# Reading option tables Canonical URL: https://encode.wiki/reference/encoder-parameters/ Content version: ca42e61ede0a24f789d7287a0001244ad22f4abf Status: current License: CC BY-SA 4.0 Checksum (SHA-256): 7a411c4a1947a1befb07a0e5ae92638c42d6b1a55dcb8f267899fb0bd0793198 Each encoder and image-format page ends with a **Full option reference**: every option of one named release, with its default and what it does. The practical guidance is at the top of each page; the tables are for looking up a specific flag. This page explains how to read them. ## Where the tables are | Area | Pages | | -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | AV1 encoders | [SVT-AV1](/tools/software-encoders/svt-av1/) and its forks ([HDR](/tools/software-encoders/svt-av1-hdr/), [PSY](/tools/software-encoders/svt-av1-psy/), [PSYEX](/tools/software-encoders/svt-av1-psyex/), [Essential](/tools/software-encoders/svt-av1-essential/), [5fish](/tools/software-encoders/svt-av1-5fish/)), [aomenc](/tools/software-encoders/aomenc/) and its forks ([AV1-lavish](/tools/software-encoders/aom-av1-lavish/), [aom-psy101](/tools/software-encoders/aom-psy101/)), [rav1e](/tools/software-encoders/rav1e/), [AVM](/tools/software-encoders/avm/) (AV2) | | Other video | [x264](/tools/software-encoders/x264/), [x265](/tools/software-encoders/x265/), [vpxenc](/tools/software-encoders/vpxenc/), [VVenC](/tools/software-encoders/vvenc/) | | Hardware | [NVENC](/tools/hardware-encoders/nvenc/), [QSV](/tools/hardware-encoders/qsv/), [AMF](/tools/hardware-encoders/amf/), [VAAPI](/tools/hardware-encoders/vaapi/), [Vulkan](/tools/hardware-encoders/vulkan/), [MediaCodec](/tools/hardware-encoders/mediacodec/) (FFmpeg wrapper options) | | Audio | [Opus](/codecs/audio/opus/) (`opusenc`, `libopus`), [AAC](/codecs/audio/aac/) (FFmpeg `aac`, `libfdk_aac`, `fdkaac`), [qaac](/tools/software-encoders/qaac/), [exhale](/tools/software-encoders/exhale/) | | Images | [AVIF](/codecs/images/avif/), [HEIC](/codecs/images/heic/), [JPEG XL](/codecs/images/jxl/), [WebP](/codecs/images/webp/), [JPEG](/codecs/images/jpeg/), [JPEG 2000](/codecs/images/jpeg2000/), [PNG](/codecs/images/png/), [GIF](/codecs/images/gif/), [QOI](/codecs/images/qoi/) | | Pipeline tools | [FFmpeg](/tools/utilities/ffmpeg/), [Av1an](/tools/utilities/av1an/), [MKVToolNix](/tools/utilities/mkvtoolnix/), [MP4Box](/tools/utilities/mp4box/), [dav1d](/tools/utilities/dav1d/), [dovi_tool](/tools/utilities/dovi_tool/), [hdr10plus_tool](/tools/utilities/hdr10plus_tool/) — the options that matter, not full inventories | Commercial SDKs such as [Eve-AV1](/tools/software-encoders/eve-av1/) and [Aurora1](/tools/software-encoders/aurora1/) publish no option reference. A table covers one interface at one release. `aomenc`, `SvtAv1EncApp`, FFmpeg's `libsvtav1` wrapper and a GPU driver accept different flags with different defaults, and a fork can change both, so check the version named above the table against the one you run. ## What the Default column means The Default column says what happens when you **omit** the option. | Default shown | Meaning | | ------------------------- | -------------------------------------------------------------------------------------------------------------------------- | | A value | The interface uses this value unless you override it. | | Automatic / sentinel | A value is chosen later from the input, preset or hardware. `-1`, `0` and `auto` mean different things in different tools. | | Preset- or tune-dependent | The preset or tune sets it; the row gives the value for the default preset where it matters. | | Input- or mode-dependent | Picture size, channel count, sample rate or rate-control mode changes it. | | Unset | Nothing is passed, so the library's own behaviour applies. Not the same as zero. | | Required | You must supply it. | A displayed range can include sentinel values, so read the description before using an endpoint: `0` often means "automatic" rather than "minimum". An option with an optional value can behave differently when written bare — Gifsicle's omitted `--lossy` is 0, a bare `--lossy` means 20. Quality scales are private to each encoder: CRF 30 in x264, SVT-AV1 and libvpx are three unrelated settings, and "quality 90" in two image encoders are not comparable. ## FFmpeg options that apply to every encoder `ffmpeg -h encoder=` lists only an encoder wrapper's private options. These generic options apply to every encoder and are not repeated in the per-encoder tables: | Option | What it sets | | ----------------------------------------------- | ---------------------------------------------------------------------------------------------------- | | `-b:v`, `-b:a` | Target bitrate in bits/s (`5M`, `160k`). | | `-maxrate`, `-minrate`, `-bufsize` | Rate-control limits in bits/s and the VBV buffer in bits, for encoders and modes that honour them. | | `-g`, `-bf`, `-refs` | Maximum GOP length in frames, consecutive B-frames and reference frames. | | `-q:v`, `-global_quality`, `-crf`, `-cq`, `-qp` | Quality controls. Which one an encoder uses, and its scale, is encoder-specific. | | `-preset`, `-tune`, `-profile:v`, `-level:v` | Encoder-specific names. A profile or level constrains compatibility; it is not a quality setting. | | `-pix_fmt`, `-ar`, `-ac` | Pixel format, audio sample rate in Hz and channel count. Setting them converts if the input differs. | | `-threads` | Requested threads; encoders may cap or ignore it. | Use stream specifiers (`-b:v:0`, `-c:a:1`) when an option could match several streams. Library pass-through strings such as `-svtav1-params`, `-x264-params` and `-x265-params` use the library's own `key=value:key=value` syntax, not the standalone command-line spelling.