Python FFmpeg Skill

Comprehensive guide to using FFmpeg with Python for video/audio processing, encoding, streaming, and media manipulation.

Quick Reference

Library	Best For	Performance	Complexity
ffmpeg-python	Complex filter graphs, readable code	Medium	Low
PyAV	Frame-level access, real-time processing	High	Medium
subprocess	Simple tasks, full FFmpeg control	Medium	Low
moviepy	Quick edits, simple compositing	Low	Very Low

Installation

# System FFmpeg (REQUIRED for ffmpeg-python and subprocess)
# Windows: winget install ffmpeg
# macOS: brew install ffmpeg
# Ubuntu: sudo apt install ffmpeg

# Python libraries
uv add ffmpeg-python  # Wrapper library
uv add av             # PyAV - Cython bindings
uv add moviepy        # High-level editing

Critical Gotchas

1. Audio Stream Loss (MOST COMMON BUG)

import ffmpeg

# BAD: Video filters can drop audio!
(
    ffmpeg
    .input('input.mp4')
    .filter('scale', 1280, 720)
    .output('output.mp4')
    .run()
)
# Result: Video only, NO AUDIO!

# GOOD: Explicitly handle audio stream
input_file = ffmpeg.input('input.mp4')
video = input_file.video.filter('scale', 1280, 720)
audio = input_file.audio
(
    ffmpeg
    .output(video, audio, 'output.mp4')
    .run()
)

# ALTERNATIVE: Copy audio stream
(
    ffmpeg
    .input('input.mp4')
    .output('output.mp4', vf='scale=1280:720', acodec='copy')
    .run()
)

2. Subprocess Deadlock

import subprocess

# BAD: Can deadlock with large outputs!
process = subprocess.Popen(
    ['ffmpeg', '-i', 'input.mp4', '-f', 'rawvideo', 'pipe:1'],
    stdout=subprocess.PIPE
)
output = process.stdout.read()  # DEADLOCK if output > buffer size

# GOOD: Use communicate() for small outputs
process = subprocess.Popen(
    ['ffmpeg', '-i', 'input.mp4', '-f', 'null', '-'],
    stdout=subprocess.PIPE,
    stderr=subprocess.PIPE
)
stdout, stderr = process.communicate()

# GOOD: Stream processing for large outputs
process = subprocess.Popen(
    ['ffmpeg', '-i', 'input.mp4', '-f', 'rawvideo', '-pix_fmt', 'rgb24', 'pipe:1'],
    stdout=subprocess.PIPE,
    stderr=subprocess.DEVNULL
)
while True:
    # Read frame by frame (width * height * 3 bytes for RGB24)
    frame_data = process.stdout.read(1920 * 1080 * 3)
    if not frame_data:
        break
    # Process frame...

3. Overwrite Without Prompt

# BAD: FFmpeg prompts for overwrite, blocking script
ffmpeg.input('input.mp4').output('output.mp4').run()

# GOOD: Always use overwrite_output()
ffmpeg.input('input.mp4').output('output.mp4').overwrite_output().run()

# Or with subprocess
subprocess.run(['ffmpeg', '-y', '-i', 'input.mp4', 'output.mp4'])

4. Error Handling

import ffmpeg

# BAD: No error handling
ffmpeg.input('input.mp4').output('output.mp4').run()

# GOOD: Catch and log errors
try:
    ffmpeg.input('input.mp4').output('output.mp4').overwrite_output().run(
        capture_stdout=True,
        capture_stderr=True
    )
except ffmpeg.Error as e:
    print(f"FFmpeg error: {e.stderr.decode()}")
    raise

# Check if file exists first
from pathlib import Path
if not Path('input.mp4').exists():
    raise FileNotFoundError("Input file not found")

5. Path Handling on Windows

from pathlib import Path

# BAD: Backslashes can cause issues
path = "C:\\Users\\video.mp4"

# GOOD: Use forward slashes or Path
path = "C:/Users/video.mp4"
# Or
path = str(Path("C:\\Users\\video.mp4").as_posix())

# GOOD: Quote paths with spaces
ffmpeg.input('my video.mp4')  # ffmpeg-python handles quoting
subprocess.run(['ffmpeg', '-i', 'my video.mp4', 'output.mp4'])  # List handles quoting

