dvdnav, tv: force-disable caching

On dvdnav, caching kind of works but not really. (Not our fault, at
least not fully. It's due to libdvdnav being slightly misdesigned; see
previous commit for some explanations.)

The TV code is implemented in the demuxer, and the stream implementation
is just a wrapper, so caching makes no sense here.

stream/stream.c

@@ -290,6 +290,7 @@ static int open_internal(const stream_info_t *sinfo, struct stream *underlying,
     s->url = talloc_strdup(s, url);
     s->path = talloc_strdup(s, path);
     s->source = underlying;
+    s->allow_caching = true;
 
     // Parse options
     if (sinfo->priv_size) {
@@ -805,7 +806,7 @@ static int stream_enable_cache(stream_t **stream, int64_t size, int64_t min,
 {
     stream_t *orig = *stream;
 
-    if (orig->mode != STREAM_READ)
+    if (orig->mode != STREAM_READ || !orig->allow_caching)
         return 1;
 
     stream_t *cache = new_stream();

stream/stream.h

@@ -164,6 +164,7 @@ typedef struct stream {
     char *demuxer; // request demuxer to be used
     char *lavf_type; // name of expected demuxer type for lavf
     bool safe_origin; // used for playlists that can be opened safely
+    bool allow_caching; // stream cache makes sense
     struct MPOpts *opts;
 
     FILE *capture_file;

stream/stream_dvdnav.c

@@ -696,14 +696,12 @@ static int open_s(stream_t *stream, int mode)
     stream->type = STREAMTYPE_DVD;
     stream->demuxer = "lavf";
     stream->lavf_type = "mpeg";
+    stream->allow_caching = false;
 
     if (!stream->pos && p->track > 0)
         mp_msg(MSGT_OPEN, MSGL_ERR, "INIT ERROR: couldn't get init pos %s\r\n",
                dvdnav_err_to_string(priv->dvdnav));
 
-    mp_msg(MSGT_OPEN, MSGL_INFO, "Remember to disable mpv's cache when "
-           "playing dvdnav:// streams (adding -no-cache to your command line)\n");
-
     return STREAM_OK;
 }
 

stream/stream_tv.c

@@ -92,6 +92,7 @@ tv_stream_open (stream_t *stream, int mode)
   stream->type = STREAMTYPE_TV;
   stream->close=tv_stream_close;
   stream->demuxer = "tv";
+  stream->allow_caching = false;
 
   return STREAM_OK;
 }