.h264 .h265 压缩率的直观感受

1.资源文件

https://download.csdn.net/download/twicave/89579327

上面是.264 .265和原始的YUV420文件,各自的大小。

2.转换工具:

2.1 .h264 .h265互转

可以使用ffmpeg工具:Builds - CODEX FFMPEG @ gyan.dev

命令行参数:

ffmpeg -i Tennis1080p.h264 -c:v libx265 -preset medium -crf 28 Tennis1080p.h265

2.2 .h264 转 yuv

我因为要测试rk3588上一个硬件解码器,使用的是一个.c代码:

mpp-test: Rockchip MPP的简单案例

2.3 yuv file reader

这个可以使用python直接处理:

python 复制代码
import cv2
import numpy as np


yuv_frame_pack_file = "Tennis1080p.yuv"

def yuv420sp_to_rgb(nv12, width, height):
        print('lenOfframe = ', len(nv12))
        nv12_array = np.frombuffer(nv12, dtype=np.uint8)
        #if len(nv12_array) > (width * height * 3 // 2):
        #    height += ((len(nv12_array) - (width * height * 3 // 2)) // width * 2) // 3
        y_plane_size = height * width
        uv_plane_size = (height // 2) * (width // 2) * 2
        # Split the NV12 data into Y plane and UV plane
        y_plane = nv12_array[0:y_plane_size].reshape(height, width)
        
        uv_plane = nv12_array[y_plane_size:y_plane_size+uv_plane_size].reshape(height // 2, width)  # UV plane is half the height of Y plane
    
        # Create a new NumPy array for the YUV image, with the same data as Y plane
        # but with a shape that OpenCV expects for YUV420sp (NV12)
        yuv420sp = np.zeros((height + height // 2, width), dtype=np.uint8)
        yuv420sp[:height, :] = y_plane  # Copy Y plane data
        yuv420sp[height:, ::2] = uv_plane[:, 1::2]  # Copy U plane data
        yuv420sp[height:, 1::2] = uv_plane[:, ::2]  # Copy V plane data

        '''
        # 文件路径
        file_path = 'yuv420sp.bin'
        # 打开文件并写入数据
        with open(file_path, 'wb') as file:
            file.write(nv12)
        sys.exit(0)
        '''
    
        # Use OpenCV to convert YUV420sp (NV12) to RGB
        rgb_image = cv2.cvtColor(yuv420sp, cv2.COLOR_YUV2RGB_NV12)
    
        return rgb_image


# 设置图像的宽度和高度
width, height = 1920, 1080

# 读取一帧YUV420数据
cnt = 23
with open(yuv_frame_pack_file , 'rb') as file:
    while(cnt>0):
        cnt -=1
        yuv420_frame = file.read(width * height * 3 // 2)  # YUV420格式,每帧大小为width * height * 3 / 2
        continue
    yuv420_frame = file.read(width * height * 3 // 2)  # YUV420格式,每帧大小为width * height * 3 / 2
    yuv420_frame = np.frombuffer(yuv420_frame, dtype=np.uint8)
    rgb_frame = yuv420sp_to_rgb(yuv420_frame, width, height)
    cv2.imshow('RGB Image', rgb_frame)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

2.3.1解码效果

附录A h.265=>yuv frames file转换工具

实际测试过程中,您可能需要对.h264, .h265的转换速度做比对,这里给出.h265转储为yuv frames file的C代码,相较2.2的原始c代码修改很少:

我只改了mpp_init,和需要处理的.h265文件名。

cpp 复制代码
/**
 * 1. make
 * 2. ./mpp-dec-h264-to-yuv-file
 * 3. gst-launch-1.0 filesrc location=Tennis1080p.yuv ! videoparse width=1920 height=1080 format=nv12 ! videoconvert ! xvimagesink
 * 4. gst-launch-1.0 filesrc location=Tennis1080p.h264 ! h264parse ! mppvideodec ! xvimagesink
 */
#include <unistd.h>
#include <stdio.h>
#include <rockchip/rk_mpi.h>

