在上一篇文章中已经成功编译mpp并导入到项目中，接下来基于mpi接口实现解码器
说明一下视频图像是通过ipc摄像头采集的。在项目中通过FFmpeg的RTSP拉流获取ipc摄像头的码流数据，FFmpeg拉流这部分不作叙述，只需要知道FFmpeg拉流后数据保存在AVPacket这个结构体当中。
一、MPI接口使用说明
官方文档中给出的图示已经介绍了MPI接口的使用过程
关于解码过程可以参照test目录下的mpi_dec_test.c文件
二、AVPacket转为MppPacket
mpp的使用流程可以参考官方的mpi_dec_test.c。因为官方demo传入的是一个容器文件（比如MP4文件），我的项目要处理的是FFmpeg拉取的码流数据，数据保存在AVPacket结构体中。mpp要处理的是MppPacket结构体，所以要将AVPacket中的码流数据转到MppPacket中保存
三、分帧处理的问题
这个问题在官方文档中已有解释
四、相关代码实现
#mppvideodecode.h
#ifndef MPPVIDEODECODE_H
#define MPPVIDEODECODE_H
#define myDebug() qDebug()<<"["<
#include
#include
#include
#include "libavcodec/packet.h"
#include "rk_mpi.h"
#include "mpp_log.h"
#include "mpp_mem.h"
#include "mpi_dec_utils.h"
#include "utils.h"
#include "mpp_time.h"
#include "libavcodec/avcodec.h"
typedef struct
{
MppCtx ctx;
MppApi *mpi;
MppBufferGroup frm_grp;
size_t max_usage;
RK_S32 frame_count; //解出帧的计数
} MpiDecLoopData;
class MppVideoDecode : public QObject
{
Q_OBJECT
public:
MppVideoDecode();
void initMpiDecLoopData(); //初始化mpp相关参数
QVector
QString getFrameFormat(MppFrame frame); //获取图像像素格式
void deInit(); //释放相关资源
private:
MppFrame m_frame = NULL;
MppPacket m_packet = NULL;
MpiDecLoopData m_data;
QVector
};
#endif // MPPVIDEODECODE_H
#mppvideodecode.cpp
#include "mppvideodecode.h"
MppVideoDecode::MppVideoDecode()
{
initMpiDecLoopData();
}
void MppVideoDecode::deInit()
{
if(m_packet){
mpp_packet_deinit(&m_packet);
m_packet = NULL;
}
if (m_data.frm_grp) {
mpp_buffer_group_put(m_data.frm_grp);
m_data.frm_grp = NULL;
}
for(MppFrame frame : m_vecMppFrame){
if(frame){
mpp_frame_deinit(&frame);
frame = NULL;
}
}
m_vecMppFrame.clear();
// if (m_data.ctx) {
// mpp_destroy(m_data.ctx);
// m_data.ctx = NULL;
// }
// if(!m_vecMppFrame.isEmpty()){
// m_vecMppFrame.clear();
// }
}
void MppVideoDecode::initMpiDecLoopData()
{
MPP_RET ret = MPP_OK; //操作结果
MppCtx ctx = NULL;
MppApi *mpi = NULL;
MpiCmd mpi_cmd = MPP_CMD_BASE; //控制模式
MppParam param = NULL; //控制参数
RK_U32 need_split = 1; //分帧标志位
MppCodingType type = MPP_VIDEO_CodingAVC; //解码格式h.264
memset(&m_data, 0, sizeof(m_data));
ret = mpp_create(&ctx, &mpi);
if (MPP_OK != ret) {
mpp_err("mpp_create failed\n");
if (m_data.ctx) {
mpp_destroy(m_data.ctx);
m_data.ctx = NULL;
}
}
//内部分帧处理
mpi_cmd = MPP_DEC_SET_PARSER_SPLIT_MODE;
param = &need_split;
ret = mpi->control(ctx, mpi_cmd, param);
if (MPP_OK != ret) {
mpp_err("mpi->control failed\n");
if (m_data.ctx) {
mpp_destroy(m_data.ctx);
m_data.ctx = NULL;
}
}
mpi_cmd = MPP_SET_INPUT_BLOCK; //处理输入是否为阻塞模式(param为1表示输入缓冲区满时会阻塞)
param = &need_split;
ret = mpi->control(ctx, mpi_cmd, param);
if (MPP_OK != ret) {
mpp_err("mpi->control failed\n");
if (m_data.ctx) {
mpp_destroy(m_data.ctx);
m_data.ctx = NULL;
}
}
ret = mpp_init(ctx, MPP_CTX_DEC, type);
if (MPP_OK != ret) {
mpp_err("mpp_init failed\n");
if (m_data.ctx) {
