+
+ command=strprintf("ffmpeg -ss 00:00:00.%d -i \"%s\" -an -f image2pipe -vcodec ppm -\n",frame,filename.c_str());
+
+ file=popen(command.c_str(),POPEN_BINARY_READ_TYPE);
+
+#elif defined(UNIX_PIPE_TO_PROCESSES)
+
+ int p[2];
+
+ if (pipe(p)) {
+ cerr<<"Unable to open pipe to ffmpeg"<<endl;
+ return false;
+ };
+
+ pid = fork();
+
+ if (pid == -1) {
+ cerr<<"Unable to open pipe to ffmpeg"<<endl;
+ return false;
+ }
+
+ if (pid == 0){
+ // Child process
+ // Close pipein, not needed
+ close(p[0]);
+ // Dup pipein to stdout
+ if( dup2( p[1], STDOUT_FILENO ) == -1 ){
+ cerr<<"Unable to open pipe to ffmpeg"<<endl;
+ return false;
+ }
+ // Close the unneeded pipein
+ close(p[1]);
+ string time = strprintf("00:00:00.%d",frame);
+ execlp("ffmpeg", "ffmpeg", "-ss", time.c_str(), "-i", filename.c_str(), "-an", "-f", "image2pipe", "-vcodec", "ppm", "-", (const char *)NULL);
+ // We should never reach here unless the exec failed
+ cerr<<"Unable to open pipe to ffmpeg"<<endl;
+ _exit(1);
+ } else {
+ // Parent process
+ // Close pipeout, not needed
+ close(p[1]);
+ // Save pipein to file handle, will read from it later
+ file = fdopen(p[0], "rb");
+ }
+
+#else
+ #error There are no known APIs for creating child processes
+#endif
+