X264 reference frames It is documented in the header file. . frames: 3 (for more compatibility, otherwise 4) If I set 2 or 3 B-frames here, I get the following AVC encoder message (Elecard Converter Studio): 2 B-frames: "It is recommended to use one B-frame or three B-frames with the following options for encoding: 'Adaptive B-frames', 'Use reference B-frames' and 'Pyramid coding'" x264 is a free software library and application for encoding video streams into the H. x264 B-Frame옵션> - direct mode: 이 옵션은 압축률에 영향을 준다. 2k次。X264是一款研究的是H. 264, maximum, reference frames, wikipedia, x264 Encoding Presets for x264. With new enough ffmpeg you can also use private libx264 options using -x264opts or -x264-params params. CodeBlocks. 那么接下来和帧编码有关 ref, number of reference frame 参考帧数量，一帧最多可以参考多少帧。因此越大，相对能节约体积，但是增加编解码负担，降低效率 正常来说日常编码6或8就可以满足要求。追求极致压缩比ref可以选择13. Wir sprechen in diesem Kapitel nahezu sämtliche Parameter von x264 kurz an. I-frames are complete frames stored 1. 4. sout-x264-keyint <integer> : Maximum GOP size default value: 250 sout-x264-min-keyint <integer> : Minimum GOP size default value: 25 sout-x264-opengop <boolean> : Use recovery points to close GOPs default value: disabled sout-x264-bluray-compat <boolean> : Enable compatibility hacks for Blu-ray support default value: disabled sout-x264-scenecut x264 Parameters. Without B-frames, a typical x264 stream has frame types like so Max. etc; initial parameters for adaptive MB level quantization by calling function x264_adaptive_quant_frame. It increases latency, but allows the encoder to make better frame-type choices (I, P, B). b-frames are most efficiently compressed, but allowing more of them increases both encoding and x264 (and x265) and compressed video in general have different kind of frames. 本文包含以下内容 1、H. 1-refs 1 means use (at most) 1 reference frame. x264 is an advanced commandline encoder for creating H. Best encoding quality can only be archived through lossless encoding. Sets the maximum number of concurrent B-frames that x264 can use. a. But if I invoke invalidate_reference while doing P-frame encoding, then encoder will forget So, I put this little table together to work as a reference. For content with a lot of repetition (eg. Reference Frames --bframes 8 --ref 12. Without B-frames, a typical x264 stream has frame types like so Make x264 more likely to choose higher numbers of B-frames during the adaptive lookahead. 0k次，点赞12次，收藏27次。x264_encoder_encode中实现了实际编码一帧的功能，其中涉及到了编码器中诸多方面的 --b-pyramid strict does not affect P frames. In your example if you use 5 refs and your content is 1080p you break the restrictions of level 4. 文章浏览阅读3. c中编码一帧的函数x264_encoder_encode中有关frame的调用： x264_reference_update 这个函数里最主要的工作的是将上一个参考帧放入参考帧队列，并从空闲帧队列中取出一帧作为当前的参考工作帧（即解码操作的目的帧），即h->fdec。 struct x264_t x264_param_t param; //编码器编码参数，包括量化步长、编码级别等等一些参数 int i_frame; //编码帧号，用于计算POC（picture of count 标识视频帧的解码顺序） int i_nal_type; /* Nal 单元的类型，可以查看编码标准，有哪几种类型，需要理解的类型有：不分区（一帧作为一个片）非IDR图像的片；片分区A You may have to use x264 standalone encoder with qpfile option. 39. frames: In contrast to MPEG-4 ASP, H. Number of reference frames [3] --no-deblock Disable loop filter -f, --deblock <alpha:beta> Loop filter parameters [0:0] MediaInfo is reading out the DPB size, not the number of reference frames. 1 and L3. In this case, is it possible to have 2 videos, one only with an I frame and another frame only with 4 P frames? To decode all 4 P frames, I require the first I frame video but can we construct the videos in this way? X264是一款研究的是H. x264介绍 X264是一款研究的是H. 2w次，点赞42次，收藏63次。本文分析x264编码器主干部分的源代码。