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创建 x264 编码器后#xff0c;其有一组默认的编码器配置参数#xff0c;也可以根据需要修改参数#xff0c;来满足编码要求。
具体参数
可修改的参数#xff0c;比较多#xff0c;这边只列举一些常用的。
获取可以配置的参数
方式1
查看 ffmpeg源码 libx264.c…背景
创建 x264 编码器后其有一组默认的编码器配置参数也可以根据需要修改参数来满足编码要求。
具体参数
可修改的参数比较多这边只列举一些常用的。
获取可以配置的参数
方式1
查看 ffmpeg源码 libx264.c其中 static const AVOption options[] {xx}这表示其可修改的参数其他编码器类似。
static const AVOption options[] {{ preset, Set the encoding preset (cf. x264 --fullhelp), OFFSET(preset), AV_OPT_TYPE_STRING, { .str medium }, 0, 0, VE},{ tune, Tune the encoding params (cf. x264 --fullhelp), OFFSET(tune), AV_OPT_TYPE_STRING, { 0 }, 0, 0, VE},{ profile, Set profile restrictions (cf. x264 --fullhelp), OFFSET(profile_opt), AV_OPT_TYPE_STRING, { 0 }, 0, 0, VE},{ fastfirstpass, Use fast settings when encoding first pass, OFFSET(fastfirstpass), AV_OPT_TYPE_BOOL, { .i64 1 }, 0, 1, VE},{level, Specify level (as defined by Annex A), OFFSET(level), AV_OPT_TYPE_STRING, {.strNULL}, 0, 0, VE},{passlogfile, Filename for 2 pass stats, OFFSET(stats), AV_OPT_TYPE_STRING, {.strNULL}, 0, 0, VE},{wpredp, Weighted prediction for P-frames, OFFSET(wpredp), AV_OPT_TYPE_STRING, {.strNULL}, 0, 0, VE},{a53cc, Use A53 Closed Captions (if available), OFFSET(a53_cc), AV_OPT_TYPE_BOOL, {.i64 1}, 0, 1, VE},{x264opts, x264 options, OFFSET(x264opts), AV_OPT_TYPE_STRING, {.strNULL}, 0, 0, VE},{ crf, Select the quality for constant quality mode, OFFSET(crf), AV_OPT_TYPE_FLOAT, {.dbl -1 }, -1, FLT_MAX, VE },{ crf_max, In CRF mode, prevents VBV from lowering quality beyond this point.,OFFSET(crf_max), AV_OPT_TYPE_FLOAT, {.dbl -1 }, -1, FLT_MAX, VE },{ qp, Constant quantization parameter rate control method,OFFSET(cqp), AV_OPT_TYPE_INT, { .i64 -1 }, -1, INT_MAX, VE },{ aq-mode, AQ method, OFFSET(aq_mode), AV_OPT_TYPE_INT, { .i64 -1 }, -1, INT_MAX, VE, aq_mode},{ none, NULL, 0, AV_OPT_TYPE_CONST, {.i64 X264_AQ_NONE}, INT_MIN, INT_MAX, VE, aq_mode },{ variance, Variance AQ (complexity mask), 0, AV_OPT_TYPE_CONST, {.i64 X264_AQ_VARIANCE}, INT_MIN, INT_MAX, VE, aq_mode },{ autovariance, Auto-variance AQ, 0, AV_OPT_TYPE_CONST, {.i64 X264_AQ_AUTOVARIANCE}, INT_MIN, INT_MAX, VE, aq_mode },
#if X264_BUILD 144{ autovariance-biased, Auto-variance AQ with bias to dark scenes, 0, AV_OPT_TYPE_CONST, {.i64 X264_AQ_AUTOVARIANCE_BIASED}, INT_MIN, INT_MAX, VE, aq_mode },
