pandora_render/ffmpeg.py

#!/usr/bin/python3
import json
import os
import subprocess
import sys

def run(cmd):
    #print(' '.join('"%s"' % c for c in cmd))
    subprocess.call(cmd)


edit_json = sys.argv[1]
edit = json.load(open(edit_json))

render = '/tmp/out'
output = '/tmp/test.mp4'
height = 270
aspect = 16/9
width = int(height * aspect)

files = []
for clip in edit:
    out = render + '/%s_%0.3f-%0.3f.ts' % (clip['oshash'], clip['in'], clip['out'])
    files.append(out)
    if os.path.exists(out):
        continue
    clip_aspect = clip['resolution'][0] / clip['resolution'][1]
    if clip_aspect < aspect:
        x = width
        y = int(x / clip_aspect)
    else:
        y = height
        x = int(y * clip_aspect)
    vf = 'scale=%s:%s' % (x, y)
    if x != width:
        vf += ',crop=%s:%s' % (width, height)  # crop center
    elif y != height:
        offset = int((y - height) / 2)
        vf += ',crop=w=%s:h=%s:x=0:y=%s' % (width, height, offset)
    options = [
        '-vf', vf,
        '-aspect', str(aspect),
        '-c:v', 'libx264',
        '-b:v', '8M',
        '-r:v', '25',
        '-c:a', 'aac',
        '-ar', '48000',
        '-ac', '2',
        '-b:a', '192k',
    ]
    cmd = [
        'ffmpeg',
        '-ss', str(clip['in']),
        '-i', clip['path']
    ] + options + [
        '-t', str(clip['out'] - clip['in']),
        out
    ]
    run(cmd)

txt = output + '.txt'
with open(txt, 'w') as fd:
    fd.write('file ' + '\nfile '.join(files))
cmd = ['ffmpeg', '-y', '-f', 'concat', '-safe', '0', '-i', txt, '-c', 'copy', output]
run(cmd)
os.unlink(txt)