我希望通过使用 streamlink.streams(url)(返回 .m3u8 url)向其提供直接直播 URL 来录制 Twitch 直播。这样，我可以毫无问题地读取流，甚至从中写入一些图像，但当将其写入视频时，我会遇到错误。
P.S.:是的，我知道还有其他选项，例如 Streamlink 和 yt-dwl，但我想仅在 python 中操作，而不是使用 CLI...我相信这两个只是处理(用于录制)。
这是我目前拥有的:
if streamlink.streams(url):
stream = streamlink.streams(url)['best']
stream = str(stream).split(', ')
stream = stream[1].strip("'")
cap = cv2.VideoCapture(stream)
gst_out = "appsrc ! video/x-raw, format=BGR ! queue ! nvvidconv ! omxh264enc ! h264parse ! qtmux ! filesink location=stream "
out = cv2.VideoWriter(gst_out, cv2.VideoWriter_fourcc(*'mp4v'), 30, (1920, 1080))
while True:
_, frame = cap.read()
out.write(frame)
对于此代码，我收到此错误消息:
[tls @ 0x1278a74f0] Error in the pull function.
如果我删除 gst_out 并提供 stream ，并将 cap 和 out 移入 while像这样循环:
if streamlink.streams(url):
stream = streamlink.streams(url)['best']
stream = str(stream).split(', ')
stream = stream[1].strip("'")
while True:
cap = cv2.VideoCapture(stream)
_, frame = cap.read()
out = cv2.VideoWriter(stream, cv2.VideoWriter_fourcc(*'mp4v'), 30, (1920, 1080))
out.write(frame)
我得到:
OpenCV: FFMPEG: tag 0x7634706d/'mp4v' is not supported with codec id 12 and format 'hls / Apple HTTP Live Streaming'
我在这里缺少什么？
最佳答案
第一部分使用 GStreamer 语法，而 OpenCV for Python 很可能不是用 GStreamer 构建的。
答案将集中在第二部分(也是因为我不太了解 GStreamer)。
有几个问题:
cap = cv2.VideoCapture(stream)应位于while True循环之前。out = cv2.VideoWriter(stream, cv2.VideoWriter_fourcc(*'mp4v'), 30, (1920, 1080))应位于while True循环之前.cv2.VideoWriter的第一个参数应该是 MP4 文件名，而不是stream。- 为了获取有效的输出文件，我们必须在循环后执行
out.release()，但循环可能永远不会结束。
建议获取输入视频的帧大小和速率，并相应地设置
VideoWriter:width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)) height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)) fps = int(cap.get(cv2.CAP_PROP_FPS)) video_file_name = 'output.mp4' out = cv2.VideoWriter(video_file_name, cv2.VideoWriter_fourcc(*'mp4v'), fps, (width, height)) # Open video file for writing如果
ret为False，建议中断循环:ret, frame = cap.read() if not ret: break结束录制的一个选项是当用户按
Esc键时。
如果cv2.waitKey(1) == 27则中断循环。
cv2.waitKey(1)仅在执行cv2.imshow后才起作用。
一个简单的解决方案是每 30 帧执行一次cv2.imshow(例如)。if (frame_counter % 30 == 0): cv2.imshow('frame', frame) # Show frame every 30 frames (for testing) if cv2.waitKey(1) == 27: # Press Esc for stop recording (cv2.waitKey is going to work only when cv2.imshow is used). break
完整代码示例:
from streamlink import Streamlink
import cv2
def stream_to_url(url, quality='best'):
session = Streamlink()
streams = session.streams(url)
if streams:
return streams[quality].to_url()
else:
raise ValueError('Could not locate your stream.')
url = 'https://www.twitch.tv/noraexplorer' # Need to login to twitch.tv first (using the browser)...
quality='best'
stream_url = stream_to_url(url, quality) # Get the video URL
cap = cv2.VideoCapture(stream_url, cv2.CAP_FFMPEG) # Open video stream for capturing
# Get frame size and rate of the input video
width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
fps = int(cap.get(cv2.CAP_PROP_FPS))
video_file_name = 'output.mp4'
out = cv2.VideoWriter(video_file_name, cv2.VideoWriter_fourcc(*'mp4v'), fps, (width, height)) # Open video file for writing
frame_counter = 0
while True:
ret, frame = cap.read()
if not ret:
break
if (frame_counter % 30 == 0):
cv2.imshow('frame', frame) # Show frame every 30 frames (for testing)
out.write(frame) # Write frame to output.mp4
if cv2.waitKey(1) == 27: # Press Esc for stop recording (cv2.waitKey is going to work only when cv2.imshow is used).
break
frame_counter += 1
cap.release()
out.release()
cv2.destroyAllWindows()
使用FFplay和subprocess模块测试设置:
from streamlink import Streamlink
import subprocess
def stream_to_url(url, quality='best'):
session = Streamlink()
streams = session.streams(url)
if streams:
return streams[quality].to_url()
else:
raise ValueError('Could not locate your stream.')