#endif{ aq-strength, AQ strength. Reduces blocking and blurring in flat and textured areas., OFFSET(aq_strength), AV_OPT_TYPE_FLOAT, {.dbl -1}, -1, FLT_MAX, VE},{ psy, Use psychovisual optimizations., OFFSET(psy), AV_OPT_TYPE_BOOL, { .i64 -1 }, -1, 1, VE },{ psy-rd, Strength of psychovisual optimization, in psy-rd:psy-trellis format., OFFSET(psy_rd), AV_OPT_TYPE_STRING, {0 }, 0, 0, VE},{ rc-lookahead, Number of frames to look ahead for frametype and ratecontrol, OFFSET(rc_lookahead), AV_OPT_TYPE_INT, { .i64 -1 }, -1, INT_MAX, VE },{ weightb, Weighted prediction for B-frames., OFFSET(weightb), AV_OPT_TYPE_BOOL, { .i64 -1 }, -1, 1, VE },{ weightp, Weighted prediction analysis method., OFFSET(weightp), AV_OPT_TYPE_INT, { .i64 -1 }, -1, INT_MAX, VE, weightp },{ none, NULL, 0, AV_OPT_TYPE_CONST, {.i64 X264_WEIGHTP_NONE}, INT_MIN, INT_MAX, VE, weightp },{ simple, NULL, 0, AV_OPT_TYPE_CONST, {.i64 X264_WEIGHTP_SIMPLE}, INT_MIN, INT_MAX, VE, weightp },{ smart, NULL, 0, AV_OPT_TYPE_CONST, {.i64 X264_WEIGHTP_SMART}, INT_MIN, INT_MAX, VE, weightp },{ ssim, Calculate and print SSIM stats., OFFSET(ssim), AV_OPT_TYPE_BOOL, { .i64 -1 }, -1, 1, VE },{ intra-refresh, Use Periodic Intra Refresh instead of IDR frames.,OFFSET(intra_refresh),AV_OPT_TYPE_BOOL, { .i64 -1 }, -1, 1, VE },{ bluray-compat, Bluray compatibility workarounds., OFFSET(bluray_compat) ,AV_OPT_TYPE_BOOL, { .i64 -1 }, -1, 1, VE },{ b-bias, Influences how often B-frames are used, OFFSET(b_bias), AV_OPT_TYPE_INT, { .i64 INT_MIN}, INT_MIN, INT_MAX, VE },{ b-pyramid, Keep some B-frames as references., OFFSET(b_pyramid), AV_OPT_TYPE_INT, { .i64 -1 }, -1, INT_MAX, VE, b_pyramid },{ none, NULL, 0, AV_OPT_TYPE_CONST, {.i64 X264_B_PYRAMID_NONE}, INT_MIN, INT_MAX, VE, b_pyramid },{ strict, Strictly hierarchical pyramid, 0, AV_OPT_TYPE_CONST, {.i64 X264_B_PYRAMID_STRICT}, INT_MIN, INT_MAX, VE, b_pyramid },{ normal, Non-strict (not Blu-ray compatible), 0, AV_OPT_TYPE_CONST, {.i64 X264_B_PYRAMID_NORMAL}, INT_MIN, INT_MAX, VE, b_pyramid },{ mixed-refs, One reference per partition, as opposed to one reference per macroblock, OFFSET(mixed_refs), AV_OPT_TYPE_BOOL, { .i64 -1}, -1, 1, VE },{ 8x8dct, High profile 8x8 transform., OFFSET(dct8x8), AV_OPT_TYPE_BOOL, { .i64 -1 }, -1, 1, VE},{ fast-pskip, NULL, OFFSET(fast_pskip), AV_OPT_TYPE_BOOL, { .i64 -1 }, -1, 1, VE},{ aud, Use access unit delimiters., OFFSET(aud), AV_OPT_TYPE_BOOL, { .i64 -1 }, -1, 1, VE},{ mbtree, Use macroblock tree ratecontrol., OFFSET(mbtree), AV_OPT_TYPE_BOOL, { .i64 -1 }, -1, 1, VE},{ deblock, Loop filter parameters, in alpha:beta