Podcast Reference

Here we handle generation of podcasts from texts.

Podcaster

Source code in biochatter/podcast.py

class Podcaster:
    def __init__(
        self,
        document: Document,
        model_name: str = "gpt-3.5-turbo",
    ) -> None:
        """
        Orchestrates the podcasting of a document.
        """
        self.document = document
        self.model_name = model_name

    def generate_podcast(self, characters_per_paragraph: int) -> None:
        """
        Podcasts the document.

        TODO:
        - chain of density prompting for variable summary length
        """
        full_text = self.document[0].page_content

        # split text by sentence
        sentences = self._split_text(full_text)

        # could embed sentences and cluster on cosine similarity to identify
        # paragraphs here

        # preprocess text
        for i, sentence in enumerate(sentences):
            # special cases i.e. and e.g. - if sentence ends with one of these,
            # append next sentence
            special_cases = ["i.e.", "e.g."]
            if sentence.endswith(tuple(special_cases)):
                sentences[i] = sentence + " " + sentences[i + 1]
                del sentences[i + 1]

        # concatenate first 5 sentences for title and author extraction
        first_5 = "\n".join(sentences[:5])
        self.podcast_info = self._title_and_authors(first_5)

        # LLM to determine section breaks?

        # go through sections and summarise each
        self.processed_sections = self._process_sections(
            sentences,
            characters_per_paragraph,
        )

        # summarise the summaries

    def _split_text(self, text: str) -> list[str]:
        """
        Splits consecutive text into sentences.
        """
        nltk.download("punkt")
        tokenizer = nltk.data.load("tokenizers/punkt/english.pickle")
        return tokenizer.tokenize(text)

    def _title_and_authors(self, text: str) -> str:
        """
        Extracts title and authors from document.

        Args:
            text (str): text to extract title and authors from

        Returns:
            str: title and authors
        """
        # first sentence - extract title, authors
        c_first = GptConversation(
            model_name=self.model_name,
            prompts={},
            correct=False,
        )
        c_first.set_api_key(api_key=os.getenv("OPENAI_API_KEY"), user="podcast")
        c_first.append_system_message(FIRST_PROMPT)
        msg, token_usage, correction = c_first.query(text)
        # split at authors ('Authors:' or '\nAuthors:')
        if "Authors:" in msg:
            title = msg.split("Title:")[1].split("Authors:")[0].strip()
            authors = msg.split("Authors:")[1].strip()
            return f"{title}, by {authors}, podcasted by biochatter."
        else:
            return "A podcast by biochatter."

    def _process_section(self, text: str, summarise: bool = False) -> str:
        """
        Processes a section of the document. Summarises if summarise is True,
        otherwise just makes the text more listenable.

        Args:
            text (str): text to summarise

            summarise (bool): whether to summarise the text

        Returns:
            str: summarised text
        """
        # summarise section
        c = GptConversation(
            model_name=self.model_name,
            prompts={},
            correct=False,
        )
        c.set_api_key(api_key=os.getenv("OPENAI_API_KEY"), user="podcast")
        if summarise:
            c.append_system_message(SUMMARISE_PROMPT)
        else:
            c.append_system_message(PROCESS_PROMPT)
        msg, token_usage, correction = c.query(text)
        return msg

    def _process_sections(
        self, sentences: list, characters_per_paragraph: int
    ) -> list:
        """

        Processes sections of the document. Concatenates sentences until
        characters_per_paragraph is reached, removing each sentence from the
        list as it is added to the section to be processed.

