Use dlopen to resolve ffmpeg symbols at runtime.

Signed-off-by: Yong Tang <[email protected]>

tensorflow_io/video/python/ops/video_dataset_ops.py

@@ -18,20 +18,56 @@
 from __future__ import print_function
 
 import os
+import ctypes
+import _ctypes
 
 import tensorflow
 from tensorflow import dtypes
 from tensorflow import errors
 from tensorflow.compat.v1 import data
 from tensorflow_io import _load_library
-video_ops = None
-for f in ['_video_ops_ffmpeg_3.4.so', '_video_ops_ffmpeg_2.8.so', '_video_ops_libav_9.20.so']:
-  try:
-    video_ops = _load_library(f)
-    break;
-  except NotImplementedError as e:
-    print(e)
 
+def load_dependency_and_library(p):
+  for library in p:
+    # First try load all dependencies with RTLD_LOCAL
+    entries = []
+    for dependency in p[library]:
+      try:
+        entries.append(ctypes.CDLL(dependency))
+      except OSError as e:
+        pass
+    if len(entries) == len(p[library]):
+      # Dependencies has been satisfied, load dependencies again with RTLD_GLOBAL, no error is expected
+      for dependency in p[library]:
+        ctypes.CDLL(dependency, mode=ctypes.RTLD_GLOBAL)
+      # Load video_op
+      return _load_library(library)
+    # Otherwise we dlclose and retry
+    entries.reverse()
+    for entry in entries:
+      _ctypes.dlclose(entry._handle)
+  raise NotImplementedError("could not find ffmpeg after search through ", p)
+
+video_ops = load_dependency_and_library({
+    '_video_ops_ffmpeg_3.4.so' : [
+        "libavformat.so.57",
+        "libavformat.so.57",
+        "libavutil.so.55",
+        "libswscale.so.4",
+    ],
+    '_video_ops_ffmpeg_2.8.so' : [
+        "libavformat-ffmpeg.so.56",
+        "libavcodec-ffmpeg.so.56",
+        "libavutil-ffmpeg.so.54",
+        "libswscale-ffmpeg.so.3",
+    ],
+    '_video_ops_libav_9.20.so' : [
+        "libavformat.so.54",
+        "libavcodec.so.54",
+        "libavutil.so.52",
+        "libswscale.so.2",
+    ],
+})
 
 class VideoDataset(data.Dataset):
   """A Video File Dataset that reads the video file."""