lavf/dashenc: require experimental mode to be enabled for WebM

It has not ever been working and has not been validated,
Additionally, mention that the segment file names should be changed
to end with webm instead of m4s, which is utilized for ISOBMFF
fragments.

diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
index 4f8f61b704cb09f461fc7268baeac018218edc29..45f7830aecfccc5572eea67d48918f8fff5a2b74 100644 (file)
--- a/libavformat/dashenc.c
+++ b/libavformat/dashenc.c
@@ -966,6 +966,16 @@ static int dash_init(AVFormatContext *s)
             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");
+
+            if (s->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL) {
+                av_log(s, AV_LOG_ERROR,
+                       "WebM support in dashenc is experimental and has not "
+                       "been validated. For testing purposes, make sure "
+                       "to add -strict experimental and override "
+                       "-init_seg_name and -media_seg_name to end with "
+                       "the extension 'webm'.\n");
+                return AVERROR(EINVAL);
+            }
         } else {
             snprintf(os->format_name, sizeof(os->format_name), "mp4");
         }