#define __IN_FILE__ ("Tennis1080p.h265")
#define __OUT_FILE__ ("Tennis1080p.yuv")

void dump_frame(MppFrame frame, FILE *out_fp)
{
    printf("dump_frame_to_file\n");

    RK_U32 width    = 0;
    RK_U32 height   = 0;
    RK_U32 h_stride = 0;
    RK_U32 v_stride = 0;
    MppFrameFormat fmt  = MPP_FMT_YUV420SP;
    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);
    fmt      = mpp_frame_get_fmt(frame);
    buffer   = mpp_frame_get_buffer(frame);

    RK_U32 buf_size = mpp_frame_get_buf_size(frame);
    printf("w x h: %dx%d hor_stride:%d ver_stride:%d buf_size:%d\n",
           width, height, h_stride, v_stride, buf_size);
           
    if (NULL == buffer) {
        printf("buffer is null\n");
        return ;
    }

    base = (RK_U8 *)mpp_buffer_get_ptr(buffer);

    // MPP_FMT_YUV420SP
    if (fmt != MPP_FMT_YUV420SP) {
        printf("fmt %d not supported\n", fmt);
        return;
    }

    RK_U32 i;
    RK_U8 *base_y = base;
    RK_U8 *base_c = base + h_stride * v_stride;

    for (i = 0; i < height; i++, base_y += h_stride) {
        fwrite(base_y, 1, width, out_fp);
    }
    for (i = 0; i < height / 2; i++, base_c += h_stride) {
        fwrite(base_c, 1, width, out_fp);
    }
}

void dump_frame_to_file(MppCtx ctx, MppApi *mpi, MppFrame frame, FILE *out_fp)
{
    printf("decode_and_dump_to_file\n");

    MPP_RET ret;

    if (mpp_frame_get_info_change(frame)) {
        printf("mpp_frame_get_info_change\n");
        /**
         * 第一次解码会到这个分支,需要为解码器设置缓冲区.
         * 解码器缓冲区支持3种模式。参考【图像内存分配以及交互模式】Rockchip_Developer_Guide_MPP_CN.pdf
         * 这里使用纯内部模式。
         */
        ret = mpi->control(ctx, MPP_DEC_SET_INFO_CHANGE_READY, NULL);
        if (ret) {
            printf("mpp_frame_get_info_change mpi->control error"
                    "MPP_DEC_SET_INFO_CHANGE_READY %d\n", ret);
        }
        return;
    }

    RK_U32 err_info = mpp_frame_get_errinfo(frame);
    RK_U32 discard = mpp_frame_get_discard(frame);    
    printf("err_info: %u discard: %u\n", err_info, discard);

    if (err_info) {
        return;
    }
        
    // save
    dump_frame(frame, out_fp);
    return;
}

int main(void)
{
    printf("---------- mpp start ----------\n");

    // 1. 打开输入文件
    FILE *in_fp = fopen(__IN_FILE__, "rb");
    if (!in_fp) {
        printf("fopen error\n");
        return -1;
    }

    // 2. 打开输出文件
    FILE *out_fp = fopen(__OUT_FILE__, "wb+");
    if (!out_fp) {
        printf("fopen error\n");
        return -1;
    }

    // 3. 初始化解码器上下文,MppCtx MppApi
    MppCtx ctx = NULL;
    MppApi *mpi = NULL;
    MPP_RET ret = mpp_create(&ctx, &mpi);
    if (MPP_OK != ret) {
        printf("mpp_create error\n");
        return -1;
    }

