autosub

#!/usr/bin/env python
import argparse
import audioop
from googleapiclient.discovery import build
import json
import math
import multiprocessing
import os
import requests
import subprocess
import sys
import tempfile
import wave

from progressbar import ProgressBar, Percentage, Bar, ETA

from autosub.constants import LANGUAGE_CODES, \
    GOOGLE_SPEECH_API_KEY, GOOGLE_SPEECH_API_URL
from autosub.formatters import FORMATTERS


def percentile(arr, percent):
    arr = sorted(arr)
    k = (len(arr) - 1) * percent
    f = math.floor(k)
    c = math.ceil(k)
    if f == c: return arr[int(k)]
    d0 = arr[int(f)] * (c - k)
    d1 = arr[int(c)] * (k - f)
    return d0 + d1


def is_same_language(lang1, lang2):
    return lang1.split("-")[0] == lang2.split("-")[0]


class FLACConverter(object):
    def __init__(self, source_path, include_before=0.25, include_after=0.25):
        self.source_path = source_path
        self.include_before = include_before
        self.include_after = include_after

    def __call__(self, region):
        try:
            start, end = region
            start = max(0, start - self.include_before)
            end += self.include_after
            temp = tempfile.NamedTemporaryFile(suffix='.flac')
            command = ["ffmpeg","-ss", str(start), "-t", str(end - start),
                       "-y", "-i", self.source_path,
                       "-loglevel", "error", temp.name]
            subprocess.check_output(command, stdin=open(os.devnull))
            return temp.read()

        except KeyboardInterrupt:
            return


class SpeechRecognizer(object):
    def __init__(self, language="en", rate=44100, retries=3, api_key=GOOGLE_SPEECH_API_KEY):
        self.language = language
        self.rate = rate
        self.api_key = api_key
        self.retries = retries

    def __call__(self, data):
        try:
            for i in range(self.retries):
                url = GOOGLE_SPEECH_API_URL.format(lang=self.language, key=self.api_key)
                headers = {"Content-Type": "audio/x-flac; rate=%d" % self.rate}

                try:
                    resp = requests.post(url, data=data, headers=headers)
                except requests.exceptions.ConnectionError:
                    continue

                for line in resp.content.split("\n"):
                    try:
                        line = json.loads(line)
                        line = line['result'][0]['alternative'][0]['transcript']
                        return line[:1].upper() + line[1:]
                    except:
                        # no result
                        continue

        except KeyboardInterrupt:
            return


class Translator(object):
    def __init__(self, language, api_key, src, dst):
        self.language = language
        self.api_key = api_key
        self.service = build('translate', 'v2',
                             developerKey=self.api_key)
        self.src = src
        self.dst = dst

    def __call__(self, sentence):
        try:
            if not sentence: return
            result = self.service.translations().list(
                source=self.src,
                target=self.dst,
                q=[sentence]
            ).execute()
            if 'translations' in result and len(result['translations']) and \
                            'translatedText' in result['translations'][0]:
                return result['translations'][0]['translatedText']
            return ""

        except KeyboardInterrupt:
            return


def which(program):
    def is_exe(fpath):
        return os.path.isfile(fpath) and os.access(fpath, os.X_OK)

    fpath, fname = os.path.split(program)
    if fpath:
        if is_exe(program):
            return program
    else:
        for path in os.environ["PATH"].split(os.pathsep):
            path = path.strip('"')
            exe_file = os.path.join(path, program)
            if is_exe(exe_file):
                return exe_file
    return None


def extract_audio(filename, channels=1, rate=16000):
    temp = tempfile.NamedTemporaryFile(suffix='.wav', delete=False)
    if not os.path.isfile(filename):
        print "The given file does not exist: {0}".format(filename)
        raise Exception("Invalid filepath: {0}".format(filename))
    if not which("ffmpeg"):
        print "ffmpeg: Executable not found on machine."
        raise Exception("Dependency not found: ffmpeg")
    command = ["ffmpeg", "-y", "-i", filename, "-ac", str(channels), "-ar", str(rate), "-loglevel", "error", temp.name]
    subprocess.check_output(command, stdin=open(os.devnull))
    return temp.name, rate


def find_speech_regions(filename, frame_width=4096, min_region_size=0.5, max_region_size=6):
    reader = wave.open(filename)
    sample_width = reader.getsampwidth()
    rate = reader.getframerate()
    n_channels = reader.getnchannels()

    total_duration = reader.getnframes() / rate
    chunk_duration = float(frame_width) / rate

    n_chunks = int(math.ceil(reader.getnframes()*1.0 / frame_width))
    energies = []

    for i in range(n_chunks):
        chunk = reader.readframes(frame_width)
        energies.append(audioop.rms(chunk, sample_width * n_channels))

    threshold = percentile(energies, 0.2)

    elapsed_time = 0

    regions = []
    region_start = None

    for energy in energies:
        is_silence = energy <= threshold
        max_exceeded = region_start and elapsed_time - region_start >= max_region_size

        if (max_exceeded or is_silence) and region_start:
            if elapsed_time - region_start >= min_region_size:
                regions.append((region_start, elapsed_time))
                region_start = None

        elif (not region_start) and (not is_silence):
            region_start = elapsed_time
        elapsed_time += chunk_duration
    return regions


