Cover art handling: significantly reduce memory usage. fixes #93

src/libs/av/impl/AvInfo.cpp

@@ -45,7 +45,7 @@ static std::string averror_to_string(int error)
 }
 
 MediaFileException::MediaFileException(int avError)
-: AvException("MediaFileException: " + averror_to_string(avError))
+: AvException {"MediaFileException: " + averror_to_string(avError)}
 {
 }
 
@@ -181,8 +181,8 @@ MediaFile::hasAttachedPictures(void) const
 	return false;
 }
 
-std::vector<Picture>
-MediaFile::getAttachedPictures(std::size_t nbMaxPictures) const
+void
+MediaFile::visitAttachedPictures(std::function<void(const Picture&)> func) const
 {
 	static const std::map<int, std::string> codecMimeMap =
 	{
@@ -194,8 +194,6 @@ MediaFile::getAttachedPictures(std::size_t nbMaxPictures) const
 		{ AV_CODEC_ID_PPM, "image/x-portable-pixmap" },
 	};
 
-	std::vector<Picture> pictures;
-
 	for (std::size_t i = 0; i < _context->nb_streams; ++i)
 	{
 		AVStream *avstream = _context->streams[i];
@@ -225,15 +223,11 @@ MediaFile::getAttachedPictures(std::size_t nbMaxPictures) const
 
 		const AVPacket& pkt {avstream->attached_pic};
 
-		std::copy(pkt.data, pkt.data + pkt.size, std::back_inserter(picture.data));
+		picture.data = reinterpret_cast<const std::byte*>(pkt.data);
+		picture.dataSize = pkt.size;
 
-		pictures.push_back( picture );
-
-		if (pictures.size() >= nbMaxPictures)
-			break;
+		func(picture);
 	}
-
-	return pictures;
 }
 
 std::optional<MediaFileFormat>

src/libs/av/include/av/AvInfo.hpp

@@ -23,6 +23,7 @@
 
 #include <chrono>
 #include <filesystem>
+#include <functional>
 #include <map>
 #include <optional>
 #include <string>
@@ -40,7 +41,8 @@ void AvInit();
 struct Picture
 {
 	std::string mimeType;
-	std::vector<uint8_t> data;
+	const std::byte* data {};
+	std::size_t dataSize;
 };
 
 struct StreamInfo
@@ -76,11 +78,11 @@ class MediaFile
 		std::vector<StreamInfo>	getStreamInfo() const;
 		std::optional<std::size_t>	getBestStream() const; // none if failure/unknown
 		bool			hasAttachedPictures(void) const;
-		std::vector<Picture>	getAttachedPictures(std::size_t nbMaxPictures) const;
+		void			visitAttachedPictures(std::function<void(const Picture&)> func) const;
 
 	private:
 
-		std::filesystem::path	_p;
+		const std::filesystem::path	_p;
 		AVFormatContext* _context {};
 };