demux_lavf: make minimum probe score customizable, remove lavf_preferred

libavformat wants to read a full ~400KB of data to determine whether
it's really AAC. This causes slow startup with AAC web radio streams [1]
(possible due to a broken initial packet). There are similar issues
with other file formats.

Make the probe "score" (libavformat's mechanism for testing file
formats) configurable with the -lavfdtops:probescore option. This allows
lowering the amount of data read on probing. If the probe score is below
the probescore option value, demux_lavf will try to get a higher score
by feeding more data to libavformat, until the required score or the
max. probe size is reached.

Remove the lavf_preferred demuxer entry. This had a purpose in
mplayer-svn, but now there doesn't seem to be any good reason for it
to exist. Make sure that our native "good" demuxers are above
demux_lavf in demuxer_list[] instead (so that they are preferred).

[1] http://lr2mp0.latvijasradio.lv:8000

DOCS/man/en/options.rst

@@ -1028,6 +1028,12 @@
 
     analyzeduration=<value>
         Maximum length in seconds to analyze the stream properties.
+    probescore=<1-100>
+        Minimum required libavformat probe score. Lower values will require
+        less data to be loaded (makes streams start faster), but makes file
+        format detection less reliable. Can be used to force auto-detected
+        libavformat demuxers, even if libavformat considers the detection not
+        reliable enough. (Default: 26.)
     format=<value>
         Force a specific libavformat demuxer.
     o=<key>=<value>[,<key>=<value>[,...]]

core/options.h

@@ -150,6 +150,7 @@ typedef struct MPOpts {
 
     struct lavfdopts {
         unsigned int probesize;
+        int probescore;
         unsigned int analyzeduration;
         char *format;
         char *cryptokey;

demux/demux.c

@@ -57,7 +57,6 @@ extern const demuxer_desc_t demuxer_desc_avi;
 extern const demuxer_desc_t demuxer_desc_asf;
 extern const demuxer_desc_t demuxer_desc_matroska;
 extern const demuxer_desc_t demuxer_desc_lavf;
-extern const demuxer_desc_t demuxer_desc_lavf_preferred;
 extern const demuxer_desc_t demuxer_desc_mng;
 extern const demuxer_desc_t demuxer_desc_mpeg_ps;
 extern const demuxer_desc_t demuxer_desc_mpeg_pes;
@@ -79,11 +78,10 @@ const demuxer_desc_t *const demuxer_list[] = {
 #ifdef CONFIG_TV
     &demuxer_desc_tv,
 #endif
-    &demuxer_desc_lavf_preferred,
-    &demuxer_desc_avi,
-    &demuxer_desc_asf,
     &demuxer_desc_matroska,
     &demuxer_desc_lavf,
+    &demuxer_desc_avi,
+    &demuxer_desc_asf,
 #ifdef CONFIG_MNG
     &demuxer_desc_mng,
 #endif
@@ -920,6 +918,7 @@ static struct demuxer *open_given_type(struct MPOpts *opts,
 {
     struct demuxer *demuxer;
     int fformat;
+    mp_msg(MSGT_DEMUXER, MSGL_V, "Trying demuxer: %s\n", desc->name);
     demuxer = new_demuxer(opts, stream, desc->type, audio_id,
                           video_id, sub_id, filename);
     demuxer->params = params;

demux/demux.h

@@ -68,7 +68,6 @@ enum demuxer_type {
     DEMUXER_TYPE_AVS,
     DEMUXER_TYPE_AAC,
     DEMUXER_TYPE_MPC,
-    DEMUXER_TYPE_LAVF_PREFERRED,
     DEMUXER_TYPE_MNG,
     DEMUXER_TYPE_EDL,
     DEMUXER_TYPE_CUE,

demux/demux_lavf.c

@@ -49,13 +49,13 @@
 #include "mp_taglists.h"
 
