player: simplistic HLS bitrate selection

--hls-bitrate=min/max lets you select the min or max bitrate. That's it.
Something more sophisticated might be possible, but is probably not even
worth the effort.

DOCS/man/options.rst

@@ -2838,11 +2838,9 @@ Network
     Use ``<string>`` as user agent for HTTP streaming.
 
 ``--cookies``, ``--no-cookies``
-    (network only)
     Support cookies when making HTTP requests. Disabled by default.
 
 ``--cookies-file=<filename>``
-    (network only)
     Read HTTP cookies from <filename>. The file is assumed to be in Netscape
     format.
 
@@ -2882,6 +2880,17 @@ Network
     network transport when playing ``rtsp://...`` URLs. The value ``lavf``
     leaves the decision to libavformat.
 
+``--hls-bitrate=<no|min|max>``
+    If HLS streams are played, this option controls what streams are selected
+    by default. The option allows the following parameters:
+
+    :no:        Don't do anything special. Typically, this will simply pick the
+                first audio/video streams it can find. (Default.)
+    :min:       Pick the streams with the lowest bitrate.
+    :max:       Same, but highest bitrate.
+
+    The bitrate as used is sent by the server, and there's no guarantee it's
+    actually meaningful.
 
 DVB
 ---

demux/demux_lavf.c

@@ -429,6 +429,19 @@ static void export_replaygain(demuxer_t *demuxer, sh_audio_t *sh, AVStream *st)
 #endif
 }
 
+// Return a dictionary entry as (decimal) integer.
+static int dict_get_decimal(AVDictionary *dict, const char *entry, int def)
+{
+    AVDictionaryEntry *e = av_dict_get(dict, entry, NULL, 0);
+    if (e && e->value) {
+        char *end = NULL;
+        long int r = strtol(e->value, &end, 10);
+        if (end && !end[0] && r >= INT_MIN && r <= INT_MAX)
+            return r;
+    }
+    return def;
+}
+
 static void handle_stream(demuxer_t *demuxer, int i)
 {
     lavf_priv_t *priv = demuxer->priv;
@@ -505,13 +518,9 @@ static void handle_stream(demuxer_t *demuxer, int i)
         if (sd)
             sh_video->rotate = -av_display_rotation_get((uint32_t *)sd);
 #else
-        AVDictionaryEntry *rot = av_dict_get(st->metadata, "rotate", NULL, 0);
-        if (rot && rot->value) {
-            char *end = NULL;
-            long int r = strtol(rot->value, &end, 10);
-            if (end && !end[0])
-                sh_video->rotate = r;
-        }
+        int rot = dict_get_decimal(st->metadata, "rotate", -1);
+        if (rot >= 0)
+            sh_video->rotate = rot;
 #endif
         sh_video->rotate = ((sh_video->rotate % 360) + 360) % 360;
 
@@ -589,6 +598,7 @@ static void handle_stream(demuxer_t *demuxer, int i)
         AVDictionaryEntry *lang = av_dict_get(st->metadata, "language", NULL, 0);
         if (lang && lang->value)
             sh->lang = talloc_strdup(sh, lang->value);
+        sh->hls_bitrate = dict_get_decimal(st->metadata, "variant_bitrate", 0);
     }
 
     select_tracks(demuxer, i);

demux/stheader.h

@@ -55,6 +55,7 @@ struct sh_stream {
     char *title;
     char *lang;                 // language code
     bool default_track;         // container default track flag
+    int hls_bitrate;
 
     // stream is a picture (such as album art)
     struct demux_packet *attached_picture;

options/options.c

@@ -202,6 +202,9 @@ const m_option_t mp_opts[] = {
     OPT_STRING("quvi-format", quvi_format, 0),
     OPT_FLAG("quvi-fetch-subtitles", quvi_fetch_subtitles, 0),
 
+    OPT_CHOICE("hls-bitrate", hls_bitrate, M_OPT_FIXED,
+               ({"no", 0}, {"min", 1}, {"max", 2})),
+
 #if HAVE_CDDA
     OPT_SUBSTRUCT("cdda", stream_cdda_opts, stream_cdda_conf, 0),
     OPT_STRING("cdrom-device", cdrom_device, 0),

options/options.h

@@ -123,6 +123,7 @@ typedef struct MPOpts {
     char *force_configdir;
     int use_filedir_conf;
     int network_rtsp_transport;
+    int hls_bitrate;
     struct mp_cache_opts stream_cache;
     int chapterrange[2];
     int edition_id;

player/loadfile.c

@@ -464,13 +464,15 @@ static int match_lang(char **langs, char *lang)
  * 1b) track was passed explicitly (is not an auto-loaded subtitle)
  * 2) earlier match in lang list
  * 3) track is marked default
- * 4) lower track number
- * If select_fallback is not set, 4) is only used to determine whether a
+ * 4) attached picture, HLS bitrate
+ * 5) lower track number
+ * If select_fallback is not set, 5) is only used to determine whether a
  * matching track is preferred over another track. Otherwise, always pick a
  * track (if nothing else matches, return the track with lowest ID).
  */
 // Return whether t1 is preferred over t2
-static bool compare_track(struct track *t1, struct track *t2, char **langs)
+static bool compare_track(struct track *t1, struct track *t2, char **langs,
+                          struct MPOpts *opts)
 {
     bool ext1 = t1->is_external && !t1->no_default;
     bool ext2 = t2->is_external && !t2->no_default;
@@ -485,6 +487,11 @@ static bool compare_track(struct track *t1, struct track *t2, char **langs)
         return t1->default_track;
     if (t1->attached_picture != t2->attached_picture)
         return !t1->attached_picture;
+    if (t1->stream && t2->stream && opts->hls_bitrate) {
+        int d = t1->stream->hls_bitrate - t2->stream->hls_bitrate;
+        if (d)
+            return opts->hls_bitrate == 1 ? d < 0 : d > 0;
+    }
     return t1->user_tid <= t2->user_tid;
 }
 static struct track *select_track(struct MPContext *mpctx,
@@ -500,7 +507,7 @@ static struct track *select_track(struct MPContext *mpctx,
             continue;
         if (track->user_tid == tid)
             return track;
-        if (!pick || compare_track(track, pick, langs))
+        if (!pick || compare_track(track, pick, langs, mpctx->opts))
             pick = track;
     }
     if (pick && !select_fallback && !(pick->is_external && !pick->no_default)