如题eac3to抽取truehd音轨，原本24bit的抽出来变成16bit的。 有无大神知道是什么原因，用了好多方法抽，依然出来是16bit的。
log如下
eac3to v3.31
command line: eac3to "H:\[TSDM@小雨]Kurozuka BDMVs\Kurozuka BDMVs\DISC 1\BDMV\STREAM\00000.m2ts" 2:audio_3.thd
------------------------------------------------------------------------------
M2TS, 1 video track, 1 audio track, 1 subtitle track, 0:23:01, 24p /1.001
1: h264/AVC, 1080p24 /1.001 (16:9)
2: TrueHD/AC3, Japanese, 5.1 channels, 48kHz
(embedded: AC3, 5.1 channels, 640k
bp
s, 48kHz)
3: Subtitle (PGS), Japanese
[a02] Extracting audio track number 2...
[a02] Extracting TrueHD stream...
[a02] Creating file "audio_3.thd"...
Video track 1 contains 33112 frames.
eac3to processing took 1 minute, 12 seconds.
Done.
源盘是24bit的
c

如果源是原生16bit的，通过bit padding升至24bit，eac3to检测到后会移除padding还原回16bit。

那怎样判断源16bit还是24bit的，哪个软件检测得准确？

Q: How do I check whether a TrueHD track is 16, 20 or 24 bit?
A: Every TrueHD track has a bit-depth of 24 bit. Every one. Every TrueHD decoder always outputs 24 bit. However, here comes the big key: Most times, only some of those 24 bits are filled with real audio data and the rest is just zeroed out. This means that some TrueHD tracks contain full 24 bit of information, while others have 4 bit or 8 bit of those 24 bit filled up with nothing but zeroes. eac3to detects both situations and behaves accordingly. It will never throw away any audio data when doing a conversion, unless you explicitly tell it to.

说是只是抽取，不改变源原本信息，但是目前确实出来之后是改变了。

However, here comes the big key: Most times, only some of those 24 bits are filled with real audio data and the rest is just zeroed out.