Video Encoding

H.264 (Best Compatibility)

import ffmpeg

# CRF encoding (recommended for quality)
# CRF 0 = lossless, 23 = default, 51 = worst
# Lower = better quality, larger file
(
    ffmpeg
    .input('input.mp4')
    .output('output.mp4',
        vcodec='libx264',
        crf=23,           # Quality (18-28 typical range)
        preset='medium',  # Speed vs compression
        acodec='aac',
        audio_bitrate='192k'
    )
    .overwrite_output()
    .run()
)

# Presets (fastest to slowest, worst to best compression):
# ultrafast, superfast, veryfast, faster, fast, medium, slow, slower, veryslow, placebo
# Use 'medium' or 'slow' for best quality/time tradeoff

# Two-pass encoding for target file size
import os

# Calculate bitrate for target size (in kbps)
duration_seconds = 120
target_size_mb = 50
video_bitrate = (target_size_mb * 8192 / duration_seconds) - 192  # Subtract audio bitrate

# Pass 1
(
    ffmpeg
    .input('input.mp4')
    .output('NUL' if os.name == 'nt' else '/dev/null',
        vcodec='libx264',
        video_bitrate=f'{int(video_bitrate)}k',
        preset='slow',
        **{'pass': 1},
        f='null'
    )
    .overwrite_output()
    .run()
)

# Pass 2
(
    ffmpeg
    .input('input.mp4')
    .output('output.mp4',
        vcodec='libx264',
        video_bitrate=f'{int(video_bitrate)}k',
        preset='slow',
        **{'pass': 2},
        acodec='aac',
        audio_bitrate='192k'
    )
    .overwrite_output()
    .run()
)

H.265/HEVC (Better Compression)

# CRF 28 for H.265 ≈ CRF 23 for H.264
(
    ffmpeg
    .input('input.mp4')
    .output('output.mp4',
        vcodec='libx265',
        crf=28,
        preset='medium',
        acodec='aac',
        audio_bitrate='128k',
        **{'tag:v': 'hvc1'}  # For Apple compatibility
    )
    .overwrite_output()
    .run()
)

VP9/WebM (Web Streaming)

(
    ffmpeg
    .input('input.mp4')
    .output('output.webm',
        vcodec='libvpx-vp9',
        crf=30,
        video_bitrate='0',  # Required for CRF mode
        acodec='libopus',
        audio_bitrate='128k'
    )
    .overwrite_output()
    .run()
)

AV1 (Best Compression, Slowest)

(
    ffmpeg
    .input('input.mp4')
    .output('output.mp4',
        vcodec='libaom-av1',
        crf=30,
        cpu_used=4,  # 0-8, higher = faster but lower quality
        acodec='libopus'
    )
    .overwrite_output()
    .run()
)

Hardware Acceleration

NVIDIA NVENC

# Check if NVENC is available
import subprocess
result = subprocess.run(
    ['ffmpeg', '-encoders'],
    capture_output=True,
    text=True
)
nvenc_available = 'h264_nvenc' in result.stdout

if nvenc_available:
    (
        ffmpeg
        .input('input.mp4')
        .output('output.mp4',
            vcodec='h264_nvenc',
            preset='p4',  # p1 (fastest) to p7 (best quality)
            cq=23,        # Constant quality (like CRF)
            acodec='copy'
        )
        .overwrite_output()
        .run()
    )

Intel Quick Sync (QSV)

(
    ffmpeg
    .input('input.mp4', hwaccel='qsv')
    .output('output.mp4',
        vcodec='h264_qsv',
        preset='medium',
        global_quality=23,
        acodec='copy'
    )
    .overwrite_output()
    .run()
)

AMD AMF (Windows) / VAAPI (Linux)

