     chapters     = start_ebml_master(pb, MATROSKA_ID_CHAPTERS    , 0);
     editionentry = start_ebml_master(pb, MATROSKA_ID_EDITIONENTRY, 0);
@@ -1160,8 +1164,10 @@ static int mkv_write_tag(AVFormatContext *s, AVDictionary *m, unsigned int eleme
     int ret;
 
     if (!tags->pos) {
+        if (s->pb->seekable) {
         ret = mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_TAGS, avio_tell(s->pb));
         if (ret < 0) return ret;
+        }
 
         *tags = start_ebml_master(s->pb, MATROSKA_ID_TAGS, 0);
     }
@@ -1772,7 +1778,7 @@ static int mkv_write_packet_internal(AVFormatContext *s, AVPacket *pkt, int add_
 
     if (codec->codec_type != AVMEDIA_TYPE_SUBTITLE) {
         mkv_write_block(s, pb, MATROSKA_ID_SIMPLEBLOCK, pkt, keyframe);
-        if (codec->codec_type == AVMEDIA_TYPE_VIDEO && keyframe || add_cue) {
+        if (s->pb->seekable && (codec->codec_type == AVMEDIA_TYPE_VIDEO && keyframe || add_cue)) {
             ret = mkv_add_cuepoint(mkv->cues, pkt->stream_index, dash_tracknum, ts, mkv->cluster_pos, relative_packet_pos, -1);
             if (ret < 0) return ret;
         }
@@ -1792,11 +1798,13 @@ static int mkv_write_packet_internal(AVFormatContext *s, AVPacket *pkt, int add_
         end_ebml_master(pb, blockgroup);
     }
 
+    if (s->pb->seekable) {
     ret = mkv_add_cuepoint(mkv->cues, pkt->stream_index, dash_tracknum, ts,
                            mkv->cluster_pos, relative_packet_pos, duration);
     if (ret < 0)
         return ret;
     }
+    }
 
     mkv->duration = FFMAX(mkv->duration, ts + duration);
     return 0;