Question

为了加速视频中一系列matplotlib制作的图像的动画，我想将以下（工作）示例转换为gstreamer，以便能够使用硬件编码Raspberry Pi 2 GPU的功能。

起点是下面的代码，它使用stdin将ARGB视频帧流式传输到ffmpeg。如何替换命令字符串以使用gst-launch-1.0代替？

import numpy as np
import matplotlib.pylab as plt
import time
import subprocess

# Number of frames
nframes = 200

# Generate data
x = np.linspace(0, 100, num=nframes)
y = np.random.random_sample(np.size(x))

def testSubprocess(x, y):

    start_time = time.time()

    #set up the figure
    fig = plt.figure(figsize=(15, 9))
    canvas_width, canvas_height = fig.canvas.get_width_height()

    # First frame
    ax0 = plt.plot(x,y)
    pointplot, = plt.plot(x[0], y[0], 'or')

    def update(frame):
        # your matplotlib code goes here
        pointplot.set_data(x[frame],y[frame])

    # Open an ffmpeg process
    outf = 'testSubprocess.mp4'
    cmdstring = ('ffmpeg', 
                 '-y', '-r', '1', # overwrite, 1fps
                 '-s', '%dx%d' % (canvas_width, canvas_height), # size of image string
                 '-pix_fmt', 'argb', # format
                 '-f', 'rawvideo',  '-i', '-', # tell ffmpeg to expect raw video from the pipe
                 '-vcodec', 'mpeg4', outf) # output encoding
    p = subprocess.Popen(cmdstring, stdin=subprocess.PIPE)

    # Draw frames and write to the pipe
    for frame in range(nframes):
        # draw the frame
        update(frame)
        fig.canvas.draw()

        # extract the image as an ARGB string
        string = fig.canvas.tostring_argb()

        # write to pipe
        p.stdin.write(string)

    # Finish up
    p.communicate()

    print("Movie written in %s seconds" % (time.time()-start_time))

if __name__ == "__main__":
    testSubprocess(x, y)

管道中使用的组件是omxh264enc，但是一旦我理解了如何将数据提供给管道，这也可以作为第二步实现。基于gst-python的答案也是完全可以接受的。

Answer 1

“videoparse”看起来像是你想在这里使用的关键词，告诉GStreamer你的输入是什么格式。

gst-launch-1.0 fdsrc！视频宽度= 128高度= 128格式= argb 帧率= 5/1！视频！视频转换！ omxh264enc！ h264parse！ mp4mux！ filesink location = OUTPUTFILE

ARGB图像到gstreamer管道

1 个答案: