.. DO NOT EDIT. .. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY. .. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE: .. "tutorials/streaming_api_tutorial.py" .. LINE NUMBERS ARE GIVEN BELOW. .. only:: html .. note:: :class: sphx-glr-download-link-note Click :ref:`here ` to download the full example code .. rst-class:: sphx-glr-example-title .. _sphx_glr_tutorials_streaming_api_tutorial.py: Media Stream API - Pt. 1 ======================== This tutorial shows how to use torchaudio's I/O stream API to fetch and decode audio/video data and apply preprocessings that libavfilter provides. .. GENERATED FROM PYTHON SOURCE LINES 12-25 .. note:: This tutorial requires Streaming API and FFmpeg libraries (>=4.1, <5). The Streaming API is available in nightly builds. Please refer to https://pytorch.org/get-started/locally/ for instructions. There are multiple ways to install FFmpeg libraries. If you are using Anaconda Python distribution, ``conda install -c anaconda 'ffmpeg<5'`` will install the required libraries. .. GENERATED FROM PYTHON SOURCE LINES 28-58 Overview -------- Streaming API leverages the powerful I/O features of ffmpeg. It can - Load audio/video in variety of formats - Load audio/video from local/remote source - Load audio/video from file-like object - Load audio/video from microphone, camera and screen - Generate synthetic audio/video signals. - Load audio/video chunk by chunk - Change the sample rate / frame rate, image size, on-the-fly - Apply filters and preprocessings The streaming API works in three steps. 1. Open media source (file, device, synthetic pattern generator) 2. Configure output stream 3. Stream the media At this moment, the features that the ffmpeg integration provides are limited to the form of ` -> -> ` If you have other forms that can be useful to your usecases, (such as integration with `torch.Tensor` type) please file a feature request. .. GENERATED FROM PYTHON SOURCE LINES 60-63 Preparation ----------- .. GENERATED FROM PYTHON SOURCE LINES 63-70 .. code-block:: default import torch import torchaudio print(torch.__version__) print(torchaudio.__version__) .. rst-class:: sphx-glr-script-out Out: .. code-block:: none 1.12.0 0.12.0 .. GENERATED FROM PYTHON SOURCE LINES 72-102 .. code-block:: default try: from torchaudio.io import StreamReader except ModuleNotFoundError: try: import google.colab print( """ To enable running this notebook in Google Colab, install nightly torch and torchaudio builds and the requisite third party libraries by adding the following code block to the top of the notebook before running it: !pip3 uninstall -y torch torchvision torchaudio !pip3 install --pre torch torchaudio --extra-index-url https://download.pytorch.org/whl/nightly/cpu !add-apt-repository -y ppa:savoury1/ffmpeg4 !apt-get -qq install -y ffmpeg """ ) except ModuleNotFoundError: pass raise import IPython import matplotlib.pyplot as plt base_url = "https://download.pytorch.org/torchaudio/tutorial-assets" AUDIO_URL = f"{base_url}/Lab41-SRI-VOiCES-src-sp0307-ch127535-sg0042.wav" VIDEO_URL = f"{base_url}/stream-api/NASAs_Most_Scientifically_Complex_Space_Observatory_Requires_Precision-MP4.mp4" .. GENERATED FROM PYTHON SOURCE LINES 103-126 Opening the source ------------------ There are mainly three different sources that streaming API can handle. Whichever source is used, the remaining processes (configuring the output, applying preprocessing) are same. 1. Common media formats (resource indicator of string type or file-like object) 2. Audio / Video devices 3. Synthetic audio / video sources The following section covers how to open common media formats. For the other streams, please refer to the `Media Stream API - Pt.2 <./streaming_api2_tutorial.html>`__. .. note:: The coverage of the supported media (such as containers, codecs and protocols) depend on the FFmpeg libraries found in the system. If `StreamReader` raises an error opening a source, please check that `ffmpeg` command can handle