    /**
     * 4. 配置解器
     *      - 解码文件需要 split 模式
     *      - 设置非阻塞模式,0非阻塞(默认),-1阻塞,+val 超时(ms)
     */
    RK_U32 need_split = -1;
    ret = mpi->control(ctx, MPP_DEC_SET_PARSER_SPLIT_MODE, (MppParam*)&need_split);
    if (MPP_OK != ret) {
        printf("mpi->control error MPP_DEC_SET_PARSER_SPLIT_MODE\n");
        return -1;
    }
    
    ret = mpp_init(ctx, MPP_CTX_DEC, MPP_VIDEO_CodingHEVC);  // 固定为H265 https://blog.csdn.net/weixin_38807927/article/details/135760601
    if (MPP_OK != ret) {
        printf("mpp_init error\n");
        return -1;
    }

    // 5. 初始化包,MppPacket
    int buf_size = 5 * 1024 * 1024;
    char *buf = (char*)malloc(buf_size);
    if (!buf) {
        printf("malloc error\n");
        return -1;
    }
    MppPacket pkt = NULL;
    ret = mpp_packet_init(&pkt, buf, buf_size);
    if (MPP_OK != ret) {
        printf("mpp_packet_init error\n");
        return -1;
    }

    // 6. 循环读取文件,输入解码器,解码,保存结果
    int over = 0;
    while (!over) {
        printf("decode...\n");
        int len = fread(buf, 1, buf_size, in_fp);
        printf("read file length:%d\n", len);

        if (0 < len) {
            mpp_packet_write(pkt, 0, buf, len);
            mpp_packet_set_pos(pkt, buf);
            mpp_packet_set_length(pkt, len);
            if (feof(in_fp) || len < buf_size) {  // 文件读完,设置结束标志位
                mpp_packet_set_eos(pkt);
                printf("mpp_packet_set_eos\n");
            }
        }

        /**
         * decode_put_packet返回失败,意味着内部缓冲区已满。
         * 非阻塞模式,使用pkt_is_send判断当前读取的数据包(buf)是否成功发送。
         */
        int pkt_is_send = 0;
        while (!pkt_is_send && !over) {
            if (0 < len) {
                printf("pkt remain:%d\n", mpp_packet_get_length(pkt));
                ret = mpi->decode_put_packet(ctx, pkt);
                if (MPP_OK == ret) {
                    printf("pkt send success remain:%d\n", mpp_packet_get_length(pkt));
                    pkt_is_send = 1;
                }
            }

            MppFrame frame;
            MPP_RET ret;
            ret = mpi->decode_get_frame(ctx, &frame);
            if (MPP_OK != ret || !frame) {
                printf("decode_get_frame falied ret:%d\n", ret);
                usleep(2000);  // 等待一下2ms,通常1080p解码时间2ms
                continue;
            }

            printf("decode_get_frame success\n");
            dump_frame_to_file(ctx, mpi, frame, out_fp);

            if (mpp_frame_get_eos(frame)) {
                printf("mpp_frame_get_eos\n");
                mpp_frame_deinit(&frame);
                over = 1;
                continue;
            }
            mpp_frame_deinit(&frame);
        }
    }

    // 7. 释放资源
    fclose(in_fp);
    fclose(out_fp);
    mpi->reset(ctx);
    mpp_packet_deinit(&pkt);
    mpp_destroy(ctx);
    free(buf);
    
    printf("---------- mpp over ----------\n");
    return 0;
}

A.1相应的make file :

将文件放置在.c文件的同级目录,命名为:makefile

bash 复制代码
app: mpp-dec-h264-to-yuv-file.c mpp-multi-thread-demo.c mpp-dec-h265-to-yuv-file.c
	gcc mpp-dec-h264-to-yuv-file.c -o mpp-dec-h264-to-yuv-file -lrockchip_mpp
	gcc mpp-dec-h265-to-yuv-file.c -o mpp-dec-h265-to-yuv-file -lrockchip_mpp
	gcc mpp-multi-thread-demo.c -o mpp-multi-thread-demo -lrockchip_mpp -lpthread -I/usr/include/glib-2.0 -I/usr/lib/aarch64-linux-gnu/glib-2.0/include -lglib-2.0

需要编译时:执行

make

即可。

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