#url = 'https://www.twitch.tv/noraexplorer' # Need to login to twitch.tv first (using the browser)...
url = 'https://www.twitch.tv/valorant'
quality='best'
stream_url = stream_to_url(url, quality) # Get the video URL
subprocess.run(['ffplay', stream_url])
更新:
使用ffmpeg-python用于读取视频，OpenCV 用于录制视频:
如果cv2.VideoCapture不起作用，我们可以使用FFmpeg CLI作为子进程。
ffmpeg-python 模块是 FFmpeg CLI 的 Python 绑定(bind)。
使用ffmpeg-python几乎和使用subprocess模块一样，这里使用它主要是为了简化FFprobe的使用。
使用 FFprobe 获取视频帧分辨率和帧速率(不使用 OpenCV):
p = ffmpeg.probe(stream_url, select_streams='v');
width = p['streams'][0]['width']
height = p['streams'][0]['height']
r_frame_rate = p['streams'][0]['r_frame_rate'] # May return 60000/1001
if '/' in r_frame_rate:
fps = float(r_frame_rate.split("/")[0]) / float(r_frame_rate.split("/")[1]) # Convert from 60000/1001 to 59.94
elif r_frame_rate != '0':
fps = float(r_frame_rate)
else:
fps = 30 # Used as default
获取帧速率可能有点困难......
注意:ffprobe CLI 应位于执行路径中。
使用 stdout 作为管道启动 FFmpeg 子进程:
ffmpeg_process = (
ffmpeg
.input(stream_url)
.video
.output('pipe:', format='rawvideo', pix_fmt='bgr24')
.run_async(pipe_stdout=True)
)
注意:ffmpeg CLI 应位于执行路径中。
从管道读取帧，并将其从字节转换为 NumPy 数组:
in_bytes = ffmpeg_process.stdout.read(width*height*3)
frame = np.frombuffer(in_bytes, np.uint8).reshape([height, width, 3])
关闭 FFmpeg 子进程:
关闭 stdout 管道结束 FFmpeg(出现“管道损坏”错误)。
ffmpeg_process.stdout.close()
ffmpeg_process.wait() # Wait for the sub-process to finish
完整代码示例:
from streamlink import Streamlink
import cv2
import numpy as np
import ffmpeg
def stream_to_url(url, quality='best'):
session = Streamlink()
streams = session.streams(url)
if streams:
return streams[quality].to_url()
else:
raise ValueError('Could not locate your stream.')
#url = 'https://www.twitch.tv/noraexplorer' # Need to login to twitch.tv first (using the browser)...
url = 'https://www.twitch.tv/valorant'
quality='best'
stream_url = stream_to_url(url, quality) # Get the video URL
#subprocess.run(['ffplay', stream_url]) # Use FFplay for testing
# Use FFprobe to get video frames resolution and framerate.
################################################################################
p = ffmpeg.probe(stream_url, select_streams='v');
width = p['streams'][0]['width']
height = p['streams'][0]['height']
r_frame_rate = p['streams'][0]['r_frame_rate'] # May return 60000/1001
if '/' in r_frame_rate:
fps = float(r_frame_rate.split("/")[0]) / float(r_frame_rate.split("/")[1]) # Convert from 60000/1001 to 59.94
elif r_frame_rate != '0':
fps = float(r_frame_rate)
else:
fps = 30 # Used as default
#cap = cv2.VideoCapture(stream_url, cv2.CAP_FFMPEG) # Open video stream for capturing
#width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
#height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
#fps = int(cap.get(cv2.CAP_PROP_FPS))
################################################################################
# Use FFmpeg sub-process instead of using cv2.VideoCapture
################################################################################
ffmpeg_process = (
ffmpeg
.input(stream_url, an=None) # an=None applies -an argument (used for ignoring the input audio - it is not required, just more elegant).
.video
.output('pipe:', format='rawvideo', pix_fmt='bgr24')
.run_async(pipe_stdout=True)
)
################################################################################
video_file_name = 'output.mp4'
out = cv2.VideoWriter(video_file_name, cv2.VideoWriter_fourcc(*'mp4v'), fps, (width, height)) # Open video file for writing
frame_counter = 0
while True:
#ret, frame = cap.read()
in_bytes = ffmpeg_process.stdout.read(width*height*3) # Read raw video frame from stdout as bytes array.
if len(in_bytes) < width*height*3: #if not ret:
break
frame = np.frombuffer(in_bytes, np.uint8).reshape([height, width, 3]) # Convert bytes array to NumPy array.
if (frame_counter % 30 == 0):
cv2.imshow('frame', frame) # Show frame every 30 frames (for testing)
out.write(frame) # Write frame to output.mp4
if cv2.waitKey(1) == 27: # Press Esc for stop recording (cv2.waitKey is going to work only when cv2.imshow is used).
break
frame_counter += 1
#cap.release()
ffmpeg_process.stdout.close() # Close stdout pipe (it also closes FFmpeg).
out.release()
cv2.destroyAllWindows()
ffmpeg_process.wait() # Wait for the sub-process to finish
注意:
如果您关心录制视频的质量，使用 cv2.VideoWriter 并不是最佳选择...
关于python - cv2.VideoWriter 问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/73324872/