“主干部分”指的就是libx264中最核心的接口函数——x264_encoder_encode()，以及相关的几个接口函 对H. Wenn wir noch überhaupt nicht mit x264 vertraut sind, sollten wir besser im Kapitel zur x264-Konfiguration einsteigen, wo das Zusammenspiel der Optionen bei einem konkreten Encoding erklärt wird. 264的特性工具，包括:CABAC和 CAVLC高效嫡编码、多参考帧预测、所有的帧内预测宏块类型(16x6l和4x4)、所有的前向帧间预测P(帧)宏块类型 (16xl6，16x8，8xl6，8x8，8x4，4x8和4x4)、最常用的双向帧间预测(B X264是一款研究的是H. 264编码标准一直停留在理解原理的基础上，对于一个实际投入使用的编码器是如何构建起来一直感觉很神秘，于是决定在理解理论的基础上潜心于编码器实现框架。关于开源的H264编码器有很多，JMVC，T264、X264，这里选择X264，因为网上关于X264源码分析资源很多。X264编码器是一个开源的经 IDR-frames are 'delimiters' in the stream - no frame can reference data from the other side of the IDR-frame. prepare thread for encoding task; setup new frame from picture list. 264 allows multiple reference frames. I believe there are still actually 4 reference frames max in the decoded picture buffer with BD, but one is a "different" kind from the x264 perspective. 1 is restricted to 4 reference frames. they take A LOT of cpu to process. fast_pskip=0 or no-fast-pskip=1 — slight quality increase; worth it IMO. 1st I'm not going to tell you that I spent a long time on the subject, but I can't find a reference that says that 4. --ref <integer> Number of reference frames [3] --no-deblock Disable loop filter -f, --deblock <alpha:beta> Loop filter parameters [0:0 In the hypothetical reference decoder (VBV) mode, x264 allows each macroblock to have a different QP, while in other modes QP is determined for an entire frame. x264 with manually setted "ref" parameter and MediaInfo report not the same. if both frames are similar). 7% So, in IBBPBBP GOP every B frame can use previous I frame & next P frame to make prediction. Comments and corrections are welcome 摘要： 本文作为 “x264视频编码器应用与实现” 系列博文的第八篇，主要讨论x264编码器实例的图像编码API的实现。. In x264 terms, it's the span including all of the B-frames between two P-frames In short, to determine the maximum number of reference frames, you choose which level you're encoding at, refer to the chart, and specify the target x & y resolution of the encoded video, then do the math. Re-sampling H264 video to reduce frame rate while maintaining high image quality. You do set the GOP structure to 4 -g 4 and get a 4 frame GOP. As you see , I need num_ref_frame=3 (worst case is P8, which needs I,P4,P6 as refeerence frames). But eigentlich i want to tell the encoder BEFORE coding P1, that this frame is NOT used as a reference frame (there is no need to waiste time in re-decode the encoded picture). 264的特性工具，包括:CABAC和 CAVLC高效嫡编码、多参考帧预测、所有的帧内预测宏块类型(16x6l和4x4)、所有的前向帧间预测P(帧)宏块类型 (16xl6，16x8，8xl6，8x8，8x4，4x8和4x4)、最常用 从上述代码中可知，针对IDR、I、P和BREF帧，都调用了以下两个函数之一： reference_reset; reference_hierarchy_reset; 这两个函数的作用是重置参考帧列表，其实现为： 文章浏览阅读1. 264 supports multiple reference frames, so each macroblock in each P- or B-frame can refer to a different reference frame with its motion vectors, allowing better matches to be found, resulting in a less Reference frames are used by the x264 codec to find redundant blocks from nearby frames. 1k次。static inline void x264_reference_hierarchy_reset( x264_t *h ){ int ref; int b_hasdelayframe = 0; // 非参考B帧一般是IS_DISPOSABLE /* look for delay frames -- chain must only contain f I would like to encode a video using x264 in such a way, that the keyframes (a. No matter what I do, ffmpeg always spits out a file with 3 reference frames. 一、整体结构. 1 and making the wrong conclusion that 4. A p frame is (forward) "predicted. k. Higher values will usually result in a more efficient compression, which 关于参考帧中的x264_reference_update函数的补充及h->frames. – ffmpeg 和 x264的参数对照x264 ffmpeg 说明命令行字段命令行字段 qpqp_constantcqp cqp固定量化因子。取值范围0到51。经常取值在20-40之间，越小质量越好,要求的码率越高。 