Google Text-to-Speech (gTTS)

gTTS is a Python library that converts text to speech using Google's Text-to-Speech API. It's free to use and doesn't require an API key.

Installation

pip install gtts pydub

pydub is useful for manipulating and concatenating audio files.

Basic Usage

from gtts import gTTS

# Create speech
tts = gTTS(text="Hello, world!", lang='en')

# Save to file
tts.save("output.mp3")

Language Options

# US English (default)
tts = gTTS(text="Hello", lang='en')

# British English
tts = gTTS(text="Hello", lang='en', tld='co.uk')

# Slow speech
tts = gTTS(text="Hello", lang='en', slow=True)

Python Example for Long Text

from gtts import gTTS
from pydub import AudioSegment
import tempfile
import os
import re

def chunk_text(text, max_chars=4500):
    """Split text into chunks at sentence boundaries."""
    sentences = re.split(r'(?<=[.!?])\s+', text)
    chunks = []
    current_chunk = ""

    for sentence in sentences:
        if len(current_chunk) + len(sentence) < max_chars:
            current_chunk += sentence + " "
        else:
            if current_chunk:
                chunks.append(current_chunk.strip())
            current_chunk = sentence + " "

    if current_chunk:
        chunks.append(current_chunk.strip())

    return chunks


def text_to_audiobook(text, output_path):
    """Convert long text to a single audio file."""
    chunks = chunk_text(text)
    audio_segments = []

    for i, chunk in enumerate(chunks):
        # Create temp file for this chunk
        with tempfile.NamedTemporaryFile(suffix='.mp3', delete=False) as tmp:
            tmp_path = tmp.name

        # Generate speech
        tts = gTTS(text=chunk, lang='en', slow=False)
        tts.save(tmp_path)

        # Load and append
        segment = AudioSegment.from_mp3(tmp_path)
        audio_segments.append(segment)

        # Cleanup
        os.unlink(tmp_path)

    # Concatenate all segments
    combined = audio_segments[0]
    for segment in audio_segments[1:]:
        combined += segment

    # Export
    combined.export(output_path, format="mp3")

Handling Large Documents

gTTS has a character limit per request (~5000 chars). For long documents:

1. Split text into chunks at sentence boundaries
2. Generate audio for each chunk using gTTS
3. Use pydub to concatenate the chunks

Alternative: Using ffmpeg for Concatenation

If you prefer ffmpeg over pydub:

# Create file list
echo "file 'chunk1.mp3'" > files.txt
echo "file 'chunk2.mp3'" >> files.txt

# Concatenate
ffmpeg -f concat -safe 0 -i files.txt -c copy output.mp3

Best Practices

• Split at sentence boundaries to avoid cutting words mid-sentence
• Use slow=False for natural speech speed
• Handle network errors gracefully (gTTS requires internet)
• Consider adding brief pauses between chapters/sections

Limitations

• Requires internet connection (uses Google's servers)
• Voice quality is good but not as natural as paid services
• Limited voice customization options
• May have rate limits for very heavy usage