The encoder parameters are listed in this table below along with their
status of support, command line parameter and the range of values that
the parameters can take. Any of the parameters below that have a non-empty
Configuration file parameter field, can be set by adding them to the
Sample.cfg file.
| Configuration file parameter | Command line | Range | Default | Description |
|---|---|---|---|---|
| --help | Shows the command line options currently available | |||
| --color-help | Reproduces Appendix A.2 of the SVT-AV1 User Guide for AV1 metadata | |||
| --version | Shows the version of the library that's linked to the library | |||
| InputFile | -i | any string | None | Input raw video (y4m and yuv) file path, use stdin or - to read from pipe |
| StreamFile | -b | any string | None | Output compressed file path, use stdout or - to write to pipe. Format is auto-detected from extension (.ivf or .obu), default is IVF |
| --ivf | Output bitstream in IVF container format (default) | |||
| --obu | Output bitstream as raw OBU (Open Bitstream Units) without IVF container | |||
| -c | any string | None | Configuration file path | |
| ErrorFile | --errlog | any string | stderr |
Error file path |
| ReconFile | -o | any string | None | Reconstructed yuv file path |
| StatFile | --stat-file | any string | None | PSNR / SSIM per picture stat output file path, requires --enable-stat-report 1 |
| Progress | --progress | [0-2] | 1 | Verbosity of the output [0: no progress is printed, 1: default output, 2: detailed output] |
| NoProgress | --no-progress | [0-1] | 0 | Do not print out progress [1: --progress 0, 0: --progress 1] |
| EncoderMode | --preset | [-1-13] | 8 | Encoder preset, presets < 0 are for debugging. Higher presets means faster encodes, but with a quality tradeoff |
| SvtAv1Params | --svtav1-params | any string | None | Colon-separated list of key=value pairs of parameters with keys based on command line options without -- |
To use the --svtav1-params option, the syntax is --svtav1-params option1=value1:option2=value2....
An example is:
SvtAv1EncApp \
-i input.y4m \
-b output.ivf \
--svtav1-params \
"preset=10:crf=30:irefresh-type=kf:matrix-coefficients=bt709:mastering-display=G(0.2649,0.6900)B(0.1500,0.0600)R(0.6800,0.3200)WP(0.3127,0.3290)L(1000.0,1)"This will set --preset to 10 and --crf to 30 inside the API along with some other parameters.
Do note however, that there is no error checking for duplicate keys and only for invalid keys or values.
For more information on valid values for specific keys, refer to the EbEncSettings file.
| Configuration file parameter | Command line | Range | Default | Description |
|---|---|---|---|---|
| SourceWidth | -w | [4-16384] | None | Frame width in pixels, inferred if y4m. |
| SourceHeight | -h | [4-8704] | None | Frame height in pixels, inferred if y4m. |
| ForcedMaximumFrameWidth | --forced-max-frame-width | [4-16384] | None | Maximum frame width value to force. |
| ForcedMaximumFrameheight | --forced-max-frame-height | [4-8704] | None | Maximum frame height value to force. |
| FrameToBeEncoded | -n | [0-(2^63)-1] |
0 | Number of frames to encode. If n is larger than the input, the encoder will loop back and continue encoding |
| FrameToBeSkipped | --skip | [0-(2^63)-1] |
0 | Number of frames to skip. |
| BufferedInput | --nb | [-1, 1-(2^31)-1] |
-1 | Buffer n input frames into memory and use them to encode. Only buffered frames will be encoded. |
| EncoderColorFormat | --color-format | [0-3] | 1 | Color format, only yuv420 is supported at this time [0: yuv400, 1: yuv420, 2: yuv422, 3: yuv444] |
| Profile | --profile | [0-2] | 0 | Bitstream profile [0: main, 1: high, 2: professional] |
| Level | --level | [0,2.0-7.3] | 0 | Bitstream level, defined in A.3 of the av1 spec [0: auto] |
| FrameRateNumerator | --fps-num | [0-2^32-1] | 60000 | Input video frame rate numerator |
| FrameRateDenominator | --fps-denom | [0-2^32-1] | 1000 | Input video frame rate denominator |
| EncoderBitDepth | --input-depth | [8, 10] | 8 | Input video file and output bitstream bit-depth |
| Injector | --inj | [0-1] | 0 | Inject pictures to the library at defined frame rate |
| InjectorFrameRate | --inj-frm-rt | [0-240] | 60 | Set injector frame rate, only applicable with --inj 1 |
| StatReport | --enable-stat-report | [0-1] | 0 | Calculates and outputs PSNR SSIM metrics at the end of encoding |