# Linux VAAPI
(
    ffmpeg
    .input('input.mp4', hwaccel='vaapi', hwaccel_device='/dev/dri/renderD128')
    .output('output.mp4',
        vcodec='h264_vaapi',
        acodec='copy'
    )
    .overwrite_output()
    .run()
)

Audio Processing

Extract Audio

# Extract to MP3
(
    ffmpeg
    .input('video.mp4')
    .output('audio.mp3',
        acodec='libmp3lame',
        audio_bitrate='320k',
        vn=None  # No video
    )
    .overwrite_output()
    .run()
)

# Extract to WAV (lossless)
(
    ffmpeg
    .input('video.mp4')
    .output('audio.wav',
        acodec='pcm_s16le',
        ar=44100,  # Sample rate
        ac=2,      # Channels (stereo)
        vn=None
    )
    .overwrite_output()
    .run()
)

# Extract to FLAC (lossless compressed)
(
    ffmpeg
    .input('video.mp4')
    .output('audio.flac',
        acodec='flac',
        vn=None
    )
    .overwrite_output()
    .run()
)

Audio Conversion

# MP3 with variable bitrate (recommended)
(
    ffmpeg
    .input('audio.wav')
    .output('audio.mp3',
        acodec='libmp3lame',
        q=2  # VBR quality 0-9 (0 = best, ~245kbps; 2 ≈ 190kbps)
    )
    .overwrite_output()
    .run()
)

# AAC (best for video)
(
    ffmpeg
    .input('audio.wav')
    .output('audio.m4a',
        acodec='aac',
        audio_bitrate='256k'
    )
    .overwrite_output()
    .run()
)

# Opus (best quality per bitrate)
(
    ffmpeg
    .input('audio.wav')
    .output('audio.opus',
        acodec='libopus',
        audio_bitrate='128k'
    )
    .overwrite_output()
    .run()
)

Audio Filters

# Volume adjustment
(
    ffmpeg
    .input('audio.mp3')
    .filter('volume', 1.5)  # 1.5x volume
    .output('louder.mp3')
    .overwrite_output()
    .run()
)

# Normalize audio (loudnorm)
(
    ffmpeg
    .input('audio.mp3')
    .filter('loudnorm', I=-16, TP=-1.5, LRA=11)
    .output('normalized.mp3')
    .overwrite_output()
    .run()
)

# Fade in/out
(
    ffmpeg
    .input('audio.mp3')
    .filter('afade', type='in', duration=3)
    .filter('afade', type='out', start_time=57, duration=3)
    .output('faded.mp3')
    .overwrite_output()
    .run()
)

# Resample
(
    ffmpeg
    .input('audio.mp3')
    .filter('aresample', 48000)
    .output('resampled.mp3')
    .overwrite_output()
    .run()
)

Video Filters

Scaling/Resizing

# Scale to specific size
(
    ffmpeg
    .input('input.mp4')
    .filter('scale', 1920, 1080)
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Scale maintaining aspect ratio
(
    ffmpeg
    .input('input.mp4')
    .filter('scale', 1280, -1)  # -1 = auto-calculate
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Scale with padding (letterbox/pillarbox)
(
    ffmpeg
    .input('input.mp4')
    .filter('scale', 1920, 1080, force_original_aspect_ratio='decrease')
    .filter('pad', 1920, 1080, '(ow-iw)/2', '(oh-ih)/2')
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Scale algorithms
# fast_bilinear, bilinear, bicubic, lanczos (best for downscaling)
(
    ffmpeg
    .input('input.mp4')
    .filter('scale', 1280, 720, flags='lanczos')
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

Cropping

# Crop to size (width:height:x:y)
(
    ffmpeg
    .input('input.mp4')
    .filter('crop', 1280, 720, 100, 50)  # 1280x720 starting at (100, 50)
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Center crop
(
    ffmpeg
    .input('input.mp4')
    .filter('crop', 1280, 720, '(in_w-1280)/2', '(in_h-720)/2')
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Crop to aspect ratio (16:9)
(
    ffmpeg
    .input('input.mp4')
    .filter('crop', 'min(iw,ih*16/9)', 'min(ih,iw*9/16)')
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

