Read video from memory newapi (#6771)

* add tensor as optional param

* add init from memory

* fix bug

* fix bug

* first working version

* apply formatting and add tests

* simplify tests

* fix tests

* fix wrong variable name

* add path as optional parameter

* add src as optional

* address pr comments

* Fix warning messages

* address pr comments

* make tests stricter

* Revert "make tests stricter"

This reverts commit 6c92e94.

test/test_videoapi.py

@@ -77,6 +77,7 @@ def test_frame_reading(self, test_video):
                 # compare the frames and ptss
                 for i in range(len(vr_frames)):
                     assert float(av_pts[i]) == approx(vr_pts[i], abs=0.1)
+
                     mean_delta = torch.mean(torch.abs(av_frames[i].float() - vr_frames[i].float()))
                     # on average the difference is very small and caused
                     # by decoding (around 1%)
@@ -114,6 +115,46 @@ def test_frame_reading(self, test_video):
                     # we assure that there is never more than 1% difference in signal
                     assert max_delta.item() < 0.001
 
+    @pytest.mark.parametrize("stream", ["video", "audio"])
+    @pytest.mark.parametrize("test_video", test_videos.keys())
+    def test_frame_reading_mem_vs_file(self, test_video, stream):
+        full_path = os.path.join(VIDEO_DIR, test_video)
+
+        # Test video reading from file vs from memory
+        vr_frames, vr_frames_mem = [], []
+        vr_pts, vr_pts_mem = [], []
+        # get vr frames
+        video_reader = VideoReader(full_path, stream)
+        for vr_frame in video_reader:
+            vr_frames.append(vr_frame["data"])
+            vr_pts.append(vr_frame["pts"])
+
+        # get vr frames = read from memory
+        f = open(full_path, "rb")
+        fbytes = f.read()
+        f.close()
+        video_reader_from_mem = VideoReader(fbytes, stream)
+
+        for vr_frame_from_mem in video_reader_from_mem:
+            vr_frames_mem.append(vr_frame_from_mem["data"])
+            vr_pts_mem.append(vr_frame_from_mem["pts"])
+
+        # same number of frames
+        assert len(vr_frames) == len(vr_frames_mem)
+        assert len(vr_pts) == len(vr_pts_mem)
+
+        # compare the frames and ptss
+        for i in range(len(vr_frames)):
+            assert vr_pts[i] == vr_pts_mem[i]
+            mean_delta = torch.mean(torch.abs(vr_frames[i].float() - vr_frames_mem[i].float()))
+            # on average the difference is very small and caused
+            # by decoding (around 1%)
+            # TODO: asses empirically how to set this? atm it's 1%
+            # averaged over all frames
+            assert mean_delta.item() < 2.55
+
+        del vr_frames, vr_pts, vr_frames_mem, vr_pts_mem
+
     @pytest.mark.parametrize("test_video,config", test_videos.items())
     def test_metadata(self, test_video, config):
         """

torchvision/csrc/io/decoder/defs.h

@@ -165,7 +165,7 @@ struct MediaFormat {
 struct DecoderParameters {
   // local file, remote file, http url, rtmp stream uri, etc. anything that
   // ffmpeg can recognize
-  std::string uri;
+  std::string uri{std::string()};
   // timeout on getting bytes for decoding
   size_t timeoutMs{1000};
   // logging level, default AV_LOG_PANIC

torchvision/csrc/io/video/video.cpp

@@ -156,14 +156,34 @@ void Video::_getDecoderParams(
 
 } // _get decoder params
 
-Video::Video(std::string videoPath, std::string stream, int64_t numThreads) {
-  C10_LOG_API_USAGE_ONCE("torchvision.csrc.io.video.video.Video");
+void Video::initFromFile(
+    std::string videoPath,
+    std::string stream,
+    int64_t numThreads) {
+  TORCH_CHECK(!initialized, "Video object can only be initialized once");
+  initialized = true;
+  params.uri = videoPath;
+  _init(stream, numThreads);
+}
+
+void Video::initFromMemory(
+    torch::Tensor videoTensor,
+    std::string stream,
+    int64_t numThreads) {
+  TORCH_CHECK(!initialized, "Video object can only be initialized once");
+  initialized = true;
+  callback = MemoryBuffer::getCallback(
+      videoTensor.data_ptr<uint8_t>(), videoTensor.size(0));
+  _init(stream, numThreads);
+}
+
+void Video::_init(std::string stream, int64_t numThreads) {
   // set number of threads global
   numThreads_ = numThreads;
   // parse stream information
   current_stream = _parseStream(stream);
   // note that in the initial call we want to get all streams
-  Video::_getDecoderParams(
+  _getDecoderParams(
       0, // video start
       0, // headerOnly
       std::get<0>(current_stream), // stream info - remove that
@@ -175,11 +195,6 @@ Video::Video(std::string videoPath, std::string stream, int64_t numThreads) {
 
   std::string logMessage, logType;
 
