# coding=utf-8
# Copyright 2020 The Google AI Perception Team Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
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"""Utils for AIST++ Dataset."""
import os

import ffmpeg
import numpy as np


def ffmpeg_video_read(video_path, fps=None):
  """Video reader based on FFMPEG.

  This function supports setting fps for video reading. It is critical
  as AIST++ Dataset are constructed under exact 60 fps, while some of
  the AIST dance videos are not percisely 60 fps.

  Args:
    video_path: A video file.
    fps: Use specific fps for video reading. (optional)
  Returns:
    A `np.array` with the shape of [seq_len, height, width, 3]
  """
  assert os.path.exists(video_path), f'{video_path} does not exist!'
  try:
    probe = ffmpeg.probe(video_path)
  except ffmpeg.Error as e:
    print('stdout:', e.stdout.decode('utf8'))
    print('stderr:', e.stderr.decode('utf8'))
    raise e
  video_info = next(stream for stream in probe['streams']
                    if stream['codec_type'] == 'video')
  width = int(video_info['width'])
  height = int(video_info['height'])
  stream = ffmpeg.input(video_path)
  if fps:
    stream = ffmpeg.filter(stream, 'fps', fps=fps, round='up')
  stream = ffmpeg.output(stream, 'pipe:', format='rawvideo', pix_fmt='rgb24')
  out, _ = ffmpeg.run(stream, capture_stdout=True)
  out = np.frombuffer(out, np.uint8).reshape([-1, height, width, 3])
  return out.copy()


def ffmpeg_video_write(data, video_path, fps=25):
  """Video writer based on FFMPEG.

  Args:
    data: A `np.array` with the shape of [seq_len, height, width, 3]
    video_path: A video file.
    fps: Use specific fps for video writing. (optional)
  """
  assert len(data.shape) == 4, f'input shape is not valid! Got {data.shape}!'
  _, height, width, _ = data.shape
  os.makedirs(os.path.dirname(video_path), exist_ok=True)
  writer = (
      ffmpeg
      .input('pipe:', framerate=fps, format='rawvideo',
             pix_fmt='rgb24', s='{}x{}'.format(width, height))
      .output(video_path, pix_fmt='yuv420p')
      .overwrite_output()
      .run_async(pipe_stdin=True)
  )
  for frame in data:
    writer.stdin.write(frame.astype(np.uint8).tobytes())
  writer.stdin.close()