Add remux subtitles example

docs/cookbook/audio.rst

@@ -0,0 +1,8 @@
+Audio
+=====
+
+
+Filters
+-------
+
+.. literalinclude:: ../../examples/audio/atempo.py

docs/cookbook/subtitles.rst

@@ -0,0 +1,10 @@
+Subtitles
+=========
+
+
+Remuxing
+--------
+
+Remuxing is copying stream(s) from one container to the other without transcoding it. By doing so, the data does not suffer any generational loss, and is the full quality that it was in the source container.
+
+.. literalinclude:: ../../examples/subtitles/remux.py

examples/audio_atempo.py → examples/audio/atempo.py

@@ -6,12 +6,9 @@
 output_file = av.open("output.wav", mode="w")
 
 input_stream = input_file.streams.audio[0]
-
 output_stream = output_file.add_stream("pcm_s16le", rate=input_stream.rate)
-assert isinstance(output_stream, av.audio.AudioStream)
 
 graph = av.filter.Graph()
-
 graph.link_nodes(
     graph.add_abuffer(template=input_stream),
     graph.add("atempo", "2.0"),
@@ -31,6 +28,5 @@
 for packet in output_stream.encode(None):
     output_file.mux(packet)
 
-# Close the files
 input_file.close()
 output_file.close()

examples/basics/remux.py

@@ -1,6 +1,8 @@
 import av
 import av.datasets
 
+av.logging.set_level(av.logging.VERBOSE)
+
 input_ = av.open(av.datasets.curated("pexels/time-lapse-video-of-night-sky-857195.mp4"))
 output = av.open("remuxed.mkv", "w")
 

examples/basics/save_keyframes.py

@@ -7,11 +7,6 @@
     stream = container.streams.video[0]
     stream.codec_context.skip_frame = "NONKEY"
 
-    for frame in container.decode(stream):
+    for i, frame in enumerate(container.decode(stream)):
         print(frame)
-
-        # We use `frame.pts` as `frame.index` won't make must sense with the `skip_frame`.
-        frame.to_image().save(
-            "night-sky.{:04d}.jpg".format(frame.pts),
-            quality=80,
-        )
+        frame.to_image().save(f"night-sky.{i:04d}.jpg", quality=80)

examples/subtitles/remux.py

@@ -0,0 +1,25 @@
+import av
+
+av.logging.set_level(av.logging.VERBOSE)
+
+input_ = av.open("resources/webvtt.mkv")
+output = av.open("remuxed.vtt", "w")
+
+in_stream = input_.streams.subtitles[0]
+out_stream = output.add_stream(template=in_stream)
+
+for packet in input_.demux(in_stream):
+    if packet.dts is None:
+        continue
+    packet.stream = out_stream
+    output.mux(packet)
+
+input_.close()
+output.close()
+
+print("Remuxing done")
+
+with av.open("remuxed.vtt") as f:
+    for subset in f.decode(subtitles=0):
+        for sub in subset:
+            print(sub.ass)