提取出编码的代码后，现在提取解码例程，供以后需要的时候使用。
完整的解码代码如下，做了一些改动，指令参数全部去除，输入H264数据，解码后的数据保存在本地，官方示例解码后的数据是YUV_420sp和YUV_422sp格式，这里将其改为了YUV_420p格式。
#if defined(_WIN32)
#include "vld.h"
#endif
#define MODULE_TAG "mpi_dec_test"
#include <string.h>
#include "utils.h"
#include "rk_mpi.h"
#include "mpp_log.h"
#include "mpp_mem.h"
#include "mpp_env.h"
#include "mpp_time.h"
#include "mpp_common.h"
#include "mpp_frame.h"
#include "mpp_buffer_impl.h"
#include "mpp_frame_impl.h"
#define MPI_DEC_STREAM_SIZE (SZ_4K)
#define MPI_DEC_LOOP_COUNT 4
#define MAX_FILE_NAME_LENGTH 256
typedef struct
{
MppCtx ctx;
MppApi *mpi;
RK_U32 eos;
char *buf;
MppBufferGroup frm_grp;
MppBufferGroup pkt_grp;
MppPacket packet;
size_t packet_size;
MppFrame frame;
FILE *fp_input;
FILE *fp_output;
RK_S32 frame_count;
RK_S32 frame_num;
size_t max_usage;
} MpiDecLoopData;
typedef struct
{
char file_input[MAX_FILE_NAME_LENGTH];
char file_output[MAX_FILE_NAME_LENGTH];
MppCodingType type;
MppFrameFormat format;
RK_U32 width;
RK_U32 height;
RK_U32 debug;
RK_U32 have_input;
RK_U32 have_output;
RK_U32 simple;
RK_S32 timeout;
RK_S32 frame_num;
size_t max_usage;
} MpiDecTestCmd;
size_t mpp_frame_get_buf_size(const MppFrame s)
{
check_is_mpp_frame((MppFrameImpl*)s);
return ((MppFrameImpl*)s)->buf_size;
}
void dump_mpp_frame_to_file(MppFrame frame, FILE *fp)
{
RK_U32 width = 0;
RK_U32 height = 0;
RK_U32 h_stride = 0;
RK_U32 v_stride = 0;
MppBuffer buffer = NULL;
RK_U8 *base = NULL;
width = mpp_frame_get_width(frame);
height = mpp_frame_get_height(frame);
h_stride = mpp_frame_get_hor_stride(frame);
v_stride = mpp_frame_get_ver_stride(frame);
buffer = mpp_frame_get_buffer(frame);
base = (RK_U8 *)mpp_buffer_get_ptr(buffer);
RK_U32 buf_size = mpp_frame_get_buf_size(frame);
size_t base_length = mpp_buffer_get_size(buffer);
mpp_log("base_length = %dn",base_length);
RK_U32 i;
RK_U8 *base_y = base;
RK_U8 *base_c = base + h_stride * v_stride;
//保存为YUV420sp格式
/*for (i = 0; i < height; i++, base_y += h_stride)
{
fwrite(base_y, 1, width, fp);
}
for (i = 0; i < height / 2; i++, base_c += h_stride)
{
fwrite(base_c, 1, width, fp);
}*/
//保存为YUV420p格式
for(i = 0; i < height; i++, base_y += h_stride)
{
fwrite(base_y, 1, width, fp);
}
for(i = 0; i < height * width / 2; i+=2)
{
fwrite((base_c + i), 1, 1, fp);
}
for(i = 1; i < height * width / 2; i+=2)
{
fwrite((base_c + i), 1, 1, fp);
}
}
size_t mpp_buffer_group_usage(MppBufferGroup group)
{
if (NULL == group)
{
mpp_err_f("input invalid group %pn", group);
return MPP_BUFFER_MODE_BUTT;
}
MppBufferGroupImpl *p = (MppBufferGroupImpl *)group;
return p->usage;
}
static int decode_simple(MpiDecLoopData *data)
{
RK_U32 pkt_done = 0;
RK_U32 pkt_eos = 0;
RK_U32 err_info = 0;
MPP_RET ret = MPP_OK;
MppCtx ctx = data->ctx;
MppApi *mpi = data->mpi;
char *buf = data->buf;
MppPacket packet = data->packet;
MppFrame frame = NULL;
size_t read_size = fread(buf, 1, data->packet_size, data->fp_input);
if (read_size != data->packet_size || feof(data->fp_input))