| Asm | --asm | [0-11, c-max] | max | Limit assembly instruction set [c, mmx, sse, sse2, sse3, ssse3, sse4_1, sse4_2, avx, avx2, avx512, avx512icl, max] for x86 platforms, [c, neon, crc32, neon_dotprod, neon_i8mm, sve, sve2] for Arm platforms. |
| LevelOfParallelism | --lp | [0, 6] | 0 | Controls the number of threads to create and the number of picture buffers to allocate (higher level means more parallelism). 0 means choose level based on machine core count. Refer to Appendix A.1 |
| FastDecode | --fast-decode | [0,2] | 0 | Tune settings to output bitstreams that can be decoded faster, [0 = OFF, 1,2 = levels for decode-targeted optimization (2 yields faster decoder speed)]. Defaults to 5 temporal layers structure but may override with --hierarchical-levels |
| Tune | --tune | [0-5] | 1 | Optimize the encoding process for different desired outcomes [0 = VQ (video and still image), 1 = PSNR (video and still image), 2 = SSIM (video and still image), 3 = IQ (still image only), 4 = MS-SSIM (video and still image), 5 = VMAF (video only)] |
| AdaptiveFilmGrain | --adaptive-film-grain | [0,1] | 1 | Allows film grain synthesis to be sourced from different block sizes depending on resolution |
| MaxTxSize | --max-tx-size | [32,64] | 64 | Restricts use of block transform sizes to the specified value |
| Configuration file parameter | Command line | Range | Default | Description |
|---|---|---|---|---|
| RateControlMode | --rc | [0-2] | 0 | Rate control mode [0: CRF or CQP (if --aq-mode is 0) [Default], 1: VBR, 2: CBR] |
| QP | --qp | [1-63] | 35 | Initial QP level value |
| CRF | --crf | [1-70] | 35 | Constant Rate Factor value, setting this value is similar to --rc 0 --aq-mode 2 --qp x. Compared to --qp, --crf can take a value up to 70, and can be set in 0.25 increments |
| CQP | --cqp | [1-70] | 35 | Constant Quality value, setting this value is similar to --rc 0 --aq-mode 0 --qp x. Compared to --qp, --cqp can take a value up to 70, and can be set in 0.25 increments |
| TargetBitRate | --tbr | [1-100000] | 2000 | Target Bitrate (kbps), only applicable for VBR and CBR encoding, also accepts b, k, and m suffixes |
| MaxBitRate | --mbr | [1-100000] | 0 | Maximum Bitrate (kbps) only applicable for CRF encoding, also accepts b, k, and m suffixes |
| UseQpFile | --use-q-file | [0-1] | 0 | Overwrite the encoder default picture based QP assignments and use QP values from --qp-file |
| QpFile | --qpfile | any string | Null | Path to a file containing per picture QP value |
| MaxQpAllowed | --max-qp | [0-63] | 63 | Maximum quantizer (lowest quality) |
| MinQpAllowed | --min-qp | [0-63] | 0 | Minimum quantizer (highest quality) |
| EnableVarianceBoost | --enable-variance-boost | [0-1] | 0 | Enable Variance Boost |
| VarianceBoostStrength | --variance-boost-strength | [1-4] | 2 | Set variance curve strength for Variance Boost feature [1: mild, 2: gentle [Default], 3: medium, 4: aggressive] |
| VarianceOctile | --variance-octile | [1-8] | 5 | Set variance algorithm 8x8 block selectivity level [1: 1st octile, 4: median, 5: 5th octile [Default], 8: maximum] |
| AdaptiveQuantization | --aq-mode | [0-2] | 2 | Set adaptive QP level [0: off, 1: variance base using AV1 segments, 2: deltaq pred efficiency] |
| HBDMDS | --hbd-mds | [-1-2] | -1 | Activation of high bit depth mode decisions; 10-bit MD only works with 10-bit inputs (-1: default preset behavior, 0: full 8b MD 1: full 10b MD, 2: hybrid 8/10b MD) |
| QpScaleCompressStrength | --qp-scale-compress-strength | [0-3] | 0 | Sets the strength the QP scale algorithm compresses values across all temporal layers, which results in more consistent video quality (less quality variation across frames in a mini-gop) |
| AcBias | --ac-bias | [0.0-8.0] | 0.0 | Sets the strength of the internal RD metric to bias toward high-frequency error (helps with texture preservation and film grain retention) |
| UseFixedQIndexOffsets | --use-fixed-qindex-offsets | [0-2] | 0 | Overwrite the encoder default hierarchical layer based QP assignment and use fixed Q index offsets |
| KeyFrameQIndexOffset | --key-frame-qindex-offset | [-64-63] | 0 | Overwrite the encoder default keyframe Q index assignment |
| KeyFrameChromaQIndexOffset | --key-frame-chroma-qindex-offset | [-64-63] | 0 | Overwrite the encoder default chroma keyframe Q index assignment |
| LumaYDCQindexOffset | --luma-y-dc-qindex-offset | [-64-63] | 0 | Overwrite the encoder default dc Q index offset for luma plane |