        Args:
            sentences (list): list of sentences to summarise

            characters_per_paragraph (int): number of characters per paragraph

        Returns:
            list: list of processed sections
        """
        summarised_sections = []
        section = ""
        while sentences:
            sentence = sentences.pop(0)
            tmp = section + sentence
            if len(tmp) < characters_per_paragraph and sentences:
                section += sentence
            else:
                if sentences:
                    sentences.insert(0, sentence)
                summarised_section = self._process_section(section)
                # filter "no content" sections
                if not (
                    "no content" in summarised_section.lower()
                    and len(summarised_section) < 30
                ):
                    summarised_sections.append(summarised_section)
                section = ""

        return summarised_sections

    def podcast_to_file(
        self,
        path: str,
        model: str = "gtts",
        voice: str = "alloy",
    ) -> None:
        """
        Uses text-to-speech to generate audio for the summarised paper podcast.

        Args:
            path (str): path to save audio file to

            model (str): model to use for text-to-speech. Currently supported:
                'gtts' (Google Text-to-Speech, free),
                'tts-1' (OpenAI API, paid, prioritises speed),
                'tts-1-hd' (OpenAI API, paid, prioritises quality)

            voice (str): voice to use for text-to-speech. See OpenAI API
                documentation for available voices.
        """

        full_text = self.podcast_to_text()

        if model == "gtts":
            audio = gTTS(text=full_text)
            audio.save(path)
        else:
            client = OpenAI()

            # Save the intro to the original file
            response = client.audio.speech.create(
                model=model,
                voice=voice,
                input=(
                    "You are listening to: \n\n"
                    + self.podcast_info
                    + "\n\n"
                    + " Text-to-speech generated by OpenAI."
                ),
            )
            first_path = path.rsplit(".", 1)[0] + "_0.mp3"
            response.stream_to_file(first_path)

            # Concatenate the sections
            full_text = ""
            for i, section in enumerate(self.processed_sections):
                full_text += section + "\n\n"

            # Make sections of 4000 characters max (at sentence boundaries)
            nltk.download("punkt")
            tokenizer = nltk.data.load("tokenizers/punkt/english.pickle")
            sentences = deque(
                tokenizer.tokenize(full_text)
            )  # Use a deque instead of a list

            # Split the text into sections by filling one section until it
            # exceeds 4000 characters, then starting a new section (not adding
            # the sentence that would exceed the limit)
            sections = []
            section = ""
            while sentences:
                sentence = sentences[0]
                tmp = section + sentence
                if len(tmp) < 4000:
                    section += sentences.popleft()
                else:
                    sections.append(section)
                    section = ""

            sections.append(section)  # Add the penultimate section

            # Last section: conclude the podcast
            sections.append(
                f"This was {self.podcast_info}. Thank you for listening."
            )

            # Save each section to a separate file with an integer suffix
            for i, section in enumerate(sections):
                response = client.audio.speech.create(
                    model=model,
                    voice=voice,
                    input=section,
                )
                # Insert the integer suffix just before the .mp3 extension
                section_path = path.rsplit(".", 1)[0] + f"_{i+1}.mp3"
                response.stream_to_file(section_path)

    def podcast_to_text(self):
        """
        Returns the summarised paper podcast as text.
        """
        full_text = "You are listening to: " + self.podcast_info + "\n\n"
        for section in self.processed_sections:
            full_text += section + "\n\n"
        return full_text

__init__(document, model_name='gpt-3.5-turbo')

Orchestrates the podcasting of a document.

Source code in biochatter/podcast.py

def __init__(
    self,
    document: Document,
    model_name: str = "gpt-3.5-turbo",
) -> None:
    """
    Orchestrates the podcasting of a document.
    """
    self.document = document
    self.model_name = model_name

generate_podcast(characters_per_paragraph)

Podcasts the document.

TODO: - chain of density prompting for variable summary length

Source code in biochatter/podcast.py

def generate_podcast(self, characters_per_paragraph: int) -> None:
    """
    Podcasts the document.