it. .. GENERATED FROM PYTHON SOURCE LINES 128-150 Local files ~~~~~~~~~~~ To open a media file, you can simply pass the path of the file to the constructor of `StreamReader`. .. code:: StreamReader(src="audio.wav") StreamReader(src="audio.mp3") This works for image file, video file and video streams. .. code:: # Still image StreamReader(src="image.jpeg") # Video file StreamReader(src="video.mpeg") .. GENERATED FROM PYTHON SOURCE LINES 152-168 Network protocols ~~~~~~~~~~~~~~~~~ You can directly pass a URL as well. .. code:: # Video on remote server StreamReader(src="https://example.com/video.mp4") # Playlist format StreamReader(src="https://example.com/playlist.m3u") # RTMP StreamReader(src="rtmp://example.com:1935/live/app") .. GENERATED FROM PYTHON SOURCE LINES 170-222 File-like objects ~~~~~~~~~~~~~~~~~ You can also pass a file-like object. A file-like object must implement ``read`` method conforming to :py:attr:`io.RawIOBase.read`. If the given file-like object has ``seek`` method, StreamReader uses it as well. In this case the ``seek`` method is expected to conform to :py:attr:`io.IOBase.seek`. .. code:: # Open as fileobj with seek support with open("input.mp4", "rb") as src: StreamReader(src=src) In case where third-party libraries implement ``seek`` so that it raises an error, you can write a wrapper class to mask the ``seek`` method. .. code:: class UnseekableWrapper: def __init__(self, obj): self.obj = obj def read(self, n): return self.obj.read(n) .. code:: import requests response = requests.get("https://example.com/video.mp4", stream=True) s = StreamReader(UnseekableWrapper(response.raw)) .. code:: import boto3 response = boto3.client("s3").get_object(Bucket="my_bucket", Key="key") s = StreamReader(UnseekableWrapper(response["Body"])) .. note:: When using an unseekable file-like object, the source media has to be streamable. For example, a valid MP4-formatted object can have its metadata either at the beginning or at the end of the media data. Those with metadata at the beginning can be opened without method `seek`, but those with metadata at the end cannot be opened without `seek`. .. GENERATED FROM PYTHON SOURCE LINES 224-244 Headerless media ~~~~~~~~~~~~~~~~ If attempting to load headerless raw data, you can use ``format`` and ``option`` to specify the format of the data. Say, you converted an audio file into faw format with ``sox`` command as follow; .. code:: # Headerless, 16-bit signed integer PCM, resampled at 16k Hz. $ sox original.wav -r 16000 raw.s2 Such audio can be opened like following. .. code:: StreamReader(src="raw.s2", format="s16le", option={"sample_rate": "16000"}) .. GENERATED FROM PYTHON SOURCE LINES 246-270 Checking the source streams --------------------------- Once the media is opened, we can inspect the streams and configure the output streams. You can check the number of source streams with :py:attr:`~torchaudio.io.StreamReader.num_src_streams`. .. note:: The number of streams is NOT the number of channels. Each audio stream can contain an arbitrary number of channels. To check the metadata of source stream you can use :py:meth:`~torchaudio.io.StreamReader.get_src_stream_info` method and provide the index of the source stream. This method returns :py:class:`~torchaudio.io.StreamReader.SourceStream`. If a source stream is audio type, then the return type is :py:class:`~torchaudio.io.StreamReader.SourceAudioStream`, which is a subclass of `SourceStream`, with additional audio-specific attributes. Similarly, if a source stream is video type, then the return type is :py:class:`~torchaudio.io.StreamReader.SourceVideoStream`. .. GENERATED FROM PYTHON SOURCE LINES 272-275 For regular audio formats and still image formats, such as `WAV` and `JPEG`, the number of souorce streams is 1. .. GENERATED FROM PYTHON SOURCE LINES 275-280 .. code-block:: default streamer = StreamReader(AUDIO_URL) print("The number of source streams:", streamer.num_src_streams) print(streamer.get_src_stream_info(0)) .. rst-class:: sphx-glr-script-out