input/decoder.c: Drop buffer instead of entire decoder fifo, when its full.

If the decoder fifo is full (growing to large), then instead of flushing and
producing a big artefact in the stream, just drop one buffer. This still limits
the size of the fifo, but does not produce a big artefact as the original code.

Also make the size configurable with a commandline option.

src/input/decoder.c

@@ -114,6 +114,7 @@ struct decoder_owner_sys_t
 
     /* fifo */
     block_fifo_t *p_fifo;
+    size_t        i_max_fifo_size;
 
     /* Lock for communication with decoder thread */
     vlc_mutex_t lock;
@@ -398,17 +399,21 @@ void input_DecoderDecode( decoder_t *p_dec, block_t *p_block, bool b_do_pace )
         if( !p_owner->b_buffering )
             block_FifoPace( p_owner->p_fifo, 10, SIZE_MAX );
     }
-#ifdef __arm__
-    else if( block_FifoSize( p_owner->p_fifo ) > 50*1024*1024 /* 50 MiB */ )
-#else
-    else if( block_FifoSize( p_owner->p_fifo ) > 400*1024*1024 /* 400 MiB, ie ~ 50mb/s for 60s */ )
-#endif
+    else if( block_FifoSize( p_owner->p_fifo ) > p_owner->i_max_fifo_size )
     {
         /* FIXME: ideally we would check the time amount of data
          * in the FIFO instead of its size. */
+#if 0
         msg_Warn( p_dec, "decoder/packetizer fifo full (data not "
                   "consumed quickly enough), resetting fifo!" );
         block_FifoEmpty( p_owner->p_fifo );
+#else
+        msg_Warn( p_dec, "decoder/packetizer fifo full (data not "
+                  "consumed quickly enough), dropping buffers!" );
+        block_t *p_block = block_FifoGet( p_owner->p_fifo );
+        if ( p_block )
+             block_Release( p_block );
+#endif
     }
 
     block_FifoPut( p_owner->p_fifo, p_block );
@@ -797,6 +802,8 @@ static decoder_t * CreateDecoder( vlc_object_t *p_parent,
         vlc_object_release( p_dec );
         return NULL;
     }
+    p_owner->i_max_fifo_size =
+        var_InheritInteger( p_dec, "decoder-buffer-size" ) * 1024 * 1024;
 
     /* Set buffers allocation callbacks for the decoders */
     p_dec->pf_aout_buffer_new = aout_new_buffer;

src/libvlc-module.c

@@ -602,6 +602,13 @@ static const char *const ppsz_pos_descriptions[] =
     "You should only disable this option if your video has a " \
     "non-standard format requiring all 1088 lines.")
 
+#define DECODER_BUFFER_SIZE_TEXT N_("Adjust decodering buffering size in MiB")
+#define DECODER_BUFFER_SIZE_LONGTEXT N_( \
+    "Adjust buffering size between decoder and output/stream_output modules. " \
+    "By default this value is 400 * 1024 * 1024 MiB (50 mb/s for 60 seconds), however " \
+    "in certain situations one might need to adjust this. This options is for " \
+    "advanced usage only." )
+
 #define MASPECT_RATIO_TEXT N_("Monitor pixel aspect ratio")
 #define MASPECT_RATIO_LONGTEXT N_( \
     "This forces the monitor aspect ratio. Most monitors have square " \
@@ -1747,6 +1754,13 @@ vlc_module_begin ()
     add_string( "custom-aspect-ratios", NULL, CUSTOM_ASPECT_RATIOS_TEXT,
                 CUSTOM_ASPECT_RATIOS_LONGTEXT, false )
     add_bool( "hdtv-fix", 1, HDTV_FIX_TEXT, HDTV_FIX_LONGTEXT, true )
+#ifdef __arm__
+# define DECODER_BUFFER_SIZE (50) /* 50 * 1024 *1024 = 50 MiB */
+#else
+# define DECODER_BUFFER_SIZE (400) /* 400 * 1024 *1024 = 400 MiB, ie ~ 50mb/s for 60s */
+#endif
+    add_integer( "decoder-buffer-size", DECODER_BUFFER_SIZE, DECODER_BUFFER_SIZE_TEXT,
+                 DECODER_BUFFER_SIZE_LONGTEXT, true )
     add_bool( "video-deco", 1, VIDEO_DECO_TEXT,
               VIDEO_DECO_LONGTEXT, true )
     add_string( "video-title", NULL, VIDEO_TITLE_TEXT,