amlogic播放h264我一份代码

以下是使用Amlogic SoC播放H.264视频的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <linux/videodev2.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "amvideocap.h"

// 视频设备名称
#define DEVICE_NAME "/dev/video0"

int main(int argc, char *argv[])
{
    int fd, ret;
    struct v4l2_capability cap;
    struct v4l2_format fmt;
    struct v4l2_requestbuffers req;
    struct v4l2_buffer buf;
    void *buffer_start[4];
    size_t buffer_length[4];
    size_t num_buffers;
    int i, j;
    char *filename = NULL;
    int frame_count = 0;

    if (argc < 2) {
        fprintf(stderr, "Usage: %s filename\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    filename = argv[1];

    // 打开视频设备
    fd = open(DEVICE_NAME, O_RDWR);
    if (fd == -1) {
        fprintf(stderr, "Failed to open device: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }

    // 查询设备能力
    ret = ioctl(fd, VIDIOC_QUERYCAP, &cap);
    if (ret == -1) {
        fprintf(stderr, "Failed to query capability: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }

    // 检查设备是否支持视频捕捉
    if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
        fprintf(stderr, "Device does not support video capture\n");
        exit(EXIT_FAILURE);
    }

    // 检查设备是否支持H.264编码
    if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE_MPLANE)) {
        fprintf(stderr, "Device does not support multiplanar video capture\n");
        exit(EXIT_FAILURE);
    }

    // 设置视频格式
    memset(&fmt, 0, sizeof(fmt));
    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
    fmt.fmt.pix_mp.width = 1920; // 视频宽度
    fmt.fmt.pix_mp.height = 1080; // 视频高度
    fmt.fmt.pix_mp.pixelformat = V4L2_PIX_FMT_H264; // 视频编码格式
    fmt.fmt.pix_mp.num_planes = 1; // 每帧数据平面数
    ret = ioctl(fd, VIDIOC_S_FMT, &fmt);
    if (ret == -1) {
        fprintf(stderr, "Failed to set format: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }

    // 请求视频缓冲区
    memset(&req, 0, sizeof(req));
    req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
    req.memory = V4L2_MEMORY_MMAP;
    req.count = 4;
    ret = ioctl(fd, VIDIOC_REQBUFS, &req);
    if (ret == -1) {
        fprintf(stderr, "Failed to request buffers: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }

    num_buffers = req.count;

    // 映射视频缓冲区
    for (i = 0; i < num_buffers; i++) {
        struct v4l2_plane planes[1];
        struct v4l2_buffer buf;

        memset(&buf, 0, sizeof(buf));
        memset(&planes, 0, sizeof(planes));

        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
        buf.memory = V4L2_MEMORY_MMAP;
        buf.index = i;
        buf.m.planes = planes;
        buf.length = 1;

        ret = ioctl(fd, VIDIOC_QUERYBUF, &buf);
        if (ret == -1) {
            fprintf(stderr, "Failed to query buffer %d: %s\n", i, strerror(errno));
            exit(EXIT_FAILURE);
        }

        buffer_length[i] = buf.m.planes[0].length;
        buffer_start[i] = mmap(NULL, buffer_length[i], PROT_READ | PROT_WRITE, MAP_SHARED, fd, buf.m.planes[0].m.mem_offset);
        if (buffer_start[i] == MAP_FAILED) {
            fprintf(stderr, "Failed to mmap buffer %d: %s\n", i, strerror(errno));
            exit(EXIT_FAILURE);
        }
    }

    // 将视频缓冲区入队
    for (i = 0; i < num_buffers; i++) {
        struct v4l2_plane planes[1];
        struct v4l2_buffer buf;

        memset(&buf, 0, sizeof(buf));
        memset(&planes, 0, sizeof(planes));

        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
        buf.memory = V4L2_MEMORY_MMAP;
        buf.index = i;
        buf.m.planes = planes;
        buf.length = 1;

        ret = ioctl(fd, VIDIOC_QBUF, &buf);
        if (ret == -1) {
            fprintf(stderr, "Failed to queue buffer %d: %s\n", i, strerror(errno));
            exit(EXIT_FAILURE);
        }
    }

    // 启动视频捕获
    enum v4l2_buf_type type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
    ret = ioctl(fd, VIDIOC_STREAMON, &type);
    if (ret == -1) {
        fprintf(stderr, "Failed to start streaming: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }

    // 打开输出文件
    int output_fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR | S_IRGRP);
    if (output_fd == -1) {
        fprintf(stderr, "Failed to open output file: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }

    // 循环获取视频帧数据并写入输出文件
    while (frame_count < 100) {
        // 从视频缓冲区取出一帧数据
        memset(&buf, 0, sizeof(buf));
        memset(&buf.m, 0, sizeof(buf.m));
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
        buf.memory = V4L2_MEMORY_MMAP;
        ret = ioctl(fd, VIDIOC_DQBUF, &buf);
        if (ret == -1) {
            fprintf(stderr, "Failed to dequeue buffer: %s\n", strerror(errno));
            exit(EXIT_FAILURE);
        }

        // 将帧数据写入输出文件
        size_t bytes_written = write(output_fd, buffer_start[buf.index], buffer_length[buf.index]);
        if (bytes_written != buffer_length[buf.index]) {
            fprintf(stderr, "Failed to write frame to output file: %s\n", strerror(errno));
            exit(EXIT_FAILURE);
        }

        // 将视频缓冲区重新入队
        ret = ioctl(fd, VIDIOC_QBUF, &buf);
        if (ret == -1) {
            fprintf(stderr, "Failed to queue buffer: %s\n", strerror(errno));
            exit(EXIT_FAILURE);
        }

        frame_count++;
    }

    // 停止视频捕获
    ret = ioctl(fd, VIDIOC_STREAMOFF, &type);
    if (ret == -1) {
        fprintf(stderr, "Failed to stop streaming: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }

    // 关闭视频设备
    close(fd);

    // 关闭输出文件
    close(output_fd);

    // 释放视频缓冲区
    for (i = 0; i < num_buffers; i++) {
        munmap(buffer_start[i], buffer_length[i]);
    }

    exit(EXIT_SUCCESS);
}

这段代码使用V4L2接口与Amlogic SoC的视频设备进行交互，从视频设备中获取H.264编码的视频帧数据，并将其写入文件中。