-  // TODO: add read from memory option
-  params.uri = videoPath;
-  logType = "file";
-  logMessage = videoPath;
-
   // locals
   std::vector<double> audioFPS, videoFPS;
   std::vector<double> audioDuration, videoDuration, ccDuration, subsDuration;
@@ -190,7 +205,8 @@ Video::Video(std::string videoPath, std::string stream, int64_t numThreads) {
   c10::Dict<std::string, std::vector<double>> subsMetadata;
 
   // callback and metadata defined in struct
-  succeeded = decoder.init(params, std::move(callback), &metadata);
+  DecoderInCallback tmp_callback = callback;
+  succeeded = decoder.init(params, std::move(tmp_callback), &metadata);
   if (succeeded) {
     for (const auto& header : metadata) {
       double fps = double(header.fps);
@@ -225,16 +241,24 @@ Video::Video(std::string videoPath, std::string stream, int64_t numThreads) {
   streamsMetadata.insert("subtitles", subsMetadata);
   streamsMetadata.insert("cc", ccMetadata);
 
-  succeeded = Video::setCurrentStream(stream);
+  succeeded = setCurrentStream(stream);
   LOG(INFO) << "\nDecoder inited with: " << succeeded << "\n";
   if (std::get<1>(current_stream) != -1) {
     LOG(INFO)
         << "Stream index set to " << std::get<1>(current_stream)
         << ". If you encounter trouble, consider switching it to automatic stream discovery. \n";
   }
+}
+
+Video::Video(std::string videoPath, std::string stream, int64_t numThreads) {
+  C10_LOG_API_USAGE_ONCE("torchvision.csrc.io.video.video.Video");
+  if (!videoPath.empty()) {
+    initFromFile(videoPath, stream, numThreads);
+  }
 } // video
 
 bool Video::setCurrentStream(std::string stream = "video") {
+  TORCH_CHECK(initialized, "Video object has to be initialized first");
   if ((!stream.empty()) && (_parseStream(stream) != current_stream)) {
     current_stream = _parseStream(stream);
   }
@@ -256,19 +280,23 @@ bool Video::setCurrentStream(std::string stream = "video") {
   );
 
   // callback and metadata defined in Video.h
-  return (decoder.init(params, std::move(callback), &metadata));
+  DecoderInCallback tmp_callback = callback;
+  return (decoder.init(params, std::move(tmp_callback), &metadata));
 }
 
 std::tuple<std::string, int64_t> Video::getCurrentStream() const {
+  TORCH_CHECK(initialized, "Video object has to be initialized first");
   return current_stream;
 }
 
 c10::Dict<std::string, c10::Dict<std::string, std::vector<double>>> Video::
     getStreamMetadata() const {
+  TORCH_CHECK(initialized, "Video object has to be initialized first");
   return streamsMetadata;
 }
 
 void Video::Seek(double ts, bool fastSeek = false) {
+  TORCH_CHECK(initialized, "Video object has to be initialized first");
   // initialize the class variables used for seeking and retrurn
   _getDecoderParams(
       ts, // video start
@@ -282,11 +310,14 @@ void Video::Seek(double ts, bool fastSeek = false) {
   );
 
   // callback and metadata defined in Video.h
-  succeeded = decoder.init(params, std::move(callback), &metadata);
+  DecoderInCallback tmp_callback = callback;
+  succeeded = decoder.init(params, std::move(tmp_callback), &metadata);
+
   LOG(INFO) << "Decoder init at seek " << succeeded << "\n";
 }
 
 std::tuple<torch::Tensor, double> Video::Next() {
+  TORCH_CHECK(initialized, "Video object has to be initialized first");
   // if failing to decode simply return a null tensor (note, should we
   // raise an exeption?)
   double frame_pts_s;
@@ -345,6 +376,8 @@ std::tuple<torch::Tensor, double> Video::Next() {
 static auto registerVideo =
     torch::class_<Video>("torchvision", "Video")
         .def(torch::init<std::string, std::string, int64_t>())
+        .def("init_from_file", &Video::initFromFile)
+        .def("init_from_memory", &Video::initFromMemory)
         .def("get_current_stream", &Video::getCurrentStream)
         .def("set_current_stream", &Video::setCurrentStream)
         .def("get_metadata", &Video::getStreamMetadata)