| ChromaUDCQindexOffset | --chroma-u-dc-qindex-offset | [-64-63] | 0 | Overwrite the encoder default dc Q index offset for chroma Cb plane |
| ChromaUACQindexOffset | --chroma-u-ac-qindex-offset | [-64-63] | 0 | Overwrite the encoder default ac Q index offset for chroma Cb plane |
| ChromaVDCQindexOffset | --chroma-v-dc-qindex-offset | [-64-63] | 0 | Overwrite the encoder default dc Q index offset for chroma Cr plane |
| ChromaVACQindexOffset | --chroma-v-ac-qindex-offset | [-64-63] | 0 | Overwrite the encoder default ac Q index offset for chroma Cr plane |
| QIndexOffsets | --qindex-offsets | any string | 0,0,..,0 |
list of luma Q index offsets per hierarchical layer, separated by , with each offset in the range of [-64-63] |
| ChromaQIndexOffsets | --chroma-qindex-offsets | any string | 0,0,..,0 |
list of chroma Q index offsets per hierarchical layer, separated by , with each offset in the range of [-64-63] |
| StartupGopQpOffset | --startup-qp-offset | [-63-63] | 0 | Start-up GOP QP offset; will be added to the sequence-QP before deriving the picture-QP |
| UnderShootPct | --undershoot-pct | [0-100] | 25, 50 | Allowable datarate undershoot (min) target (%), default depends on the rate control mode (25 for CBR, 50 for VBR) |
| OverShootPct | --overshoot-pct | [0-100] | 25 | Allowable datarate overshoot (max) target (%), default depends on the rate control mode |
| MbrOverShootPct | --mbr-overshoot-pct | [0-100] | 50 | Allowable datarate overshoot (max) target (%), Only applicable for Capped CRF |
| BufSz | --buf-sz | [20-10000] | 1000 | Client maximum buffer size (ms), only applicable for CBR |
| BufInitialSz | --buf-initial-sz | [20-10000] | 600 | Client initial buffer size (ms), only applicable for CBR |
| BufOptimalSz | --buf-optimal-sz | [20-10000] | 600 | Client optimal buffer size (ms), only applicable for CBR |
| RecodeLoop | --recode-loop | [0-4] | 4 | Recode loop level, look at the "Recode loop level table" in the user's guide for more info [0: off, 4: preset based] |
| MinSectionPct | --minsection-pct | [0-100] | 0 | GOP min bitrate (expressed as a percentage of the target rate) |
| MaxSectionPct | --maxsection-pct | [0-10000] | 2000 | GOP max bitrate (expressed as a percentage of the target rate) |
| GopConstraintRc | --gop-constraint-rc | [0-1] | 0 | Constrains the rate control to match the target rate for each GoP [0 = OFF, 1 = ON] |
| EnableQM | --enable-qm | [0-1] | 0 | Enable quantisation matrices |
| MinQmLevel | --qm-min | [0-15] | 8 | Min quant matrix flatness |
| MaxQmLevel | --qm-max | [0-15] | 15 | Max quant matrix flatness |
| MinChromaQmLevel | --chroma-qm-min | [0-15] | 8 | Min chroma quant matrix flatness |
| MaxChromaQmLevel | --chroma-qm-max | [0-15] | 15 | Max chroma quant matrix flatness |
| LambdaScaleFactors | --lambda-scale-factors | [0- ] | '128,.,128' | list of scale factors for lambda values used for different SvtAv1FrameUpdateType, separated by , divide by 128 is the actual scale factor in float |
| RoiMapFile | --roi-map-file | any string | Null | Path to a file containing picture based QP offset map |
| TemporalFilteringStrength | --tf-strength | [0-4] | 3 | Manually adjust temporal filtering strength. Higher values = stronger temporal filtering |
| LuminanceQpBias | --luminance-qp-bias | [0-100] | 0 | Adjusts a frame's QP based on its average luma value |
| Sharpness | --sharpness | [-7-7] | 0 | Bias towards decreased/increased sharpness |
UseFixedQIndexOffsets and its associated arguments (HierarchicalLevels,
QIndexOffsets, ChromaQIndexOffsets, KeyFrameQIndexOffset,
KeyFrameChromaQIndexOffset) are used together to specify the qindex offsets
based on frame type and temporal layer when rc is set to 0.
QP value specified by the --qp argument is assigned to the pictures at the
highest temporal layer. It is first converted to a qindex, then the
corresponding qindex offsets are added on top of it based on the frame types
(Key/Inter) and temporal layer id.
Qindex offset can be negative. The final qindex value will be clamped within the valid min/max qindex range.
For chroma plane, after deciding the qindex for the luma plane, the corresponding chroma qindex offsets are added on top of the luma plane qindex based on frame types and temporal layer id.
--qindex-offsets and --chroma-qindex-offsets have to be used after the
--hierarchical-levels parameter. The number of qindex offsets should be
HierarchicalLevels plus 1, and they can be enclosed in [] to separate the
list.
