webm-project-draft.py

gistfile1.txt

#!/usr/bin/python3

import os
import sys
import datetime
import argparse
import yaml
import json
import subprocess
import tempfile
import base64

parser = argparse.ArgumentParser(description='Merge webm files according to a proeject file.')
parser.add_argument('-info', action='store_true',
    help='return the encoding, width and height of webm file')
parser.add_argument('-svg', action='store_true',
    help='create the svg template')
parser.add_argument('-svg-frame', dest='svg_frame', action='store',
    type=lambda t: datetime.datetime.strptime(t, '%M:%S'),
    default=None,
    help='create an svg with the screenshot from a specific frame')
parser.add_argument('-to-vp9', dest='to_vp9', action='store_true',
    help='convert a webm file to use the vp9 video codec')
parser.add_argument('-generate', dest='generate', action='store_true',
    help='generate the project yaml file')
parser.add_argument('-o', dest='output_file', metavar='out-file', type=argparse.FileType('wt'),
    help='output file')
parser.add_argument('file', type=argparse.FileType('r'), nargs=1,
    default=None,
    help='file to be processed')
parser.add_argument('-debug', action='store_true',
    help='output debug information')
args = parser.parse_args()

debug = args.debug

def get_if_debug(*args):
    return locals()['args'] if debug else []

def get_if_not_debug(*args):
    return locals()['args'] if not debug else []

svg_template = """<svg version="1.1"
    baseProfile="full"
    width="{width}" height="{height}"
    xmlns="http://www.w3.org/2000/svg">

    {content}
</svg>"""

svg_image_template = '<image id="image1JPEG" x="0" y="0" width="{width}" height="{height}" xlink:href="data:image/png;base64,{image}">'

def get_webm_info(filename):
    # mkvmerge --identification-format json --identify 01.webm
    data = subprocess.check_output(['mkvmerge', '--identification-format', 'json', '--identify', filename])
    data_json = json.loads(data)
    # print(data_json)
    track_0 = data_json['tracks'][0]
    dimensions = track_0['properties']['pixel_dimensions'].split('x') # or display_dimensions
    return {'encoding': track_0['codec'], 'width': dimensions[0], 'height': dimensions[1]}

# returns VP9 or VP8
def get_webm_codec(filename):
    data = subprocess.check_output(['mkvmerge', '--identification-format', 'json', '--identify', filename])
    data_json = json.loads(data)
    return data_json['tracks'][0]['codec'] # VP9 | VP8

def webm_extract_frame(filename, duration):
    # https://stackoverflow.com/questions/8577137/creating-a-tmp-file-in-python
    fd, path = tempfile.mkstemp(suffix='.png')
    os.remove(path)
    call_args = ['ffmpeg', '-i', filename, '-ss', duration, '-vframes', '1', path]
    subprocess.call(call_args)

    with open(path, "rb") as f:
        image = base64.b64encode(f.read()).decode('utf-8')
    f.close()
    os.close(fd)
    return image
 
def webm_to_vp9(filename, output):
    call_args = ['ffmpeg', '-i', filename, '-c:v', 'libvpx-vp9', path]
    subprocess.call(call_args)


def write_svg_file(filename, dimension, content = ''):
    svg = svg_template.format(width = dimension[0], height = dimension[1], content = content)
    put_file_data(filename, svg)
    with open(filename, 'w') as f:
        f.write(svg + '\n')
    f.close()

def generate_project_yaml(filename, info, reference_filename):
    project = {
        'size' : {
            'width': info[width],
            'height': info[height]
        },
        'tracks' : [
            {'file': 'cover.svg', 'duration': 4},
            {'file': reference_filename},
            {'file': 'closing.svg', 'duration': 4}
        ]
    }
    print(project)
    with open(filename, 'w') as f:
        yaml.dump(project, f, default_flow_style=False)
    f.close()

def get_png_from_svg(filename, dimension):
    fd, path = tempfile.mkstemp(suffix='.png')
    os.remove(path)
    call_args = ['convert', '-density', str(300), '-resize', '{}x{}'.format(dimension[0], dimension[1]), filename, path]
    subprocess.call(call_args)
    os.close(fd)
    return path

def get_webm_from_png(filename, duration):
    fd, path = tempfile.mkstemp(suffix='.webm')
    os.remove(path)
    # eventually  '-vf scale=320:240' after yuv420p
    # libvpx-vp9 for vp9
    call_args = ['ffmpeg', *get_if_not_debug('-loglevel', 'panic'), '-loop', str(1), '-i', filename, '-t', str(duration), '-c:v', 'libvpx-vp9', '-pix_fmt', 'yuv420p', path]
    print(' '.join(call_args))
    subprocess.call(call_args)
    os.close(fd)
    return path

def generate_merged_webm(filename, tracks):
    print(tracks)
    call_args = ['mkvmerge', '-o', filename, '-w', ' +'.join(tracks)]
    print(' '.join(call_args))
    subprocess.call(call_args)

# first, process the "special" actions and exit

if args.info:
    print(get_webm_info(args.file[0].name))
    sys.exit()

if args.svg:
    output_filename = 'template.svg' if args.output_file is None else args.output_file.name
    info = get_webm_info(args.file[0].name)
    write_svg_file(output_filename, info['width'], info['height'])
    sys.exit()

if args.svg_frame:
    # TODO: add the timestamp to the default file name
    output_filename = 'frame.svg' if args.output_file is None else args.output_file.name
    # TODO: make sure that the timestamp is inside the webm length
    image = webm_extract_frame(args.file[0].name, '{0:%M:%S}'.format(args.svg_frame))
    info = get_webm_info(args.file[0].name)
    width, height = (info['width'], info['height'])
    write_svg_file(output_filename, [width, height], svg_image_template.format(width=width, height=height, image=image))
    sys.exit()

if args.to_vp9:
    output_filename = 'output.webm' if args.output_file is None else args.output_file.name
    webm_to_vp9(args.file[0].name, output_filename)
    sys.exit()

if args.generate:
    output_filename = 'webm-project.yaml' if args.output_file is None else args.output_file.name
    generate_project_yaml(output_filename, get_webm_info(args.file[0].name), args.file[0].name)
    sys.exit()

# how to require another argumets when one is set
# if ...
#      parser.error("-svg-frame requires -o")
#      sys.exit()

# if we got here, we're in the default mode and are processing the project

project = yaml.load(args.file[0], Loader=yaml.Loader)
# print(project)

output_filename = 'output.webm' if args.output_file is None else args.output_file.name

webm_tracks = []

print(project['tracks'])
for track in project['tracks']:
    file_basename, file_extension = os.path.splitext(track['file'])
    # print(track['file'])
    # print(file_extension)
    if file_extension == '.webm':
        filename = track['file']
    elif file_extension == '.svg':
        filename_png = get_png_from_svg(track['file'], [project['size']['width'], project['size']['height']])
        # TODO: how to cleanup this file?
        filename = get_webm_from_png(filename_png, track['duration'])
        os.remove(filename_png)
    elif file_extension == '.png':
        filename = get_webm_from_png(filename, track['duration'])
    # print(filename)
    webm_tracks.append(filename)

if webm_tracks:
    generate_merged_webm(output_filename, webm_tracks)