x265命令行选项与API接口指南

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"x265_cmd_api_thrd_preset_lossless_svt.pdf" 是一份详细介绍了x265命令行选项和应用编程接口（API）的文档，适合视频编码领域的专业人士参考。文档包含了关于HEVC（高效视频编码）的基本信息、x265编码器的法律声明以及各种配置参数，旨在帮助用户理解和优化x265编码器的性能。 1. **HEVC（高效视频编码）**：HEVC是新一代的视频压缩标准，相比H.264/AVC，它在相同质量下可以实现更高的压缩比，降低存储和传输成本。 2. **x265**：x265是一个开源的HEVC视频编码器，它提供了多种编码模式和参数调整，以适应不同的编码需求，如质量优先、速率控制等。 3. **命令行选项**：文档详细列出了x265的命令行选项，包括执行选项、日志和统计选项、性能选项、输入/输出文件选项、配置文件、模式决策/分析、时间轴/运动搜索选项、空间内选项、心理视觉选项、切片决策选项、质量、率控制和率失真选项、量化选项、环路滤波器、视频可使用信息（VUI）选项、位流选项、离散余弦变换近似、调试选项以及SVT-HEVC编码器特有的选项。 4. **应用编程接口（API）**：x265的API允许开发者在应用程序中集成编码功能，文档涵盖了API的引入、构建注意事项、编码器结构、参数类、图片处理、分析缓冲区、编码过程、清理过程、VMAF（视频多方法评估融合）集成以及多库接口。 5. **线程处理**：文档还讨论了x265的多线程支持，包括线程池的使用，这对于充分利用多核处理器的性能至关重要。 6. **性能优化**：通过调整上述的命令行选项和API设置，用户能够根据具体需求优化编码速度和质量，例如使用特定的编码预设（preset）来实现无损编码，或利用性能选项提高编码效率。 7. **质量控制**：x265提供了丰富的质量控制选项，如率控制、率失真优化和量化参数，使得用户可以在压缩率和视频质量之间找到平衡。 8. **VMAF**：VMAF是一种视频质量评估工具，它被集成到x265中，用于在编码过程中评估视频的质量，帮助优化编码设置。 9. **多库接口**：对于需要同时使用多个编码库的应用，x265的多库接口提供了便利，允许灵活地切换和组合不同编码技术。这份文档是x265编码器的全面指南，对于理解和使用x265进行高效视频编码具有极高价值。无论是对初学者还是高级开发者，都能从中获取到必要的知识和技巧，提升视频编码的效率和效果。

x265

--interlace <false|tff|bff>, --no-interlace

0. progressive pictures (default)

1. top ﬁeld ﬁrst

2. bottom ﬁeld ﬁrst

HEVC encodes interlaced content as ﬁelds. Fields must be provided to the encoder in the correct temporal order.

The source dimensions must be ﬁeld dimensions and the FPS must be in units of ﬁelds per second. The decoder

must re-combine the ﬁelds in their correct orientation for display.

--seek <integer>

Number of frames to skip at start of input ﬁle. Default 0

CLI ONLY

--frames, -f <integer>

Number of frames of input sequence to be encoded. Default 0 (all)

CLI ONLY

--output, -o <filename>

Bitstream output ﬁle name. If there are two extra CLI options, the ﬁrst is implicitly the input ﬁlename and the

second is the output ﬁlename, making the --output option optional.

The output ﬁle will always contain a raw HEVC bitstream, the CLI does not support any container ﬁle formats.

CLI ONLY

--output-depth, -D 8|10|12

Bitdepth of output HEVC bitstream, which is also the internal bit depth of the encoder. If the requested bit

depth is not the bit depth of the linked libx265, it will attempt to bind libx265_main for an 8bit encoder,

libx265_main10 for a 10bit encoder, or libx265_main12 for a 12bit encoder, with the same API version as

the linked libx265.

If the output depth is not speciﬁed but --profile is speciﬁed, the output depth will be derived from the proﬁle

name.

CLI ONLY

--chunk-start <integer>

First frame of the chunk. Frames preceeding this in display order will be encoded, however, they will be

discarded in the bitstream. This feature can be enabled only in closed GOP structures. Default 0 (disabled).

--chunk-end <integer>

Last frame of the chunk. Frames following this in display order will be used in taking lookahead decisions, but,

they will not be encoded. This feature can be enabled only in closed GOP structures. Default 0 (disabled).

2.5 Proﬁle, Level, Tier

--profile, -P <string>

Enforce the requirements of the speciﬁed proﬁle, ensuring the output stream will be decodable by a decoder

which supports that proﬁle. May abort the encode if the speciﬁed proﬁle is impossible to be supported by the

compile options chosen for the encoder (a high bit depth encoder will be unable to output bitstreams compliant

with Main or MainStillPicture).

