112 lines
4.3 KiB
Python
112 lines
4.3 KiB
Python
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# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# =============================================================================
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"""Encoding and decoding audio using FFmpeg."""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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from tensorflow.contrib.ffmpeg.ops import gen_decode_audio_op_py
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from tensorflow.contrib.ffmpeg.ops import gen_decode_video_op_py
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from tensorflow.contrib.ffmpeg.ops import gen_encode_audio_op_py
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from tensorflow.contrib.util import loader
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from tensorflow.python.framework import ops
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from tensorflow.python.platform import resource_loader
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_ffmpeg_so = loader.load_op_library(
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resource_loader.get_path_to_datafile('ffmpeg.so'))
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def decode_audio(contents, file_format=None, samples_per_second=None,
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channel_count=None, stream=None):
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"""Create an op that decodes the contents of an audio file.
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Note that ffmpeg is free to select the "best" audio track from an mp4.
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https://trac.ffmpeg.org/wiki/Map
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Args:
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contents: The binary contents of the audio file to decode. This is a
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scalar.
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file_format: A string or scalar string tensor specifying which
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format the contents will conform to. This can be mp3, mp4, ogg,
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or wav.
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samples_per_second: The number of samples per second that is
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assumed, as an `int` or scalar `int32` tensor. In some cases,
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resampling will occur to generate the correct sample rate.
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channel_count: The number of channels that should be created from the
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audio contents, as an `int` or scalar `int32` tensor. If the
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`contents` have more than this number, then some channels will
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be merged or dropped. If `contents` has fewer than this, then
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additional channels will be created from the existing ones.
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stream: A string specifying which stream from the content file
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should be decoded, e.g., '0' means the 0-th stream.
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The default value is '' which leaves the decision to ffmpeg.
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Returns:
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A rank-2 tensor that has time along dimension 0 and channels along
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dimension 1. Dimension 0 will be `samples_per_second *
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length_in_seconds` wide, and dimension 1 will be `channel_count`
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wide. If ffmpeg fails to decode the audio then an empty tensor will
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be returned.
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"""
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return gen_decode_audio_op_py.decode_audio_v2(
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contents, file_format=file_format, samples_per_second=samples_per_second,
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channel_count=channel_count, stream=stream)
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ops.NotDifferentiable('DecodeAudio')
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def encode_audio(audio, file_format=None, samples_per_second=None):
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"""Creates an op that encodes an audio file using sampled audio from a tensor.
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Args:
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audio: A rank-2 `Tensor` that has time along dimension 0 and
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channels along dimension 1. Dimension 0 is `samples_per_second *
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length_in_seconds` long.
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file_format: The type of file to encode, as a string or rank-0
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string tensor. "wav" is the only supported format.
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samples_per_second: The number of samples in the audio tensor per
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second of audio, as an `int` or rank-0 `int32` tensor.
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Returns:
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A scalar tensor that contains the encoded audio in the specified file
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format.
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"""
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return gen_encode_audio_op_py.encode_audio_v2(
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audio,
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file_format=file_format,
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samples_per_second=samples_per_second,
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bits_per_second=192000) # not used by WAV
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ops.NotDifferentiable('EncodeAudio')
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def decode_video(contents):
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"""Create an op that decodes the contents of a video file.
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Args:
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contents: The binary contents of the video file to decode. This is a
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scalar.
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Returns:
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A rank-4 `Tensor` that has `[frames, height, width, 3]` RGB as output.
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"""
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return gen_decode_video_op_py.decode_video(contents)
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ops.NotDifferentiable('DecodeVideo')
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