{
mpp_log("found last packetn");
data->eos = pkt_eos = 1;
}
mpp_packet_write(packet, 0, buf, read_size);
mpp_packet_set_pos(packet, buf);
mpp_packet_set_length(packet, read_size);
if (pkt_eos)
{
mpp_packet_set_eos(packet);
}
do {
if (!pkt_done)
{
ret = mpi->decode_put_packet(ctx, packet);
if (MPP_OK == ret)
{
pkt_done = 1;
}
}
do {
RK_S32 get_frm = 0;
RK_U32 frm_eos = 0;
ret = mpi->decode_get_frame(ctx, &frame);
if (frame)
{
if (mpp_frame_get_info_change(frame))
{
RK_U32 width = mpp_frame_get_width(frame);
RK_U32 height = mpp_frame_get_height(frame);
RK_U32 hor_stride = mpp_frame_get_hor_stride(frame);
RK_U32 ver_stride = mpp_frame_get_ver_stride(frame);
RK_U32 buf_size = mpp_frame_get_buf_size(frame);
mpp_log("decode_get_frame get info changed foundn");
mpp_log("decoder require buffer w:h [%d:%d] stride [%d:%d] buf_size %d", width, height, hor_stride, ver_stride, buf_size);
if (NULL == data->frm_grp)
{
ret = mpp_buffer_group_get_internal(&data->frm_grp, MPP_BUFFER_TYPE_ION);
if (ret)
{
mpp_err("get mpp buffer group failed ret %dn", ret);
break;
}
ret = mpi->control(ctx, MPP_DEC_SET_EXT_BUF_GROUP, data->frm_grp);
if (ret)
{
mpp_err("set buffer group failed ret %dn", ret);
break;
}
}
else
{
ret = mpp_buffer_group_clear(data->frm_grp);
if (ret)
{
mpp_err("clear buffer group failed ret %dn", ret);
break;
}
}
ret = mpp_buffer_group_limit_config(data->frm_grp, buf_size, 24);
if (ret)
{
mpp_err("limit buffer group failed ret %dn", ret);
break;
}
ret = mpi->control(ctx, MPP_DEC_SET_INFO_CHANGE_READY, NULL);
if (ret)
{
mpp_err("info change ready failed ret %dn", ret);
break;
}
}
else
{
err_info = mpp_frame_get_errinfo(frame) | mpp_frame_get_discard(frame);
if (err_info)
{
mpp_log("decoder_get_frame get err info:%d discard:%d.n", mpp_frame_get_errinfo(frame), mpp_frame_get_discard(frame));
}
data->frame_count++;
mpp_log("decode_get_frame get frame %dn", data->frame_count);
if (data->fp_output && !err_info)
{
dump_mpp_frame_to_file(frame, data->fp_output);
}
}
frm_eos = mpp_frame_get_eos(frame);
mpp_frame_deinit(&frame);
frame = NULL;
get_frm = 1;
}
if (data->frm_grp)
{
size_t usage = mpp_buffer_group_usage(data->frm_grp);
if (usage > data->max_usage)
{
data->max_usage = usage;
}
}
if (pkt_eos && pkt_done && !frm_eos)
{
msleep(10);
continue;
}
if (frm_eos)
{
mpp_log("found last framen");
break;
}
if (data->frame_num && data->frame_count >= data->frame_num)
{
data->eos = 1;
break;
}
if (get_frm)
{
continue;
}
break;
} while (1);
if (data->frame_num && data->frame_count >= data->frame_num)
{
data->eos = 1;
mpp_log("reach max frame number %dn", data->frame_count);
break;
}
if (pkt_done)
{
break;
}
} while (1);
return ret;
}
int mpi_dec_test_decode(MpiDecTestCmd *cmd)
{
MPP_RET ret = MPP_OK;
size_t file_size = 0;
MppCtx ctx = NULL;
MppApi *mpi = NULL;
MppPacket packet = NULL;
MppFrame frame = NULL;
MpiCmd mpi_cmd = MPP_CMD_BASE;
MppParam param = NULL;
RK_U32 need_split = 1;