mpp_destroy(m_data.ctx);
m_data.ctx = NULL;
}
}
m_data.ctx = ctx;
m_data.mpi = mpi;
m_data.frame_count = 0;
}
QVector
{
RK_U32 pkt_done = 0;
RK_U32 err_info = 0;
MPP_RET ret = MPP_OK;
MppCtx ctx = m_data.ctx;
MppApi *mpi = m_data.mpi;
//RK_S64 t_s, t_e;
mpp_packet_init(&m_packet, avpacket->data, avpacket->size);
mpp_packet_set_pts(m_packet, avpacket->pts); //显示时间戳
// t_s = mpp_time();
//第一层循环用于确认必须把packet送进解码器
do {
RK_S32 times = 5;
ret = mpi->decode_put_packet(ctx, m_packet);
if (MPP_OK == ret)
pkt_done = 1;
// then get all available frame and release
do {
RK_S32 get_frm = 0; //用于判断一包packet中是否还有frame
RK_U32 frm_eos = 0; //表示图像结束的标志
try_again:
ret = mpi->decode_get_frame(ctx, &m_frame);
if (MPP_ERR_TIMEOUT == ret) {
if (times > 0) {
times--;
msleep(2);
goto try_again;
}
mpp_err("decode_get_frame failed too much time\n");
}
if (MPP_OK != ret) {
mpp_err("decode_get_frame failed ret %d\n", ret);
break;
}
if (m_frame) {
if (mpp_frame_get_info_change(m_frame)) {
RK_U32 width = mpp_frame_get_width(m_frame);
RK_U32 height = mpp_frame_get_height(m_frame);
RK_U32 hor_stride = mpp_frame_get_hor_stride(m_frame);
RK_U32 ver_stride = mpp_frame_get_ver_stride(m_frame);
RK_U32 buf_size = mpp_frame_get_buf_size(m_frame);
mpp_log("decode_get_frame get info changed found\n");
mpp_log("decoder require buffer w:h [%d:%d] stride [%d:%d] buf_size %d",
width, height, hor_stride, ver_stride, buf_size);
ret = mpp_buffer_group_get_internal(&m_data.frm_grp, MPP_BUFFER_TYPE_ION);
if (ret) {
mpp_err("get mpp buffer group failed ret %d\n", ret);
break;
}
mpi->control(ctx, MPP_DEC_SET_EXT_BUF_GROUP, m_data.frm_grp);
mpi->control(ctx, MPP_DEC_SET_INFO_CHANGE_READY, NULL);
} else {
err_info = mpp_frame_get_errinfo(m_frame) | mpp_frame_get_discard(m_frame);
if (err_info) {
mpp_log("decoder_get_frame get err info:%d discard:%d.\n",
mpp_frame_get_errinfo(m_frame), mpp_frame_get_discard(m_frame));
}
// MppBuffer buffer = mpp_frame_get_buffer(m_frame);
// myDebug() << "buffer addr:" << buffer;
}
// myDebug() << "the frame format is:" << getFrameFormat(frame); //获取图像格式(yuv or rgb)
m_data.frame_count++;
mpp_log("decode_get_frame get frame %d\n", m_data.frame_count);
frm_eos = mpp_frame_get_eos(m_frame); //图像结束标志
get_frm = 1;
m_vecMppFrame.append(m_frame);
}
// try get runtime frame memory usage
if (m_data.frm_grp) {
size_t usage = mpp_buffer_group_usage(m_data.frm_grp);
if (usage > m_data.max_usage)
m_data.max_usage = usage;
}
if (frm_eos) {
mpp_log("found last frame\n");
break;
}
if (get_frm)
continue;
break;
} while (1);
if(pkt_done)
break;
/*
* why sleep here:
* mpi->decode_put_packet will failed when packet in internal queue is
* full,waiting the package is consumed .Usually hardware decode one
* frame which resolution is 1080p needs 2 ms,so here we sleep 3ms
* * is enough.