0表示无损压缩max-keyinti_keyint_maxggop_size关键帧的最 i_frame_reference rc_lookahead is how many frames the encoder will buffer to have an overview of "what is coming". Follow edited Dec 12, 2019 at 14:42. An I frame is a key frame, it stores the full picture. For detail x264 supports 8- to 10-bit color spaces. FFmpeg only supports one bit depth in one particular build. Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion. x264's default is 3 reference frames, which is also what YouTube uses. Don't forget though, the default setting for some x264 options x264的编码器结构体x264_t中的子结构体字段frames包含了4个临时视频帧序列空间：current、next、unused和reference，分别保存当前编码帧、将编码帧序列、未处理原始视频帧序列和参考帧序列，同时x264编码器申请了fenc和fdec空间用于存放已编码帧和重建帧。H264中“帧”和“片”都是图像帧，如果不加说明 x264 --fullhelp x264 core:160 r3000 33f9e14 Syntax: x264 [options] -o outfile infile Infile can be raw (in which case resolution is required), or YUV4MPEG (*. 3 Initialization process for reference picture lists for B slices in frames: When this process is invoked, there shall be at least one reference entry that is currently marked as "used for reference" (i. - animation – good for cartoons; uses higher deblocking and more reference frames grain – preserves the grain structure in old, grainy film material stillimage – good for slideshow-like content x264 offers a -tune zerolatency option for low latency streaming. IMO using 6000kbps you have plenty of headroom for bframes. The name is technically misleading, as x264 does not actually use pyramid coding; it simply adds B-references to the normal reference list. Commented Feb 1, 2017 at 11:24. I'm wondering, is there any reason to use a different number of reference frames than the number used in the original video stream? Take for instance the following two examples, taken from Blu-ray remuxes. 264编码的开源代码软件，相比JM而言，其编码性能有很大的提高，其支持大多数H. 특정의 경우엔 Reference Frame을 높게 잡아야 하는 경우도 있다. 参数名称 x264_param_t的成员 说明; ref: i_frame_reference: Number of reference frames [3] scenecut: i_scenecut_threshold: How aggressively to insert extra I-frames [40] So, wie ich das sehe, entsprechen die Encoding Settings hinsichtlich der Reference Frames und B-Frames in Kdenlive denen, die auch in der x264-Referenz angegeben sind: https://encodingwissen. <4. If a large number of reference frames is selected, then the "Mixed References" options should also be selected 文章浏览阅读5. animation), a reference frame of 8 to 10 can be used. ref=4 — four reference frames (it may be better to just leave this at 1. It really use I(DR)BBPBBP pattern. Before you start posting please read the forum rules. Unless you have a player that needs it leave b-pyramid as normal. x264_frame_t *unused[X264_BFRAME_MAX* 4 + X264_THREAD_MAX* 2 + 16 + 4]; /* 这个数组用于回收那些在编码中分配的frame空间，当有新的需要时，直接拿过来用，不用重新分配新的空间，提高效率 */ /* For adaptive B decision */ x264_frame_t * last_nonb; /* frames used for reference + sentinels */ x264_frame_t Depends. x264 has a feature called “reference frame invalidation”. 0. 264编码流程详述与对应x264源码解析首先简单介绍一下x264源码调试与修改的基本方法。就是基本的conifigure和make，configure命令使用最简单的就可以，需要注意的是要--enable-debug，如果是 第一阶段：x264的入口函数为main()。main()函数首先调用parse()解析输入的参数，parse()首先调用x264_param_default()为保存参数的x264_param_t结构体赋 前言. 264/MPEG-4 AVC compression format Multiple reference frames; Ratecontrol: constant quantizer, constant quality, single or multipass ABR, optional VBV; Scenecut detection; 文章浏览阅读424次。本文详细介绍了x264参考帧管理机制，包括初始化、重排序、更新和列表构建。i_frame_num是帧编号，影响编码顺序和引用，涉及编码流程中的多个关键步骤，如x264_t、x264_frame_t结构体中的声明，以及在不同函数中的赋值和计算。通过对i_frame_num的有效管理，x264提高了编码质量和效率。 x264编码主流程当中，主要涉及的内容包括多线程处理，读取配置文件，处理帧的头部信息，处理帧级别的配置信息，进行帧编码之后，释放掉配置文件。应当思考的内容包括： 1. Strict limits the use of b-frames to enforce compatibility, normal allows b-frames to be used far more effectively. c 文件中） 。 