An example command line is:
SvtAv1EncApp -i in.y4m -b out.ivf --rc 0 -q 42 --hierarchical-levels 3 --use-fixed-qindex-offsets 1 --qindex-offsets [-12,-8,-4,0] --key-frame-qindex-offset -20 --key-frame-chroma-qindex-offset -6 --chroma-qindex-offsets [-6,0,12,24]For this command line, corresponding qindex values are:
| Frame Type | Luma qindex | Chroma qindex |
|---|---|---|
| Key Frame | 148 (42x4 - 20) | 142 (148 - 6) |
| Layer0 Frame | 156 (42x4 - 12) | 150 (156 - 6) |
| Layer1 Frame | 160 (42x4 - 8) | 160 (160 + 0) |
| Layer2 Frame | 164 (42x4 - 4) | 176 (164 + 12) |
| Layer3 Frame | 168 (42x4 + 0) | 192 (168 + 24) |
With EnableQM, MinQmLevel and MaxQmLevel, user can customize the quantization
matrix used in luma quantization procedure (MinChromaQmLevel & MaxChromaQmLevel for chroma control)
instead of using the default one. With the default quantization matrix, all coefficients share the
same weight, whereas with non-default ones, coefficients can have different weight throughMore actions
the settings made by users. The deviation of weight (or flatness, equivalently)
is controlled by arguments MinQmLevel and MaxQmLevel. There are sixteen quantization matrix levels,
ranging from level 0 to level 15. The lower the level is the larger deviation of weight the
quantization matrix will provide. Level 15 is fully flat in weight and is set as the default
quantization matrix. A lower level quantization matrix typically results in bitstreams with
lower bitrate and slightly worse quality in CRF rate control mode. The reduction in bitrate is more
obvious with low CRF than high CRF.
The quantization matrices feature signals at frame level. When the feature is enabled,
the encoder decides each frame’s quantization matrix level by normalizing its qindex to
user specified quantization matrix level range (from MinQmLevel to MaxQmLevel).
An example command line is:
SvtAv1EncApp -i in.y4m -b out.ivf --keyint -1 --enable-qm 1 --qm-min 0 --qm-max 15Another example with chroma QM min/max specified:
SvtAv1EncApp -i in.y4m -b out.ivf --keyint -1 --enable-qm 1 --qm-min 0 --qm-max 15 --chroma-qm-min 4 --chroma-qm-max 8| level | description |
|---|---|
| 0 | Off |
| 1 | Allow recode for KF and exceeding maximum frame bandwidth |
| 2 | Allow recode only for key frames, alternate reference frames, and Golden frames |
| 3 | Allow recode for all frame types based on bitrate constraints |
| 4 | Preset based decision |
In some applications such as AR / VR, identifying the ROI (Region Of Interest) helps the encoder focus the bit usage where it's needed. This is realized by allowing applications to pass a picture based ROI map to the encoder.
The QP Offset Map file contains one or more picture based QP offset maps. Every line consists of a frame number and the QP offsets for each 64x64 block set in a row-by-row order. Below is an example ROI map file for a 352x288 content:
0 12 -32 -32 -32 -32 -32 12 -32 -32 -32 -32 -32 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16The encoder uses alternate quantizer segment feature to set block level qindex and uses alternate loop filter segment feature to set loop filter strength level. When both AQ mode 1 (variance base adaptive QP) and ROI are enabled, segment QP is decided by ROI map instead of by variance.
An example command line is:
SvtAv1EncApp -i in.y4m -b out.ivf --roi-map-file roi_map.txt| Configuration file parameter | Command line | Range | Default | Description |
|---|---|---|---|---|
| Pass | --pass | [0-2] | 0 | Multi-pass selection [0: single pass encode, 1: first pass, 2: second pass] |
| Stats | --stats | any string | "svtav1_2pass.log" | Filename for multi-pass encoding |
| Passes | --passes | [1-2] | 1 | Number of encoding passes, default is preset dependent [1: one pass encode, 2: multi-pass encode] |
| Pass | Stats io |
|---|---|
| 0 | "" |
| 1 | "w" |
| 2 | "r" |
--pass 2 is only available for non-crf modes and all passes except single-pass requires the --stats parameter to point to a valid path
| Configuration file parameter | Command line | Range | Default | Description |
|---|---|---|---|---|
| Keyint | --keyint | [-2-(2^31)-1] |
-2 | GOP size (frames), use s suffix for seconds (SvtAv1EncApp only) [-2: ~5 seconds, -1: "infinite" only for CRF, 0: == -1] |
| IntraRefreshType | --irefresh-type | [1-2] | 2 | Intra refresh type [1: FWD Frame (Open GOP), 2: KEY Frame (Closed GOP)] |
| SceneChangeDetection | --scd | [0-1] | 0 | Scene change detection control |
| Lookahead | --lookahead | [-1,0-120] | -1 | Number of frames in the future to look ahead, beyond minigop, temporal filtering, and rate control [-1: auto] |
| HierarchicalLevels | --hierarchical-levels | [2-5] | <=M12:5 , else: 4 | Set hierarchical levels beyond the base layer [2: 3 temporal layers, 3: 4 temporal layers, 5: 6 temporal layers] |
| PredStructure | --pred-struct | [0-2] | 2 | Set prediction structure [0: all intra, 1: low delay, 2: random access] |
| ForceKeyFrames | --force-key-frames | any string | None | Force key frames at the comma separated specifiers. #f for frames, #.#s for seconds |
| EnableDg | --enable-dg | [0-1] | 1 | Enable Dynamic GoP. The algorithm changes the hierarchical structure based on the content |
| StartupMgSize | --startup-mg-size | [0, 2, 3, 4] | 0 | Specify another mini-gop configuration for the first mini-gop after the key-frame [0: OFF, 2: 3 temporal layers, 3: 4 temporal layers, 4: 5 temporal layers] |
