FFMpeg时间转换计算

int seconds = formatContext->duration / AV_TIME_BASE;
int us = formatContext->duration % AV_TIME_BASE;
int minutes = seconds / 60;
[s appendFormat:@"%02d:%02d:%02d.%01d",
minutes / 60, minutes % 60, seconds % 60, (10 * us) / AV_TIME_BASE];