03-编码篇-x264编译与介绍

使用FFMPEG作编码操作时，会涉及到将yuv数据编码成h264数据，FFmpeg的libavcodec中的libx264.c会调用x264库的源码作编码：

1.x264库编译
下载X264，地址为：http://www.videolan.org/developers/x264.html，并解压。
mkdir my_build
./configure --enable-shared --prefix=./my_build/
make -j4
make install

2.编译后可以查看
.
|-- bin
| -- x264 |-- include | |-- x264.h | – x264_config.h
-- lib |-- libx264.so -> libx264.so.164 |-- libx264.so.164 – pkgconfig
`-- x264.pc
其中bin目录下x264为可执行文件，我们通过此可执行文件来分析x264库的相关功能

3.运行
通过-h信令，我们大致可以了解x264的主要功能和使用方法
./x264 -h

$ ./x264 -h
x264 core:164
Syntax: x264 [options] -o outfile infile

Infile can be raw (in which case resolution is required),
  or YUV4MPEG (*.y4m),
  or Avisynth if compiled with support (yes).
  or libav* formats if compiled with lavf support (no) or ffms support (no).
Outfile type is selected by filename:
 .264 -> Raw bytestream
 .mkv -> Matroska
 .flv -> Flash Video
 .mp4 -> MP4 if compiled with GPAC or L-SMASH support (no)
Output bit depth: 8/10

Options:

  -h, --help                  List basic options
      --longhelp              List more options
      --fullhelp              List all options

Example usage:

      Constant quality mode:
            x264 --crf 24 -o <output> <input>

      Two-pass with a bitrate of 1000kbps:
            x264 --pass 1 --bitrate 1000 -o <output> <input>
            x264 --pass 2 --bitrate 1000 -o <output> <input>

      Lossless:
            x264 --qp 0 -o <output> <input>

      Maximum PSNR at the cost of speed and visual quality:
            x264 --preset placebo --tune psnr -o <output> <input>

      Constant bitrate at 1000kbps with a 2 second-buffer:
            x264 --vbv-bufsize 2000 --bitrate 1000 -o <output> <input>

Presets:

      --profile <string>      Force the limits of an H.264 profile
                                  Overrides all settings.
                                  - baseline, main, high, high10, high422, high444
      --preset <string>       Use a preset to select encoding settings [medium]
                                  Overridden by user settings.
                                  - ultrafast,superfast,veryfast,faster,fast
                                  - medium,slow,slower,veryslow,placebo
      --tune <string>         Tune the settings for a particular type of source
                              or situation
                                  Overridden by user settings.
                                  Multiple tunings are separated by commas.
                                  Only one psy tuning can be used at a time.
                                  - psy tunings: film,animation,grain,
                                                 stillimage,psnr,ssim
                                  - other tunings: fastdecode,zerolatency

Frame-type options:

  -I, --keyint <integer or "infinite"> Maximum GOP size [250]
      --tff                   Enable interlaced mode (top field first)
      --bff                   Enable interlaced mode (bottom field first)
      --pulldown <string>     Use soft pulldown to change frame rate
                                  - none, 22, 32, 64, double, triple, euro (requires cfr input)

Ratecontrol:

  -B, --bitrate <integer>     Set bitrate (kbit/s)
      --crf <float>           Quality-based VBR (-12-51) [23.0]
      --vbv-maxrate <integer> Max local bitrate (kbit/s) [0]
      --vbv-bufsize <integer> Set size of the VBV buffer (kbit) [0]
  -p, --pass <integer>        Enable multipass ratecontrol
                                  - 1: First pass, creates stats file
                                  - 2: Last pass, does not overwrite stats file

Input/Output:

  -o, --output <string>       Specify output file
      --sar width:height      Specify Sample Aspect Ratio
      --fps <float|rational>  Specify framerate
      --seek <integer>        First frame to encode
      --frames <integer>      Maximum number of frames to encode
      --level <string>        Specify level (as defined by Annex A)
      --quiet                 Quiet Mode

Filtering:

      --vf, --video-filter <filter0>/<filter1>/... Apply video filtering to the input file

      Filter options may be specified in <filter>:<option>=<value> format.

      Available filters:
      crop:left,top,right,bottom
      select_every:step,offset1[,...]