Out: .. code-block:: none The number of source streams: 1 StreamReaderSourceAudioStream(media_type='audio', codec='pcm_s16le', codec_long_name='PCM signed 16-bit little-endian', format='s16', bit_rate=256000, num_frames=0, bits_per_sample=0, sample_rate=16000.0, num_channels=1) .. GENERATED FROM PYTHON SOURCE LINES 281-284 Container formats and playlist formats may contain multiple streams of different media type. .. GENERATED FROM PYTHON SOURCE LINES 284-291 .. code-block:: default src = "https://devstreaming-cdn.apple.com/videos/streaming/examples/img_bipbop_adv_example_fmp4/master.m3u8" streamer = StreamReader(src) print("The number of source streams:", streamer.num_src_streams) for i in range(streamer.num_src_streams): print(streamer.get_src_stream_info(i)) .. rst-class:: sphx-glr-script-out Out: .. code-block:: none The number of source streams: 27 StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=350041, num_frames=0, bits_per_sample=8, width=960, height=540, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=1471810, num_frames=0, bits_per_sample=8, width=1920, height=1080, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=1076143, num_frames=0, bits_per_sample=8, width=1920, height=1080, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=783546, num_frames=0, bits_per_sample=8, width=1920, height=1080, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=535363, num_frames=0, bits_per_sample=8, width=1280, height=720, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=193825, num_frames=0, bits_per_sample=8, width=768, height=432, frame_rate=30.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=116805, num_frames=0, bits_per_sample=8, width=640, height=360, frame_rate=30.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=62544, num_frames=0, bits_per_sample=8, width=480, height=270, frame_rate=30.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=350041, num_frames=0, bits_per_sample=8, width=960, height=540, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=1471810, num_frames=0, bits_per_sample=8, width=1920, height=1080, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=1076143, num_frames=0, bits_per_sample=8, width=1920, height=1080, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=783546, num_frames=0, bits_per_sample=8, width=1920, height=1080, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=535363, num_frames=0, bits_per_sample=8, width=1280, height=720, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=193825, num_frames=0, bits_per_sample=8, width=768, height=432, frame_rate=30.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=116805, num_frames=0, bits_per_sample=8, width=640, height=360, frame_rate=30.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=62544, num_frames=0, bits_per_sample=8, width=480, height=270, frame_rate=30.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=350041, num_frames=0, bits_per_sample=8, width=960, height=540, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=1471810, num_frames=0, bits_per_sample=8, width=1920, height=1080, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=1076143, num_frames=0, bits_per_sample=8, width=1920, height=1080, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=783546, num_frames=0, bits_per_sample=8, width=1920, height=1080, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=535363, num_frames=0, bits_per_sample=8, width=1280, height=720, frame_rate=60.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=193825, num_frames=0, bits_per_sample=8, width=768, height=432, frame_rate=30.