extend video reader to support fast video probing (#1437)

* extend video reader to support fast video probing

* fix c++ lint

* small fix

* allow to accept input video of type torch.Tensor

Author: stephenyan1231

test/test_io.py

@@ -86,6 +86,22 @@ def test_write_read_video(self):
             self.assertTrue(data.equal(lv))
             self.assertEqual(info["video_fps"], 5)
 
+    @unittest.skipIf(not io._HAS_VIDEO_OPT, "video_reader backend is not chosen")
+    def test_probe_video_from_file(self):
+        with temp_video(10, 300, 300, 5) as (f_name, data):
+            video_info = io._probe_video_from_file(f_name)
+            self.assertAlmostEqual(video_info["video_duration"], 2, delta=0.1)
+            self.assertAlmostEqual(video_info["video_fps"], 5, delta=0.1)
+
+    @unittest.skipIf(not io._HAS_VIDEO_OPT, "video_reader backend is not chosen")
+    def test_probe_video_from_memory(self):
+        with temp_video(10, 300, 300, 5) as (f_name, data):
+            with open(f_name, "rb") as fp:
+                filebuffer = fp.read()
+            video_info = io._probe_video_from_memory(filebuffer)
+            self.assertAlmostEqual(video_info["video_duration"], 2, delta=0.1)
+            self.assertAlmostEqual(video_info["video_fps"], 5, delta=0.1)
+
     def test_read_timestamps(self):
         with temp_video(10, 300, 300, 5) as (f_name, data):
             if _video_backend == "pyav":

test/test_video_reader.py

@@ -31,6 +31,7 @@
 VIDEO_DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), "assets", "videos")
 
 CheckerConfig = [
+    "duration",
     "video_fps",
     "audio_sample_rate",
     # We find for some videos (e.g. HMDB51 videos), the decoded audio frames and pts are
@@ -44,6 +45,7 @@
 )
 
 all_check_config = GroundTruth(
+    duration=0,
     video_fps=0,
     audio_sample_rate=0,
     check_aframes=True,
@@ -52,50 +54,58 @@
 
 test_videos = {
     "RATRACE_wave_f_nm_np1_fr_goo_37.avi": GroundTruth(
+        duration=2.0,
         video_fps=30.0,
         audio_sample_rate=None,
         check_aframes=True,
         check_aframe_pts=True,
     ),
     "SchoolRulesHowTheyHelpUs_wave_f_nm_np1_ba_med_0.avi": GroundTruth(
+        duration=2.0,
         video_fps=30.0,
         audio_sample_rate=None,
         check_aframes=True,
         check_aframe_pts=True,
     ),
     "TrumanShow_wave_f_nm_np1_fr_med_26.avi": GroundTruth(
+        duration=2.0,
         video_fps=30.0,
         audio_sample_rate=None,
         check_aframes=True,
         check_aframe_pts=True,
     ),
     "v_SoccerJuggling_g23_c01.avi": GroundTruth(
+        duration=8.0,
         video_fps=29.97,
         audio_sample_rate=None,
         check_aframes=True,
         check_aframe_pts=True,
     ),
     "v_SoccerJuggling_g24_c01.avi": GroundTruth(
+        duration=8.0,
         video_fps=29.97,
         audio_sample_rate=None,
         check_aframes=True,
         check_aframe_pts=True,
     ),
     "R6llTwEh07w.mp4": GroundTruth(
+        duration=10.0,
         video_fps=30.0,
         audio_sample_rate=44100,
         # PyAv miss one audio frame at the beginning (pts=0)
         check_aframes=False,
         check_aframe_pts=False,
     ),
     "SOX5yA1l24A.mp4": GroundTruth(
+        duration=11.0,
         video_fps=29.97,
         audio_sample_rate=48000,
         # PyAv miss one audio frame at the beginning (pts=0)
         check_aframes=False,
         check_aframe_pts=False,
     ),
     "WUzgd7C1pWA.mp4": GroundTruth(
+        duration=11.0,
         video_fps=29.97,
         audio_sample_rate=48000,
         # PyAv miss one audio frame at the beginning (pts=0)
@@ -272,13 +282,22 @@ class TestVideoReader(unittest.TestCase):
     def check_separate_decoding_result(self, tv_result, config):
         """check the decoding results from TorchVision decoder
         """
-        vframes, vframe_pts, vtimebase, vfps, aframes, aframe_pts, atimebase, asample_rate = (
-            tv_result
+        vframes, vframe_pts, vtimebase, vfps, vduration, aframes, aframe_pts, \
+            atimebase, asample_rate, aduration = tv_result
+
+        video_duration = vduration.item() * Fraction(
+            vtimebase[0].item(), vtimebase[1].item()
         )
+        self.assertAlmostEqual(video_duration, config.duration, delta=0.5)
 
