ffmpeg 转换教学视频

之前还有重命名
对bat不熟悉，所以我就用Javascript生成了一堆命令，重命名
然后保存bat。文件夹运行

OK，
现在材料都准备好了。我有avi 和mp3

test.avi 93.9 MB (93,912,066 字节)
test.MP3 3.4 MB (3,440,840 字节)

test.avi的信息
Input #0, avi, from 'test.avi':
Metadata:
encoder : Lavf52.31.0
Duration: 00:28:51.83, start: 0.000000, bitrate: 433 kb/s
Stream #0:0: Video: mpeg4 (Simple Profile) (XVID / 0x44495658), yuv420p, 720x400 [SAR 1:1 DAR 9:5], 6 tbr, 6 tbn, 6 tbc
Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 44100 Hz, stereo, s16p, 128 kb/s
test.MP3的信息
Input #0, mp3, from 'test.MP3':
Duration: 00:28:40.42, start: 0.000000, bitrate: 16 kb/s
Stream #0:0: Audio: mp3, 11025 Hz, mono, s16p, 16 kb/s

首先给avi去声音并转码mkv
[xy@localhost ~]$ ffmpeg -i test.avi -an test.mkv

生成的test.mkv的信息
Input #0, matroska,webm, from 'test.mkv':
Metadata:
ENCODER : Lavf54.63.104
Duration: 00:28:52.17, start: 0.000000, bitrate: 42 kb/s
Stream #0:0: Video: h264 (High), yuv420p, 720x400 [SAR 1:1 DAR 9:5], 6 fps, 6 tbr, 1k tbn, 12 tbc (default)

这个时候，如果我直接合成的话
ffmpeg -i test.mkv -i test.MP3 test1.mkv
15.4 MB (15,377,891 字节)
大小有15.4MB，大于原 视频mkv(9.2 MB) + 音频mp3(3.4 MB)=12.6M
应该算mp3被转码了，查看 test1.mkv的信息
Input #0, matroska,webm, from 'test1.mkv':
Metadata:
ENCODER : Lavf54.63.104
Duration: 00:28:52.19, start: 0.000000, bitrate: 71 kb/s
Stream #0:0: Video: h264 (High), yuv420p, 720x400 [SAR 1:1 DAR 9:5], 6 fps, 6 tbr, 1k tbn, 12 tbc (default)
Stream #0:1: Audio: vorbis, 11025 Hz, mono, fltp

[xy@localhost ~]$ ffmpeg -i test.mkv -i test.MP3 -vcodec copy -acodec copy test2.mkv
---------------------------------------------------------------------------------------------
–vcodec copy为force video codec(‘copy’ to copy stream)
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这时候生成的test2.mkv 大小为 12.8 MB，完美了
---------------------------------------------------------------------------------------------
test2.mkv的信息
Input #0, matroska,webm, from 'test2.mkv':
Metadata:
ENCODER : Lavf54.63.104
Duration: 00:28:52.17, start: 0.000000, bitrate: 59 kb/s
Stream #0:0: Video: h264 (High), yuv420p, 720x400 [SAR 1:1 DAR 9:5], 6 fps, 6 tbr, 1k tbn, 12 tbc (default)
Stream #0:1: Audio: mp3, 11025 Hz, mono, s16p, 16 kb/s