实现ffplay命令行执行命令,数字1模拟播放/暂停,数字2切换下一首,数字3切换上一首,数字4切换歌曲模式,例如单曲模式,单曲循环,列表循环等,默认为单曲模式。
note:暂停时结束所有进程,记录播放的时间戳,播放时把命令行执行的出书重定向到一个日志文件中去,从日志中获取时间戳开始播放。
至于模式的选择,需要设置信号处理函数,处理子进程的退出状态,执行相应的操作,以下为例程c语言源码。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sys/wait.h>
#define MAX_SONGS 3
typedef enum {
SINGLE_PLAY,
SINGLE_REPEAT,
PLAYLIST_REPEAT
} PlaybackMode;
char *songs[MAX_SONGS] = {
"/mnt/hgfs/share/poxiao.mp3",
"/mnt/hgfs/share/talk_anymore.mp3",
"/mnt/hgfs/share/attention.mp3"
};
int current_song = 0;
pid_t player_pid = 0;
double pause_timestamp = 0.0;
PlaybackMode current_mode = SINGLE_PLAY;
// 获取当前播放时间
double get_current_playback_time() {
char buffer[256];
double time = 0.0;
FILE *ffplay_pipe;
// 确保 /tmp/ffplay_log 文件存在并且 ffplay 正在写入时间戳
ffplay_pipe = popen("grep -oP '\\b[0-9]+\\.[0-9]{2}\\b' /tmp/ffplay_log | tail -n 1", "r");
if (ffplay_pipe) {
if (fgets(buffer, sizeof(buffer), ffplay_pipe) != NULL) {
sscanf(buffer, "%lf", &time);
}
pclose(ffplay_pipe);
}
return time;
}
// 停止播放
void stop_playback() {
if (player_pid > 0) {
// 发送 SIGKILL 信号到进程组
if (kill(-player_pid, SIGKILL) < 0) {
perror("无法终止播放进程组");
}
// 等待进程组中的所有进程结束
waitpid(player_pid, NULL, 0);
player_pid = 0;
printf("播放已停止。\n");
}
}
// 处理子进程结束的信号
void handle_sigchld(int sig) {
int status;
pid_t pid;
while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
if (pid == player_pid) {
if (WIFEXITED(status) || WIFSIGNALED(status)) {
player_pid = 0;
handle_song_end();
}
}
}
}
// 播放歌曲
void play_song(int song_index, double start_time) {
char command[512];
stop_playback();
// 清空日志文件
FILE *log_file = fopen("/tmp/ffplay_log", "w");
if (log_file) {
fclose(log_file);
}
// 构建 ffplay 命令
if (start_time > 0) {
snprintf(command, sizeof(command), "ffplay -nodisp -autoexit -ss %f \"%s\" 2> /tmp/ffplay_log", start_time, songs[song_index]);
} else {
snprintf(command, sizeof(command), "ffplay -nodisp -autoexit \"%s\" 2> /tmp/ffplay_log", songs[song_index]);
}
player_pid = fork();
if (player_pid == 0) {
// 子进程
// 创建新的会话,使其成为进程组的领导者
if (setsid() < 0) {
perror("setsid 失败");
exit(1);
}
execl("/bin/sh", "sh", "-c", command, (char *)NULL);
perror("execl 失败");
exit(1);
} else if (player_pid > 0) {
// 父进程
// 确保信号处理器只注册一次
// 此处无需每次播放歌曲都注册信号处理器,因此可以在 main 函数中注册
}
printf("播放开始,歌曲编号: %d, PID: %d, 时间戳: %f\n", song_index, player_pid, start_time);
pause_timestamp = 0.0;
}
// 切换播放/暂停
void toggle_play_pause() {
if (player_pid > 0) {
pause_timestamp = get_current_playback_time();
stop_playback();
printf("暂停播放,时间戳: %f 秒\n", pause_timestamp);
} else {
play_song(current_song, pause_timestamp);
printf("继续播放,时间戳: %f 秒\n", pause_timestamp);
}
}
// 处理单曲播放结束
void handle_single_play_end() {
pause_timestamp = 0.0;
printf("单曲播放完成。\n");
}
// 处理歌曲结束,根据模式决定下一步
void handle_song_end() {
printf("歌曲播放结束,当前模式: %d\n", current_mode);
switch (current_mode) {
case SINGLE_PLAY:
handle_single_play_end();
break;
case SINGLE_REPEAT:
play_song(current_song, 0.0);
break;
case PLAYLIST_REPEAT:
current_song = (current_song + 1) % MAX_SONGS;
play_song(current_song, 0.0);
break;
}
}
// 播放下一首歌曲
void play_next_song() {
stop_playback();
current_song = (current_song + 1) % MAX_SONGS;
pause_timestamp = 0.0;
play_song(current_song, pause_timestamp);
}
// 播放上一首歌曲
void play_previous_song() {
stop_playback();
current_song = (current_song - 1 + MAX_SONGS) % MAX_SONGS;
pause_timestamp = 0.0;
play_song(current_song, pause_timestamp);
}
// 切换播放模式
void toggle_mode() {
current_mode = (PlaybackMode)((current_mode + 1) % 3);
switch (current_mode) {
case SINGLE_PLAY:
printf("模式切换为: 单曲播放\n");
break;
case SINGLE_REPEAT:
printf("模式切换为: 单曲循环\n");
break;
case PLAYLIST_REPEAT:
printf("模式切换为: 列表循环\n");
break;
}
}
int main() {
int command;
// 在主函数中注册 SIGCHLD 信号处理器,只需注册一次
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = handle_sigchld;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART | SA_NOCLDSTOP;
if (sigaction(SIGCHLD, &sa, NULL) < 0) {
perror("sigaction 注册失败");
exit(1);
}
while (1) {
printf("请输入指令 (1: 播放/暂停, 2: 下一首, 3: 上一首, 4: 切换模式): ");
if (scanf("%d", &command) != 1) {
// 清理输入缓冲区
int c;
while ((c = getchar()) != '\n' && c != EOF);
printf("输入无效,请输入数字。\n");
continue;
}
switch (command) {
case 1:
toggle_play_pause();
break;
case 2:
play_next_song();
break;
case 3:
play_previous_song();
break;
case 4:
toggle_mode();
break;
default:
printf("无效的指令\n");
break;
}
}
return 0;
}