 #define INITIAL_PROBE_SIZE STREAM_BUFFER_SIZE
-#define SMALL_MAX_PROBE_SIZE (32 * 1024)
 #define PROBE_BUF_SIZE (2 * 1024 * 1024)
 
 const m_option_t lavfdopts_conf[] = {
     OPT_INTRANGE("probesize", lavfdopts.probesize, 0, 32, INT_MAX),
     OPT_STRING("format", lavfdopts.format, 0),
     OPT_INTRANGE("analyzeduration", lavfdopts.analyzeduration, 0, 0, INT_MAX),
+    OPT_INTRANGE("probescore", lavfdopts.probescore, 0, 0, 100),
     OPT_STRING("cryptokey", lavfdopts.cryptokey, 0),
     OPT_STRING("o", lavfdopts.avopt, 0),
     {NULL, NULL, 0, 0, 0, 0, NULL}
@@ -175,8 +175,8 @@ static int lavf_check_file(demuxer_t *demuxer)
     int read_size = INITIAL_PROBE_SIZE;
     int score;
 
-    if (!demuxer->priv)
-        demuxer->priv = talloc_zero(NULL, lavf_priv_t);
+    assert(!demuxer->priv);
+    demuxer->priv = talloc_zero(NULL, lavf_priv_t);
     priv = demuxer->priv;
     priv->autoselect_sub = -1;
 
@@ -194,7 +194,7 @@ static int lavf_check_file(demuxer_t *demuxer)
         char *sep = strchr(priv->filename, ':');
         if (!sep) {
             mp_msg(MSGT_DEMUX, MSGL_FATAL,
-                "Must specify filename in 'format:filename' form\n");
+                   "Must specify filename in 'format:filename' form\n");
             return 0;
         }
         avdevice_format = talloc_strndup(priv, priv->filename,
@@ -219,9 +219,16 @@ static int lavf_check_file(demuxer_t *demuxer)
         }
         mp_msg(MSGT_DEMUX, MSGL_INFO, "Forced lavf %s demuxer\n",
                priv->avif->long_name);
-        return DEMUXER_TYPE_LAVF;
+        goto success;
     }
 
+    // AVPROBE_SCORE_RETRY + 1 is the "recommended" limit. Below that, the user
+    // is supposed to retry with larger probe sizes until a higher value is
+    // reached.
+    int min_probe = AVPROBE_SCORE_RETRY + 1;
+    if (lavfdopts->probescore)
+        min_probe = lavfdopts->probescore;
+
     avpd.buf = av_mallocz(FFMAX(BIO_BUFFER_SIZE, PROBE_BUF_SIZE) +
                           FF_INPUT_BUFFER_PADDING_SIZE);
     do {
@@ -237,19 +244,27 @@ static int lavf_check_file(demuxer_t *demuxer)
 
         score = 0;
         priv->avif = av_probe_input_format2(&avpd, probe_data_size > 0, &score);
+
+        if (priv->avif) {
+            mp_msg(MSGT_HEADER, MSGL_V, "Found '%s' at score=%d size=%d.\n",
+                   priv->avif->name, score, probe_data_size);
+        }
+
+        if (priv->avif && score >= min_probe)
+            break;
+
+        priv->avif = NULL;
         read_size = FFMIN(2 * read_size, PROBE_BUF_SIZE - probe_data_size);
-    } while ((demuxer->desc->type != DEMUXER_TYPE_LAVF_PREFERRED ||
-              probe_data_size < SMALL_MAX_PROBE_SIZE) &&
-             score <= AVPROBE_SCORE_MAX / 4 &&
-             read_size > 0 && probe_data_size < PROBE_BUF_SIZE);
+    } while (read_size > 0 && probe_data_size < PROBE_BUF_SIZE);
     av_free(avpd.buf);
 