Rotation

# Rotate 90 degrees clockwise
(
    ffmpeg
    .input('input.mp4')
    .filter('transpose', 1)  # 0=ccw+vflip, 1=cw, 2=ccw, 3=cw+vflip
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Rotate arbitrary angle
(
    ffmpeg
    .input('input.mp4')
    .filter('rotate', 'PI/6')  # 30 degrees in radians
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Horizontal flip
(
    ffmpeg
    .input('input.mp4')
    .filter('hflip')
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Vertical flip
(
    ffmpeg
    .input('input.mp4')
    .filter('vflip')
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

Text Overlay

# Simple text
(
    ffmpeg
    .input('input.mp4')
    .filter('drawtext',
        text='Hello World',
        fontsize=48,
        fontcolor='white',
        x='(w-text_w)/2',  # Center horizontally
        y='h-th-20'        # Bottom with padding
    )
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Text with background box
(
    ffmpeg
    .input('input.mp4')
    .filter('drawtext',
        text='Watermark',
        fontsize=24,
        fontcolor='white',
        box=1,
        boxcolor='black@0.5',
        boxborderw=5,
        x=10,
        y=10
    )
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Timestamp
(
    ffmpeg
    .input('input.mp4')
    .filter('drawtext',
        text='%{pts\\:hms}',  # Escape colons
        fontsize=24,
        fontcolor='white',
        x=10,
        y=10
    )
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Custom font (specify path)
(
    ffmpeg
    .input('input.mp4')
    .filter('drawtext',
        text='Custom Font',
        fontfile='/path/to/font.ttf',
        fontsize=48,
        fontcolor='yellow'
    )
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

Image Overlay (Watermark)

# Overlay image in corner
main = ffmpeg.input('video.mp4')
logo = ffmpeg.input('logo.png')

(
    ffmpeg
    .overlay(main, logo, x=10, y=10)  # Top-left
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Overlay with scaling
main = ffmpeg.input('video.mp4')
logo = ffmpeg.input('logo.png').filter('scale', 100, -1)

(
    ffmpeg
    .overlay(main, logo, x='main_w-overlay_w-10', y=10)  # Top-right
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Semi-transparent overlay
logo = ffmpeg.input('logo.png').filter('format', 'rgba').filter('colorchannelmixer', aa=0.5)

Color Adjustments

# Brightness, contrast, saturation
(
    ffmpeg
    .input('input.mp4')
    .filter('eq',
        brightness=0.1,    # -1 to 1, default 0
        contrast=1.2,      # 0 to 2, default 1
        saturation=1.3     # 0 to 3, default 1
    )
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Gamma correction
(
    ffmpeg
    .input('input.mp4')
    .filter('eq', gamma=1.5)
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Grayscale
(
    ffmpeg
    .input('input.mp4')
    .filter('format', 'gray')
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

# Color balance
(
    ffmpeg
    .input('input.mp4')
    .filter('colorbalance',
        rs=0.1,  # Red shadows
        gm=0.1,  # Green midtones
        bh=0.1   # Blue highlights
    )
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

Trimming and Concatenation

Trimming

# Trim by time
(
    ffmpeg
    .input('input.mp4', ss=10, t=30)  # Start at 10s, duration 30s
    .output('output.mp4', c='copy')   # Stream copy (fast, no re-encode)
    .overwrite_output()
    .run()
)

# Trim to end time
(
    ffmpeg
    .input('input.mp4', ss=10, to=40)  # Start at 10s, end at 40s
    .output('output.mp4', c='copy')
    .overwrite_output()
    .run()
)

# Accurate trimming (re-encode, slower but precise)
(
    ffmpeg
    .input('input.mp4')
    .trim(start=10, end=40)
    .setpts('PTS-STARTPTS')  # Reset timestamps
    .output('output.mp4', vcodec='libx264', crf=18)
    .overwrite_output()
    .run()
)