| RealTime | --rtc | [0-1] | 0 | Enables fast settings for real-time communication when using low-delay mode. Forces low-delay pred struct to be used. |
| Configuration file parameter | Command line | Range | Default | Description |
|---|---|---|---|---|
| TileRow | --tile-rows | [0-6] | 0 | Number of tile rows to use, TileRow == log2(x), default changes per resolution |
| TileCol | --tile-columns | [0-4] | 0 | Number of tile columns to use, TileCol == log2(x), default changes per resolution |
| LoopFilterEnable | --enable-dlf | [0-2] | 1 | Deblocking loop filter control (1: enabled, 2: slower, more accurate filtering) |
| CDEFLevel | --enable-cdef | [0-1] | 1 | Enable Constrained Directional Enhancement Filter |
| EnableRestoration | --enable-restoration | [0-1] | 1 | Enable loop restoration filter |
| Mfmv | --enable-mfmv | [-1-1] | -1 | Motion Field Motion Vector control [-1: auto] |
| EnableTF | --enable-tf | [0-2] | 1 | Enable ALT-REF (temporally filtered) frames [0: off, 1: on, 2: adaptive] |
| EnableTfKey | --enable-kf-tf | [0-1] | 1 | Enable MCTF for key frames [0: off, 1: on] |
| EnableOverlays | --enable-overlays | [0-1] | 0 | Enable the insertion of overlayer pictures which will be used as an additional reference frame for the base layer picture |
| ScreenContentMode | --scm | [0-3] | 2 | Set screen content detection level [0: None, 1: Block Copy + Palette, 2: content adaptive, 3: content adaptive (anti-alias aware)] |
| EnableIntraBC | --enable-intrabc | [0-1] | 1 | Enable Intra Block Copy [0: off, 1: on (preset-based)] |
| FilmGrain | --film-grain | [0-50] | 0 | Enable film grain [0: off, 1-50: level of denoising for film grain] |
| FilmGrainDenoise | --film-grain-denoise | [0-1] | 0 | Apply denoising when film grain is ON, default is 0 [0: no denoising, film grain data sent in frame header, 1: level of denoising is set by the film-grain parameter] |
| FGSTable | --fgs-table | any string | None | Path to a file containing a pre-generated film grain table for grain synthesis, only available through SvtAv1Enc interface |
| SuperresMode | --superres-mode | [0-4] | 0 | Enable super-resolution mode, refer to the super-resolution section below for more info |
| SuperresDenom | --superres-denom | [8-16] | 8 | Super-resolution denominator, only applicable for mode == 1 [8: no scaling, 16: half-scaling] |
| SuperresKfDenom | --superres-kf-denom | [8-16] | 8 | Super-resolution denominator for key frames, only applicable for mode == 1 [8: no scaling, 16: half-scaling] |
| SuperresQthres | --superres-qthres | [0-63] | 43 | Super-resolution q-threshold, only applicable for mode == 3 |
| SuperresKfQthres | --superres-kf-qthres | [0-63] | 43 | Super-resolution q-threshold for key frames, only applicable for mode == 3 |
| SframeInterval | --sframe-dist | [0-(2^31)-1] |
0 | S-Frame interval (frames) [0: OFF, > 0: ON] |
| SframeMode | --sframe-mode | [1-4] | 2 | S-Frame insertion mode [1: the considered frame will be made into an S-Frame only if it is an altref frame, 2: the next altref frame will be made into an S-Frame， 3: adjust minigop size to make an S-Frame at specific position, 4. adjust minigop size to make an S-Frame inserting at specific position in decode order] |
| SframePositions | --sframe-posi | any string | None | S-Frame insertion positions, a list separated by ',', S-Frame process inserts by the specified frame numbers (0 based), only applicable for mode 3 and mode 4 |
| SframeQPs | --sframe-qp | any string | None | S-Frame setup QP, a list separated by ',', QP value(s) set with S-Frame insertion, with each QP in the range of [1-63]. If only one QP value is set, this QP is applied to all S-Frames |
| SframeQPOffsets | --sframe-qp-offset | any string | None | S-Frame setup QP offset, a list separated by ',', QP offset value(s) set with S-Frame insertion, with each QP offset value in the range of [-63-63]. If only one QP offset value is set, this QP offset is applied to all S-Frames |
| ResizeMode | --resize-mode | [0-4] | 0 | Enable reference scaling mode |
| ResizeDenom | --resize-denom | [8-16] | 8 | Reference scaling denominator, only applicable for mode == 1 [8: no scaling, 16: half-scaling] |
| ResizeKfDenom | --resize-kf-denom | [8-16] | 8 | Reference scaling denominator for key frames, only applicable for mode == 1 [8: no scaling, 16: half-scaling] |
| ResizeFrameEvents | --frame-resz-events | any string | None | Frame scale events, in a list separated by ',', scaling process starts from the given frame number (0 based) with new denominators, only applicable for mode == 4 |
| ResizeFrameKfDenoms | --frame-resz-kf-denoms | [8-16] | 8 | Frame scale denominator for key frames in event, in a list separated by ',', only applicable for mode == 4 |
| ResizeFrameDenoms | --frame-resz-denoms | [8-16] | 8 | Frame scale denominator in event, in a list separated by ',', only applicable for mode == 4 |
| Avif | --avif | [0-1] | 0 | Enable still-picture coding optimizations for improved coding efficiency and reduced memory usage |
Super resolution is better described in the Super-Resolution documentation, but this basically allows the input to be encoded at a lower resolution, horizontally, but then later upscaled back to the original resolution by the decoder.