Referenced frames are frames that refer to other frames (eg. Basically no speed loss. x264_frame_pop_unused函数的实现如下： Hi I am trying to change reference frames from 4 to 3 but it didn't work. (this includes me), check the x264 documentation. 追求极致编码速度ref可以选4 ref13比ref4 man x264 (1): x264 core:133 r2339 585324f Syntax: x264 [options] -o outfile infile Infile can be raw (in which case resolution is required), x264(1) fast h264 encoder. iTunes uses 4 for 1080p, but only 2 for 720p, presumably for compatibility with older, slower computers (Apple also avoids CABAC at 720p, presumably for the How-To: Determine the maximum number of Reference Frames MPEG-4 AVC / H. You can just invalidate every frame after the first one. B-frames are frames that are small in size, but when placed correctly, offer no loss of quality. That's why pictures in bitstream are reordered. so if you want mediainfo to say "ReFrames 2", add -refs 1 -x264opts b-pyramid=0 Yes, maxing out ref-frames and b-frames and using placebo should improve compressibility. In older video encoding standards, such as MPEG-2, only one reference frame – the previous frame – was used for P-frames. Fortunately, constrained CRF, yuv420p, high profile, medium preset, b-pyramid strict and letting x264 autoselect the level for the resolution and you'll end up Reference frames. 5w次。I帧和IDR帧的区别： IDR帧属于I帧。解码器收到IDR frame 时，将所有的参考帧队列丢弃（用x264_reference_reset函数实现——在encoder. 264的特性工具，包括:CABAC和 CAVLC高效嫡编码、多参考帧预测、所有的帧内预测宏块类型(16x6l和4x4)、所有的前向帧间预测P(帧)宏块类型 (16xl6，16x8，8xl6，8x8，8x4，4x8和4x4)、最常用的双向帧间 <br /> X264是一款研究的是H. I used mediainfo to read the x264 encoding options from the video. Having a high referenced frame will improve quality but slow up encoding. Reference Frames: 8 Maximum B-Frames: 16 CABAC: Checked 8x8 Transform: Checked Weighted P-Frames: Checked Pyramidal B-Frames: Normal (Default) Adaptive B-Frames: Optimal Adaptive Direct Mode: Spatial (Default) Motion Estimation Method: Hexagon (Default) Subpixel Motion Estimation: 10: QPRD in all frames 几天来，我一直试图在网上找到解决方案，但没有成功。我正在使用 Ubuntu 并尝试编译支持 x264 的最新 FFMPEG 稳定版本（1. You can modify the x264 source code to add references frame invalidation to all non IDR frames. 264会把需要编码的图像分为三种类型：I、P、B，其中的B、P类型的图像由于采用了帧间编码的这种编码方式，而帧间编码又是以参考图像为基础进行的，因此需要有个参考图像列表来管理之前生成的参考图像，方便用于对当前图像进行编码。 It is also the maximum number of consecutive B-frames x264 can use if the "Adaptive" B-frames option (see next section) is selected. 2. Have tried to change gop, b frames with reference frames but didn't work ffmpeg8 -report -ss 00:00:00. h. i use x264 in constant QP mode (QP=25), closed GOP = 30 frames On the testing yuv-sequence “container” (384×320, 300 frames): the bit-size saving is ~0. 264. 3k次，点赞2次，收藏15次。I 帧和 IDR 帧的区别I 帧和 IDR 帧的区别IDR与GOP:疑问：解答：结论QQ交流群：697773082（流媒体人的后院）I 帧和 IDR 帧的区别IDR 帧属于 I 帧。解码器收到 IDR frame 时，将所有的参考帧队列丢弃 （用x264_reference_reset 函数实现——在 encoder. " A b frame is bi-directional, it can predict forward and backward. This happens for any number of reference frames as long as B-frames are enabled, More reference frames require more processing power because every frame is searched by the motion search (except when an early skip decision is made). And ME algorithm and subpixel refinement What do these settings make in meGUI? !!! I need brief explanation !! If you change an x264 advanced option and it's command line entry disappears, then you've changed it to it's default setting. X264是一款研究的是H. The exact bit depth is controlled at x264’s configure time. 1) with x264 support. 以下逐个函数分析encoder. 3k次。 x264的编码器结构体x264_t中的子结构体字段frames包含了4个临时视频帧序列空间：current、next、unused和reference，分别保存当前编码帧、将编码帧序列、未处理原始视频帧序列和参考帧序列，同时x264编码器申请了fenc和fdec空间用于存放已编码 x264 Reference Frames, x264 BFrames, B-Frames Fast vs Optimal, number of BFrames. 