在Python中从亚马逊Kinesis输出中读取字节图像

Question

我使用imageio.get_reader(BytesIO(a), 'ffmpeg')来加载一个字节图像并将其保存为普通图像。

但是当我使用imageio.get_reader(BytesIO(a), 'ffmpeg')读取图像时，会抛出以下错误：

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/tango/anaconda3/lib/python3.6/site-packages/imageio/core/functions.py", line 186, in get_reader
    return format.get_reader(request)
  File "/home/tango/anaconda3/lib/python3.6/site-packages/imageio/core/format.py", line 164, in get_reader
    return self.Reader(self, request)
  File "/home/tango/anaconda3/lib/python3.6/site-packages/imageio/core/format.py", line 214, in __init__
    self._open(**self.request.kwargs.copy())
  File "/home/tango/anaconda3/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 323, in _open
    self._initialize()
  File "/home/tango/anaconda3/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 466, in _initialize
    self._meta.update(self._read_gen.__next__())
  File "/home/tango/anaconda3/lib/python3.6/site-packages/imageio_ffmpeg/_io.py", line 150, in read_frames
    raise IOError(fmt.format(err2))
OSError: Could not load meta information
=== stderr ===

ffmpeg version 4.2 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 7.3.0 (crosstool-NG 1.23.0.449-a04d0)
  configuration: --prefix=/home/tango/anaconda3 --cc=/home/conda/feedstock_root/build_artifacts/ffmpeg_1566210161358/_build_env/bin/x86_64-conda_cos6-linux-gnu-cc --disable-doc --disable-openssl --enable-avresample --enable-gnutls --enable-gpl --enable-hardcoded-tables --enable-libfreetype --enable-libopenh264 --enable-libx264 --enable-pic --enable-pthreads --enable-shared --enable-static --enable-version3 --enable-zlib --enable-libmp3lame
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
[matroska,webm @ 0x5619b9da3cc0] File ended prematurely
[matroska,webm @ 0x5619b9da3cc0] Could not find codec parameters for stream 0 (Video: h264, none, 1280x720): unspecified pixel format
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, matroska,webm, from '/tmp/imageio_zm6hhpgr':
  Metadata:
    title           : Kinesis Video SDK
    encoder         : Kinesis Video SDK 1.0.0
    AWS_KINESISVIDEO_FRAGMENT_NUMBER: 91343852333183888465720004820715065721442989478
    AWS_KINESISVIDEO_SERVER_TIMESTAMP: 1580791384.096
    AWS_KINESISVIDEO_PRODUCER_TIMESTAMP: 1580791377.843
  Duration: N/A, bitrate: N/A
    Stream #0:0(eng): Video: h264, none, 1280x720, SAR 1:1 DAR 16:9, 1k tbr, 1k tbn, 2k tbc (default)
    Metadata:
      title           : kinesis_video
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> rawvideo (native))
Press [q] to stop, [?] for help
Cannot determine format of input stream 0:0 after EOF
Error marking filters as finished
Conversion failed!

上述读取MKV字节文件的方法是基于这个线程完成的。

还有没有其他方法来解析和读取MKV字节文件。

- Varun_Rathinam

---

你正在对数据进行base64解码吗？ - poida

这是什么类型的Kinesis流？数据是如何进入其中的？ - poida

数据使用H.264编解码器进行编码，并流式传输到Kinesis视频流中，在接收端它将以mkv格式（以字节为单位）呈现。需要实时解析mkv块。 - Varun_Rathinam

你确定你先读取了字节，然后再使用 imageio.get_reader 吗？能否请您分享一下在 imageio.get_reader 函数之前使用的内容？ - Vasyl Vaskivskyi

Answer 1

虽然这是一个老问题，但我还是会留下答案供未来的读者参考 :)

一般来说，如果你有一个编码了视频（或图像）的字节字符串，很有可能直接将其传递到ImageIO的高级API中，它就可以直接读取这些字节。对于MKV （以及其他一些视频格式），ImageIO 需要一些帮助，因为当前的ffmpeg插件在处理字节字符串时存在一些问题。[有一个新的插件正在开发中，用于解决这个和其他问题。]

ImageIO<2.15.0

import imageio as iio

req = iio.core.Request(mkv_bytes, "r")

# note: this is where imageIO needs some help, see
# https://github.com/imageio/imageio/issues/686
req._extension = ".mkv"

first_frame = iio.imread(req)

ImageIO>2.15.0（本周发布 - W6 2022）

import imageio as iio

first_frame = iio.v3.imread(mkv_bytes, format_hint=".mkv")

- FirefoxMetzger