Fix last frame request

Author: NicolasHug

src/torchcodec/decoders/_core/VideoDecoder.cpp

@@ -1123,6 +1123,7 @@ VideoDecoder::BatchDecodedOutput VideoDecoder::getFramesDisplayedByTimestamps(
           return ptsToSeconds(info.nextPts, stream.timeBase) <= start;
         });
     int64_t frameIndex = it - stream.allFrames.begin();
+    frameIndex = std::min(frameIndex, (int64_t)stream.allFrames.size() - 1);
     frameIndices[i] = frameIndex;
   }
 

test/decoders/test_video_decoder_ops.py

@@ -162,7 +162,8 @@ def test_get_frames_by_pts(self):
         scan_all_streams_to_update_metadata(decoder)
         stream_index = 3
 
-        frame_ptss = [2, 0, 1, 0 + 1e-3, 2 + 1e-3]
+        # Note: 13.01 should give the last video frame for the NASA video
+        frame_ptss = [2, 0, 1, 0 + 1e-3, 13.01, 2 + 1e-3]
 
         expected_frames = [
             get_frame_at_pts(decoder, seconds=pts)[0] for pts in frame_ptss