RK_U32 width = cmd->width;
RK_U32 height = cmd->height;
MppCodingType type = cmd->type;
char *buf = NULL;
size_t packet_size = MPI_DEC_STREAM_SIZE;
MppBuffer pkt_buf = NULL;
MppBuffer frm_buf = NULL;
MpiDecLoopData data;
mpp_log("mpi_dec_test startn");
memset(&data, 0, sizeof(data));
data.fp_input = fopen("test.h264", "rb");
if (NULL == data.fp_input)
{
mpp_err("failed to open input file %sn", cmd->file_input);
goto MPP_TEST_OUT;
}
fseek(data.fp_input, 0L, SEEK_END);
file_size = ftell(data.fp_input);
rewind(data.fp_input);
mpp_log("input file size %ldn", file_size);
data.fp_output = fopen("output.yuv", "w+b");
if (cmd->simple)
{
buf = mpp_malloc(char, packet_size);
ret = mpp_packet_init(&packet, buf, packet_size);
}
mpp_log("mpi_dec_test decoder test start w %d h %d type %dn", width, height, type);
ret = mpp_create(&ctx, &mpi);
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 failedn");
goto MPP_TEST_OUT;
}
ret = mpp_init(ctx, MPP_CTX_DEC, type);
if (MPP_OK != ret)
{
mpp_err("mpp_init failedn");
goto MPP_TEST_OUT;
}
mpp_log("packet_size = %dn", packet_size);
data.ctx = ctx;
data.mpi = mpi;
data.eos = 0;
data.buf = buf;
data.packet = packet;
data.packet_size = packet_size;
data.frame = frame;
data.frame_count = 0;
data.frame_num = cmd->frame_num;
mpp_log("data.packet_size = %dn", data.packet_size);
if (cmd->simple)
{
while (!data.eos)
{
decode_simple(&data);
mpp_log("data.eos = %dn", data.eos);
}
}
cmd->max_usage = data.max_usage;
ret = mpi->reset(ctx);
if (MPP_OK != ret)
{
mpp_err("mpi->reset failedn");
goto MPP_TEST_OUT;
}
MPP_TEST_OUT:
if (packet)
{
mpp_packet_deinit(&packet);
packet = NULL;
}
if (frame)
{
mpp_frame_deinit(&frame);
frame = NULL;
}
if (ctx)
{
mpp_destroy(ctx);
ctx = NULL;
}
if (cmd->simple)
{
if (buf)
{
mpp_free(buf);
buf = NULL;
}
}
if (data.pkt_grp)
{
mpp_buffer_group_put(data.pkt_grp);
data.pkt_grp = NULL;
}
if (data.frm_grp)
{
mpp_buffer_group_put(data.frm_grp);
data.frm_grp = NULL;
}
if (data.fp_output)
{
fclose(data.fp_output);
data.fp_output = NULL;
}
if (data.fp_input)
{
fclose(data.fp_input);
data.fp_input = NULL;
}
return ret;
}
int main(int argc, char **argv)
{
RK_S32 ret = 0;
MpiDecTestCmd cmd_ctx;
MpiDecTestCmd* cmd = &cmd_ctx;
cmd->simple = 1;
cmd->type = 7;
cmd->width = 640;
cmd->height = 480;
ret = mpi_dec_test_decode(cmd);
return ret;
}
具体分析：
1、MPI接口的结构和使用，可以参考上篇内容，解码与编码基本一致。
2、解码器接口
decode_put_packet：
MPP_RET decode_put_packet（MppCtx ctx，MppPacket packet）
ctx：MPP解码器实例；
packet：待输入的码流数据；
输入码流的方式：分帧与不分帧。裸码流输入有两种，一种是按帧分段的数据，每一个输入给decode_put_packet函数的数据包都包含完整的一帧，不多也不少。在这种情况下，MPP可以直接按包处理码流。另一种是按长度读取数据，无法判断一个包的数据是否为完整的一帧，需要MPP内部进行分帧处理。在进行这种形式的输入时，需要在mpp_init前，通过control接口的MPP_DEC_SET_PARSER_SPLIT_MODE命令，打开need_split标志。分帧方式效率高，但需要在输入码流前进行解析与分帧，不分帧方式使用简单，效率会受影响。官方解码示例采用的是不分帧方式，因此上述代码也是不分帧方式。
decode_get_frame：
MPP_RET decode_get_frame（MppCtx ctx，MppFrame *frame）
ctx：MPP解码器实例；
frame：用于MppFrame实例的指针；
完整的解码过程是上面两个函数的结合。
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