# Trim with audio (both streams)
input_file = ffmpeg.input('input.mp4')
video = input_file.video.trim(start=10, end=40).setpts('PTS-STARTPTS')
audio = input_file.audio.filter('atrim', start=10, end=40).filter('asetpts', 'PTS-STARTPTS')
(
    ffmpeg
    .output(video, audio, 'output.mp4')
    .overwrite_output()
    .run()
)

Concatenation

# Method 1: Concat demuxer (same codec, fast)
# Create file list
with open('filelist.txt', 'w') as f:
    f.write("file 'video1.mp4'\n")
    f.write("file 'video2.mp4'\n")
    f.write("file 'video3.mp4'\n")

(
    ffmpeg
    .input('filelist.txt', f='concat', safe=0)
    .output('output.mp4', c='copy')
    .overwrite_output()
    .run()
)

# Method 2: Concat filter (different codecs, re-encodes)
video1 = ffmpeg.input('video1.mp4')
video2 = ffmpeg.input('video2.mp4')

(
    ffmpeg
    .concat(video1, video2, v=1, a=1)  # v=video streams, a=audio streams
    .output('output.mp4')
    .overwrite_output()
    .run()
)

# Concatenate multiple videos
videos = [ffmpeg.input(f'video{i}.mp4') for i in range(1, 5)]
(
    ffmpeg
    .concat(*videos, v=1, a=1)
    .output('output.mp4')
    .overwrite_output()
    .run()
)

Streaming

HLS (HTTP Live Streaming)

# Create HLS stream
(
    ffmpeg
    .input('input.mp4')
    .output('stream.m3u8',
        vcodec='libx264',
        crf=23,
        preset='fast',
        acodec='aac',
        audio_bitrate='128k',
        f='hls',
        hls_time=10,           # Segment duration
        hls_list_size=0,       # Keep all segments
        hls_segment_filename='segment_%03d.ts'
    )
    .overwrite_output()
    .run()
)

# Multi-bitrate HLS (adaptive streaming)
input_file = ffmpeg.input('input.mp4')

# Create multiple quality streams
streams = []
for height, bitrate in [(1080, '5000k'), (720, '2500k'), (480, '1000k')]:
    stream = (
        input_file
        .filter('scale', -2, height)
        .output(f'stream_{height}p.m3u8',
            vcodec='libx264',
            video_bitrate=bitrate,
            preset='fast',
            acodec='aac',
            f='hls',
            hls_time=10,
            hls_segment_filename=f'segment_{height}p_%03d.ts'
        )
    )
    streams.append(stream)

# Create master playlist manually

DASH (Dynamic Adaptive Streaming)

(
    ffmpeg
    .input('input.mp4')
    .output('manifest.mpd',
        vcodec='libx264',
        acodec='aac',
        f='dash',
        seg_duration=10,
        adaptation_sets='id=0,streams=v id=1,streams=a'
    )
    .overwrite_output()
    .run()
)

RTMP Streaming

# Stream to RTMP server
(
    ffmpeg
    .input('input.mp4', re=None)  # Read at native rate
    .output('rtmp://server/live/stream',
        vcodec='libx264',
        preset='ultrafast',
        tune='zerolatency',
        acodec='aac',
        f='flv'
    )
    .overwrite_output()
    .run()
)

# Stream from webcam
(
    ffmpeg
    .input('0', f='dshow', i='video="Webcam Name"')  # Windows
    # .input('/dev/video0', f='v4l2')  # Linux
    .output('rtmp://server/live/stream',
        vcodec='libx264',
        preset='ultrafast',
        tune='zerolatency',
        f='flv'
    )
    .run()
)

Metadata and Probing

Get Video Information

import ffmpeg
import json

# Probe file
probe = ffmpeg.probe('video.mp4')

# Get format info
format_info = probe['format']
duration = float(format_info['duration'])
size_bytes = int(format_info['size'])
bitrate = int(format_info['bit_rate'])

print(f"Duration: {duration:.2f}s")
print(f"Size: {size_bytes / 1024 / 1024:.2f}MB")
print(f"Bitrate: {bitrate / 1000:.0f}kbps")

