MPP-编码示例

了解MPP的基本功能后，接下来具体分析编码的代码。首先把编码的代码提取出来，方便以后的使用。

完整的编码代码如下，相比较给出的示例代码，做了一些改动，输入的指令全部去除，将函数入口改为利用OpenCV打开USB摄像头，调用编码函数编码，编码后的数据保存在本地。

 #if defined(_WIN32)
 #include "vld.h"
 #endif

 #define MODULE_TAG "mpi_enc_test"

 #include <string.h>
 #include <sys/time.h>

 #include "utils.h"
 #include "rk_mpi.h"
 #include "mpp_env.h"
 #include "mpp_mem.h"
 #include "mpp_log.h"
 #include "mpp_time.h"
 #include "mpp_common.h"

 #include <opencv2/core/core.hpp>
 #include <opencv2/highgui/highgui.hpp>
 #include <opencv2/opencv.hpp>

 using namespace std;
 using namespace cv;

 #define MAX_FILE_NAME_LENGTH 256
 #define calTimeCost(begin,end)(end.tv_sec*1000.-begin.tv_sec*1000.+end.tv_usec/1000.-begin.tv_usec/1000.)

 typedef struct
 {
     MppCodingType   type;
     RK_U32          width;
     RK_U32          height;
     MppFrameFormat  format;

     RK_U32          num_frames;
 } MpiEncTestCmd;

 typedef struct
 {
     //global flow control flag
     RK_U32 frm_eos;
     RK_U32 pkt_eos;
     RK_U32 frame_count;
     RK_U64 stream_size;

     //input ang output file
     FILE *fp_input;
     FILE *fp_output;

     //input and output
     MppBuffer frm_buf;
     MppEncSeiMode sei_mode;

     //base flow context
     MppCtx ctx;
     MppApi *mpi;
     MppEncPrepCfg prep_cfg;
     MppEncRcCfg rc_cfg;
     MppEncCodecCfg codec_cfg;   

     //paramter for resource malloc
     RK_U32 width;
     RK_U32 height;
     RK_U32 hor_stride; //horizontal stride
     RK_U32 ver_stride; //vertical stride
     MppFrameFormat fmt;
     MppCodingType type;
     RK_U32 num_frames;

     //resources
     size_t frame_size;
     //NOTE: packet buffer may overflow
     size_t packet_size;

     //rate control runtime parameter
     RK_S32 gop;
     RK_S32 fps;
     RK_S32 bps;
 } MpiEncTestData;

 MpiEncTestData data;
 MpiEncTestCmd  cmd_ctx;
 MpiEncTestData *ptr1;

 MPP_RET ret = MPP_OK;

 FILE *fp_out = fopen("result.h264", "w+b");

 MPP_RET test_ctx_init(MpiEncTestData **data, MpiEncTestCmd *cmd)
 {
     MpiEncTestData *p = NULL;
     MPP_RET ret = MPP_OK;

     if (!data || !cmd)
        {
         mpp_err_f("invalid input data %p cmd %p\n", data, cmd);
         return MPP_ERR_NULL_PTR;
     }

     p = mpp_calloc(MpiEncTestData, );
     if (!p)
     {
         mpp_err_f("create MpiEncTestData failed\n");
         ret = MPP_ERR_MALLOC;
         goto RET;
     }

     //get paramter from cmd
        p->width        = cmd->width;
     p->height       = cmd->height;
        p->hor_stride   = MPP_ALIGN(cmd->width, );
     p->ver_stride   = MPP_ALIGN(cmd->height, );
     p->fmt          = cmd->format;
     p->type         = cmd->type;
     p->num_frames   = cmd->num_frames;

     p->frame_size = p->hor_stride * p->ver_stride *  / ;
     p->packet_size  = p->width * p->height;

 RET:
     *data = p;
     return ret;
 }

 MPP_RET test_mpp_setup(MpiEncTestData *p2)
 {
     MPP_RET ret;
     MppApi *mpi;
     MppCtx ctx;
     MppEncCodecCfg *codec_cfg;
     MppEncPrepCfg *prep_cfg;
     MppEncRcCfg *rc_cfg;

     if (NULL == p2)
     {
         return MPP_ERR_NULL_PTR;
     }

     mpi = p2->mpi;
     ctx = p2->ctx;
     codec_cfg = &p2->codec_cfg;
     prep_cfg = &p2->prep_cfg;
     rc_cfg = &p2->rc_cfg;

     p2->fps = ;
     p2->gop = ;
     //p2->bps = p2->width * p2->height / 5 * p2->fps;
     p2->bps = *;