         self.assertAlmostEqual(vfps.item(), config.video_fps, delta=0.5)
         if asample_rate.numel() > 0:
             self.assertEqual(asample_rate.item(), config.audio_sample_rate)
+            audio_duration = aduration.item() * Fraction(
+                atimebase[0].item(), atimebase[1].item()
+            )
+            self.assertAlmostEqual(audio_duration, config.duration, delta=0.5)
+
         # check if pts of video frames are sorted in ascending order
         for i in range(len(vframe_pts) - 1):
             self.assertEqual(vframe_pts[i] < vframe_pts[i + 1], True)
@@ -288,6 +307,20 @@ def check_separate_decoding_result(self, tv_result, config):
             for i in range(len(aframe_pts) - 1):
                 self.assertEqual(aframe_pts[i] < aframe_pts[i + 1], True)
 
+    def check_probe_result(self, result, config):
+        vtimebase, vfps, vduration, atimebase, asample_rate, aduration = result
+        video_duration = vduration.item() * Fraction(
+            vtimebase[0].item(), vtimebase[1].item()
+        )
+        self.assertAlmostEqual(video_duration, config.duration, delta=0.5)
+        self.assertAlmostEqual(vfps.item(), config.video_fps, delta=0.5)
+        if asample_rate.numel() > 0:
+            self.assertEqual(asample_rate.item(), config.audio_sample_rate)
+            audio_duration = aduration.item() * Fraction(
+                atimebase[0].item(), atimebase[1].item()
+            )
+            self.assertAlmostEqual(audio_duration, config.duration, delta=0.5)
+
     def compare_decoding_result(self, tv_result, ref_result, config=all_check_config):
         """
         Compare decoding results from two sources.
@@ -297,18 +330,17 @@ def compare_decoding_result(self, tv_result, ref_result, config=all_check_config
                         decoder or TorchVision decoder with getPtsOnly = 1
             config: config of decoding results checker
         """
-        vframes, vframe_pts, vtimebase, _vfps, aframes, aframe_pts, atimebase, _asample_rate = (
-            tv_result
-        )
+        vframes, vframe_pts, vtimebase, _vfps, _vduration, aframes, aframe_pts, \
+            atimebase, _asample_rate, _aduration = tv_result
         if isinstance(ref_result, list):
             # the ref_result is from new video_reader decoder
             ref_result = DecoderResult(
                 vframes=ref_result[0],
                 vframe_pts=ref_result[1],
                 vtimebase=ref_result[2],
-                aframes=ref_result[4],
-                aframe_pts=ref_result[5],
-                atimebase=ref_result[6],
+                aframes=ref_result[5],
+                aframe_pts=ref_result[6],
+                atimebase=ref_result[7],
             )
 
         if vframes.numel() > 0 and ref_result.vframes.numel() > 0:
@@ -351,12 +383,12 @@ def test_stress_test_read_video_from_file(self):
         audio_start_pts, audio_end_pts = 0, -1
         audio_timebase_num, audio_timebase_den = 0, 1
 
-        for i in range(num_iter):
-            for test_video, config in test_videos.items():
+        for _i in range(num_iter):
+            for test_video, _config in test_videos.items():
                 full_path = os.path.join(VIDEO_DIR, test_video)
 
                 # pass 1: decode all frames using new decoder
-                _ = torch.ops.video_reader.read_video_from_file(
+                torch.ops.video_reader.read_video_from_file(
                     full_path,
                     seek_frame_margin,
                     0,  # getPtsOnly
@@ -460,9 +492,8 @@ def test_read_video_from_file_read_single_stream_only(self):
                     audio_timebase_den,
                 )
 