-    if (!priv->avif || score <= AVPROBE_SCORE_MAX / 4) {
+    if (!priv->avif) {
         mp_msg(MSGT_HEADER, MSGL_V,
-               "LAVF_check: no clue about this gibberish!\n");
+               "No format found, try lowering probescore.\n");
         return 0;
-    } else
-        mp_msg(MSGT_HEADER, MSGL_V, "LAVF_check: %s\n", priv->avif->long_name);
+    }
+
+success:
 
     demuxer->filetype = priv->avif->long_name;
     if (!demuxer->filetype)
@@ -273,27 +288,6 @@ static bool matches_avinputformat_name(struct lavf_priv *priv,
     }
 }
 
-/* formats for which an internal demuxer is preferred */
-static const char * const preferred_internal[] = {
-    /* lavf Matroska demuxer doesn't support ordered chapters and fails
-     * for more files */
-    "matroska",
-    NULL
-};
-
-static int lavf_check_preferred_file(demuxer_t *demuxer)
-{
-    if (lavf_check_file(demuxer)) {
-        const char * const *p;
-        lavf_priv_t *priv = demuxer->priv;
-        for (p = preferred_internal; *p; p++)
-            if (matches_avinputformat_name(priv, *p))
-                return 0;
-        return DEMUXER_TYPE_LAVF_PREFERRED;
-    }
-    return 0;
-}
-
 static uint8_t char2int(char c)
 {
     if (c >= '0' && c <= '9') return c - '0';
@@ -600,6 +594,10 @@ static demuxer_t *demux_open_lavf(demuxer_t *demuxer)
     lavf_priv_t *priv = demuxer->priv;
     int i;
 
+    // do not allow forcing the demuxer
+    if (!priv->avif)
+        return NULL;
+
     stream_seek(demuxer->stream, 0);
 
     avfc = avformat_alloc_context();
@@ -659,13 +657,11 @@ static demuxer_t *demux_open_lavf(demuxer_t *demuxer)
     }
 
     priv->avfc = avfc;
-
     if (avformat_find_stream_info(avfc, NULL) < 0) {
         mp_msg(MSGT_HEADER, MSGL_ERR,
                "LAVF_header: av_find_stream_info() failed\n");
         return NULL;
     }
-
     /* Add metadata. */
     while ((t = av_dict_get(avfc->metadata, "", t,
                             AV_DICT_IGNORE_SUFFIX)))
@@ -1078,7 +1074,7 @@ const demuxer_desc_t demuxer_desc_lavf = {
     "Michael Niedermayer",
     "supports many formats, requires libavformat",
     DEMUXER_TYPE_LAVF,
-    0, // Check after other demuxer
+    1,
     lavf_check_file,
     demux_lavf_fill_buffer,
     demux_open_lavf,
@@ -1086,19 +1082,3 @@ const demuxer_desc_t demuxer_desc_lavf = {
     demux_seek_lavf,
     demux_lavf_control
 };
-
-const demuxer_desc_t demuxer_desc_lavf_preferred = {
-    "libavformat preferred demuxer",
-    "lavfpref",
-    "libavformat",
-    "Michael Niedermayer",
-    "supports many formats, requires libavformat",
-    DEMUXER_TYPE_LAVF_PREFERRED,
-    1,
-    lavf_check_preferred_file,
-    demux_lavf_fill_buffer,
-    demux_open_lavf,
-    demux_close_lavf,
-    demux_seek_lavf,
-    demux_lavf_control
-};

demux/video.c

@@ -590,7 +590,6 @@ int video_read_frame(sh_video_t* sh_video,float* frame_time_ptr,unsigned char**
       }
       break;
       case DEMUXER_TYPE_LAVF:
-      case DEMUXER_TYPE_LAVF_PREFERRED:
         if((int)sh_video->fps==1000 || (int)sh_video->fps<=1){
           double next_pts = ds_get_next_pts(d_video);
           double d= (next_pts != MP_NOPTS_VALUE) ? next_pts - d_video->pts : d_video->pts-pts1;