     prep_cfg->change        = MPP_ENC_PREP_CFG_CHANGE_INPUT | MPP_ENC_PREP_CFG_CHANGE_ROTATION | MPP_ENC_PREP_CFG_CHANGE_FORMAT;
     prep_cfg->width         = p2->width;
     prep_cfg->height        = p2->height;
     prep_cfg->hor_stride    = p2->hor_stride;
     prep_cfg->ver_stride    = p2->ver_stride;
     prep_cfg->format        = p2->fmt;
     prep_cfg->rotation      = MPP_ENC_ROT_0;
     ret = mpi->control(ctx, MPP_ENC_SET_PREP_CFG, prep_cfg);
     if (ret)
     {
         mpp_err("mpi control enc set prep cfg failed ret %d\n", ret);
         goto RET;
     }    

     rc_cfg->change  = MPP_ENC_RC_CFG_CHANGE_ALL;
     rc_cfg->rc_mode = MPP_ENC_RC_MODE_VBR;
     //rc_cfg->quality = MPP_ENC_RC_QUALITY_MEDIUM;
     rc_cfg->quality = MPP_ENC_RC_QUALITY_CQP;

     if (rc_cfg->rc_mode == MPP_ENC_RC_MODE_CBR)
     {
         //constant bitrate has very small bps range of 1/16 bps
         rc_cfg->bps_target   = p2->bps;
         rc_cfg->bps_max      = p2->bps *  / ;
         rc_cfg->bps_min      = p2->bps *  / ;
     }
     else if (rc_cfg->rc_mode ==  MPP_ENC_RC_MODE_VBR)
     {
         if (rc_cfg->quality == MPP_ENC_RC_QUALITY_CQP)
         {
             //constant QP does not have bps
             //rc_cfg->bps_target   = -1;
             //rc_cfg->bps_max      = -1;
             //rc_cfg->bps_min      = -1;

             rc_cfg->bps_target   = p2->bps;
             rc_cfg->bps_max      = p2->bps *  / ;
             rc_cfg->bps_min      = p2->bps *  / ;
         }
         else
         {
             //variable bitrate has large bps range
             rc_cfg->bps_target   = p2->bps;
             rc_cfg->bps_max      = p2->bps *  / ;
             rc_cfg->bps_min      = p2->bps *  / ;
         }
     }

     //fix input / output frame rate
     rc_cfg->fps_in_flex      = ;
     rc_cfg->fps_in_num       = p2->fps;
     rc_cfg->fps_in_denorm    = ;
     rc_cfg->fps_out_flex     = ;
     rc_cfg->fps_out_num      = p2->fps;
     rc_cfg->fps_out_denorm   = ;

     rc_cfg->gop              = p2->gop;
     rc_cfg->skip_cnt         = ;

     mpp_log("mpi_enc_test bps %d fps %d gop %d\n", rc_cfg->bps_target, rc_cfg->fps_out_num, rc_cfg->gop);
     ret = mpi->control(ctx, MPP_ENC_SET_RC_CFG, rc_cfg);
     if (ret)
     {
         mpp_err("mpi control enc set rc cfg failed ret %d\n", ret);
         goto RET;
     }

     codec_cfg->coding = p2->type;
     codec_cfg->h264.change = MPP_ENC_H264_CFG_CHANGE_PROFILE | MPP_ENC_H264_CFG_CHANGE_ENTROPY | MPP_ENC_H264_CFG_CHANGE_TRANS_8x8;

      //66  - Baseline profile
      //77  - Main profile
      //100 - High profile
     codec_cfg->h264.profile = ;

     /*
          * H.264 level_idc parameter
          * 10 / 11 / 12 / 13    - qcif@15fps / cif@7.5fps / cif@15fps / cif@30fps
          * 20 / 21 / 22         - cif@30fps / half-D1@@25fps / D1@12.5fps
          * 30 / 31 / 32         - D1@25fps / 720p@30fps / 720p@60fps
          * 40 / 41 / 42         - 1080p@30fps / 1080p@30fps / 1080p@60fps
          * 50 / 51 / 52         - 4K@30fps
      */

     codec_cfg->h264.level    = ;
     codec_cfg->h264.entropy_coding_mode  = ;
     codec_cfg->h264.cabac_init_idc  = ;
     //codec_cfg->h264.qp_min = 0;
     //codec_cfg->h264.qp_max = 50;

     //codec_cfg->h264.transform8x8_mode = 0;

     ret = mpi->control(ctx, MPP_ENC_SET_CODEC_CFG, codec_cfg);
     if (ret)
     {
         mpp_err("mpi control enc set codec cfg failed ret %d\n", ret);
         goto RET;
     }

