学校拍了段视频，我拿到了mp4文件，看文件是sony机器拍的：
但是这个mp4很奇怪，无法用常规的mp4box提取里边的音视频文件，得出错误提示：
F:\20170706>mp4box -info 194_0091_01.mp4
[iso file] Unknown box type twos
[iso file] Unknown box type twos
[iso file] Unknown box type twos
[iso file] Unknown box type twos
[iso file] Unknown box type
[isom] not enough bytes in box xml : 0 left, reading 1 (file ..\..\src\isomedia\
box_code_base.c, line 10395)
[iso file] Read Box "xml " failed (Invalid IsoMedia File) - skipping
[iso file] Read Box "meta" failed (Invalid IsoMedia File) - skipping
[iso file] Read Box "moov" failed (Invalid IsoMedia File) - skipping
Error opening file 194_0091_01.mp4: Invalid IsoMedia File
F:\20170706>
后来我想了个弯路，先把这个mp4 mux成mkv，再从这个mkv里边剥音频，得到了里边的1个视频和4个音频，这4个音频我导入au里边看了下，都是一样的波形，不懂为啥会弄成这样一样的4条音轨出来，难道是拍摄的时候没设置好？
还有个邪门的事，sony这个机器默认文件大小是3.58g，当录制文件大小超过这个容量就自动分割。我总共有10个这样的mp4，我把这10个mp4用mkv mux成一个mkv了，然后播放的时候发现，每个文件衔接的地方，都会卡一下，总共卡了9下（刚好是10个mp4衔接的地方）
请教dv高手帮忙给点思路，该怎么弄?

这个mp4的mediainfo：
General
Complete name : F:\20170706\194_0091_05.MP4
Format : MPEG-4
Commercial name : XDCAM EX 35
Format profile : Base Media / Version 2
Codec ID : mp42 (mp42)
File size : 3.59 GiB
Duration : 13 min 32 s
Overall bit rate mode : Variable
Overall bit rate : 37.9 Mb/s
Encoded date : UTC 2017-07-06 02:20:18
Tagged date : UTC 2017-07-06 02:20:18
Video
ID : 1
Format : MPEG Video
Commercial name : XDCAM EX 35
Format version : Version 2
Format profile : Main@High
Format settings, BVOP : Yes
Format settings, Matrix : Custom
Format settings, GOP : M=3, N=12
Format settings, picture struc : Frame
Codec ID : 61
Duration : 13 min 32 s
Bit rate mode : Variable
Bit rate : 35.0 Mb/s
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 25.000 FPS
Standard : Component
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Interlaced
Scan order : Top Field First
Compression mode : Lossy
Bits/(Pixel*Frame) : 0.675
Stream size : 3.30 GiB (92%)
Language : English
Encoded date : UTC 2017-07-06 02:20:18
Tagged date : UTC 2017-07-06 02:20:18
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
Audio #1
ID : 2
Format : PCM
Format settings, Endianness : Big
Format settings, Sign : Signed
Codec ID : twos
Duration : 13 min 32 s
Bit rate mode : Constant
Bit rate : 768 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Bit depth : 16 bits
Stream size : 74.4 MiB (2%)
Language : English
Encoded date : UTC 2017-07-06 02:20:18
Tagged date : UTC 2017-07-06 02:20:18
Audio #2
ID : 3
Format : PCM
Format settings, Endianness : Big
Format settings, Sign : Signed
Codec ID : twos
Duration : 13 min 32 s
Bit rate mode : Constant
Bit rate : 768 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Bit depth : 16 bits
Stream size : 74.4 MiB (2%)
Language : English
Encoded date : UTC 2017-07-06 02:20:18
Tagged date : UTC 2017-07-06 02:20:18
Audio #3
ID : 4
Format : PCM
Format settings, Endianness : Big
Format settings, Sign : Signed
Codec ID : twos
Duration : 13 min 32 s
Bit rate mode : Constant
Bit rate : 768 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Bit depth : 16 bits
Stream size : 74.4 MiB (2%)
Language : English
Encoded date : UTC 2017-07-06 02:20:18
Tagged date : UTC 2017-07-06 02:20:18
Audio #4
ID : 5
Format : PCM
Format settings, Endianness : Big
Format settings, Sign : Signed
Codec ID : twos
Duration : 13 min 32 s
Bit rate mode : Constant
Bit rate : 768 kb/s
Channel(s) : 1 channel
Sampling rate : 48.0 kHz
Bit depth : 16 bits
Stream size : 74.4 MiB (2%)
Language : English
Encoded date : UTC 2017-07-06 02:20:18
Tagged date : UTC 2017-07-06 02:20:18

我现在的做法是用mp4box把视频（音频就是不行）提取出来，格式是m2v，然后再合并，发现每个文件之间衔接的停顿消失了，很流畅，不知道是为什么。

摄像机有这么多条音轨是因为对应不同的音频输入源

还有，音频codec id是twos什么鬼？

没用xavc格式么