liminfoVideo Convert
Free reference guide: Video Convert
About Video Convert
The Video Convert Reference is a searchable cheat sheet of ffmpeg commands for video codec transcoding, container remuxing, resolution scaling, bitrate control, audio extraction, and hardware-accelerated encoding. It covers the five major video codecs (H.264/AVC, H.265/HEVC, VP9, AV1, ProRes), four container formats (MP4, MKV, WebM, MOV), and practical conversion recipes such as MKV to MP4 remux, GIF to MP4, MP4 to GIF with palette generation, and H.264 to H.265 re-compression.
Each entry includes the exact ffmpeg command-line syntax with flags like -crf for constant rate factor encoding, -preset for speed/quality tradeoffs, -movflags +faststart for streaming optimization, and -tag:v hvc1 for Apple HEVC compatibility. Audio codec entries cover AAC, Opus, and AC3 (Dolby Digital) with recommended bitrate tiers for voice, music, and surround sound. Hardware acceleration entries provide ready-to-use commands for NVIDIA NVENC, Intel Quick Sync Video (QSV), and Apple VideoToolbox.
The reference is organized into six categories — Codecs, Containers, Conversions, Settings, Audio, and Hardware Acceleration — with full bilingual Korean/English content. It runs entirely in the browser as a filterable, searchable RefTool component with syntax highlighting for bash. No software installation, account registration, or ffmpeg expertise is needed to look up commands.
Key Features
- Complete ffmpeg commands for H.264, H.265, VP9, AV1, and ProRes with CRF/preset/profile options
- Container format guide for MP4, MKV, WebM, and MOV with pros/cons and codec compatibility
- Step-by-step conversion recipes: MKV to MP4, GIF to MP4, MP4 to GIF, MP4 to WebM, H.264 to H.265
- Resolution scaling, bitrate tables (4K/1080p/720p/480p), frame rate, trimming, and cropping commands
- Audio codec reference: AAC bitrate tiers, Opus low-bitrate efficiency, AC3 5.1 surround setup
- Audio extraction to MP3 (320k), WAV (lossless), and FLAC with exact ffmpeg flags
- Hardware encoding commands for NVIDIA NVENC, Intel QSV, and Apple VideoToolbox (H.264 + H.265)
- Searchable, filterable interface with bash syntax highlighting and bilingual Korean/English content
Frequently Asked Questions
What CRF value should I use for H.264 encoding?
CRF (Constant Rate Factor) ranges from 0 (lossless) to 51 (lowest quality). For visually transparent quality, use CRF 18. The default CRF 23 offers a good balance between quality and file size. CRF 28 produces noticeably smaller files with some quality loss. Each increment of 6 roughly halves or doubles the file size.
How do I convert MKV to MP4 without re-encoding?
Use ffmpeg -i input.mkv -c copy output.mp4 to remux the MKV container into MP4 without re-encoding the audio or video streams. This is nearly instant because only the container metadata changes. It works only if the MKV contains MP4-compatible codecs (e.g., H.264 video + AAC audio).
What is the difference between H.264 and H.265?
H.265 (HEVC) achieves approximately 50% better compression than H.264 (AVC) at the same visual quality, meaning the same video can be stored in roughly half the file size. However, H.265 encoding is slower and has less universal device/browser support. H.264 remains the safest choice for maximum compatibility.
How do I create a high-quality GIF from a video?
Use the two-pass palette method: first generate a palette with ffmpeg palettegen filter (fps=15, scale=480:-1, lanczos), then apply it with paletteuse. This produces GIFs with far better color accuracy than the default single-pass method, which is limited to a global 256-color palette.
What is the -movflags +faststart option?
The +faststart flag moves the MP4 moov atom (metadata) to the beginning of the file. Without it, the moov atom is at the end, requiring the entire file to be downloaded before playback can begin. For web streaming or progressive download, always include -movflags +faststart.
How much faster is NVIDIA NVENC compared to software encoding?
NVENC hardware encoding is typically 10-20x faster than libx264/libx265 software encoding. The tradeoff is a slight reduction in compression efficiency at the same quality target. NVENC uses -cq instead of -crf for quality targeting, and preset p7 corresponds to the highest quality preset.
When should I use VP9 or AV1 instead of H.264/H.265?
VP9 is ideal for WebM containers and web delivery (YouTube uses VP9 extensively). AV1 offers approximately 30% better compression than HEVC but encodes very slowly. Use VP9 for web-first content with good browser support; use AV1 when encoding time is not a constraint and maximum compression is the priority.
How do I extract audio from a video file?
Use ffmpeg -i input.mp4 -vn -c:a libmp3lame -b:a 320k output.mp3 for MP3, or replace the audio codec with pcm_s16le for lossless WAV, or flac for lossless compressed FLAC. The -vn flag disables video stream copying, and -b:a sets the audio bitrate.