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• NumPy array of a video changes from the original after writing into the same video

  29 mars 2021, par Rashiq

  I have a video (test.mkv) that I have converted into a 4D NumPy array - (frame, height, width, color_channel). I have even managed to convert that array back into the same video (test_2.mkv) without altering anything. However, after reading this new, test_2.mkv, back into a new NumPy array, the array of the first video is different from the second video's array i.e. their hashes don't match and the numpy.array_equal() function returns false. I have tried using both python-ffmpeg and scikit-video but cannot get the arrays to match.

  


  Python-ffmpeg attempt :

  


  import ffmpeg
import numpy as np
import hashlib

file_name = 'test.mkv'

# Get video dimensions and framerate
probe = ffmpeg.probe(file_name)
video_stream = next((stream for stream in probe['streams'] if stream['codec_type'] == 'video'), None)
width = int(video_stream['width'])
height = int(video_stream['height'])
frame_rate = video_stream['avg_frame_rate']

# Read video into buffer
out, error = (
    ffmpeg
        .input(file_name, threads=120)
        .output("pipe:", format='rawvideo', pix_fmt='rgb24')
        .run(capture_stdout=True)
)

# Convert video buffer to array
video = (
    np
        .frombuffer(out, np.uint8)
        .reshape([-1, height, width, 3])
)

# Convert array to buffer
video_buffer = (
    np.ndarray
        .flatten(video)
        .tobytes()
)

# Write buffer back into a video
process = (
    ffmpeg
        .input('pipe:', format='rawvideo', s='{}x{}'.format(width, height))
        .output("test_2.mkv", r=frame_rate)
        .overwrite_output()
        .run_async(pipe_stdin=True)
)
process.communicate(input=video_buffer)

# Read the newly written video
out_2, error = (
    ffmpeg
        .input("test_2.mkv", threads=40)
        .output("pipe:", format='rawvideo', pix_fmt='rgb24')
        .run(capture_stdout=True)
)

# Convert new video into array
video_2 = (
    np
        .frombuffer(out_2, np.uint8)
        .reshape([-1, height, width, 3])
)

# Video dimesions change
print(f'{video.shape} vs {video_2.shape}') # (844, 1080, 608, 3) vs (2025, 1080, 608, 3)
print(f'{np.array_equal(video, video_2)}') # False

# Hashes don't match
print(hashlib.sha256(bytes(video_2)).digest()) # b'\x88\x00\xc8\x0ed\x84!\x01\x9e\x08 \xd0U\x9a(\x02\x0b-\xeeA\xecU\xf7\xad0xa\x9e\\\xbck\xc3'
print(hashlib.sha256(bytes(video)).digest()) # b'\x9d\xc1\x07xh\x1b\x04I\xed\x906\xe57\xba\xf3\xf1k\x08\xfa\xf1\xfaM\x9a\xcf\xa9\t8\xf0\xc9\t\xa9\xb7'


  


  Scikit-video attempt :

  


  import skvideo.io as sk
import numpy as np

video_data = sk.vread('test.mkv')

sk.vwrite('test_2_ski.mkv', video_data)

video_data_2 = sk.vread('test_2_ski.mkv')

# Dimensions match but...
print(video_data.shape) # (844, 1080, 608, 3)
print(video_data_2.shape) # (844, 1080, 608, 3)

# ...array elements don't
print(np.array_equal(video_data, video_data_2)) # False

# Hashes don't match either
print(hashlib.sha256(bytes(video_2)).digest()) # b'\x8b?]\x8epD:\xd9B\x14\xc7\xba\xect\x15G\xfaRP\xde\xad&EC\x15\xc3\x07\n{a[\x80'
print(hashlib.sha256(bytes(video)).digest()) # b'\x9d\xc1\x07xh\x1b\x04I\xed\x906\xe57\xba\xf3\xf1k\x08\xfa\xf1\xfaM\x9a\xcf\xa9\t8\xf0\xc9\t\xa9\xb7'


  


  I don't understand where I'm going wrong and both the respective documentations do not highlight how to do this particular task. Any help is appreciated. Thank you.

  


• FFmpeg get frame rate

  22 septembre 2021, par zhin dins

  I have several images and I am reproducing them in 78.7ms, I am creating like the 80s video effect. But, I am unable to find the correct ms, and this images with the original videos are unsync.

  


  I dumped the video to images using this command => ffmpeg -i *.mp4 the80effect/img-%d.jpg And now, I have 48622 frames. The video FPS is 24

  


  So, 48622/24 = 2025 +- I cannot use 2025ms since those images will load very slow. And the and the approximate value is 78.7ms per frame/image

  


  How can I find the correct value ? The video duration in seconds is 2026. I have tried all math to find this but I'm failing. How many images (one frame) per msCould you help me ? Thank you.

  


• Can I use the file buffer or stream as input for fluent-ffmpeg ? I am trying to avoid saving the video locally to get its path before removing

  22 avril 2023, par Moath Thawahreh

  I am receiving the file via an api, I was trying to process the file.buffer as input for FFmpeg but it did not work, I had to save the video locally first and then process the path and remove the saved video later on.
I don't want to believe that there is no other way to solve this and I have been looking for solutions and workarounds but it was all about ffmpeg input as a path.

  


  I would love to find a solution using fluent-ffmpeg because it has some other great features, but I won't mind any suggestions for compressing the video using any different approaches if it's more efficient

  


  Again my code below works fine but I have to save the video and then remove it I am hoping for a more efficient solution :

  


    fs.writeFileSync(&#x27;temp.mp4&#x27;, file.buffer);&#xA;&#xA;    // Resize the temporary file using ffmpeg&#xA;    ffmpeg(&#x27;temp.mp4&#x27;) // here I tried pass file.buffer as readable stream,it receives paths only &#xA;      .format(&#x27;mp4&#x27;)&#xA;      .size(&#x27;50%&#x27;)&#xA;      .save(&#x27;resized.mp4&#x27;)&#xA;      .on(&#x27;end&#x27;, async () => {&#xA;        // Upload the resized file to Firebase&#xA;        const resizedFileStream = bucket.file(`video/${uniqueId}`).createWriteStream();&#xA;        fs.createReadStream(&#x27;resized.mp4&#x27;).pipe(resizedFileStream);&#xA;&#xA;        await new Promise<void>((resolve, reject) => {&#xA;          resizedFileStream&#xA;            .on(&#x27;finish&#x27;, () => {&#xA;              // Remove the local files after they have been uploaded&#xA;              fs.unlinkSync(&#x27;temp.mp4&#x27;);&#xA;              fs.unlinkSync(&#x27;resized.mp4&#x27;);&#xA;              resolve();&#xA;            })&#xA;            .on(&#x27;error&#x27;, reject);&#xA;        });&#xA;&#xA;        // Get the URL of the uploaded resized version&#xA;        const resizedFile = bucket.file(`video/${uniqueId}`);&#xA;        const url = await resizedFile.getSignedUrl({&#xA;          action: &#x27;read&#x27;,&#xA;          expires: &#x27;03-17-2025&#x27;, // Change this to a reasonable expiration date&#xA;        });&#xA;&#xA;        console.log(&#x27;Resized file uploaded successfully.&#x27;);&#xA;      })&#xA;      .on(&#x27;error&#x27;, (err) => {&#xA;        console.log(&#x27;An error occurred: &#x27; &#x2B; err.message);&#xA;      });&#xA;</void>