form., OFFSET(deblock), AV_OPT_TYPE_STRING, { 0 }, 0, 0, VE},{ cplxblur, Reduce fluctuations in QP (before curve compression), OFFSET(cplxblur), AV_OPT_TYPE_FLOAT, {.dbl -1 }, -1, FLT_MAX, VE},{ partitions, A comma-separated list of partitions to consider. Possible values: p8x8, p4x4, b8x8, i8x8, i4x4, none, all, OFFSET(partitions), AV_OPT_TYPE_STRING, { 0 }, 0, 0, VE},{ direct-pred, Direct MV prediction mode, OFFSET(direct_pred), AV_OPT_TYPE_INT, { .i64 -1 }, -1, INT_MAX, VE, direct-pred },{ none, NULL, 0, AV_OPT_TYPE_CONST, { .i64 X264_DIRECT_PRED_NONE }, 0, 0, VE, direct-pred },{ spatial, NULL, 0, AV_OPT_TYPE_CONST, { .i64 X264_DIRECT_PRED_SPATIAL }, 0, 0, VE, direct-pred },{ temporal, NULL, 0, AV_OPT_TYPE_CONST, { .i64 X264_DIRECT_PRED_TEMPORAL }, 0, 0, VE, direct-pred },{ auto, NULL, 0, AV_OPT_TYPE_CONST, { .i64 X264_DIRECT_PRED_AUTO }, 0, 0, VE, direct-pred },{ slice-max-size,Limit the size of each slice in bytes, OFFSET(slice_max_size),AV_OPT_TYPE_INT, { .i64 -1 }, -1, INT_MAX, VE },{ stats, Filename for 2 pass stats, OFFSET(stats), AV_OPT_TYPE_STRING, { 0 }, 0, 0, VE },{ nal-hrd, Signal HRD information (requires vbv-bufsize; cbr not allowed in .mp4), OFFSET(nal_hrd), AV_OPT_TYPE_INT, { .i64 -1 }, -1, INT_MAX, VE, nal-hrd },{ none, NULL, 0, AV_OPT_TYPE_CONST, {.i64 X264_NAL_HRD_NONE}, INT_MIN, INT_MAX, VE, nal-hrd },{ vbr, NULL, 0, AV_OPT_TYPE_CONST, {.i64 X264_NAL_HRD_VBR}, INT_MIN, INT_MAX, VE, nal-hrd },{ cbr, NULL, 0, AV_OPT_TYPE_CONST, {.i64 X264_NAL_HRD_CBR}, INT_MIN, INT_MAX, VE, nal-hrd },{ avcintra-class,AVC-Intra class 50/100/200/300/480, OFFSET(avcintra_class),AV_OPT_TYPE_INT, { .i64 -1 }, -1, 480 , VE},{ me_method, Set motion estimation method, OFFSET(motion_est), AV_OPT_TYPE_INT, { .i64 -1 }, -1, X264_ME_TESA, VE, motion-est},{ motion-est, Set motion estimation method, OFFSET(motion_est), AV_OPT_TYPE_INT, { .i64 -1 }, -1, X264_ME_TESA, VE, motion-est},{ dia, NULL, 0, AV_OPT_TYPE_CONST, { .i64 X264_ME_DIA }, INT_MIN, INT_MAX, VE, motion-est },{ hex, NULL, 0, AV_OPT_TYPE_CONST, { .i64 X264_ME_HEX }, INT_MIN, INT_MAX, VE, motion-est },{ umh, NULL, 0, AV_OPT_TYPE_CONST, { .i64 X264_ME_UMH }, INT_MIN, INT_MAX, VE, motion-est },{ esa, NULL, 0, AV_OPT_TYPE_CONST, { .i64 X264_ME_ESA }, INT_MIN, INT_MAX, VE, motion-est },{ tesa, NULL, 0, AV_OPT_TYPE_CONST, { .i64 X264_ME_TESA }, INT_MIN, INT_MAX, VE, motion-est },{ forced-idr, If forcing keyframes, force them as IDR frames., OFFSET(forced_idr), AV_OPT_TYPE_BOOL, { .i64 