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=116805, num_frames=0, bits_per_sample=8, width=640, height=360, frame_rate=30.0) StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=62544, num_frames=0, bits_per_sample=8, width=480, height=270, frame_rate=30.0) StreamReaderSourceAudioStream(media_type='audio', codec='aac', codec_long_name='AAC (Advanced Audio Coding)', format='fltp', bit_rate=83695, num_frames=0, bits_per_sample=0, sample_rate=48000.0, num_channels=2) StreamReaderSourceAudioStream(media_type='audio', codec='ac3', codec_long_name='ATSC A/52A (AC-3)', format='fltp', bit_rate=384000, num_frames=0, bits_per_sample=0, sample_rate=48000.0, num_channels=6) StreamReaderSourceAudioStream(media_type='audio', codec='eac3', codec_long_name='ATSC A/52B (AC-3, E-AC-3)', format='fltp', bit_rate=100150, num_frames=0, bits_per_sample=0, sample_rate=48000.0, num_channels=6) .. GENERATED FROM PYTHON SOURCE LINES 292-300 Configuring output streams -------------------------- The stream API lets you stream data from an arbitrary combination of the input streams. If your application does not need audio or video, you can omit them. Or if you want to apply different preprocessing to the same source stream, you can duplicate the source stream. .. GENERATED FROM PYTHON SOURCE LINES 302-314 Default streams ~~~~~~~~~~~~~~~ When there are multiple streams in the source, it is not immediately clear which stream should be used. FFmpeg implements some heuristics to determine the default stream. The resulting stream index is exposed via :py:attr:`~torchaudio.io.StreamReader.default_audio_stream` and :py:attr:`~torchaudio.io.StreamReader.default_video_stream`. .. GENERATED FROM PYTHON SOURCE LINES 316-359 Configuring output streams ~~~~~~~~~~~~~~~~~~~~~~~~~~ Once you know which source stream you want to use, then you can configure output streams with :py:meth:`~torchaudio.io.StreamReader.add_basic_audio_stream` and :py:meth:`~torchaudio.io.StreamReader.add_basic_video_stream`. These methods provide a simple way to change the basic property of media to match the application's requirements. The arguments common to both methods are; - ``frames_per_chunk``: How many frames at maximum should be returned at each iteration. For audio, the resulting tensor will be the shape of `(frames_per_chunk, num_channels)`. For video, it will be `(frames_per_chunk, num_channels, height, width)`. - ``buffer_chunk_size``: The maximum number of chunks to be buffered internally. When the StreamReader buffered this number of chunks and is asked to pull more frames, StreamReader drops the old frames/chunks. - ``stream_index``: The index of the source stream. - ``decoder``: If provided, override the decoder. Useful if it fails to detect the codec. - ``decoder_option``: The option for the decoder. For audio output stream, you can provide the following additional parameters to change the audio properties. - ``format``: By default the StreamReader returns tensor of `float32` dtype, with sample values ranging `[-1, 1]`. By providing ``format`` argument the resulting dtype and value range is changed. - ``sample_rate``: When provided, StreamReader resamples the audio on-the-fly. For video output stream, the following parameters are available. - ``format``: Image frame format. By default StreamReader returns frames in 8-bit 3 channel, in RGB order. - ``frame_rate``: Change the frame rate by dropping or duplicating frames. No interpolation is performed. - ``width``, ``height``: Change the image size. .. GENERATED FROM PYTHON SOURCE LINES 361-379 .. code:: streamer = StreamReader(...) # Stream audio from default audio source stream # 256 frames at a time, keeping the original sampling rate. streamer.add_basic_audio_stream( frames_per_chunk=256, ) # Stream audio from source stream `i`. # Resample audio to 8k Hz, stream 256 frames at each streamer.add_basic_audio_stream( frames_per_chunk=256, stream_index=i, sample_rate=8000, ) .. GENERATED FROM PYTHON SOURCE LINES 382-405 .. code:: # Stream video from default video source stream. # 10 frames at a time, at 30 FPS # RGB color channels. streamer.add_basic_video_stream( frames_per_chunk=10, frame_rate=30, format="rgb24" ) # Stream video from source stream `j`, # 10 frames at a time, at 30 FPS # BGR color channels with rescaling to 128x128 