The following proﬁles are supported in x265.

8bit proﬁles:

10 Chapter 2. Command Line Options

x265

main, main-intra, mainstillpicture (or msp for short)

main444-8, main444-intra, main444-stillpicture

See note below on signaling intra and stillpicture proﬁles.

10bit proﬁles:

main10, main10-intra

main422-10, main422-10-intra

main444-10, main444-10-intra

12bit proﬁles:

main12, main12-intra

main422-12, main422-12-intra

main444-12, main444-12-intra

CLI ONLY

API users must call x265_param_apply_proﬁle() after conﬁguring their param structure. Any changes made to

the param structure after this call might make the encode non-compliant.

The CLI application will derive the output bit depth from the proﬁle name if --output-depth is not speci-

ﬁed.

--level-idc <integer|float>

Minimum decoder requirement level. Defaults to 0, which implies auto-detection by the encoder. If speciﬁed,

the encoder will attempt to bring the encode speciﬁcations within that speciﬁed level. If the encoder is unable

to reach the level it issues a warning and aborts the encode. If the requested requirement level is higher than the

actual level, the actual requirement level is signaled.

Beware, specifying a decoder level will force the encoder to enable VBV for constant rate factor encodes, which

may introduce non-determinism.

The value is speciﬁed as a ﬂoat or as an integer with the level times 10, for example level 5.1 is speciﬁed as

“5.1” or “51”, and level 5.0 is speciﬁed as “5.0” or “50”.

Annex A levels: 1, 2, 2.1, 3, 3.1, 4, 4.1, 5, 5.1, 5.2, 6, 6.1, 6.2, 8.5

--high-tier, --no-high-tier

If --level-idc has been speciﬁed, –high-tier allows the support of high tier at that level. The encoder will

ﬁrst attempt to encode at the speciﬁed level, main tier ﬁrst, turning on high tier only if necessary and available

at that level.If your requested level does not support a High tier, high tier will not be supported. If –no-high-tier

has been speciﬁed, then the encoder will attempt to encode only at the main tier.

Default: enabled

--ref <1..16>

Max number of L0 references to be allowed. This number has a linear multiplier effect on the amount of work

performed in motion search, but will generally have a beneﬁcial affect on compression and distortion.

Note that x265 allows up to 16 L0 references but the HEVC speciﬁcation only allows a maximum of 8 total

reference frames. So if you have B frames enabled only 7 L0 refs are valid and if you have --b-pyramid

enabled (which is enabled by default in all presets), then only 6 L0 refs are the maximum allowed by the HEVC

speciﬁcation. If x265 detects that the total reference count is greater than 8, it will issue a warning that the

resulting stream is non-compliant and it signals the stream as proﬁle NONE and level NONE and will abort the

encode unless --allow-non-conformance it speciﬁed. Compliant HEVC decoders may refuse to decode

such streams.

Default 3

2.5. Proﬁle, Level, Tier 11

x265

--allow-non-conformance, --no-allow-non-conformance

Allow libx265 to generate a bitstream with proﬁle and level NONE. By default it will abort any encode which

does not meet strict level compliance. The two most likely causes for non-conformance are --ctu being too

small, --ref being too high, or the bitrate or resolution being out of speciﬁcation.

Default: disabled

--uhd-bd

Enable Ultra HD Blu-ray format support. If speciﬁed with incompatible encoding options, the encoder will

attempt to modify/set the right encode speciﬁcations. If the encoder is unable to do so, this option will be turned

OFF. Highly experimental.

Default: disabled

Note: --profile, --level-idc, and --high-tier are only intended for use when you are targeting a

particular decoder (or decoders) with ﬁxed resource limitations and must constrain the bitstream within those limits.

Specifying a proﬁle or level may lower the encode quality parameters to meet those requirements but it will never raise

them. It may enable VBV constraints on a CRF encode.

Also note that x265 determines the decoder requirement proﬁle and level in three steps. First, the user conﬁgures

an x265_param structure with their suggested encoder options and then optionally calls x265_param_apply_proﬁle()

to enforce a speciﬁc proﬁle (main, main10, etc). Second, an encoder is created from this x265_param instance and

the --level-idc and --high-tier parameters are used to reduce bitrate or other features in order to enforce

the target level. Finally, the encoder re-examines the ﬁnal set of parameters and detects the actual minimum decoder

requirement level and this is what is signaled in the bitstream headers. The detected decoder level will only use High

tier if the user speciﬁed a High tier level.

The signaled proﬁle will be determined by the encoder’s internal bitdepth and input color space. If --keyint is 0 or

1, then an intra variant of the proﬁle will be signaled.