# Get video stream info
video_stream = next(
    (s for s in probe['streams'] if s['codec_type'] == 'video'),
    None
)
if video_stream:
    width = video_stream['width']
    height = video_stream['height']
    fps = eval(video_stream['r_frame_rate'])  # e.g., "30/1"
    codec = video_stream['codec_name']
    print(f"Resolution: {width}x{height}")
    print(f"FPS: {fps:.2f}")
    print(f"Codec: {codec}")

# Get audio stream info
audio_stream = next(
    (s for s in probe['streams'] if s['codec_type'] == 'audio'),
    None
)
if audio_stream:
    sample_rate = audio_stream['sample_rate']
    channels = audio_stream['channels']
    audio_codec = audio_stream['codec_name']
    print(f"Audio: {audio_codec}, {sample_rate}Hz, {channels}ch")

Using ffprobe Directly

import subprocess
import json

def get_video_info(filepath: str) -> dict:
    """Get detailed video information using ffprobe."""
    cmd = [
        'ffprobe',
        '-v', 'quiet',
        '-print_format', 'json',
        '-show_format',
        '-show_streams',
        filepath
    ]
    result = subprocess.run(cmd, capture_output=True, text=True)
    return json.loads(result.stdout)

# Get specific field
def get_duration(filepath: str) -> float:
    """Get video duration in seconds."""
    cmd = [
        'ffprobe',
        '-v', 'error',
        '-show_entries', 'format=duration',
        '-of', 'default=noprint_wrappers=1:nokey=1',
        filepath
    ]
    result = subprocess.run(cmd, capture_output=True, text=True)
    return float(result.stdout.strip())

# Get frame count
def get_frame_count(filepath: str) -> int:
    """Get total frame count."""
    cmd = [
        'ffprobe',
        '-v', 'error',
        '-select_streams', 'v:0',
        '-count_frames',
        '-show_entries', 'stream=nb_read_frames',
        '-of', 'default=noprint_wrappers=1:nokey=1',
        filepath
    ]
    result = subprocess.run(cmd, capture_output=True, text=True)
    return int(result.stdout.strip())

Set Metadata

# Set video metadata
(
    ffmpeg
    .input('input.mp4')
    .output('output.mp4',
        c='copy',
        **{
            'metadata': 'title=My Video',
            'metadata:s:v:0': 'title=Video Track',
            'metadata:s:a:0': 'title=Audio Track',
        }
    )
    .overwrite_output()
    .run()
)

# Copy all metadata from another file
(
    ffmpeg
    .input('input.mp4')
    .output('output.mp4',
        c='copy',
        map_metadata=0
    )
    .overwrite_output()
    .run()
)

# Strip all metadata
(
    ffmpeg
    .input('input.mp4')
    .output('output.mp4',
        c='copy',
        map_metadata=-1
    )
    .overwrite_output()
    .run()
)

Thumbnail Generation

Single Thumbnail

# Extract frame at specific time
(
    ffmpeg
    .input('video.mp4', ss=10)  # Seek to 10 seconds
    .output('thumbnail.jpg',
        vframes=1,
        q=2  # Quality 1-31 (lower is better)
    )
    .overwrite_output()
    .run()
)

# Extract at percentage
import ffmpeg

probe = ffmpeg.probe('video.mp4')
duration = float(probe['format']['duration'])
timestamp = duration * 0.25  # 25% into video

(
    ffmpeg
    .input('video.mp4', ss=timestamp)
    .output('thumbnail.jpg', vframes=1)
    .overwrite_output()
    .run()
)

Multiple Thumbnails

# Extract every N seconds
(
    ffmpeg
    .input('video.mp4')
    .filter('fps', fps=1/10)  # 1 frame every 10 seconds
    .output('thumb_%04d.jpg', q=2)
    .overwrite_output()
    .run()
)