    TODO:
    - chain of density prompting for variable summary length
    """
    full_text = self.document[0].page_content

    # split text by sentence
    sentences = self._split_text(full_text)

    # could embed sentences and cluster on cosine similarity to identify
    # paragraphs here

    # preprocess text
    for i, sentence in enumerate(sentences):
        # special cases i.e. and e.g. - if sentence ends with one of these,
        # append next sentence
        special_cases = ["i.e.", "e.g."]
        if sentence.endswith(tuple(special_cases)):
            sentences[i] = sentence + " " + sentences[i + 1]
            del sentences[i + 1]

    # concatenate first 5 sentences for title and author extraction
    first_5 = "\n".join(sentences[:5])
    self.podcast_info = self._title_and_authors(first_5)

    # LLM to determine section breaks?

    # go through sections and summarise each
    self.processed_sections = self._process_sections(
        sentences,
        characters_per_paragraph,
    )

podcast_to_file(path, model='gtts', voice='alloy')

Uses text-to-speech to generate audio for the summarised paper podcast.

Parameters:

Name	Type	Description	Default
path	str	path to save audio file to	required
model	str	model to use for text-to-speech. Currently supported: 'gtts' (Google Text-to-Speech, free), 'tts-1' (OpenAI API, paid, prioritises speed), 'tts-1-hd' (OpenAI API, paid, prioritises quality)	'gtts'
voice	str	voice to use for text-to-speech. See OpenAI API documentation for available voices.	'alloy'

Source code in biochatter/podcast.py

def podcast_to_file(
    self,
    path: str,
    model: str = "gtts",
    voice: str = "alloy",
) -> None:
    """
    Uses text-to-speech to generate audio for the summarised paper podcast.

    Args:
        path (str): path to save audio file to

        model (str): model to use for text-to-speech. Currently supported:
            'gtts' (Google Text-to-Speech, free),
            'tts-1' (OpenAI API, paid, prioritises speed),
            'tts-1-hd' (OpenAI API, paid, prioritises quality)

        voice (str): voice to use for text-to-speech. See OpenAI API
            documentation for available voices.
    """

    full_text = self.podcast_to_text()

    if model == "gtts":
        audio = gTTS(text=full_text)
        audio.save(path)
    else:
        client = OpenAI()

        # Save the intro to the original file
        response = client.audio.speech.create(
            model=model,
            voice=voice,
            input=(
                "You are listening to: \n\n"
                + self.podcast_info
                + "\n\n"
                + " Text-to-speech generated by OpenAI."
            ),
        )
        first_path = path.rsplit(".", 1)[0] + "_0.mp3"
        response.stream_to_file(first_path)

        # Concatenate the sections
        full_text = ""
        for i, section in enumerate(self.processed_sections):
            full_text += section + "\n\n"

        # Make sections of 4000 characters max (at sentence boundaries)
        nltk.download("punkt")
        tokenizer = nltk.data.load("tokenizers/punkt/english.pickle")
        sentences = deque(
            tokenizer.tokenize(full_text)
        )  # Use a deque instead of a list

        # Split the text into sections by filling one section until it
        # exceeds 4000 characters, then starting a new section (not adding
        # the sentence that would exceed the limit)
        sections = []
        section = ""
        while sentences:
            sentence = sentences[0]
            tmp = section + sentence
            if len(tmp) < 4000:
                section += sentences.popleft()
            else:
                sections.append(section)
                section = ""

        sections.append(section)  # Add the penultimate section

        # Last section: conclude the podcast
        sections.append(
            f"This was {self.podcast_info}. Thank you for listening."
        )

        # Save each section to a separate file with an integer suffix
        for i, section in enumerate(sections):
            response = client.audio.speech.create(
                model=model,
                voice=voice,
                input=section,
            )
            # Insert the integer suffix just before the .mp3 extension
            section_path = path.rsplit(".", 1)[0] + f"_{i+1}.mp3"
            response.stream_to_file(section_path)

podcast_to_text()

Returns the summarised paper podcast as text.

Source code in biochatter/podcast.py

def podcast_to_text(self):
    """
    Returns the summarised paper podcast as text.
    """
    full_text = "You are listening to: " + self.podcast_info + "\n\n"
    for section in self.processed_sections:
        full_text += section + "\n\n"
    return full_text