streamer.add_basic_video_stream( frames_per_chunk=10, stream_index=j, frame_rate=30, width=128, height=128, format="bgr24" ) .. GENERATED FROM PYTHON SOURCE LINES 408-420 You can check the resulting output streams in a similar manner as checking the source streams. :py:attr:`~torchaudio.io.StreamReader.num_out_streams` reports the number of configured output streams, and :py:meth:`~torchaudio.io.StreamReader.get_out_stream_info` fetches the information about the output streams. .. code:: for i in range(streamer.num_out_streams): print(streamer.get_out_stream_info(i)) .. GENERATED FROM PYTHON SOURCE LINES 423-431 If you want to remove an output stream, you can do so with :py:meth:`~torchaudio.io.StreamReader.remove_stream` method. .. code:: # Removes the first output stream. streamer.remove_stream(0) .. GENERATED FROM PYTHON SOURCE LINES 434-459 Streaming --------- To stream media data, the streamer alternates the process of fetching and decoding the source data, and passing the resulting audio / video data to client code. There are low-level methods that performs these operations. :py:meth:`~torchaudio.io.StreamReader.is_buffer_ready`, :py:meth:`~torchaudio.io.StreamReader.process_packet` and :py:meth:`~torchaudio.io.StreamReader.pop_chunks`. In this tutorial, we will use the high-level API, iterator protocol. It is as simple as a ``for`` loop. .. code:: streamer = StreamReader(...) streamer.add_basic_audio_stream(...) streamer.add_basic_video_stream(...) for chunks in streamer.stream(): audio_chunk, video_chunk = chunks ... .. GENERATED FROM PYTHON SOURCE LINES 461-483 Example ------- Let's take an example video to configure the output streams. We will use the following video. .. raw:: html Source: https://svs.gsfc.nasa.gov/13013 (This video is in public domain) Credit: NASA's Goddard Space Flight Center. NASA's Media Usage Guidelines: https://www.nasa.gov/multimedia/guidelines/index.html .. GENERATED FROM PYTHON SOURCE LINES 485-490 Opening the source media ~~~~~~~~~~~~~~~~~~~~~~~~ Firstly, let's list the available streams and its properties. .. GENERATED FROM PYTHON SOURCE LINES 490-495 .. code-block:: default streamer = StreamReader(VIDEO_URL) for i in range(streamer.num_src_streams): print(streamer.get_src_stream_info(i)) .. rst-class:: sphx-glr-script-out Out: .. code-block:: none StreamReaderSourceVideoStream(media_type='video', codec='h264', codec_long_name='H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10', format='yuv420p', bit_rate=9958354, num_frames=6175, bits_per_sample=8, width=1920, height=1080, frame_rate=29.97002997002997) StreamReaderSourceAudioStream(media_type='audio', codec='aac', codec_long_name='AAC (Advanced Audio Coding)', format='fltp', bit_rate=317375, num_frames=9658, bits_per_sample=0, sample_rate=48000.0, num_channels=2) .. GENERATED FROM PYTHON SOURCE LINES 496-500 Now we configure the output stream. Configuring ouptut streams ~~~~~~~~~~~~~~~~~~~~~~~~~~ .. GENERATED FROM PYTHON SOURCE LINES 501-534 .. code-block:: default # fmt: off # Audio stream with 8k Hz streamer.add_basic_audio_stream( frames_per_chunk=8000, sample_rate=8000, ) # Audio stream with 16k Hz streamer.add_basic_audio_stream( frames_per_chunk=16000, sample_rate=16000, ) # Video stream with 960x540 at 1 FPS. streamer.add_basic_video_stream( frames_per_chunk=1, frame_rate=1, width=960, height=540, format="rgb24", ) # Video stream with 320x320 (stretched) at 3 FPS, grayscale streamer.add_basic_video_stream( frames_per_chunk=3, frame_rate=3, width=320, height=320, format="gray", ) # fmt: on .. GENERATED FROM PYTHON SOURCE LINES 535-542 .. note:: When configuring multiple output streams, in order to keep all streams synced, set parameters so that the ratio between ``frames_per_chunk`` and ``sample_rate`` or ``frame_rate`` is consistent across output streams. .. GENERATED FROM PYTHON SOURCE LINES 544-546 Checking the output streams. .. GENERATED FROM PYTHON SOURCE LINES 546-550 .. code-block:: default for i in