decoder: removed plugin method try_decode()

Instead of having a seprate try_decode() method, let the
stream_decode() and file_decode() methods decide whether they are able
to decode the song.

src/decoder/ffmpeg_plugin.c

@@ -193,12 +193,6 @@ ffmpeg_helper(struct input_stream *input,
 	return ret;
 }
 
-static bool
-ffmpeg_try_decode(struct input_stream *input)
-{
-	return ffmpeg_helper(input, NULL, NULL);
-}
-
 static enum decoder_command
 ffmpeg_send_packet(struct decoder *decoder, struct input_stream *is,
 		   const AVPacket *packet,
@@ -370,7 +364,6 @@ static const char *const ffmpeg_mime_types[] = {
 const struct decoder_plugin ffmpeg_plugin = {
 	.name = "ffmpeg",
 	.init = ffmpeg_init,
-	.try_decode = ffmpeg_try_decode,
 	.stream_decode = ffmpeg_decode,
 	.tag_dup = ffmpeg_tag,
 	.suffixes = ffmpeg_suffixes,

src/decoder/flac_plugin.c

@@ -434,13 +434,14 @@ out:
 static bool
 oggflac_decode(struct decoder *decoder, struct input_stream *inStream)
 {
-	return flac_decode_internal(decoder, inStream, true);
-}
+	if (ogg_stream_type_detect(inStream) != FLAC)
+		return false;
 
-static bool
-oggflac_try_decode(struct input_stream *inStream)
-{
-	return ogg_stream_type_detect(inStream) == FLAC;
+	/* rewind the stream, because ogg_stream_type_detect() has
+	   moved it */
+	input_stream_seek(inStream, 0, SEEK_SET);
+
+	return flac_decode_internal(decoder, inStream, true);
 }
 
 static const char *const oggflac_suffixes[] = { "ogg", "oga", NULL };
@@ -457,7 +458,6 @@ const struct decoder_plugin oggflacPlugin = {
 	.name = "oggflac",
 	.init = oggflac_init,
 #if defined(FLAC_API_VERSION_CURRENT) && FLAC_API_VERSION_CURRENT > 7
-	.try_decode = oggflac_try_decode,
 	.stream_decode = oggflac_decode,
 	.tag_dup = oggflac_tag_dup,
 	.suffixes = oggflac_suffixes,

src/decoder/oggvorbis_plugin.c

@@ -214,6 +214,13 @@ oggvorbis_decode(struct decoder *decoder, struct input_stream *inStream)
 	const char *errorStr;
 	bool initialized = false;
 
+	if (ogg_stream_type_detect(inStream) != VORBIS)
+		return false;
+
+	/* rewind the stream, because ogg_stream_type_detect() has
+	   moved it */
+	input_stream_seek(inStream, 0, SEEK_SET);
+
 	data.inStream = inStream;
 	data.decoder = decoder;
 
@@ -351,12 +358,6 @@ static struct tag *oggvorbis_TagDup(const char *file)
 	return ret;
 }
 
-static bool
-oggvorbis_try_decode(struct input_stream *inStream)
-{
-	return ogg_stream_type_detect(inStream) == VORBIS;
-}
-
 static const char *const oggvorbis_Suffixes[] = { "ogg","oga", NULL };
 static const char *const oggvorbis_MimeTypes[] = {
 	"application/ogg",
@@ -367,7 +368,6 @@ static const char *const oggvorbis_MimeTypes[] = {
 
 const struct decoder_plugin oggvorbisPlugin = {
 	.name = "oggvorbis",
-	.try_decode = oggvorbis_try_decode,
 	.stream_decode = oggvorbis_decode,
 	.tag_dup = oggvorbis_TagDup,
 	.suffixes = oggvorbis_Suffixes,

src/decoder_api.h

@@ -60,12 +60,6 @@ struct decoder_plugin {
 	 */
 	void (*finish)(void);
 
-	/**
-	 * returns true if the input stream is decodable by the
-	 * decoder plugin, false if not
-	 */
-	bool (*try_decode)(struct input_stream *);
-
 	/**
 	 * this will be used to decode InputStreams, and is
 	 * recommended for files and networked (HTTP) connections.

src/decoder_thread.c

@@ -28,23 +28,6 @@
 #include "log.h"
 #include "ls.h"
 
-static bool
-decoder_try_decode(const struct decoder_plugin *plugin,
-		   struct input_stream *input_stream)
-{
-	bool ret;
-
-	if (plugin->try_decode == NULL)
-		return true;
-
-	ret = plugin->try_decode(input_stream);
-
-	/* rewind the stream, so the next reader gets a fresh start */
-	input_stream_seek(input_stream, 0, SEEK_SET);
-
-	return ret;
-}
-
 static bool
 decoder_stream_decode(const struct decoder_plugin *plugin,
 		      struct decoder *decoder,
@@ -172,8 +155,6 @@ static void decoder_run(void)
 		while ((plugin = decoder_plugin_from_mime_type(input_stream.mime, next++))) {
 			if (plugin->stream_decode == NULL)
 				continue;
-			if (!decoder_try_decode(plugin, &input_stream))
-				continue;
 			ret = decoder_stream_decode(plugin, &decoder,
 						    &input_stream);
 			if (ret)
@@ -189,8 +170,6 @@ static void decoder_run(void)
 			while ((plugin = decoder_plugin_from_suffix(s, next++))) {
 				if (plugin->stream_decode == NULL)
 					continue;
-				if (!decoder_try_decode(plugin, &input_stream))
-					continue;
 				ret = decoder_stream_decode(plugin, &decoder,
 							    &input_stream);
 				if (ret)
@@ -215,9 +194,6 @@ static void decoder_run(void)
 		unsigned int next = 0;
 		const char *s = getSuffix(uri);
 		while ((plugin = decoder_plugin_from_suffix(s, next++))) {
-			if (!decoder_try_decode(plugin, &input_stream))
-				continue;
-
 			if (plugin->file_decode != NULL) {
 				input_stream_close(&input_stream);
 				close_instream = false;