spdl.io.FilterGraph

class FilterGraph(filter_desc: str)

Construct a filter graph

Parameters:

filter_desc – A filter graph description.

See also

• get_buffer_desc(), get_abuffer_desc(): Helper functions for constructing input audio/video frames.

Example - Audio filtering (passthrough)

For video processing use abuffer for input and abuffersink for output.

filter_desc = "abuffer=time_base=1/44100:sample_rate=44100:sample_fmt=s16:channel_layout=1c,anull,abuffersink"
filter_graph = FilterGraph(filter_desc)

filter_graph.add_frames(frames)
frames = filter_graph.get_frames()

+------------------+
| Parsed_abuffer_0 |default--[44100Hz s16:mono]--Parsed_anull_1:default
|    (abuffer)     |
+------------------+

                                                     +----------------+
Parsed_abuffer_0:default--[44100Hz s16:mono]--default| Parsed_anull_1 |default--[44100Hz s16:mono]--Parsed_abuffersink_2:default
                                                     |    (anull)     |
                                                     +----------------+

                                                   +----------------------+
Parsed_anull_1:default--[44100Hz s16:mono]--default| Parsed_abuffersink_2 |
                                                   |    (abuffersink)     |
                                                   +----------------------+

Example - Video filtering (passthrough)

For video processing use buffer for input and buffersink for output.

filter_desc = "buffer=video_size=320x240:pix_fmt=yuv420p:time_base=1/12800:pixel_aspect=1/1,null,buffersink"
filter_graph = FilterGraph(filter_desc)

filter_graph.add_frames(frames)
frames = filter_graph.get_frames()

+-----------------+
| Parsed_buffer_0 |default--[320x240 1:1 yuv420p]--Parsed_null_1:default
|    (buffer)     |
+-----------------+

                                                       +---------------+
Parsed_buffer_0:default--[320x240 1:1 yuv420p]--default| Parsed_null_1 |default--[320x240 1:1 yuv420p]--Parsed_buffersink_2:default
                                                       |    (null)     |
                                                       +---------------+

                                                     +---------------------+
Parsed_null_1:default--[320x240 1:1 yuv420p]--default| Parsed_buffersink_2 |
                                                     |    (buffersink)     |
                                                     +---------------------+

Example - Multiple Inputs

Suffix the buffer/abuffer with node name so that it can be referred later.

filter_desc = "buffer@in0=video_size=320x240:pix_fmt=yuv420p:time_base=1/12800:pixel_aspect=1/1 [in0];buffer@in1=video_size=320x240:pix_fmt=yuv420p:time_base=1/12800:pixel_aspect=1/1 [in1],[in0] [in1] vstack,buffersink"
filter_graph = FilterGraph(filter_desc)

filter_graph.add_frames(frames0, key="buffer@in0")
filter_graph.add_frames(frames1, key="buffer@in1")
frames = filter_graph.get_frames()

+------------+
| buffer@in0 |default--[320x240 1:1 yuv420p]--Parsed_vstack_2:input0
|  (buffer)  |
+------------+

+------------+
| buffer@in1 |default--[320x240 1:1 yuv420p]--Parsed_vstack_2:input1
|  (buffer)  |
+------------+

                                                 +-----------------+
buffer@in0:default--[320x240 1:1 yuv420p]--input0| Parsed_vstack_2 |default--[320x480 1:1 yuv420p]--Parsed_buffersink_3:default
buffer@in1:default--[320x240 1:1 yuv420p]--input1|    (vstack)     |
                                                 +-----------------+

                                                       +---------------------+
Parsed_vstack_2:default--[320x480 1:1 yuv420p]--default| Parsed_buffersink_3 |
                                                       |    (buffersink)     |
                                                       +---------------------+

Example - Multiple outputs

Suffix the buffersink/abuffersink with node name so that it can be referred later.

filter_desc = "buffer=video_size=320x240:pix_fmt=yuv420p:time_base=1/12800:pixel_aspect=1/1 [in];[in] split [out0][out1];[out0] buffersink@out0;[out1] buffersink@out1"
filter_graph = FilterGraph(filter_desc)

filter_graph.add_frames(frames)
frames0 = filter_graph.get_frames(key="buffersink@out0")
frames1 = filter_graph.get_frames(key="buffersink@out1")

+-----------------+
| Parsed_buffer_0 |default--[320x240 1:1 yuv420p]--Parsed_split_1:default
|    (buffer)     |
+-----------------+

                                                       +----------------+
Parsed_buffer_0:default--[320x240 1:1 yuv420p]--default| Parsed_split_1 |output0--[320x240 1:1 yuv420p]--buffersink@out0:default
                                                       |    (split)     |output1--[320x240 1:1 yuv420p]--buffersink@out1:default
                                                       +----------------+

                                                      +-----------------+
Parsed_split_1:output0--[320x240 1:1 yuv420p]--default| buffersink@out0 |
                                                      |  (buffersink)   |
                                                      +-----------------+

                                                      +-----------------+
Parsed_split_1:output1--[320x240 1:1 yuv420p]--default| buffersink@out1 |
                                                      |  (buffersink)   |
                                                      +-----------------+

Example - Multimedia filter

Using multimedia filters allows to convert audio stream to video stream.

filter_desc = "abuffer=time_base=1/44100:sample_rate=44100:sample_fmt=s16:channel_layout=1c,showwaves,buffersink"
filter_graph = FilterGraph(filter_desc)

filter_graph.add_frames(audio_frames)
video_frames = filter_graph.get_frames()

+------------------+
| Parsed_abuffer_0 |default--[44100Hz s16:mono]--Parsed_showwaves_1:default
|    (abuffer)     |
+------------------+

                                                     +--------------------+
Parsed_abuffer_0:default--[44100Hz s16:mono]--default| Parsed_showwaves_1 |default--[600x240 1:1 rgba]--Parsed_buffersink_2:default
                                                     |    (showwaves)     |
                                                     +--------------------+

                                                       +---------------------+
Parsed_showwaves_1:default--[600x240 1:1 rgba]--default| Parsed_buffersink_2 |
                                                       |    (buffersink)     |
                                                       +---------------------+

Methods

add_frames(frames, *[, key])	Add a frame to an input node of the filter graph.
flush()	Notify the graph that all the input stream reached the end.
get_frames(*[, key])	Get a frame from an output node of the filter graph.

add_frames(frames: AudioFrames | VideoFrames | ImageFrames, *, key: str | None = None) → None

Add a frame to an input node of the filter graph.

Parameters:

• frames – An input frames object.

• key – The name of the input node. This is required when the graph has multiple input nodes.

flush() → None

Notify the graph that all the input stream reached the end.

get_frames(*, key: str | None = None) → AudioFrames | VideoFrames | ImageFrames | None

Get a frame from an output node of the filter graph.

Parameters:

key – The name of the output node. This is required when the graph has multiple output nodes.

Returns:

A Frames object if an output is ready, otherwise None.