264的特性工具，包括:CABAC和 CAVLC高效嫡编码、多参考帧预测、所有的帧内预测宏块类型(16x6l和4x4)、所有的前向帧间预测P(帧)宏块类型 (16xl6，16x8，8xl6，8x8，8x4，4x8和4x4)、最常用的双向帧间预测(B 在上一篇博客《x264代码学习笔记（三）：x264_slicetype_decide函数》里，在解读x264_slicetype_decide函数过程中，一直有这样的疑问，即B帧是何时被确定类型的，具体是怎样将视频帧由输入序列（播放序列）转换为编码序列呢？为求解答案，我书写了一个实例进行代码调试，如下所示： #include <assert. , as "used for short-term reference" or "used for 文章浏览阅读1. 000 -t 00:04:47. 264 specs and find out that it says in 8. So I'm not sure if i"m understanding the issue since -g 2 should x264的编码器结构体x264_t中的子结构体字段frames包含了4个临时视频帧序列空间：current、next、unused和reference，分别保存当前编码帧、将编码帧序列、未处理原始视频帧序列和参考帧序列，同时x264编码器申请了fenc和fdec空间用于存放已编码帧和重建帧。_牛客网_牛客在手,offer不愁 If you also want also fixed I-frames intervals than you need to disable scenecut detection algorithm also, for example "-sc_threshold 0 -g 50" for fixed 50 frames interval between I-frames. 多线程在工程之上应用很多，尤其是多流的发送和接收，与 Yes. In reordered group IPBBPBB, every B frame uses I frame & P frame, which both are previous, and that's faster. 264 video must comply with the L4. 264的特性工具，包括:CABAC和 CAVLC高效嫡编码、多参考帧预测、所有的帧内预测宏块类型(16x6l和4x4)、所有的前向帧间预测P(帧)宏块类型 (16xl6，16x8，8xl6，8x8，8x4，4x8和4x4)、最常用的双向帧间预测(B帧)宏 H264 Maximum References Frames. 1)。 x264 est une bibliothèque libre sous licence publique générale GNU issue du projet VideoLAN permettant de coder des flux vidéo H. 5k次。本文详细解析了x264编码器中参考帧的管理机制，特别是x264_encoder_encode函数内的x264_reference_update函数工作流程。通过分析未使用帧的缓存管理，即**unused[]数组的使用方式，帮助读者理解B帧作为参考帧的条件及多线程环境下参考帧的 Just the command line tool. None prevents b-frames from being referenced. 1 limitations for the Decoded Picture Buffer (DPB) size, which limits the video resolution and number of reference frames. Sunday, 12 May 2013. Two reference frames (one past and one future) were used for B-frames. 264编码算法，故不是重 To answer your other question about a "mini-GOP", this is the equivalent to what x264 calls a frame pyramid. The reference frames (ref) setting determines how many frames P frames can use as reference. i-frames) are coinciding with shot boundaries (a. Since x264 doesn't write *all* of the encoding settings (that I can see, partitions is an example), this may not be I have been trying to find a solution online for a couple of days with no luck. --ref <integer> Number of reference frames [3] --no-deblock Disable loop filter -f, --deblock <alpha:beta> Loop filter parameters [0:0 x264_encoder_invalidate_reference is not currently compatible with the use of B-frames or intra refresh. 参考图像列表（reference picture list） 一般来说，h. Depends. 1 Mb/s Writing application : Lavf57. 2. 1. It’s already a supported and existing function in x264 It just need to be called on the P/B frames. Since x264 doesn't write all of the encoding settings (that we can see), this may not be 100% accurate. MediaInfo used to read x264 encoding options from video files for reference. 264 (Multiple Reference Frames) Tous les types de macroblocs intrapolés (16x16, Placement adaptatif des B-Frames, avec l'option de garder les B-Frames en tant qu'images de référence, ordre des trames 文章浏览阅读5. Blu-ray. unu 时间:2012-12-27 10:04 来源:CSDN博客 作者:vblittleboy 点击: 次 Ref. Not generally recommended. in that case, the encoder forgets (erase) the frame. By Surlias in forum Newbie / General discussions Replies: 17 Last Post: 17th Mar 2019, 14:32. Higher values will usually result in a more efficient compression, which means better visual quality at same file size. cuts). I use 1, as I have found they are simply not necessary in my use case. X264的编码器结构体x264_t中的子结构体字段frames包含了4个临时视频帧序列空间：current、next、unused和reference，分别保存当前编码帧、将编码帧序列、未处理原始视频帧序列和参考帧序列，同时x264编码器申请了fenc和fdec空间用于存放已编码帧和重建帧。 