在python中输入ffmpeg的输入和输出

问题描述

我正在使用ffmpeg从我传送到ffmpeg的base64编码图像列表中创建视频.

I'm using ffmpeg to create a video, from a list of base64 encoded images that I pipe into ffmpeg.

输出到文件(使用下面的附加代码)可以完美地工作，但是我想要实现的是将输出改为Python变量-意味着管道输入和管道输出，但我似乎无法得到它工作

Outputting to a file (using the attached code below) works perfectly, but what I would like to achieve is to get the output to a Python variable instead - meaning piping input and piping output but I can't seem to get it to work

我当前的代码:

output = os.path.join(screenshots_dir, 'video1.mp4')

cmd_out = ['ffmpeg',
           '-y',  # (optional) overwrite output file if it exists
           '-f', 'image2pipe',
           '-vcodec', 'png',
           '-r', str(fps),  # frames per second
           '-i', '-',  # The input comes from a pipe
           '-vcodec', 'png',
           '-qscale', '0',
           output]

pipe = sp.Popen(cmd_out, stdin=sp.PIPE)

for screenshot in screenshot_list:
    im = Image.open(BytesIO(base64.b64decode(screenshot)))
    im.save(pipe.stdin, 'PNG')

pipe.stdin.close()
pipe.wait()

这会导致mp4正常工作，但我想避免保存到本地.

This results in a working mp4, but I would like to avoid saving to local.

在将output更改为'-'或'pipe:1'并添加stdout=sp.PIPE的情况下运行相同的代码会导致错误

Running the same code with changing output to '-' or 'pipe:1' and adding stdout=sp.PIPE results in an error

推荐答案

FFmpeg通过检查输出扩展名猜测输出多路复用器.对于管道，该管道不存在，因此必须明确设置.在输出之前添加'-f', 'image2pipe'.

FFmpeg guesses the output muxer by checking the output extension. With a pipe, that doesn't exist, so it has to be expressly set. Add '-f', 'image2pipe' just before output.

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