torchvision/csrc/io/video/video.h

@@ -19,7 +19,19 @@ struct Video : torch::CustomClassHolder {
   int64_t numThreads_{0};
 
  public:
-  Video(std::string videoPath, std::string stream, int64_t numThreads);
+  Video(
+      std::string videoPath = std::string(),
+      std::string stream = std::string("video"),
+      int64_t numThreads = 0);
+  void initFromFile(
+      std::string videoPath,
+      std::string stream,
+      int64_t numThreads);
+  void initFromMemory(
+      torch::Tensor videoTensor,
+      std::string stream,
+      int64_t numThreads);
+
   std::tuple<std::string, int64_t> getCurrentStream() const;
   c10::Dict<std::string, c10::Dict<std::string, std::vector<double>>>
   getStreamMetadata() const;
@@ -34,6 +46,12 @@ struct Video : torch::CustomClassHolder {
   // time in comination with any_frame settings
   double seekTS = -1;
 
+  bool initialized = false;
+
+  void _init(
+      std::string stream,
+      int64_t numThreads); // expects params.uri OR callback to be set
+
   void _getDecoderParams(
       double videoStartS,
       int64_t getPtsOnly,

torchvision/io/video_reader.py

@@ -1,4 +1,5 @@
-from typing import Any, Dict, Iterator
+import warnings
+from typing import Any, Dict, Iterator, Optional
 
 import torch
 
@@ -71,8 +72,13 @@ class VideoReader:
         If only stream type is passed, the decoder auto-detects first stream of that type.
 
     Args:
+        src (string, bytes object, or tensor): The media source.
+            If string-type, it must be a file path supported by FFMPEG.
+            If bytes shoud be an in memory representatin of a file supported by FFMPEG.
+            If Tensor, it is interpreted internally as byte buffer.
+            It must be one-dimensional, of type ``torch.uint8``.
+
 
-        path (string): Path to the video file in supported format
 
         stream (string, optional): descriptor of the required stream, followed by the stream id,
             in the format ``{stream_type}:{stream_id}``. Defaults to ``"video:0"``.
@@ -85,17 +91,31 @@ class VideoReader:
         device (str, optional): Device to be used for decoding. Defaults to ``"cpu"``.
             To use GPU decoding, pass ``device="cuda"``.
 
+        path (str, optional):
+            .. warning:
+                This parameter was deprecated in ``0.15`` and will be removed in ``0.17``.
+                Please use ``src`` instead.
+
+
+
     """
 
-    def __init__(self, path: str, stream: str = "video", num_threads: int = 0, device: str = "cpu") -> None:
+    def __init__(
+        self,
+        src: str = "",
+        stream: str = "video",
+        num_threads: int = 0,
+        device: str = "cpu",
+        path: Optional[str] = None,
+    ) -> None:
         _log_api_usage_once(self)
         self.is_cuda = False
         device = torch.device(device)
         if device.type == "cuda":
             if not _HAS_GPU_VIDEO_DECODER:
                 raise RuntimeError("Not compiled with GPU decoder support.")
             self.is_cuda = True
-            self._c = torch.classes.torchvision.GPUDecoder(path, device)
+            self._c = torch.classes.torchvision.GPUDecoder(src, device)
             return
         if not _has_video_opt():
             raise RuntimeError(
@@ -105,7 +125,24 @@ def __init__(self, path: str, stream: str = "video", num_threads: int = 0, devic
                 + "build torchvision from source."
             )
 
-        self._c = torch.classes.torchvision.Video(path, stream, num_threads)
+        if src == "":
+            if path is None:
+                raise TypeError("src cannot be empty")
+            src = path
+            warnings.warn("path is deprecated and will be removed in 0.17. Please use src instead")
+
+        elif isinstance(src, bytes):
+            src = torch.frombuffer(src, dtype=torch.uint8)
+
+        if isinstance(src, str):
+            self._c = torch.classes.torchvision.Video(src, stream, num_threads)
+        elif isinstance(src, torch.Tensor):
+            if self.is_cuda:
+                raise RuntimeError("GPU VideoReader cannot be initialized from Tensor or bytes object.")
+            self._c = torch.classes.torchvision.Video("", "", 0)
+            self._c.init_from_memory(src, stream, num_threads)
+        else:
+            raise TypeError("`src` must be either string, Tensor or bytes object.")
 
     def __next__(self) -> Dict[str, Any]:
         """Decodes and returns the next frame of the current stream.