-                vframes, vframe_pts, vtimebase, vfps, aframes, aframe_pts, atimebase, asample_rate = (
-                    tv_result
-                )
+                vframes, vframe_pts, vtimebase, vfps, vduration, aframes, aframe_pts, \
+                    atimebase, asample_rate, aduration = tv_result
 
                 self.assertEqual(vframes.numel() > 0, readVideoStream)
                 self.assertEqual(vframe_pts.numel() > 0, readVideoStream)
@@ -489,7 +520,7 @@ def test_read_video_from_file_rescale_min_dimension(self):
         audio_start_pts, audio_end_pts = 0, -1
         audio_timebase_num, audio_timebase_den = 0, 1
 
-        for test_video, config in test_videos.items():
+        for test_video, _config in test_videos.items():
             full_path = os.path.join(VIDEO_DIR, test_video)
 
             tv_result = torch.ops.video_reader.read_video_from_file(
@@ -528,7 +559,7 @@ def test_read_video_from_file_rescale_width(self):
         audio_start_pts, audio_end_pts = 0, -1
         audio_timebase_num, audio_timebase_den = 0, 1
 
-        for test_video, config in test_videos.items():
+        for test_video, _config in test_videos.items():
             full_path = os.path.join(VIDEO_DIR, test_video)
 
             tv_result = torch.ops.video_reader.read_video_from_file(
@@ -567,7 +598,7 @@ def test_read_video_from_file_rescale_height(self):
         audio_start_pts, audio_end_pts = 0, -1
         audio_timebase_num, audio_timebase_den = 0, 1
 
-        for test_video, config in test_videos.items():
+        for test_video, _config in test_videos.items():
             full_path = os.path.join(VIDEO_DIR, test_video)
 
             tv_result = torch.ops.video_reader.read_video_from_file(
@@ -606,7 +637,7 @@ def test_read_video_from_file_rescale_width_and_height(self):
         audio_start_pts, audio_end_pts = 0, -1
         audio_timebase_num, audio_timebase_den = 0, 1
 
-        for test_video, config in test_videos.items():
+        for test_video, _config in test_videos.items():
             full_path = os.path.join(VIDEO_DIR, test_video)
 
             tv_result = torch.ops.video_reader.read_video_from_file(
@@ -651,7 +682,7 @@ def test_read_video_from_file_audio_resampling(self):
             audio_start_pts, audio_end_pts = 0, -1
             audio_timebase_num, audio_timebase_den = 0, 1
 
-            for test_video, config in test_videos.items():
+            for test_video, _config in test_videos.items():
                 full_path = os.path.join(VIDEO_DIR, test_video)
 
                 tv_result = torch.ops.video_reader.read_video_from_file(
@@ -674,18 +705,17 @@ def test_read_video_from_file_audio_resampling(self):
                     audio_timebase_num,
                     audio_timebase_den,
                 )
-                vframes, vframe_pts, vtimebase, vfps, aframes, aframe_pts, atimebase, a_sample_rate = (
-                    tv_result
-                )
+                vframes, vframe_pts, vtimebase, vfps, vduration, aframes, aframe_pts, \
+                    atimebase, asample_rate, aduration = tv_result
                 if aframes.numel() > 0:
-                    self.assertEqual(samples, a_sample_rate.item())
+                    self.assertEqual(samples, asample_rate.item())
                     self.assertEqual(1, aframes.size(1))
                     # when audio stream is found
                     duration = float(aframe_pts[-1]) * float(atimebase[0]) / float(atimebase[1])
                     self.assertAlmostEqual(
                         aframes.size(0),
-                        int(duration * a_sample_rate.item()),
-                        delta=0.1 * a_sample_rate.item(),
+                        int(duration * asample_rate.item()),
+                        delta=0.1 * asample_rate.item(),
                     )
 
     def test_compare_read_video_from_memory_and_file(self):
@@ -859,7 +889,7 @@ def test_read_video_from_memory_get_pts_only(self):
             )
 