Reference frames are used by the x264 codec to find redundant blocks from nearby frames. subme=9 — subpixel refinement on all frames. For typical content, a reference frame of 3 to 5 is recommended. de 结构体x264_param_t是x264中最重要的结构体之一，主要用于初始化编码器。以下给出了几乎每一个参数的含义，对这些参数的注释有的是参考了网上的资料，有的是自己的理解，还有的是对源代码的翻译，由于本人水平有限，错误难免，请高手指正。结构体 X264代码中定义的。 1. I looked at it. This setting controls how many frames can be referenced by P- and B-Frames. 9 MiB Duration : 35 s 80 ms Overall bit rate mode : Variable Overall bit rate : 13. By posting to this forum you agree to abide by the rules. 264的特性工具，包括:CABAC和 CAVLC高效嫡编码、多参考帧预测、所有的帧内预测宏块类型(16x6l和4x4)、所有的前向帧间预测P(帧)宏块类型 (16xl6，16x8，8xl6，8x8，8x4，4x8和4x4)、最常用的双向帧间预测(B帧)宏 <br /> X264是一款研究的是H. By aleaksunder in forum Video Conversion Replies: 2 文章浏览阅读3. I am using Ubuntu and trying to compile the latest FFMPEG stable version (1. c中，首先执行的是打开编码器操作，使用的API为x264_encoder_open，随后进行编码的主体循环结构，从输入的yuv文件中循环读取像素数据进行编码，并写出到输出的 (mediainfo shows a ref frame count even when it doesn't find x264's version/settings string). 000 So, I put this little table together to work as a reference. b-frames introduces 1 ref regardless of nr of b-frames b pyramid introduces 2 refs x264 ref as specified so to get 2 ref frames, disable b pyramid and set ref at 1. You are probably off best if you just let x264 handle the number of reference frames using the --preset and --tune commands. 文章浏览阅读1. These redundancies are the fuel for inter-frame compression which is much more x264介绍. Both of them are neither reference frames, nor key frames. As such, they are only used in inter-frame compression techniques. use them! ref=1 Reference frames are tough. In x264_encoder_encode, it . This setting controls how many frames can be referenced by P- and B-Frames. h> # B frames require the most processing because they use the previous and the next frames as a reference, while P-frames only use the previous frames and I-frames don't use any frames as reference. Maybe you are confusing the fact that some standalone players can't play more than 4 reference frames and can't work with video above 4. I will use the numer of ref frames you specify. 264 streams must declare L4. Ref. setting frame parameters like resolution, picture structure. Everyone who receives the link will be able to view this calculation i made a few Encodes with x264 and --bluray-compat Setting. 기본값은 disable이고 보통 auto를 사용하지만 spatial 을 쓰는 경우도 있다. Dev versions are in the 'experimental'-folder of my GoogleDrive, which is linked on the download page. IDR-frames are 'delimiters' in the stream - no frame can reference data from the other side of the IDR-frame. These parameters are responsible for the amount of reference frames 文章浏览阅读1. There is a similar B-skip internal to x264, which is why B-frames generally encode much faster than P-frames, but it The encode_frame() will lead to x264_encoder_encode, which is the true main encoding funcion. The x264 codec is famous for its presets ranging from Ultrafast to Placebo and you’ll see these in most P-frames, and B-frames. Recommended default: 0 flags2 +bpyramid Allows B-frames to be kept as references. c文件中）。这点是所有I帧共有的特性，但是收到IDR帧时，解码器另外需要做的工作就是：把所有的PPS和SPS参数 解码器收到 IDR frame 时，将所有的参考帧队列丢弃 （用x264_reference_reset 函数实现——在 encoder. 视频编码中为了实现压缩,通过缓存部分图片,通过帧和 运动矢量 结合生成新帧. 264会把需要编码的图像分为三种类型：I、P、B，其中的B、P类型的图像由于采用了帧间编码的这种编码方式，而帧间编码又是以参考图像为基础进行的，因此需要有个参考图像列表来管理 H264 frames split up by a special tag, called the startcode prefix, which is either of 0x00 0x00 0x01 OR 0x00 0x00 0x00 0x01. Share. Is there a bug in the software or some reason I'm unaware that Options Frame-type. Unfortunately, reference frames are subject to diminishing returns. Case b) Same problem as a. Reference frames are frames of a compressed video that are used to define future frames. 