range(streamer.num_out_streams): print(streamer.get_out_stream_info(i)) .. rst-class:: sphx-glr-script-out Out: .. code-block:: none StreamReaderOutputStream(source_index=1, filter_description='aresample=8000,aformat=sample_fmts=fltp') StreamReaderOutputStream(source_index=1, filter_description='aresample=16000,aformat=sample_fmts=fltp') StreamReaderOutputStream(source_index=0, filter_description='fps=1,scale=width=960:height=540,format=pix_fmts=rgb24') StreamReaderOutputStream(source_index=0, filter_description='fps=3,scale=width=320:height=320,format=pix_fmts=gray') .. GENERATED FROM PYTHON SOURCE LINES 551-553 Remove the second audio stream. .. GENERATED FROM PYTHON SOURCE LINES 553-558 .. code-block:: default streamer.remove_stream(1) for i in range(streamer.num_out_streams): print(streamer.get_out_stream_info(i)) .. rst-class:: sphx-glr-script-out Out: .. code-block:: none StreamReaderOutputStream(source_index=1, filter_description='aresample=8000,aformat=sample_fmts=fltp') StreamReaderOutputStream(source_index=0, filter_description='fps=1,scale=width=960:height=540,format=pix_fmts=rgb24') StreamReaderOutputStream(source_index=0, filter_description='fps=3,scale=width=320:height=320,format=pix_fmts=gray') .. GENERATED FROM PYTHON SOURCE LINES 559-562 Streaming ~~~~~~~~~ .. GENERATED FROM PYTHON SOURCE LINES 564-566 Jump to the 10 second point. .. GENERATED FROM PYTHON SOURCE LINES 566-568 .. code-block:: default streamer.seek(10.0) .. GENERATED FROM PYTHON SOURCE LINES 569-571 Now, let's finally iterate over the output streams. .. GENERATED FROM PYTHON SOURCE LINES 572-582 .. code-block:: default n_ite = 3 waveforms, vids1, vids2 = [], [], [] for i, (waveform, vid1, vid2) in enumerate(streamer.stream()): waveforms.append(waveform) vids1.append(vid1) vids2.append(vid2) if i + 1 == n_ite: break .. GENERATED FROM PYTHON SOURCE LINES 583-587 For audio stream, the chunk Tensor will be the shape of `(frames_per_chunk, num_channels)`, and for video stream, it is `(frames_per_chunk, num_color_channels, height, width)`. .. GENERATED FROM PYTHON SOURCE LINES 587-592 .. code-block:: default print(waveforms[0].shape) print(vids1[0].shape) print(vids2[0].shape) .. rst-class:: sphx-glr-script-out Out: .. code-block:: none torch.Size([8000, 2]) torch.Size([1, 3, 540, 960]) torch.Size([3, 1, 320, 320]) .. GENERATED FROM PYTHON SOURCE LINES 593-594 Let's visualize what we received. .. GENERATED FROM PYTHON SOURCE LINES 594-623 .. code-block:: default k = 3 fig = plt.figure() gs = fig.add_gridspec(3, k * n_ite) for i, waveform in enumerate(waveforms): ax = fig.add_subplot(gs[0, k * i : k * (i + 1)]) ax.specgram(waveform[:, 0], Fs=8000) ax.set_yticks([]) ax.set_xticks([]) ax.set_title(f"Iteration {i}") if i == 0: ax.set_ylabel("Stream 0") for i, vid in enumerate(vids1): ax = fig.add_subplot(gs[1, k * i : k * (i + 1)]) ax.imshow(vid[0].permute(1, 2, 0)) # NCHW->HWC ax.set_yticks([]) ax.set_xticks([]) if i == 0: ax.set_ylabel("Stream 1") for i, vid in enumerate(vids2): for j in range(3): ax = fig.add_subplot(gs[2, k * i + j : k * i + j + 1]) ax.imshow(vid[j].permute(1, 2, 0), cmap="gray") ax.set_yticks([]) ax.set_xticks([]) if i == 0 and j == 0: ax.set_ylabel("Stream 2") plt.tight_layout() plt.show(block=False) .. image-sg:: /tutorials/images/sphx_glr_streaming_api_tutorial_001.png :alt: Iteration 0, Iteration 1, Iteration 2 :srcset: /tutorials/images/sphx_glr_streaming_api_tutorial_001.png :class: sphx-glr-single-img .. rst-class:: sphx-glr-timing **Total running time of the script:** ( 0 minutes 19.068 seconds) .. _sphx_glr_download_tutorials_streaming_api_tutorial.py: .. only :: html .. container:: sphx-glr-footer :class: sphx-glr-footer-example .. container:: sphx-glr-download sphx-glr-download-python :download:`Download Python source code: streaming_api_tutorial.py ` .. container:: sphx-glr-download sphx-glr-download-jupyter :download:`Download Jupyter notebook: streaming_api_tutorial.ipynb ` .. only:: html .. rst-class:: sphx-glr-signature `Gallery generated by Sphinx-Gallery `_