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('source_path', help="Path to the video or audio file to subtitle", nargs='?')
    parser.add_argument('-C', '--concurrency', help="Number of concurrent API requests to make", type=int, default=10)
    parser.add_argument('-o', '--output',
                        help="Output path for subtitles (by default, subtitles are saved in \
                        the same directory and name as the source path)")
    parser.add_argument('-F', '--format', help="Destination subtitle format", default="srt")
    parser.add_argument('-S', '--src-language', help="Language spoken in source file", default="en")
    parser.add_argument('-D', '--dst-language', help="Desired language for the subtitles", default="en")
    parser.add_argument('-K', '--api-key',
                        help="The Google Translate API key to be used. (Required for subtitle translation)")
    parser.add_argument('--list-formats', help="List all available subtitle formats", action='store_true')
    parser.add_argument('--list-languages', help="List all available source/destination languages", action='store_true')

    args = parser.parse_args()

    if args.list_formats:
        print("List of formats:")
        for subtitle_format in FORMATTERS.keys():
            print("{format}".format(format=subtitle_format))
        return 0

    if args.list_languages:
        print("List of all languages:")
        for code, language in sorted(LANGUAGE_CODES.items()):
            print("{code}\t{language}".format(code=code, language=language))
        return 0

    if args.format not in FORMATTERS.keys():
        print("Subtitle format not supported. Run with --list-formats to see all supported formats.")
        return 1

    if args.src_language not in LANGUAGE_CODES.keys():
        print("Source language not supported. Run with --list-languages to see all supported languages.")
        return 1

    if args.dst_language not in LANGUAGE_CODES.keys():
        print(
            "Destination language not supported. Run with --list-languages to see all supported languages.")
        return 1

    if not args.source_path:
        print("Error: You need to specify a source path.")
        return 1

    audio_filename, audio_rate = extract_audio(args.source_path)

    regions = find_speech_regions(audio_filename)

    pool = multiprocessing.Pool(args.concurrency)
    converter = FLACConverter(source_path=audio_filename)
    recognizer = SpeechRecognizer(language=args.src_language, rate=audio_rate, api_key=GOOGLE_SPEECH_API_KEY)

    transcripts = []
    if regions:
        try:
            widgets = ["Converting speech regions to FLAC files: ", Percentage(), ' ', Bar(), ' ', ETA()]
            pbar = ProgressBar(widgets=widgets, maxval=len(regions)).start()
            extracted_regions = []
            for i, extracted_region in enumerate(pool.imap(converter, regions)):
                extracted_regions.append(extracted_region)
                pbar.update(i)
            pbar.finish()

            widgets = ["Performing speech recognition: ", Percentage(), ' ', Bar(), ' ', ETA()]
            pbar = ProgressBar(widgets=widgets, maxval=len(regions)).start()

            for i, transcript in enumerate(pool.imap(recognizer, extracted_regions)):
                transcripts.append(transcript)
                pbar.update(i)
            pbar.finish()

            if not is_same_language(args.src_language, args.dst_language):
                if args.api_key:
                    google_translate_api_key = args.api_key
                    translator = Translator(args.dst_language, google_translate_api_key, dst=args.dst_language,
                                            src=args.src_language)
                    prompt = "Translating from {0} to {1}: ".format(args.src_language, args.dst_language)
                    widgets = [prompt, Percentage(), ' ', Bar(), ' ', ETA()]
                    pbar = ProgressBar(widgets=widgets, maxval=len(regions)).start()
                    translated_transcripts = []
                    for i, transcript in enumerate(pool.imap(translator, transcripts)):
                        translated_transcripts.append(transcript)
                        pbar.update(i)
                    pbar.finish()
                    transcripts = translated_transcripts
                else:
                    print "Error: Subtitle translation requires specified Google Translate API key. \
                    See --help for further information."
                    return 1

        except KeyboardInterrupt:
            pbar.finish()
            pool.terminate()
            pool.join()
            print "Cancelling transcription"
            return 1

    timed_subtitles = [(r, t) for r, t in zip(regions, transcripts) if t]
    formatter = FORMATTERS.get(args.format)
    formatted_subtitles = formatter(timed_subtitles)

    dest = args.output

    if not dest:
        base, ext = os.path.splitext(args.source_path)
        dest = "{base}.{format}".format(base=base, format=args.format)

    with open(dest, 'wb') as f:
        f.write(formatted_subtitles.encode("utf-8"))

    print "Subtitles file created at {}".format(dest)

    os.remove(audio_filename)

    return 0


if __name__ == '__main__':
    sys.exit(main())