             self.assertEqual(tv_result_pts_only[0].numel(), 0)
-            self.assertEqual(tv_result_pts_only[4].numel(), 0)
+            self.assertEqual(tv_result_pts_only[5].numel(), 0)
             self.compare_decoding_result(tv_result, tv_result_pts_only)
 
     def test_read_video_in_range_from_memory(self):
@@ -899,9 +929,8 @@ def test_read_video_in_range_from_memory(self):
                 audio_timebase_num,
                 audio_timebase_den,
             )
-            vframes, vframe_pts, vtimebase, vfps, aframes, aframe_pts, atimebase, asample_rate = (
-                tv_result
-            )
+            vframes, vframe_pts, vtimebase, vfps, vduration, aframes, aframe_pts, \
+                atimebase, asample_rate, aduration = tv_result
             self.assertAlmostEqual(config.video_fps, vfps.item(), delta=0.01)
 
             for num_frames in [4, 8, 16, 32, 64, 128]:
@@ -997,6 +1026,24 @@ def test_read_video_in_range_from_memory(self):
                     # and PyAv
                     self.compare_decoding_result(tv_result, pyav_result, config)
 
+    def test_probe_video_from_file(self):
+        """
+        Test the case when decoder probes a video file
+        """
+        for test_video, config in test_videos.items():
+            full_path = os.path.join(VIDEO_DIR, test_video)
+            probe_result = torch.ops.video_reader.probe_video_from_file(full_path)
+            self.check_probe_result(probe_result, config)
+
+    def test_probe_video_from_memory(self):
+        """
+        Test the case when decoder probes a video in memory
+        """
+        for test_video, config in test_videos.items():
+            full_path, video_tensor = _get_video_tensor(VIDEO_DIR, test_video)
+            probe_result = torch.ops.video_reader.probe_video_from_memory(video_tensor)
+            self.check_probe_result(probe_result, config)
+
 
 if __name__ == '__main__':
     unittest.main()

torchvision/csrc/cpu/video_reader/FfmpegAudioStream.cpp

@@ -49,6 +49,7 @@ void FfmpegAudioStream::updateStreamDecodeParams() {
     mediaFormat_.format.audio.timeBaseDen =
         inputCtx_->streams[index_]->time_base.den;
   }
+  mediaFormat_.format.audio.duration = inputCtx_->streams[index_]->duration;
 }
 
 int FfmpegAudioStream::initFormat() {

torchvision/csrc/cpu/video_reader/FfmpegDecoder.cpp

@@ -220,6 +220,30 @@ int FfmpegDecoder::decodeMemory(
   return ret;
 }
 
+int FfmpegDecoder::probeFile(
+    unique_ptr<DecoderParameters> params,
+    const string& fileName,
+    DecoderOutput& decoderOutput) {
+  VLOG(1) << "probe file: " << fileName;
+  FfmpegAvioContext ioctx;
+  return probeVideo(std::move(params), fileName, true, ioctx, decoderOutput);
+}
+
+int FfmpegDecoder::probeMemory(
+    unique_ptr<DecoderParameters> params,
+    const uint8_t* buffer,
+    int64_t size,
+    DecoderOutput& decoderOutput) {
+  VLOG(1) << "probe video data in memory";
+  FfmpegAvioContext ioctx;
+  int ret = ioctx.initAVIOContext(buffer, size);
+  if (ret == 0) {
+    ret =
+        probeVideo(std::move(params), string(""), false, ioctx, decoderOutput);
+  }
+  return ret;
+}
+
 void FfmpegDecoder::cleanUp() {
   if (formatCtx_) {
     for (auto& stream : streams_) {
@@ -320,6 +344,16 @@ int FfmpegDecoder::decodeLoop(
   return ret;
 }
 
+int FfmpegDecoder::probeVideo(
+    unique_ptr<DecoderParameters> params,
+    const std::string& filename,
+    bool isDecodeFile,
+    FfmpegAvioContext& ioctx,
+    DecoderOutput& decoderOutput) {
+  params_ = std::move(params);
+  return init(filename, isDecodeFile, ioctx, decoderOutput);
+}
+
 bool FfmpegDecoder::initStreams() {
   for (auto it = params_->formats.begin(); it != params_->formats.end(); ++it) {
     AVMediaType mediaType;