# Extract specific number of thumbnails
probe = ffmpeg.probe('video.mp4')
duration = float(probe['format']['duration'])
num_thumbnails = 10

(
    ffmpeg
    .input('video.mp4')
    .filter('fps', fps=num_thumbnails/duration)
    .output('thumb_%04d.jpg', q=2)
    .overwrite_output()
    .run()
)

# Create thumbnail grid/sprite sheet
(
    ffmpeg
    .input('video.mp4')
    .filter('fps', fps=1/5)
    .filter('scale', 160, -1)
    .filter('tile', '5x5')
    .output('sprite_%04d.jpg')
    .overwrite_output()
    .run()
)

PyAV (High Performance)

PyAV provides direct access to FFmpeg's libraries via Cython bindings, offering better performance for frame-level operations.

import av
import numpy as np

# Read video frames
def read_frames(filepath: str):
    """Generator yielding video frames as numpy arrays."""
    container = av.open(filepath)
    for frame in container.decode(video=0):
        yield frame.to_ndarray(format='rgb24')

# Process video frame by frame
with av.open('input.mp4') as input_container:
    with av.open('output.mp4', 'w') as output_container:
        # Create output stream matching input
        input_stream = input_container.streams.video[0]
        output_stream = output_container.add_stream('libx264', rate=input_stream.rate)
        output_stream.width = input_stream.width
        output_stream.height = input_stream.height
        output_stream.pix_fmt = 'yuv420p'

        for frame in input_container.decode(video=0):
            # Convert to numpy, process, convert back
            img = frame.to_ndarray(format='rgb24')
            # Process image...
            processed = av.VideoFrame.from_ndarray(img, format='rgb24')
            processed.pts = frame.pts

            # Encode and write
            for packet in output_stream.encode(processed):
                output_container.mux(packet)

        # Flush encoder
        for packet in output_stream.encode():
            output_container.mux(packet)

# Extract audio samples
with av.open('video.mp4') as container:
    audio_stream = container.streams.audio[0]
    for frame in container.decode(audio=0):
        # frame.to_ndarray() returns audio samples
        samples = frame.to_ndarray()
        # Shape: (channels, samples)

Subprocess Patterns

For full FFmpeg control when libraries don't support specific features.

import subprocess
from pathlib import Path
from typing import Optional

def run_ffmpeg(
    input_path: str,
    output_path: str,
    options: list[str],
    timeout: Optional[int] = None
) -> tuple[int, str, str]:
    """Run FFmpeg with proper error handling."""
    cmd = [
        'ffmpeg',
        '-y',  # Overwrite output
        '-i', input_path,
        *options,
        output_path
    ]

    result = subprocess.run(
        cmd,
        capture_output=True,
        text=True,
        timeout=timeout
    )

    return result.returncode, result.stdout, result.stderr

# Example usage
returncode, stdout, stderr = run_ffmpeg(
    'input.mp4',
    'output.mp4',
    ['-c:v', 'libx264', '-crf', '23', '-c:a', 'aac']
)

if returncode != 0:
    print(f"Error: {stderr}")

# Pipe frames to FFmpeg
def write_frames_to_video(
    frames: list[np.ndarray],
    output_path: str,
    fps: int = 30,
    width: int = 1920,
    height: int = 1080
):
    """Write numpy array frames to video file."""
    process = subprocess.Popen(
        [
            'ffmpeg',
            '-y',
            '-f', 'rawvideo',
            '-vcodec', 'rawvideo',
            '-s', f'{width}x{height}',
            '-pix_fmt', 'rgb24',
            '-r', str(fps),
            '-i', 'pipe:0',
            '-c:v', 'libx264',
            '-pix_fmt', 'yuv420p',
            '-crf', '18',
            output_path
        ],
        stdin=subprocess.PIPE,
        stderr=subprocess.PIPE
    )

    for frame in frames:
        process.stdin.write(frame.tobytes())

    process.stdin.close()
    process.wait()

    if process.returncode != 0:
        raise RuntimeError(f"FFmpeg error: {process.stderr.read().decode()}")

