I used imageio.get_reader(BytesIO(a), 'ffmpeg') to load a bytes image and save it as normal image.

But the below error throws when I read the image using imageio.get_reader(BytesIO(a), 'ffmpeg')

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_readerreturn format.get_reader(request)File "/home/tango/anaconda3/lib/python3.6/site-packages/imageio/core/format.py", line 164, in get_readerreturn 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 _openself._initialize()File "/home/tango/anaconda3/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 466, in _initializeself._meta.update(self._read_gen.__next__())File "/home/tango/anaconda3/lib/python3.6/site-packages/imageio_ffmpeg/_io.py", line 150, in read_framesraise IOError(fmt.format(err2))
OSError: Could not load meta information
=== stderr ===ffmpeg version 4.2 Copyright (c) 2000-2019 the FFmpeg developersbuilt 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-libmp3lamelibavutil      56. 31.100 / 56. 31.100libavcodec     58. 54.100 / 58. 54.100libavformat    58. 29.100 / 58. 29.100libavdevice    58.  8.100 / 58.  8.100libavfilter     7. 57.100 /  7. 57.100libavresample   4.  0.  0 /  4.  0.  0libswscale      5.  5.100 /  5.  5.100libswresample   3.  5.100 /  3.  5.100libpostproc    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 SDKencoder         : Kinesis Video SDK 1.0.0AWS_KINESISVIDEO_FRAGMENT_NUMBER: 91343852333183888465720004820715065721442989478AWS_KINESISVIDEO_SERVER_TIMESTAMP: 1580791384.096AWS_KINESISVIDEO_PRODUCER_TIMESTAMP: 1580791377.843Duration: N/A, bitrate: N/AStream #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!

The above approach to read a MKV bytes file was done based on this thread

Or is there is any approach to parse and read the MKV bytes file.

Old question, but I'll leave an answer here for future readers :)

In general, if you have a bytes string that encodes a video (or image), chances are high that you can pass it directly into ImageIO's high-level API and that it can read the bytes directly. In the case of MKV (and some other video formats) ImageIO needs a bit of help because the current ffmpeg plugin struggles with byte strings. [There is a new plugin on the way to fix this and other issues.]

ImageIO<2.15.0

import imageio as iioreq = 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 (releases this week - W6 2022)

import imageio as iiofirst_frame = iio.v3.imread(mkv_bytes, format_hint=".mkv")