Automating HLS-Stream-Creator (Python)

#!/usr/bin/env python
import json
import subprocess
from subprocess import call
import os
import time
import re

# Where is HLS Stream Creator
hls_enc_path="/usr/local/bin/HLS-Stream-Creator.sh"

# Where will we find the videos (and write out to)
base_dir='/mnt/videos/HLS/'

# HLS Segment length
seg_length=5

# Set some FFMPEG flags
FFMPEG_FLAGS='-preset fast -hide_banner -strict -2 -loglevel quiet'
NUMTHREADS=2

# When calculating bitrates, what factor of the source should we create (as well as 1 which is implied)
output_rates = [0.75,0.5,0.4]

# What should we use as a tempfile for the initial compatability pass?
TEMPFILE="/tmp/tmp.mp4"

def sorted_nicely( l ):
    """ Sorts the given iterable in the way that is expected.

    Required arguments:
    l -- The iterable to be sorted.

    """
    convert = lambda text: int(text) if text.isdigit() else text
    alphanum_key = lambda key: [convert(c) for c in re.split('([0-9]+)', key)]
    return sorted(l, key = alphanum_key)

def probe_file(filename):
    """ Probe the input file to get stream information
    """
    cmnd = ['ffprobe', '-show_streams', '-print_format', 'json', '-loglevel', 'quiet', filename]
    p = subprocess.Popen(cmnd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    out, err =  p.communicate()
    if err:
        print "========= error ========"
        print err
        return False
    j = json.loads(out)
    return j

def calcBitrates(j, output_rates):
    """ Calculate the output bitrates based on the source input
    """
    bitrates = []
    for s in j['streams']:
        if s['codec_type'] != 'video':
            continue
        elif "bit_rate" not in s:
            continue

        br = int(s['bit_rate'])

        # Work out the bitrates to generate
        bitrates.append(str(int(br/1000)))

        for mod in output_rates:
        # Convert to kb/s
        # We caste to an int to remove any decimal places, and then to a string so we dont break join()
            bitrates.append(str(int((br * mod)/1000)))

        if int(bitrates[-1]) > 250:
            # Make sure there's a 200kb/s option
            bitrates.append(str(200))

        return sorted_nicely(bitrates)

    return False

def triggerMux(job):
    """

    job['job']['path'] = Path to source media

    Muxed version will be written into a directory using the original filename as a name
    but with .hls appended.

    i.e. /mnt/video/foo.mp4 would create /mnt/video/foo.mp4.hls/

    """
    notify_change('inprocess',job)
    # Call the muxing job
    path = "%s%s" % (base_dir,job['job']['path'])
    pathsplit = job['job']['path'].split("/")

    vidname=pathsplit[-1]
    viddir="%s.hls" % (path)

    if os.path.isdir(viddir):
        # Don't try and redo work that's already done
        print "already seem to have %s" % (viddir,)
        notify_change('failed',job,{'reason':'DirectoryExists'})
        return False

    if not os.path.isfile(path):
        # Do nothing if the source file is missing
        print "File doesn't exist %s" % (path,)
        notify_change('failed',job,{'reason':'MissingFile'})
        return False

    # Create the output directory
    os.mkdir(viddir)

    # Get video information and calculate variant rates
    json = probe_file(path)
    brs = calcBitrates(json, output_rates)

    if not brs:
        print "Couldn't ascertain source bitrate"
        notify_change('failed',job,{'reason':'CantGetBitRate'})
        return False        

    bitrates = ','.join(brs)

    # Set up the environment
    my_env = os.environ.copy()
    my_env["FFMPEG_FLAGS"] = FFMPEG_FLAGS
    my_env["NUMTHREADS"] = str(NUMTHREADS)

    # Build the CMD
    cmd = ['ffmpeg','-i',str(path)]

    for arg in FFMPEG_FLAGS.split(' '):
        cmd.append(arg)

    cmd.append(TEMPFILE)

    # Make a copy of the file to strip any unsupported tracks
    notify_change('compatrun',job)
    proc = subprocess.Popen(cmd,env=my_env)    
    proc.wait()

    # Get ready to start the actual mux 
    # Make a note of when it started
    start = int(time.time())

    # Trigger the mux
    notify_change('muxstarted',job)
    proc = subprocess.Popen([hls_enc_path,'-i',TEMPFILE,'-o',str(viddir),'-b',str(bitrates),'-p','manifest','-t','media','-s',str(seg_length)],env=my_env)    
    proc.wait()

    os.remove(TEMPFILE)

    if (int(time.time()) - start) < 5:
        # Completed too quick, ffmpeg errored
        print "FFMpeg exited %s" % (path,)
        notify_change('failed',job,{'reason':'FFmpegErr'})
        return False

    notify_change('complete',job)

def notify_change(state,job,data=False):
    ''' Placeholder function

    Do whatever you need here if you want to notify somewhere of task status
    '''

    return True