ffmpeg: don't warn of empty packet output

If avcodec_decode_audio2() returns no output for an AVPacket,
libavcodec may buffer some data, and return a larger chunk of output
later.  This patch disables a lot of bogus warnings.

NEWS

@@ -37,6 +37,7 @@ ver 0.15 - (200?/??/??)
 ver 0.14.2 (2009/??/??)
 * decoders:
   - ffmpeg: added support for the tags comment, genre, year
+  - ffmpeg: don't warn of empty packet output
   - wavpack: pass NULL if the .wvc file fails to open
   - mikmod: call MikMod_Exit() only in the finish() method
 * audio outputs:

src/decoder/ffmpeg_plugin.c

@@ -243,10 +243,9 @@ ffmpeg_send_packet(struct decoder *decoder, struct input_stream *is,
 		packet_data += len;
 		packet_size -= len;
 
-		if (audio_size <= 0) {
-			g_message("no audio frame\n");
+		if (audio_size <= 0)
 			continue;
-		}
+
 		cmd = decoder_data(decoder, is,
 				   audio_buf, audio_size,
 				   position,