Suppress warning when calling torch.frombuffer with non-writable buffer (#6971)

Co-authored-by: Joao Gomes <jdsgomes@fb.com>

torchvision/io/_video_opt.py

@@ -336,6 +336,9 @@ def _read_video_from_memory(
     _validate_pts(audio_pts_range)
 
     if not isinstance(video_data, torch.Tensor):
+        with warnings.catch_warnings():
+            # Ignore the warning because we actually dont modify the buffer in this function
+            warnings.filterwarnings("ignore", message="The given buffer is not writable")
             video_data = torch.frombuffer(video_data, dtype=torch.uint8)
 
     result = torch.ops.video_reader.read_video_from_memory(
@@ -378,6 +381,9 @@ def _read_video_timestamps_from_memory(
     is much faster than read_video(...)
     """
     if not isinstance(video_data, torch.Tensor):
+        with warnings.catch_warnings():
+            # Ignore the warning because we actually dont modify the buffer in this function
+            warnings.filterwarnings("ignore", message="The given buffer is not writable")
             video_data = torch.frombuffer(video_data, dtype=torch.uint8)
     result = torch.ops.video_reader.read_video_from_memory(
         video_data,
@@ -416,6 +422,9 @@ def _probe_video_from_memory(
     This function is torchscriptable
     """
     if not isinstance(video_data, torch.Tensor):
+        with warnings.catch_warnings():
+            # Ignore the warning because we actually dont modify the buffer in this function
+            warnings.filterwarnings("ignore", message="The given buffer is not writable")
             video_data = torch.frombuffer(video_data, dtype=torch.uint8)
     result = torch.ops.video_reader.probe_video_from_memory(video_data)
     vtimebase, vfps, vduration, atimebase, asample_rate, aduration = result