【测试源】bbb_sunflower_1080p_30fps_normal.mp4 等下载地址 Multi-track MP4 file 双声道 AAC LC 音频 // Generate a scaled down to 320x240 video + 2 channel AAC LC audio from the source file. ffmpeg -i bbb_sunflower_1080p_30fps_normal.mp4 -c:v libx264 -crf 36 -vf scale=320:240 -c:a libfdk_aac -ac 2 -t 24