     //optional
     p2->sei_mode = MPP_ENC_SEI_MODE_ONE_FRAME;
     ret = mpi->control(ctx, MPP_ENC_SET_SEI_CFG, &p2->sei_mode);
     if (ret)
     {
         mpp_err("mpi control enc set sei cfg failed ret %d\n", ret);
         goto RET;
     }

 RET:
     return ret;
 }

 int pic_num = ;
 MPP_RET read_yuv_buffer(RK_U8 *buf, Mat &yuvImg, RK_U32 width, RK_U32 height)
 {
     MPP_RET ret = MPP_OK;
     RK_U32 read_size;
     RK_U32 row = ;
     RK_U8 *buf_y = buf;
     RK_U8 *buf_u = buf_y + width * height;
     RK_U8 *buf_v = buf_u + width * height / ; 

     int yuv_size = width * height */;

     memcpy(buf, yuvImg.data, yuv_size);

 err:
     return ret;
 }

 MPP_RET test_mpp_run_yuv(Mat yuvImg, MppApi *mpi1, MppCtx &ctx1, unsigned char * &H264_buf, int &length)
 {
     MpiEncTestData *p3 = ptr1;
     MPP_RET ret;

     MppFrame frame = NULL;
     MppPacket packet = NULL;
     void *buf = mpp_buffer_get_ptr(p3->frm_buf);

     ret = read_yuv_buffer(buf, yuvImg, p3->width, p3->height);

     ret = mpp_frame_init(&frame);
     if (ret)
     {
         mpp_err_f("mpp_frame_init failed\n");
         goto RET;
     }

     mpp_frame_set_width(frame, p3->width);
     mpp_frame_set_height(frame, p3->height);
     mpp_frame_set_hor_stride(frame, p3->hor_stride);
     mpp_frame_set_ver_stride(frame, p3->ver_stride);
     mpp_frame_set_fmt(frame, p3->fmt);
     mpp_frame_set_buffer(frame, p3->frm_buf);
     mpp_frame_set_eos(frame, p3->frm_eos);

     ret = mpi1->encode_put_frame(ctx1, frame);

     if (ret)
     {
         mpp_err("mpp encode put frame failed\n");
         goto RET;
     }

     ret = mpi1->encode_get_packet(ctx1, &packet);
     if (ret)
     {
         mpp_err("mpp encode get packet failed\n");
         goto RET;
     }

     if (packet)
     {
         //write packet to file here
         void *ptr   = mpp_packet_get_pos(packet);
         size_t len  = mpp_packet_get_length(packet);

         p3->pkt_eos = mpp_packet_get_eos(packet);

         H264_buf = new unsigned char[len];

         memcpy(H264_buf, ptr, len);
         length = len;

         mpp_packet_deinit(&packet);
         p3->stream_size += len;
         p3->frame_count++;

         if (p3->pkt_eos)
         {
             mpp_log("found last packet\n");
             mpp_assert(p3->frm_eos);
         }
     }
 RET:
     return ret;
 }

 MppApi *mpi;
 MppCtx ctx;

 MpiEncTestData *test_mpp_run_yuv_init(MpiEncTestData *p, MpiEncTestCmd *cmd, int width , int height, unsigned char * &SPS_buf, int &SPS_length)
 {
     //MppApi *mpi;
     //MppCtx ctx;

     cmd->width = width;
     cmd->height = height;
     cmd->type = MPP_VIDEO_CodingAVC;
     cmd->format = MPP_FMT_YUV420P;
     cmd->num_frames = ;

     ret = test_ctx_init(&p, cmd);
     if (ret)
     {
         mpp_err_f("test data init failed ret %d\n", ret);
         goto MPP_TEST_OUT;
     }
     mpp_log("p->frame_size = %d----------------\n", p->frame_size);

     ret = mpp_buffer_get(NULL, &p->frm_buf, p->frame_size);
     if (ret)
     {
         mpp_err_f("failed to get buffer for input frame ret %d\n", ret);
         goto MPP_TEST_OUT;
     }
     mpp_log("mpi_enc_test encoder test start w %d h %d type %d\n",p->width, p->height, p->type);

     //encoder demo
     ret = mpp_create(&p->ctx, &p->mpi);
     if (ret)
     {
         mpp_err("mpp_create failed ret %d\n", ret);
         goto MPP_TEST_OUT;
     }

     ret = mpp_init(p->ctx, MPP_CTX_ENC, p->type);
     if (ret)
     {
         mpp_err("mpp_init failed ret %d\n", ret);
         goto MPP_TEST_OUT;
     }

     ret = test_mpp_setup(p);
     if (ret)
     {
         mpp_err_f("test mpp setup failed ret %d\n", ret);
         goto MPP_TEST_OUT;
     }

     mpi = p->mpi;
     ctx = p->ctx;