101 Video ID : 1 Format : AVC Format/Info : Advanced Video Codec Format profile : [email protected] Format settings : x264的编码器结构体x264_t中的子结构体字段frames包含了4个临时视频帧序列空间：current、next、unused和reference，分别保存当前编码帧、将编码帧序列、未处理原始视频帧序列和参考帧序列，同时x264编码器申请了fenc和fdec空间用于存放已编码帧和重建帧。H264中“帧”和“片”都是图像帧，如果不加说明 In short, will make x264 bias to dark areas and spend more bitrate there, thus dark scenes will look less bad. They are just used to change the key frame. Reference Frame의 컨트롤을 보다 효율적으로 하게한다. 1 can't have more B frames look great. 4k次，点赞29次，收藏30次。X264_B_ADAPT_TRELLIS方案：会保留前面每次计算得到的最优帧结构方案，从而插入0到bframes逐次的B帧，求得当前长度最优方案，之后再这个基础上，计算长度+1的最优方案，不断迭代，直到处理完整个GOP，对应代码见slicetype_path_cost；宏块树比较简单的解释作用 x264的编码器结构体x264_t中的子结构体字段frames包含了4个临时视频帧序列空间：current、next、unused和reference，分别保存当前编码帧、将编码帧序列、未处理原始视频帧序列和参考帧序列，同时x264编码器申请了fenc和fdec空间用于存放已编码帧和重建帧。 Number of reference frames x264. Many existing guides may provide an incorrect formula to find the 'correct' tmpg allows me to set the max b frames to 16 and the max reference frames to 9 when using QS and the same for x264 (incidentally, you can set up to 15 reference frames for Unlike previous codecs, H. for testing, I used the following encoder settings h264 reference frames. All the data between two startcodes comprises a NAL unit in H264 speak. To find the max DPB size, I guess? Or are you talking about how to find out what x264 settings libavcodec passed to libx264 when your program is encoding? x264's logging to stdout includes a histogram of usage for each ref distance. The slowdown is especially apparent with slower motion estimation methods. Don't uninstall the x264 package, but compile your new x264 and then compile your ffmpeg, telling it to use that newly compiled x264 library, by specifying that directory where your compiled x264 library is, using the mentioned LD_LIBRARY_PATH environment variable: 几天来，我一直试图在网上找到一个解决方案，但没有任何运气。我正在使用Ubuntu，并试图用x264支持编译最新的FFMPEG稳定版本(1. It's a series of inter frames that reference each other. H. In multi-pass encoding, if x264_encoder_invalidate_reference is called differently in each pass, behavior is undefined. I’ll refrain from picking holes in every preset, but they’re all highly suboptimal for 1080p encoding. 在example. 264编码的开 源代码 软件，相比JM而言，其编码性能有很大的提高，其支持大多数H. c 文件中） 。 这点是所有 I 帧共有的特性，但是收到IDR 帧时，解码器另外需要做的工作就是：把所有的 PPS 和 SPS 参数进行更新。 x264代码剖析（五）：encode()函数之x264_encoder_open()函数 我们知道x264源码从主观上分为两大块，一是解析函数parse()，另一个是编码函数encode()。解析函数parse()较简单，并且不涉及H. 1 or L3. Going beyond 40 usually has no impact, especially with a keyint of 60. 264视频编码的基本概念，包括编码顺序、frame_num及其循环计数机制、POC（图像顺序号）的作用，并通过一个简单实例展示了图像顺序与编码顺序之间的区别。. Another aim was to create video files that would play back on almost anything, something the original higher quality presets throw out of the window by using ridiculously high numbers of reference frames. X264_Reference_update和x264_reference_build_list( h, h->fdec->i_poc );之前printf("[%d][%d][%d][%d]=====",h->i_frame,h->fenc-> 在 x264 中，你不能控制 P-frame 数量，但你可以控制一个 P-frame 所能参考的 Frame 数量， 也就是 Reference frame (ref) 的数值。 B-frame: x264 --fullhelp x264 core:160 r3000 33f9e14 Syntax: x264 [options] -o outfile infile Infile can be raw (in which case resolution is required), or YUV4MPEG (*. answered Dec 12 Before dumping into the x264 settings, it’s worth noting that I used a 2-pass encode, and mixed the audio down to a 160kbps Dolby Surround encode. 1 in the "level_idc" flag (set by --level with x264) in order to achieve smooth DXVA playback. 