command: whitelist some blocking accesses for certain demuxers/streams

The properties/commands touched in this commit are all for obscure
special inputs (BD/DVD/DVB/TV), and they all block on the demuxer/stream
layer. For network streams, this blocking is very unwelcome. They will
affect playback and probably introduce pauses and frame drops. The
player can even freeze fully, and the logic that tries to make playback
abortable even if frozen complicates the player.

Since the mentioned accesses are not needed for network streams, but
they will block on network streams even though they're going to fail,
add a flag that coarsely enables/disables these accesses. Essentially it
establishes a whitelist of demuxers/streams which support them.

In theory you could to access BD/DVD images over network (or add such
support, I don't think it's a thing in mpv). In these cases these
controls still can block and could even "freeze" the player completely.

Writing to the "program" and "cache-size" properties still can block
even for network streams. Just don't use them if you don't want freezes.

2 files changed, 2 insertions, 0 deletions

diff --git a/stream/stream.h b/stream/stream.h
index 863c0cfd3c..2f59e5318f 100644
--- a/stream/stream.h
+++ b/stream/stream.h
@@ -184,6 +184,7 @@ typedef struct stream {
     bool is_local_file : 1; // from the filesystem
     bool is_directory : 1; // directory on the filesystem
     bool access_references : 1; // open other streams
+    bool extended_ctrls : 1; // supports some of BD/DVD/DVB/TV controls
     struct mp_log *log;
     struct mpv_global *global;
 
diff --git a/stream/stream_dvb.c b/stream/stream_dvb.c
index 02c5878ca9..9821119cac 100644
--- a/stream/stream_dvb.c
+++ b/stream/stream_dvb.c
@@ -1120,6 +1120,7 @@ static int dvb_open(stream_t *stream)
     stream->allow_caching = true;
     stream->demuxer = "lavf";
     stream->lavf_type = "mpegts";
+    stream->extended_ctrls = true;
 
     return STREAM_OK;