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pretty up the code a bit for ffmpeg resolution detection

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This commit is contained in:
Tim Welch 2018-12-11 20:53:42 -05:00
parent 546015d973
commit 39daaa272b
1 changed files with 7 additions and 8 deletions
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15
src/ffmpeg_reader.py
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@ -44,26 +44,25 @@ class ffmpeg_reader:
def probe(self):
""" Probe the video device to get height and width info """
# Running this command on ffmpeg unfortunatly returns with an exit code of 1, which is silly.
# Returns an error code of 1 and this text: "/dev/video2: Immediate exit requested"
args = ["ffmpeg", "-f", self.device_format, "-list_formats", "all", "-i", self.device_name]
process = Popen(args, stdout=PIPE, stderr=PIPE)
out, err = process.communicate()
return_code = process.poll()
if not err:
print("Error opening subprocess for ffmpeg.\n\n%s" % err)
sys.exit(1)
# worst case scenario, err will equal en empty byte string, b'', so probe will get set to [] here.
regex = re.compile('\s\d{3,4}x\d{3,4}')
probe = regex.findall(str(err.decode("utf-8")))
if len(probe) < 1:
# Could not determine the resolution from v4l2-ctl call. Reverting to ffmpeg.probe()
if not return_code == 1 or len(probe) < 1:
# Could not determine the resolution from ffmpeg call. Reverting to ffmpeg.probe()
probe = ffmpeg.probe(self.device_name)
height = probe['streams'][0]['height']
width = probe['streams'][0]['width']
else:
(height, width) = [x.strip() for x in probe[0].split('x')]
if height.isdigit() and self.get(CAP_PROP_FRAME_HEIGHT) == 0:
self.set(CAP_PROP_FRAME_HEIGHT, int(height))