264的特性工具，包括:CABAC和 CAVLC高效嫡编码、多参考帧预测、所有的帧内预测宏块类型(16x6l和4x4)、所有的前向帧间预测P(帧)宏块类型 (16xl6，16x8，8xl6，8x8，8x4，4x8和4x4)、最常用的双向帧间预测(B帧)宏 Format : MPEG-4 Format profile : Base Media Codec ID : isom (isom/iso2/avc1/mp41) File size : 54. D B C A (this frame, 文章浏览阅读1. x264 supports the following features: * CABAC (context-based adaptive binary arithmetic coding) and CAVLC (context-based adaptive variable length coding * multiple reference frames * 16x16, 8x8 and 4x4 intra-predicted macroblocks * all P-frame inter-predicted 1. As well as this, IDR-frames are also I-frames, so they don't reference data from any other frame. x264_frame_pop_unused，从内存缓存区中取出一帧图像存储结构对象； x264_frame_copy_picture，将外部图像数据复制到内部图像缓存结构中； x264_frame_expand_border_mod16，确保图像宽高都为16像素的倍数； x264_frame_pop_unused. 264 (MPEG-4 AVC) video streams. 1 which can't happen if you stick to presets and tunings, so you save yourself trouble. b-adapt=2 — a better B-frame decision mode. 5k次。本文详细介绍了H. For decoder, it's better when every successive frame uses only previous frames for prediction. The Settings B-frames: 1 Ref. aq-mode=2 — better adaptive quantization. No, it won't. 264的特性工具，包括:CABAC和 CAVLC高效嫡编码、多参考帧预测、所有的 帧内预测 宏块类型(16x6l和4x4)、所有的前向帧间预测P(帧)宏块类型 (16xl6，16x8，8xl6，8x8，8x4，4x8和4x4)、最常用的双向帧 Max. P frames can reference P frames, so it will not affect GOP structure. 1）。 Number of B frames and reference frames. x264 Settings Comparison - Reference Suppose I have 5 frames, I encode first one as the I or reference frame and all other as P frames in one video using x264 codec. These redundancies are the fuel for inter-frame compression which is much more My source file has 4 reference frames. After that I reread H. y4m), or Avisynth if compiled with support (no). Should not be called during an x264_encoder_encode, but multiple calls can be made simultaneously. Improve this answer. x264 can't know for which device you are encoding, can it? J_Darnley. e. 56. frames: 3 (for more compatibility, otherwise 4) If I set 2 or 3 B-frames here, I get the following AVC encoder message (Elecard Converter Studio): 2 B-frames: "It is recommended to use one B-frame or three B-frames with the following options for encoding: 'Adaptive B-frames', 'Use reference B-frames' and 'Pyramid coding'" # apt-get remove x264 and compile your new x264 from source. 1 Two pass (2pass) use the reference frame finally selected, but this is compensated by scaling those MVs inversely proportional to their temporal length. Since x264 doesn't write *all* of the encoding settings (that I can see, partitions is an example), this may not be 100% Here ‘B’ denotes B-frame used for reference and ‘b’ denotes B-frame not used for reference. 这些帧被叫做 参考帧 参考帧以frame_num为索引查找,但是frame num是由最大值的,达到最大值后会被取模,如果frame num达到最大值后取模为0,就索引不 struct x264_t x264_param_t param; //编码器编码参数，包括量化步长、编码级别等等一些参数 int i_frame; //编码帧号，用于计算POC（picture of count 标识视频帧的解码顺序） int i_nal_type; /* Nal 单元的类型，可以查看编码标准，有哪几种类型，需要理解的类型有：不分区（一帧作为一个片）非IDR图像的片；片分区A FFMpeg使用x264和x265编码库 最近收到一个小任务是转换1920x1080@120Hz片源出来确认下平台120Hz的支持能力 然后看了下spec 120Hz的支持规 X264是一款研究的是H. It increases memory consumed, but doesn't impact performance. Wir sollten auf jeden Fall eine aktuelle Version von x264 verwenden; zum einen, weil sich der It indicates 4 reference frames despite also reporting conflicting x264 encoder settings on the video track, very clearly 2 refs and 2 B-frames. In other words, it is not possible to build one FFmpeg with multiple versions of x264 with different bit depths. Parameters to pretty much always use: me=umh — better motion estimation. It allows for b-frames to be used as references for other frames. 1. The whole definition of "number of reference frames" is a little too ambiguous . xgannvghhemuzlfwnbdfzhizaadljtkzeqxsqblrhiqxrvrsvfsoehydyaddoozvchqrrkqgxd