| SuperresMode | Value |
|---|---|
| 0 | None, no frame super-resolution allowed |
| 1 | All frames are encoded at the specified scale of 8/denom, thus a denom of 8 means no scaling, and 16 means half-scaling |
| 2 | All frames are coded at a random scale |
| 3 | Super-resolution scale for a frame is determined based on the q_index, a qthreshold of 63 means no scaling |
| 4 | Automatically select the super-resolution mode for appropriate frames |
The performance of the encoder will be affected for all modes other than mode 0. And for mode 4, it should be noted that the encoder will run at least twice, one for down scaling, and another with no scaling, and then it will choose the best one for each of the appropriate frames.
For more information on the decision-making process, please look at section 2.2 of the super-resolution doc
Reference Scaling is better described in the reference scaling documentation, but this basically allows the input to be encoded and the output at a lower resolution, scaling ratio applys on both horizontally and vertically.
| ResizeMode | Value |
|---|---|
| 0 | None, no frame resize allowed |
| 1 | Fixed mode, all frames are encoded at the specified scale of 8/denom, thus a denom of 8 means no scaling, and 16 means half-scaling |
| 2 | Random mode, all frames are coded at a random scale, the scaling denom can be picked from 8 to 16 |
| 3 | Dynamic mode, scale for a frame is determined based on buffer level and average qp in rate control, scaling ratio can be 3/4 or 1/2. This mode can only work in 1-pass CBR low-delay mode |
| 4 | Random access mode, scaling is controlled by scale events, which determine scaling in a specified scaling denom or recover to original resolution |
Example CLI of reference scaling dynamic mode:
-i input.yuv -b output.ivf --resize-mode 3 --rc 2 --pred-struct 1 --tbr 1000
Example CLI of reference scaling random access mode:
-i input.yuv -b output.ivf --resize-mode 4 --frame-resz-events 5,10,15,20,25,30 --frame-resz-kf-denoms 8,9,10,11,12,13 --frame-resz-denoms 16,15,14,13,12,11
--frame-resz-events,--frame-resz-kf-denomsand--frame-resz-denomsshall be all set in same amount of parameters in list
The --force-key-frames option is meant to allow the non-uniform placement of key frames within the stream. While this option is currently supported only for the CRF mode via the commandline, using it within the CBR mode
can be achieved by passing the command of inserting a keyframe through the API field EbAv1PictureType pic_type; in the EbBufferHeaderType structure. A sample programming usage of this option can be found in the sample application file EbAppProcessCmd.c
tracking the FTR_KF_ON_FLY_SAMPLE macro defined in EbDebugMacros.h. Similarly by setting the field uint32_t qp; in the EbBufferHeaderType structure at a key frame placement, the encoder will update the sequence
QP or CRF level according to the newly defined level (only applicable to CRF mode).
Other options such as updating the Bitrate and resolution during the encoding sessions have been added to the API (starting v1.8.0) by using the abstract structure EbPrivDataNode and a programming sample showing its
usage can be found by tracking the marcos FTR_RATE_ON_FLY_SAMPLE and FTR_RES_ON_FLY_SAMPLE respectively. In the case of a resolution update request, please note that the encoder library will assume
the upscaling and downscaling to have been performed prior to passing the frames.
| Configuration file parameter | Command line | Range | Default | Description |
|---|---|---|---|---|
| ColorPrimaries | --color-primaries | [0-12, 22] | 2 | Color primaries, refer to the user guide Appendix A.2 for full details |
| TransferCharacteristics | --transfer-characteristics | [0-22] | 2 | Transfer characteristics, refer to the user guide Appendix A.2 for full details |
| MatrixCoefficients | --matrix-coefficients | [0-14] | 2 | Matrix coefficients, refer to the user guide Appendix A.2 for full details |
| ColorRange | --color-range | [0-1] | 0 | Color range [0: Studio, 1: Full] |
| ChromaSamplePosition | --chroma-sample-position | any string | unknown | Chroma sample position ['unknown', 'vertical'/'left', 'colocated'/'topleft'] |
| MasteringDisplay | --mastering-display | any string | none | Mastering display metadata in the format of "G(x,y)B(x,y)R(x,y)WP(x,y)L(max,min)", refer to the user guide Appendix A.2 for full details |
| ContentLightLevel | --content-light | any string | none | Set content light level in the format of "max_cll,max_fall", refer to the user guide Appendix A.2 for full details |
LevelOfParallelism (previously LogicalProcessors, which was deprecated in v3.0
and replaced with LevelOfParallelism) is used to specify how much parallelism is
desired; higher levels will create more threads and process more pictures in
parallel, leading to greater fps but larger memory use. If LevelOfParallelism is not
set, the amount of parallelism (threads/memory) will be decided by the encoder based
on the machine's core count.
