Recherche avancée

Sur d’autres sites (9742)

• Use ffmpeg to record 2 webcams on raspberry pi

  30 janvier 2021, par RaresBaaa

  I want to record 2 webcams using ffmpeg, i have a simple python script but it doesn't work when I run the 2 subprocesses at the same time.

  


  ROOT_PATH = os.getenv("ROOT_PATH", "/home/pi")
ENCODING = os.getenv("ENCODING", "copy")
new_dir = datetime.datetime.now().strftime("%Y_%m_%d_%H_%M_%S")
RECORDINGS_PATH1 = os.getenv("RECORDINGS_PATH", "RecordingsCam1")
RECORDINGS_PATH2 = os.getenv("RECORDINGS_PATH", "RecordingsCam2")
recording_path1 = os.path.join(ROOT_PATH, RECORDINGS_PATH1, new_dir)
recording_path2 = os.path.join(ROOT_PATH, RECORDINGS_PATH2, new_dir)
os.mkdir(recording_path1)
os.mkdir(recording_path2)
segments_path1 = os.path.join(recording_path1, "%03d.avi")
segments_path2 = os.path.join(recording_path2, "%03d.avi")
record1 = "ffmpeg -nostdin -i /dev/video0 -c:v {} -an -sn -dn -segment_time 30 -f segment {}".format(ENCODING, segments_path1)
record2 = "ffmpeg -nostdin -i /dev/video2 -c:v {} -an -sn -dn -segment_time 30 -f segment {}".format(ENCODING, segments_path2)
subprocess.Popen(record1, shell=True)
subprocess.Popen(record2, shell=True)


  


  Also, i tried capturing the 2 sources side by side but it gives the error :`Filtering and streamcopy cannot be used together.

  


• How to effectly record and encode from udp stream(4K HECV) in real time with ffmpeg ?

  25 janvier 2021, par Sa Mei

  I have a serious problem about ffmpeg to solve.
My task is to record from udp stream(4K HECV) and encode it to a mxf file.
My CPU is Intel(R) Xeon(R) Gold 5122 CPU@3.60GHz
The situation of CPU when it is recording from udp stream

  


  The situation of the udp stream

  


  The ffmpeg I used from https://github.com/BtbN/FFmpeg-Builds/commit/86af523883173be93c69d1170d1f78f79dc5e9f8 .
The command I used is :
ffmpeg -y -threads 6 -i "udp ://@225.1.2.150:6150 ?overrun_nonfatal=1&fifo_size=50000000" -threads 32 -qscale:v 2 -alternate_scan 1 -f mxf "G :\4k.xmf"

  


  Now the speed is lower than 1.0x after running for a while(about 10minutes). Maybe this is due to the temperature of the cpu gradually increasing.
The picture above displays the performance of CPU when we specify threads=6 for decoding and threads=32 for encoding.
I found that the speed would be 1.0x if I just recorded it to a .hecv file. But now I want to encode the stream to a .mxf file in real time. But as you can see, if I tried to encode it in real time, the speed of decoding and encoding would always be lower than 1.0x (around 0.98x). After running this command for about 3 hours, the recording and encoding process will be stopped.

  


  How to solve it ? I expect that the speed is 1.0x by speeding up encoding or other ways.
Or anyone knows that how to record the udp stream without re-encoding to a .hecv file and meanwhile encode the .hecv file to a .mxf file ?

  


• How to avoid stopping or record all dynamic videos in the process of capturing screen video with ffmpeg from a python program ?

  3 décembre 2020, par fengnix

  I have many robotframework test cases and in the first case, a ffmpeg command like the following is invoked to record the whole running process :

  


  ffmpeg -framerate 30 -f gdigrab -i desktop -c:v libx264rgb -crf 0 -preset ultrafast output.mkv


  


  Whenever I firstly run all cases and then manuually run the above command from an addition command console, the recorded video always looks fine, it looks like all contents on the screen can be correctly captured.

  


  However, once I execute the command the same as the above one in the first case by call the following code :

  


  p=subprocess.Popen(cmd, shell=True, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)


  


  and then in the final test case the record process is stopped by calling the following code to tell ffmpeg that we want to stop the recording :

  


  p.stdin.write(bytes("q",'UTF-8'))  


  


  the final result video only contain correct contents of the "start" and the "end" of the whole process, but all other contents no longer changed and seemd just a static image, which means all the dynamic effects on the screen cannot be captured.

  


  Could anyone be so kind as to let me know what the matter is and how to solve it ?