Add FFMS_GetTrackMetadata

Author: moi15moi

doc/ffms2-api.md

@@ -567,6 +567,15 @@ In other words, does the same thing as [FFMS_GetTrackType][GetTrackType], but do
 If you have indexed the file, use [FFMS_GetTrackType][GetTrackType] instead since the `FFMS_Indexer` object is destructed when the index is created.
 Note that specifying an invalid track number may lead to undefined behavior.
 
+### FFMS_GetTrackMetadata - gets the metadata of a given track
+
+[GetTrackMetadata]: #ffms_gettrackmetadata---gets-the-metadata-of-a-given-track
+```c++
+const char *FFMS_GetTrackMetadata(FFMS_Track *T, const char *Key);
+```
+Returns the value of the metadata entry associated with `Key` for the given track `T`.
+For the list of commonly used metadata keys, see the [metadata_api Public Metadata API](https://code.ffmpeg.org/FFmpeg/FFmpeg/src/branch/master/libavformat/avformat.h).
+
 ### FFMS_GetCodecNameI - gets the name of the codec used for a given track
 
 [GetCodecNameI]: #ffms_getcodecnamei---gets-the-name-of-the-codec-used-for-a-given-track

doc/ffms2-changelog.md

@@ -3,6 +3,7 @@
   - FFmpeg 7.1 is now the minimum requirement.
   - Added layered decoding support, for e.g. spatial MV-HEVC.
   - Added LastEndPTS to FFMS_VideoProperties. This field is the equivalent of LastEndTime, but it is expressed in the video timebase.
+  - Add FFMS_GetTrackMetadata.
 
 - 5.0
   - Fixed all issues with FFmpeg 6.1 which is now the minimum requirement

include/ffms.h

@@ -460,6 +460,7 @@ FFMS_API(int) FFMS_GetNumTracks(FFMS_Index *Index);
 FFMS_API(int) FFMS_GetNumTracksI(FFMS_Indexer *Indexer);
 FFMS_API(int) FFMS_GetTrackType(FFMS_Track *T);
 FFMS_API(int) FFMS_GetTrackTypeI(FFMS_Indexer *Indexer, int Track);
+FFMS_API(const char *) FFMS_GetTrackMetadata(FFMS_Track *T, const char *Key);
 FFMS_API(FFMS_IndexErrorHandling) FFMS_GetErrorHandling(FFMS_Index *Index);
 FFMS_API(const char *) FFMS_GetCodecNameI(FFMS_Indexer *Indexer, int Track);
 FFMS_API(const char *) FFMS_GetFormatNameI(FFMS_Indexer *Indexer);

src/core/ffms.cpp

@@ -262,6 +262,13 @@ FFMS_API(int) FFMS_GetTrackType(FFMS_Track *T) {
     return T->TT;
 }
 
+FFMS_API(const char *) FFMS_GetTrackMetadata(FFMS_Track *T, const char *Key) {
+    auto it = T->Metadata.find(Key);
+    if (it == T->Metadata.end())
+        return NULL;
+    return it->second.c_str();
+}
+
 FFMS_API(int) FFMS_GetTrackTypeI(FFMS_Indexer *Indexer, int Track) {
     return Indexer->GetTrackType(Track);
 }

src/core/indexing.cpp

@@ -32,10 +32,11 @@
 extern "C" {
 #include <libavutil/avutil.h>
 #include <libavutil/sha.h>
+#include <libavutil/dict.h>
 }
 
 #define INDEXID 0x53920873
-#define INDEX_VERSION 8
+#define INDEX_VERSION 9
 
 SharedAVContext::~SharedAVContext() {
     avcodec_free_context(&CodecContext);
@@ -445,6 +446,13 @@ FFMS_Index *FFMS_Indexer::DoIndexing() {
             !!(FormatContext->iformat->flags & AVFMT_TS_DISCONT),
             UseDTS);
 
+        AVDictionary *StreamMetadata = FormatContext->streams[i]->metadata;
+        if (StreamMetadata) {
+            const AVDictionaryEntry *Entry = nullptr;
+            while ((Entry = av_dict_iterate(StreamMetadata, Entry)))
+                (*TrackIndices)[i].Metadata[Entry->key] = Entry->value;
+        }
+
         if (IndexMask.count(i) && FormatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
             auto *VideoCodec = avcodec_find_decoder(FormatContext->streams[i]->codecpar->codec_id);
             if (!VideoCodec) {

src/core/track.cpp

@@ -99,6 +99,21 @@ FFMS_Track::FFMS_Track(ZipFile &stream)
     UseDTS = !!stream.Read<uint8_t>();
     HasTS = !!stream.Read<uint8_t>();
     HasDiscontTS = !!stream.Read<uint8_t>();
+    uint32_t MetadataNumEntry = stream.Read<uint32_t>();
+    std::vector<char> KeyBuffer;
+    std::vector<char> ValueBuffer;
+    for (uint32_t i = 0; i < MetadataNumEntry; i++) {
+        uint32_t KeyLength = stream.Read<uint32_t>();
+        KeyBuffer.resize(KeyLength);
+        stream.Read(KeyBuffer.data(), KeyLength);
+
+        uint32_t ValueLength = stream.Read<uint32_t>();
+        ValueBuffer.resize(ValueLength);
+        stream.Read(ValueBuffer.data(), ValueLength);
+
+        Metadata[std::string(KeyBuffer.data(), KeyLength)] = std::string(ValueBuffer.data(), ValueLength);
+    }
+
     size_t FrameCount = static_cast<size_t>(stream.Read<uint64_t>());
 
     if (!FrameCount) return;
@@ -122,6 +137,13 @@ void FFMS_Track::Write(ZipFile &stream) const {
     stream.Write<uint8_t>(UseDTS);
     stream.Write<uint8_t>(HasTS);
     stream.Write<uint8_t>(HasDiscontTS);
+    stream.Write<uint32_t>(Metadata.size());
+    for (const auto &iter : Metadata) {
+        stream.Write<uint32_t>(iter.first.length());
+        stream.Write(iter.first.data(), iter.first.length());
+        stream.Write<uint32_t>(iter.second.length());
+        stream.Write(iter.second.data(), iter.second.length());
+    }
     stream.Write<uint64_t>(size());
 
     if (empty()) return;

src/core/track.h

@@ -26,6 +26,8 @@
 #include <cstddef>
 #include <vector>
 #include <memory>
+#include <string>
+#include <map>
 
 class ZipFile;
 
@@ -72,6 +74,7 @@ struct FFMS_Track {
     bool HasDiscontTS = false;
     int64_t LastDuration = 0;
     int SampleRate = 0; // not persisted
+    std::map<std::string, std::string> Metadata;
 
     void AddVideoFrame(int64_t PTS, int64_t DTS, int RepeatPict, bool KeyFrame, int FrameType, int64_t FilePos = 0, bool Invisible = false, bool SecondField = false);
     void AddAudioFrame(int64_t PTS, int64_t DTS, int64_t SampleStart, uint32_t SampleCount, bool KeyFrame, int64_t FilePos = 0, bool Invisible = false);