SvtAv1EncApp.exe -i in.yuv -w 3840 -h 2160 --lp 4
The --lp level does not indicate the number of threads targeted, nor does it
constrain the encoder to run on a certain number of logical processors. The
number of threads created and memory used is determined by settings in the
code (see load_default_buffer_configuration_settings).
Parallelism is achieved in two ways:
- By creating new threads to process pictures and sub-picture blocks (e.g. superblocks) in parallel.
- By increasing the number of pictures in the pipeline, which can then be processed concurrently.
Higher LevelOfParallelism will increase both the threads and pictures in a way that optimizes speed
and memory at each level. In CRF mode, levels 4 and higher will process extra mini-gops in parallel
as well, leading to higher speed, but much higher memory. In low-delay mode, only one picture can be
processed at once, so no extra pictures will be allocated.
The --pin option allows the user to pin the execution to a specific number of cores, specifically,
the first N cores, where N is the value passed with --pin. If '--lp' is not specified, the default
parallelism will be based on the N cores available for the process to run, rather than all the cores
on the machine. If '--lp' is specified, that level of parallelism will be used, regardless of N.
To set cpu affinity a cpu affinity utility such as taskset or numactl to control could be used
to pin execution to desired threads.
Example:
taskset --cpu-list 0-3 ./SvtAv1EncApp --preset 4 -q 32 --keyint 200 -i input1.y4m -b svt_1.bin --lp 3
taskset --cpu-list 4-7 ./SvtAv1EncApp --preset 4 -q 32 --keyint 200 -i input2.y4m -b svt_2.bin --lp 3
This example will ensure that the first encode will run on the first 4 cores and the second encode will run on the second 4 cores.
In this example, if CPU utilization is not saturated for --lp 3 for these cores, higher levels of --lp could be employed for more
parallelism with a memory usage increase.
Please see the subsection 6.4.2, 6.7.3, and 6.7.4 of the AV1 Bitstream & Decoding Process Specification for more details on some expected values.
The available options for ColorPrimaries (--color-primaries) are:
- 1:
bt709, BT.709 - 2: unspecified, default
- 4:
bt470m, BT.470 System M (historical) - 5:
bt470bg, BT.470 System B, G (historical) - 6:
bt601, BT.601 - 7:
smpte240, SMPTE 240 - 8:
film, Generic film (color filters using illuminant C) - 9:
bt2020, BT.2020, BT.2100 - 10:
xyz, SMPTE 428 (CIE 1921 XYZ) - 11:
smpte431, SMPTE RP 431-2 - 12:
smpte432, SMPTE EG 432-1 - 22:
ebu3213, EBU Tech. 3213-E
The available options for TransferCharacteristics (--transfer-characteristics) are:
- 1:
bt709, BT.709 - 2: unspecified, default
- 4:
bt470m, BT.470 System M (historical) - 5:
bt470bg, BT.470 System B, G (historical) - 6:
bt601, BT.601 - 7:
smpte240, SMPTE 240 M - 8:
linear, Linear - 9:
log100, Logarithmic (100 : 1 range) - 10:
log100-sqrt10, Logarithmic (100 * Sqrt(10) : 1 range) - 11:
iec61966, IEC 61966-2-4 - 12:
bt1361, BT.1361 - 13:
srgb, sRGB or sYCC - 14:
bt2020-10, BT.2020 10-bit systems - 15:
bt2020-12, BT.2020 12-bit systems - 16:
smpte2084, SMPTE ST 2084, ITU BT.2100 PQ - 17:
smpte428, SMPTE ST 428 - 18:
hlg, BT.2100 HLG, ARIB STD-B67
The available options for MatrixCoefficients (--matrix-coefficients) are:
- 0:
identity, Identity matrix - 1:
bt709, BT.709 - 2: unspecified, default
- 4:
fcc, US FCC 73.628 - 5:
bt470bg, BT.470 System B, G (historical) - 6:
bt601, BT.601 - 7:
smpte240, SMPTE 240 M - 8:
ycgco, YCgCo - 9:
bt2020-ncl, BT.2020 non-constant luminance, BT.2100 YCbCr - 10:
bt2020-cl, BT.2020 constant luminance - 11:
smpte2085, SMPTE ST 2085 YDzDx - 12:
chroma-ncl, Chromaticity-derived non-constant luminance - 13:
chroma-cl, Chromaticity-derived constant luminance - 14:
ictcp, BT.2100 ICtCp
The available options for ColorRange (--color-range) are:
- 0:
studio, default - 1:
full
The available options for ChromaSamplePosition (--chroma-sample-position) are:
- 0:
unknown, default - 1:
vertical/left, horizontally co-located with luma samples, vertical position in the middle between two luma samples - 2:
colocated/topleft, co-located with luma samples
MasteringDisplay (--mastering-display) and ContentLightLevel (--content-light) parameters are used to set the mastering display and content light level in the AV1 bitstream.
MasteringDisplay takes the format of G(x,y)B(x,y)R(x,y)WP(x,y)L(max,min) where
G(x,y)is the green channel of the mastering displayB(x,y)is the blue channel of the mastering displayR(x,y)is the red channel of the mastering displayWP(x,y)is the white point of the mastering displayL(max,min)is the light level of the mastering display
The x and y values can be coordinates from 0.0 to 1.0, as specified in CIE 1931 while the min,max values can be floating point values representing candelas per square meter, or nits.