If --total-frames is 1, then a stillpicture variant will be signaled, but this parameter is not always set by applica-

tions, particularly not when the CLI uses stdin streaming or when libx265 is used by third-party applications.

2.6 Mode decision / Analysis

--rd <1..6>

Level of RDO in mode decision. The higher the value, the more exhaustive the analysis and the more rate

distortion optimization is used. The lower the value the faster the encode, the higher the value the smaller the

bitstream (in general). Default 3

Note that this table aims for accuracy, but is not necessarily our ﬁnal target behavior for each mode.

Level Description

0 sa8d mode and split decisions, intra w/ source pixels, currently not supported

1 recon generated (better intra), RDO merge/skip selection

2 RDO splits and merge/skip selection

3 RDO mode and split decisions, chroma residual used for sa8d

4 Currently same as 3

5 Adds RDO prediction decisions

6 Currently same as 5

Range of values: 1: least .. 6: full RDO analysis

Options which affect the coding unit quad-tree, sometimes referred to as the prediction quad-tree.

12 Chapter 2. Command Line Options

x265

--ctu, -s <64|32|16>

Maximum CU size (width and height). The larger the maximum CU size, the more efﬁciently x265 can encode

ﬂat areas of the picture, giving large reductions in bitrate. However this comes at a loss of parallelism with

fewer rows of CUs that can be encoded in parallel, and less frame parallelism as well. Because of this the faster

presets use a CU size of 32. Default: 64

--min-cu-size <32|16|8>

Minimum CU size (width and height). By using 16 or 32 the encoder will not analyze the cost of CUs below

that minimum threshold, saving considerable amounts of compute with a predictable increase in bitrate. This

setting has a large effect on performance on the faster presets.

Default: 8 (minimum 8x8 CU for HEVC, best compression efﬁciency)

Note: All encoders within a single process must use the same settings for the CU size range. --ctu and

--min-cu-size must be consistent for all of them since the encoder conﬁgures several key global data structures

based on this range.

--limit-refs <0|1|2|3>

When set to X265_REF_LIMIT_DEPTH (1) x265 will limit the references analyzed at the current depth based

on the references used to code the 4 sub-blocks at the next depth. For example, a 16x16 CU will only use the

references used to code its four 8x8 CUs.

When set to X265_REF_LIMIT_CU (2), the rectangular and asymmetrical partitions will only use references

selected by the 2Nx2N motion search (including at the lowest depth which is otherwise unaffected by the depth

limit).

When set to 3 (X265_REF_LIMIT_DEPTH && X265_REF_LIMIT_CU), the 2Nx2N motion search at each

depth will only use references from the split CUs and the rect/amp motion searches at that depth will only use

the reference(s) selected by 2Nx2N.

For all non-zero values of limit-refs, the current depth will evaluate intra mode (in inter slices), only if intra

mode was chosen as the best mode for atleast one of the 4 sub-blocks.

You can often increase the number of references you are using (within your decoder level limits) if you enable

one or both of these ﬂags.

Default 3.

--limit-modes, --no-limit-modes

When enabled, limit-modes will limit modes analyzed for each CU using cost metrics from the 4 sub-CUs.

When multiple inter modes like --rect and/or --amp are enabled, this feature will use motion cost heuristics

from the 4 sub-CUs to bypass modes that are unlikely to be the best choice. This can signiﬁcantly improve

performance when rect and/or --amp are enabled at minimal compression efﬁciency loss.

--rect, --no-rect

Enable analysis of rectangular motion partitions Nx2N and 2NxN (50/50 splits, two directions). Default disabled

--amp, --no-amp

Enable analysis of asymmetric motion partitions (75/25 splits, four directions). At RD levels 0 through 4, AMP

partitions are only considered at CU sizes 32x32 and below. At RD levels 5 and 6, it will only consider AMP

partitions as merge candidates (no motion search) at 64x64, and as merge or inter candidates below 64x64.

The AMP partitions which are searched are derived from the current best inter partition. If Nx2N (vertical

rectangular) is the best current prediction, then left and right asymmetrical splits will be evaluated. If 2NxN

(horizontal rectangular) is the best current prediction, then top and bottom asymmetrical splits will be evaluated,

If 2Nx2N is the best prediction, and the block is not a merge/skip, then all four AMP partitions are evaluated.

This setting has no effect if rectangular partitions are disabled. Default disabled

2.6. Mode decision / Analysis 13

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x265命令行选项与API接口指南

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写一段嵌套2层的for循环，将/public/work/Project/Assembly/SA2022010902_lanhua/pan_sv/data/路径下的所有fasta文件两两一组进行遍历执行上段shell代码

:error:'thrd_cst'undeclared(first use in this function)

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回答得不对，我要的不是pthread_mutex_lock的源码

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