Implemented an API to get arbitrary meta-data about

BMediaFiles and about BMediaTracks in BMessages. As an
example, one can get chapter meta-data or the language
name of an audio-track.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@38685 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/media/MediaFile.h

@@ -24,6 +24,7 @@ namespace BPrivate {
 
 // forward declarations
 class BMediaTrack;
+class BMessage;
 class BParameterWeb;
 class BView;
 
@@ -79,6 +80,12 @@ public:
 			status_t			GetFileFormatInfo(
 									media_file_format* mfi) const;
 
+	// Returns in _data hierarchical meta-data about the stream.
+	// The fields in the message shall follow a defined naming-scheme,
+	// such that applications can find the same information in different
+	// types of files.
+			status_t			GetMetaData(BMessage* _data) const;
+
 	//
 	// These functions are for read-only access to a media file.
 	// The data is read using the BMediaTrack object.

headers/os/media/MediaTrack.h

@@ -16,6 +16,7 @@ namespace BPrivate { namespace media {
 	class MediaWriter;
 } }
 
+class BMessage;
 class BView;
 class BParameterWeb;
 
@@ -90,6 +91,12 @@ public:
 			int64				CountFrames() const;
 			bigtime_t			Duration() const;
 
+	// Returns in _data hierarchical meta-data about the track.
+	// The fields in the message shall follow a defined naming-scheme,
+	// such that applications can find the same information in different
+	// types of tracks.
+			status_t			GetMetaData(BMessage* _data) const;
+
 	// CurrentFrame and CurrentTime return the current position (expressed in
 	// microseconds) within the track, expressed in frame index and time.
 

headers/private/media/MediaExtractor.h

@@ -43,6 +43,7 @@ public:
 
 			void				GetFileFormatInfo(
 									media_file_format* fileFormat) const;
+			status_t			GetMetaData(BMessage* _data) const;
 
 			int32				StreamCount();
 
@@ -65,6 +66,9 @@ public:
 			status_t			CreateDecoder(int32 stream, Decoder** _decoder,
 									media_codec_info* codecInfo);
 
+			status_t			GetStreamMetaData(int32 stream,
+									BMessage* _data) const;
+
 private:
 			void				_RecycleLastChunk(stream_info& info);
 	static	int32				_ExtractorEntry(void* arg);

headers/private/media/ReaderPlugin.h

@@ -23,6 +23,7 @@ public:
 	virtual	status_t			Sniff(int32* streamCount) = 0;
 
 	virtual	void				GetFileFormatInfo(media_file_format* mff) = 0;
+	virtual	status_t			GetMetaData(BMessage* _data);
 
 	virtual	status_t			AllocateCookie(int32 streamNumber,
 									void** cookie) = 0;
@@ -42,6 +43,9 @@ public:
 									const void** chunkBuffer, size_t* chunkSize,
 									media_header* mediaHeader) = 0;
 
+	virtual	status_t			GetStreamMetaData(void* cookie,
+									BMessage* _data);
+
 			BDataIO*			Source() const;
 
 	virtual status_t			Perform(perform_code code, void* data);

src/kits/media/MediaExtractor.cpp

@@ -178,6 +178,14 @@ MediaExtractor::GetFileFormatInfo(media_file_format* fileFormat) const
 }
 
 
+status_t
+MediaExtractor::GetMetaData(BMessage* _data) const
+{
+	CALLED();
+	return fReader->GetMetaData(_data);
+}
+
+
 int32
 MediaExtractor::StreamCount()
 {
@@ -376,6 +384,18 @@ MediaExtractor::CreateDecoder(int32 stream, Decoder** _decoder,
 }
 
 
+status_t
+MediaExtractor::GetStreamMetaData(int32 stream, BMessage* _data) const
+{
+	const stream_info& info = fStreamInfo[stream];
+
+	if (info.status != B_OK)
+		return info.status;
+
+	return fReader->GetStreamMetaData(fStreamInfo[stream].cookie, _data);
+}
+
+
 void
 MediaExtractor::_RecycleLastChunk(stream_info& info)
 {

src/kits/media/MediaFile.cpp

@@ -129,7 +129,6 @@ BMediaFile::InitCheck() const
 }
 
 
-// Get info about the underlying file format.
 status_t
 BMediaFile::GetFileFormatInfo(media_file_format* mfi) const
 {
@@ -143,6 +142,20 @@ BMediaFile::GetFileFormatInfo(media_file_format* mfi) const
 }
 
 
+status_t
+BMediaFile::GetMetaData(BMessage* _data) const
+{
+	if (fExtractor == NULL)
+		return B_NO_INIT;
+	if (_data == NULL)
+		return B_BAD_VALUE;
+
+	_data->MakeEmpty();
+
+	return fExtractor->GetMetaData(_data);
+}
+
+
 const char*
 BMediaFile::Copyright() const
 {

src/kits/media/MediaTrack.cpp

@@ -233,6 +233,21 @@ BMediaTrack::DecodedFormat(media_format *inout_format, uint32 flags)
 }
 
 
+status_t
+BMediaTrack::GetMetaData(BMessage* _data) const
+{
+	CALLED();
+	if (fExtractor == NULL)
+		return B_NO_INIT;
+	if (_data == NULL)
+		return B_BAD_VALUE;
+
+	_data->MakeEmpty();
+
+	return fExtractor->GetStreamMetaData(fStream, _data);
+}
+
+
 int64
 BMediaTrack::CountFrames() const
 {

src/kits/media/ReaderPlugin.cpp

@@ -1,4 +1,7 @@
 /*
+ * Copyright 2009-2010, Stephan Aßmus <superstippi@gmx.de>.
+ * Distributed under the terms of the MIT License.
+ *
  * Copyright 2004, Marcus Overhagen. All rights reserved.
  * Distributed under the terms of the MIT License.
  */
@@ -21,6 +24,13 @@ Reader::~Reader()
 }
 
 
+status_t
+Reader::GetMetaData(BMessage* _data)
+{
+	return B_NOT_SUPPORTED;
+}
+
+
 status_t
 Reader::Seek(void* cookie, uint32 flags, int64* frame, bigtime_t* time)
 {
@@ -35,6 +45,13 @@ Reader::FindKeyFrame(void* cookie, uint32 flags, int64* frame, bigtime_t* time)
 }
 
 
+status_t
+Reader::GetStreamMetaData(void* cookie, BMessage* _data)
+{
+	return B_NOT_SUPPORTED;
+}
+
+
 BDataIO*
 Reader::Source() const
 {
@@ -55,6 +72,7 @@ Reader::Perform(perform_code code, void* _data)
 	return B_OK;
 }
 
+
 void Reader::_ReservedReader1() {}
 void Reader::_ReservedReader2() {}
 void Reader::_ReservedReader3() {}