     //p->fp_output = fopen("output.h264", "w+b");

     if (p->type == MPP_VIDEO_CodingAVC)
     {
         MppPacket packet = NULL;

         ret = mpi->control(ctx, MPP_ENC_GET_EXTRA_INFO, &packet);
         if (ret)
         {
             mpp_err("mpi control enc get extra info failed\n");
         }

         //get and write sps/pps for H.264
         if (packet)
         {
             void *ptr    = mpp_packet_get_pos(packet);
             size_t len    = mpp_packet_get_length(packet);

             SPS_buf = new unsigned char[len];

             //fwrite(ptr, 1, len, fp_out);
             memcpy(SPS_buf, ptr, len);
             SPS_length = len;

             packet = NULL;
         }
     }

     return p;
 MPP_TEST_OUT:
     return p;
 }

 MpiEncTestData *p = &data;
 MpiEncTestCmd *cmd = &cmd_ctx;

 unsigned char *H264_buf = NULL;
 int length = ;
 unsigned char *SPS_buf = NULL;
 int SPS_length = ;

 int frame_num = ;

 int MyYuvtoH264(int width, int height, Mat yuv_frame, unsigned char* (&encode_buf), int &encode_length)
 {
     if(frame_num == )
     {
         ptr1 = test_mpp_run_yuv_init(p, cmd, width, height, SPS_buf, SPS_length);
         test_mpp_run_yuv(yuv_frame, mpi, ctx, H264_buf, length);

         encode_buf = new unsigned char[SPS_length + length];
         memcpy(encode_buf, SPS_buf, SPS_length);
         memcpy(encode_buf + SPS_length, H264_buf, length);
         encode_length = length + SPS_length;        

         frame_num++;

         delete H264_buf;
         delete SPS_buf;
     }
     else
     {
         test_mpp_run_yuv(yuv_frame, mpi, ctx, H264_buf, length);

         encode_buf = new unsigned char[length];

         memcpy(encode_buf, H264_buf, length);
         encode_length = length;    

         delete H264_buf;
     }

     //fwrite(H264_buf, 1, length, fp_out);
     return ;
 }

MPP_encode

具体分析：

1、MPI接口结构：

在看代码前，整理下MPP设计的MPI接口，下面的图都来自于官方参考文档：

MppMem：C库malloc内存的封装；

MppBuffer：dmabuf内存的封装；

MppPacket：一维缓存封装，可以从MppMem、MppBuffer生成，用来表示码流数据；

MppFrame：二维帧数据封装，可以从MppMem、MppBuffer生成，用来表示图像数据；

MppMeta、MppTask：输入输出用任务的高级组合接口，可以指定输入输出方式；

使用MppPacket和MppFrame就可以完成一般的编解码工作。

以视频编码为例，图像输入端把图像数据和大小交给MppFrame，通过encode_put_frame输入，在输出端通过encode_get_packet得到编码后的码流MppPacket，就完成了一帧数据的编码。

2、MPI接口使用：

MPI是MPP提供给用户的接口，通过C结构里的函数指针方式提供给用户，用户可以通过MPP上下文结构MppCtx与MPI接口结构MppApi组合实现编解码器。

如上图所示，mpp_create，mpp_init，mpp_destory操纵MppCtx接口，红框内是实现编码与解码的过程。红框内的函数调用分为编解码流程接口put/get_packet/frame和相关的control和reset接口。

3、编码器接口

control编码配置命令

编码开始之前要进行一定的参数配置，参数设置通过control接口。一般需要配置三类信息：

码率控制方式（MPPEncRcCfg），通过命令MPP_ENC_RC_CFG配置；

输入控制配置（MppEncPrepCfg），通过命令MPP_ENC_SET_PREP_CFG配置；

协议控制配置（MppEncCodecCfg），通过命令MPP_ENC_SET_CODEC_CFG配置；

基本流程：

三个配置中，码率控制配置和输入控制配置是必须的，协议控制配置时可选的高级选项。

encode_put_frame：

MPP_RET encode_put_frame(MppCtx ctx，MppFrame frame)

ctx：MPP编码器实例；

frame：带输入的图像数据；

encode_get_packet：

MPP_RET encode_get_packet(MppCtx ctx，MppPacket *packet)

ctx：MPP编码器实例；

packet：编码后的码流数据；

H264编码器的输出数据分为头信息（SPS/PPS/SEI）和图像数据（I/P Slice）两部分，头信息通过control接口的MPP_ENC_GET_EXTRA_INFO命令获取，图像数据通过encode_get_packet接口获取。获取头信息时，要保证所有的参数更新完毕，这样生成的头信息才是最新的。目前encode_get_packet函数获取的码流都含有00 00 00 01起始码，如果想去掉起始码，可以从起始码之后的地址进行拷贝。