Common Patterns

Video to GIF

# Basic GIF
(
    ffmpeg
    .input('video.mp4', ss=0, t=5)
    .filter('fps', fps=10)
    .filter('scale', 480, -1)
    .output('output.gif')
    .overwrite_output()
    .run()
)

# High quality GIF with palette
# Step 1: Generate palette
(
    ffmpeg
    .input('video.mp4', ss=0, t=5)
    .filter('fps', fps=10)
    .filter('scale', 480, -1, flags='lanczos')
    .filter('palettegen')
    .output('palette.png')
    .overwrite_output()
    .run()
)

# Step 2: Use palette
input_video = ffmpeg.input('video.mp4', ss=0, t=5)
palette = ffmpeg.input('palette.png')
(
    ffmpeg
    .filter([input_video, palette], 'paletteuse')
    .filter('fps', fps=10)
    .filter('scale', 480, -1, flags='lanczos')
    .output('output.gif')
    .overwrite_output()
    .run()
)

Speed Change

# Speed up 2x (video and audio)
input_file = ffmpeg.input('input.mp4')
video = input_file.video.filter('setpts', '0.5*PTS')  # Halve presentation timestamps
audio = input_file.audio.filter('atempo', 2.0)        # Double audio speed
(
    ffmpeg
    .output(video, audio, 'output.mp4')
    .overwrite_output()
    .run()
)

# Slow down 0.5x
input_file = ffmpeg.input('input.mp4')
video = input_file.video.filter('setpts', '2*PTS')
audio = input_file.audio.filter('atempo', 0.5)
(
    ffmpeg
    .output(video, audio, 'output.mp4')
    .overwrite_output()
    .run()
)

# Speed change > 2x (chain atempo filters)
# atempo only supports 0.5 to 2.0
audio = input_file.audio.filter('atempo', 2.0).filter('atempo', 2.0)  # 4x speed

Picture-in-Picture

main = ffmpeg.input('main.mp4')
pip = ffmpeg.input('pip.mp4').filter('scale', 320, 180)

(
    ffmpeg
    .overlay(main, pip, x='main_w-overlay_w-10', y=10)
    .output('output.mp4', acodec='copy')
    .overwrite_output()
    .run()
)

Blur Detection / Quality Check

def check_blur(filepath: str) -> float:
    """Check video for blur using Laplacian variance."""
    import cv2
    import numpy as np

    cap = cv2.VideoCapture(filepath)
    blur_scores = []

    try:
        while cap.isOpened():
            ret, frame = cap.read()
            if not ret:
                break

            gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
            laplacian_var = cv2.Laplacian(gray, cv2.CV_64F).var()
            blur_scores.append(laplacian_var)
    finally:
        cap.release()

    return np.mean(blur_scores)  # Higher = sharper

Error Reference

Error	Cause	Solution
No such file or directory	Input file not found	Check path, use absolute paths
Invalid data found	Corrupt input or wrong format	Verify file integrity with ffprobe
Output file already exists	Missing -y flag	Use overwrite_output()
Avi: avisynth not found	Windows path issue	Use forward slashes
Unknown encoder	Codec not available	Install FFmpeg with codec support
Device or resource busy	File locked	Close other applications using file
Too many packets buffered	Stream sync issue	Add -max_muxing_queue_size 1024
No frame!	Empty input	Check input has video/audio streams

Performance Tips

1. Use stream copy when possible: -c copy avoids re-encoding
2. Use hardware acceleration: NVENC, QSV, VAAPI for encoding
3. Use PyAV for frame-level operations: 10-50x faster than ffmpeg-python for frame access
4. Avoid pipes for large files: Use temporary files instead
5. Use appropriate presets: ultrafast for real-time, slow for final output
6. Process in parallel: Split video and process chunks simultaneously
7. Match input/output formats: Reduces transcoding overhead

Additional Resources

• FFmpeg Documentation
• ffmpeg-python Examples
• PyAV Documentation
• FFmpeg Wiki
• FFmpeg Filters