4.建立一个工程，用于将YUV转成H264

编写测试程序
代码结构

.
|-- Makefile
|-- in420.yuv
|-- inc
|-- obj
|   `-- test.o
|-- out.h264
|-- src
|   `-- test.cpp
|-- third_lib
|   `-- x264
|       |-- include
|       |   |-- x264.h
|       |   `-- x264_config.h
|       `-- lib
|           `-- libx264.so
`-- video_prj

test.cpp内容：

#include 
#include 
 
#include "stdint.h"
 
#if defined ( __cplusplus)
extern "C"
{
#include "x264.h"
};
#else
#include "x264.h"
#endif
 
 
int main(int argc, char** argv)
{
 
         int ret;
         int y_size;
         int i,j;
 
         FILE* fp_src  = fopen("./in420.yuv", "rb");
 
         FILE* fp_dst = fopen("out.h264", "wb");
        
         int frame_num=50;
         int csp=X264_CSP_I420;
         int width=640,height=360;
 
         int iNal   = 0;
         x264_nal_t* pNals = NULL;
         x264_t* pHandle   = NULL;
         x264_picture_t* pPic_in = (x264_picture_t*)malloc(sizeof(x264_picture_t));
         x264_picture_t* pPic_out = (x264_picture_t*)malloc(sizeof(x264_picture_t));
         x264_param_t* pParam = (x264_param_t*)malloc(sizeof(x264_param_t));
        
         //Check
         if(fp_src==NULL||fp_dst==NULL){
                   printf("Error open files.\n");
                   return -1;
         }
 
         x264_param_default(pParam);
         pParam->i_width   = width;
         pParam->i_height  = height;

         pParam->i_csp=csp;
         x264_param_apply_profile(pParam, x264_profile_names[5]);
        
         pHandle = x264_encoder_open(pParam);
   
         x264_picture_init(pPic_out);
         x264_picture_alloc(pPic_in, csp, pParam->i_width, pParam->i_height);
  
         y_size = pParam->i_width * pParam->i_height;
         //detect frame number
         if(frame_num==0){
                   fseek(fp_src,0,SEEK_END);
                   switch(csp){
                   case X264_CSP_I444:frame_num=ftell(fp_src)/(y_size*3);break;
                   case X264_CSP_I420:frame_num=ftell(fp_src)/(y_size*3/2);break;
                   default:printf("Colorspace Not Support.\n");return -1;
                   }
                   fseek(fp_src,0,SEEK_SET);
         }
        
         //Loop to Encode
         for( i=0;i<frame_num;i++){
                   switch(csp){
                   case X264_CSP_I444:{
                            fread(pPic_in->img.plane[0],y_size,1,fp_src);         //Y
                            fread(pPic_in->img.plane[1],y_size,1,fp_src);         //U
                            fread(pPic_in->img.plane[2],y_size,1,fp_src);         //V
                            break;}
                   case X264_CSP_I420:{
                            fread(pPic_in->img.plane[0],y_size,1,fp_src);         //Y
                            fread(pPic_in->img.plane[1],y_size/4,1,fp_src);     //U
                            fread(pPic_in->img.plane[2],y_size/4,1,fp_src);     //V
                            break;}
                   default:{
                            printf("Colorspace Not Support.\n");
                            return -1;}
                   }
                   pPic_in->i_pts = i;
 
                   ret = x264_encoder_encode(pHandle, &pNals, &iNal, pPic_in, pPic_out);
                   if (ret< 0){
                            printf("Error.\n");
                            return -1;
                   }
 
                   printf("Succeed encode frame: %5d\n",i);
 
                   for ( j = 0; j < iNal; ++j){
                             fwrite(pNals[j].p_payload, 1, pNals[j].i_payload, fp_dst);
                   }
         }
         i=0;
         //flush encoder
         while(1){
                   ret = x264_encoder_encode(pHandle, &pNals, &iNal, NULL, pPic_out);
                   if(ret==0){
                            break;
                   }
                   printf("Flush 1 frame.\n");
                   for (j = 0; j < iNal; ++j){
                            fwrite(pNals[j].p_payload, 1, pNals[j].i_payload, fp_dst);
                   }
                   i++;
         }
         x264_picture_clean(pPic_in);
         x264_encoder_close(pHandle);
         pHandle = NULL;
 
         free(pPic_in);
         free(pPic_out);
         free(pParam);
 
         fclose(fp_src);
         fclose(fp_dst);
 
         return 0;
}