0 }, -1, 1, VE },{ coder, Coder type, OFFSET(coder), AV_OPT_TYPE_INT, { .i64 -1 }, -1, 1, VE, coder },{ default, NULL, 0, AV_OPT_TYPE_CONST, { .i64 -1 }, INT_MIN, INT_MAX, VE, coder },{ cavlc, NULL, 0, AV_OPT_TYPE_CONST, { .i64 0 }, INT_MIN, INT_MAX, VE, coder },{ cabac, NULL, 0, AV_OPT_TYPE_CONST, { .i64 1 }, INT_MIN, INT_MAX, VE, coder },{ vlc, NULL, 0, AV_OPT_TYPE_CONST, { .i64 0 }, INT_MIN, INT_MAX, VE, coder },{ ac, NULL, 0, AV_OPT_TYPE_CONST, { .i64 1 }, INT_MIN, INT_MAX, VE, coder },{ b_strategy, Strategy to choose between I/P/B-frames, OFFSET(b_frame_strategy), AV_OPT_TYPE_INT, { .i64 -1 }, -1, 2, VE },{ chromaoffset, QP difference between chroma and luma, OFFSET(chroma_offset), AV_OPT_TYPE_INT, { .i64 0 }, INT_MIN, INT_MAX, VE },{ sc_threshold, Scene change threshold, OFFSET(scenechange_threshold), AV_OPT_TYPE_INT, { .i64 -1 }, INT_MIN, INT_MAX, VE },{ noise_reduction, Noise reduction, OFFSET(noise_reduction), AV_OPT_TYPE_INT, { .i64 -1 }, INT_MIN, INT_MAX, VE },{ udu_sei, Use user data unregistered SEI if available, OFFSET(udu_sei), AV_OPT_TYPE_BOOL, { .i64 0 }, 0, 1, VE },{ x264-params, Override the x264 configuration using a :-separated list of keyvalue parameters, OFFSET(x264_params), AV_OPT_TYPE_DICT, { 0 }, 0, 0, VE },{ NULL },
};方式2
通过 ffmpeg 命令行查找 ffmpeg -h encoderlibx264
常用参数讲解
preset
主要调节编码速度和质量的平衡 可以设置的值{ “ultrafast”, “superfast”, “veryfast”, “faster”, “fast”, “medium”, “slow”, “slower”, “veryslow”, “placebo”, 0 }; 如何获取可以设置哪些值看注释是编译 x264然后运行 x264 --fullhelp 可以看到。我这边嫌麻烦没有编译看 x264 源码获取的
tune
主要配合视频类型和视觉优化的参数 可以设置的值{ “film”, “animation”, “grain”, “stillimage”, “psnr”, “ssim”, “fastdecode”, “zerolatency”, 0 }; film 电影、真人类型 animation 动画 grain 需要保留大量的grain时用 psnr 为提高psnr做了优化的参数 ssim 为提高ssim做了优化的参数 fastdecode 可以快速解码的参数 zerolatency零延迟用在需要非常低的延迟的情况下比如电视电话会议的编码。
profile
支持一组特定的编码功能并支持一类特定的应用 x264_profile_names[] { “baseline”, “main”, “high”, “high10”, “high422”, “high444”, 0 }; baseline基本画质。支持I/P 帧只支持无交错Progressive和CAVLC main主流画质。提供I/P/B 帧支持无交错Progressive和交错Interlaced也支持CAVLC 和CABAC 的支持 high高级画质。在main Profile 的基础上增加了8x8内部预测、自定义量化、 无损视频编码和更多的YUV 格式
level
每个profile 都规定了一个算法特征和限制的子集任何遵守某个profile 的解码器都应该支持与其相应的子集。 每个level都规定了一组对标准中语法成员syntax element所采用的各种参数值的限制。
nal-hrd
码率控制方式 。 none —— 不使用 hrd vbr —— 可变码率 cbr —— 稳定码率
crf
qp
psy
rc-lookahead
参考文献
https://blog.csdn.net/liuzehn/article/details/124995312 https://www.cnblogs.com/poissonnotes/p/6904728.html https://blog.csdn.net/A199222/article/details/85785198