For the max,min values, they are generally specified in the range of 0.0 to 1.0, but there are no constraints on the provided values.
Invalid values will be clipped accordingly.
ContentLightLevel takes the format of max_cll,max_fall where both values are integers clipped into a range of 0 to 65535.
Examples:
SvtAv1EncApp -i in.y4m -b out.ivf \
--mastering-display "G(0.2649,0.6900)B(0.1500,0.0600)R(0.6800,0.3200)WP(0.3127,0.3290)L(1000.0,1)" \
--content-light 100,50 \
--color-primaries bt2020 \
--transfer-characteristics smpte2084 \
--matrix-coefficients bt2020-ncl \
--chroma-sample-position topleft
# Color primary is BT.2020, BT.2100
# Transfer characteristic is SMPTE ST 2084, ITU BT.2100 PQ
# matrix coefficients is BT.2020 non-constant luminance, BT.2100 YCbCr
# or
ffmpeg -y -i in.mp4 \
-strict -2 \
-c:a opus \
-c:v libsvtav1 \
-color_primaries:v bt2020 \
-color_trc:v smpte2084 \
-color_range:v pc \
-chroma_sample_location:v topleft \
-svtav1-params \
"mastering-display=G(0.2649,0.6900)B(0.1500,0.0600)R(0.6800,0.3200)WP(0.3127,0.3290)L(1000.0,1):\
content-light=100,50:\
matrix-coefficients=bt2020-ncl:\
chroma-sample-position=topleft" \
out.mp4
# chroma-sample-position needs to be repeated because it currently isn't set ffmpeg's side--max-tx-size allows the encoder to restrict selection of blocks transform sizes up to a maximum size. Valid values are 32 and 64.
In the AV1 standard, 64-pt transforms have the last 32 highest-frequency coefficients zeroed out during encoding, which means coded blocks can look visually blurry, especially when encoding fine noise-like textures.
PSNR and SSIM-based RDO metrics don't seem to detect this blurriness, so this setting combats this issue by not allowing 64-pt transforms to be considered in the first place. The result is an overall increase in output quality consistency, especially for still images in the medium to high quality range.
--qp-scale-compress-strength is meant to improve spatio-temporal quality and by design, overall quality consistency. Of course, you trade off mean (average quality) to stddev (consistency).
The stronger the algorithm strength, the more consistent quality is from keyframe to reference/bidirectional reference frames and other frame types.
In exchange however, the fewer the opportunities frames can be used as references because they're relatively lower quality than the child frames. Thus, it brings down average performance in most cases (except for one case described further below).
This parameter allows advanced users to switch between four levels of quantizer compression, compressing quantizer values across all hierarchical/temporal layers inside of a mini GOP.
-
0 disables the feature, the default value.
-
1 is
--qp-scale-compress-strength, conservatively reducing the QP range used by the encoder. Useful for increasing visual consistency at almost all quality levels with next to no cost. -
2 is
--qp-scale-compress-strength, reducing the QP range used by the encoder further. This is useful at higher quality levels where restricting the QP range across layers is more important. -
3 is
--qp-scale-compress-strength, is the upper limit that was found useful for general-purpose (not Target Quality) encoding. This is useful at maximum fidelity expectations or when the set CRF/QP is very low. In the latter scenario, the feature can actually improve fidelity.
When enabled, the --adaptive-film-grain parameter adaptively varies the film grain blocksize based on the resolution of the input video. This often greatly improves the consistency of film grain in the output video, reducing grain patterns.
Adaptive film grain is enabled by default.
--tf-strength is a parameter that allows users to configure the strength of temporal filtering on alternate reference frames, with an offset for keyframes if using Tune 0 (VQ). Based on the material, this can be perceptually salient.
--enable-tf 2 enables experimental adaptive TF strength modulation based on 64x64 block error. This is not always perceptually or metrically salient, but it should provide feature parity with aomenc.
--ac-bias is an energy-preserving psycho-visual metric that helps increase subjective quality of video. This metric is based on the difference of the "energy" (SATD - SAD) of the source and reconstituted encoded blocks, similar to x264 and x265's implementation. Alternatively, a more lightweight rate adjustment mechanism based on total block "energy" (sum of transformed AC block coefficients) used by the Fast-PD0 and Fast-PD1 code paths is provided.
-
Moderate values (1.0-1.5) help retain sharpness and acuity of textures and scenes with complex motion.
-
High values (4.0-6.0, together with disabling temporal filtering and CDEF) can dramatically improve film grain and noise retention.
When enabled, the --luminance-qp-bias parameter enables frame-level luma bias to improve quality in dark scenes by adjusting frame-level QP based on average luminance across each frame.
The --sharpness parameter allows users to manually configure deblocking loop filter sharpness, and it also affects rate control. It is used in Tune 3 (IQ) and Tune 4 (MS_SSIM), which is designed for still image compression; that being said, it still may be useful for perceptual fidelity in video.
By default, sharpness is set to 0.