*/
msleep(3);
}while (1);
// t_e = mpp_time();
// myDebug() << "解一个packet所用时间为" << (t_e - t_s) / 1000 << "ms";
for(const MppFrame frame : m_vecMppFrame){
myDebug() << "addr111111:" << frame;
}
return m_vecMppFrame;
}
QString MppVideoDecode::getFrameFormat(MppFrame frame)
{
MppFrameFormat fmt = mpp_frame_get_fmt(frame);
switch(fmt){
case MPP_FMT_YUV420SP:
return "MPP_FMT_YUV420SP";
case MPP_FMT_YUV420SP_10BIT:
return "MPP_FMT_YUV420SP_10BIT";
case MPP_FMT_YUV422SP:
return "MPP_FMT_YUV422SP";
case MPP_FMT_YUV422SP_10BIT:
return "MPP_FMT_YUV422SP_10BIT";
case MPP_FMT_YUV420P:
return "MPP_FMT_YUV420P";
case MPP_FMT_YUV420SP_VU:
return "MPP_FMT_YUV420SP_VU";
case MPP_FMT_YUV422P:
return "MPP_FMT_YUV422P";
case MPP_FMT_YUV422SP_VU:
return "MPP_FMT_YUV422SP_VU";
case MPP_FMT_YUV422_YUYV:
return "MPP_FMT_YUV422_YUYV";
case MPP_FMT_YUV422_YVYU:
return "MPP_FMT_YUV422_YVYU";
case MPP_FMT_YUV422_UYVY:
return "MPP_FMT_YUV422_UYVY";
case MPP_FMT_YUV422_VYUY:
return "MPP_FMT_YUV422_VYUY";
case MPP_FMT_YUV400:
return "MPP_FMT_YUV400";
case MPP_FMT_YUV440SP:
return "MPP_FMT_YUV440SP";
case MPP_FMT_YUV411SP:
return "MPP_FMT_YUV411SP";
case MPP_FMT_YUV444SP:
return "MPP_FMT_YUV444SP";
case MPP_FMT_YUV444P:
return "MPP_FMT_YUV444P";
case MPP_FMT_YUV444SP_10BIT:
return "MPP_FMT_YUV444SP_10BIT";
case MPP_FMT_AYUV2BPP:
return "MPP_FMT_AYUV2BPP";
case MPP_FMT_AYUV1BPP:
return "MPP_FMT_AYUV1BPP";
case MPP_FMT_YUV_BUTT:
return "MPP_FMT_YUV_BUTT";
case MPP_FMT_RGB565:
return "MPP_FMT_RGB565";
case MPP_FMT_BGR565:
return "MPP_FMT_BGR565";
case MPP_FMT_RGB555:
return "MPP_FMT_RGB555";
case MPP_FMT_BGR555:
return "MPP_FMT_BGR555";
case MPP_FMT_RGB444:
return "MPP_FMT_RGB444";
case MPP_FMT_BGR444:
return "MPP_FMT_BGR444";
case MPP_FMT_RGB888:
return "MPP_FMT_RGB888";
case MPP_FMT_BGR888:
return "MPP_FMT_BGR888";
case MPP_FMT_RGB101010:
return "MPP_FMT_RGB101010";
case MPP_FMT_BGR101010:
return "MPP_FMT_BGR101010";
case MPP_FMT_ARGB8888:
return "MPP_FMT_ARGB8888";
case MPP_FMT_ABGR8888:
return "MPP_FMT_ABGR8888";
case MPP_FMT_BGRA8888:
return "MPP_FMT_BGRA8888";
case MPP_FMT_RGBA8888:
return "MPP_FMT_RGBA8888";
case MPP_FMT_ARGB4444:
return "MPP_FMT_ARGB4444";
case MPP_FMT_ARGB1555:
return "MPP_FMT_ARGB1555";
case MPP_FMT_RGB_BUTT:
return "MPP_FMT_RGB_BUTT";
case MPP_FMT_BUTT:
return "MPP_FMT_BUTT";
}
}
可以参考
https://github.com/MUZLATAN/ffmpeg_rtsp_mpp
五、decode_get_frame返回值为NULL
我在调用mpp库的mpp_create、mpp_init、mpp_packet_init、decode_put_packet甚至decode_get_frame返回的值都是0（正常），但是decode_get_frame解出来的frame为NULL
网上搜到的原因一般有两个 （1）在调用mpp_init时传入的解码类型与实际编码类型不相符（比如摄像头码流用的是H265编码，mpp_init传入的却是H264方法） （2）FFmpeg拉流后的码流保存在AVPacket中，但是AVPacket中的码流不足以构成一帧数据所以解不出来
但是我的原因都不是以上这些。在FFmpeg拉流时，因为要不断从摄像头中拉数据，所以要用循环
while(1){
...
avformat_open_input();
...
}
我在调用mpp时，把mpp_create()和mpp_init()也放在循环中了
while(1){
...
avformat_open_input();
mpp(){
mpp_create();
mpp_init();
decode_put_packet();
decode_get_frame();
}
...
}
这就导致每拉一次流，就重新创建一个mpp对象，所以读取的frame为NULL。最后修改代码为以下，成功读取的frame
mpp(){
mpp_create();
mpp_init();
}
while(1){
...
avformat_open_input();
...
decode_put_packet();
decode_get_frame();
...
}