[SoX-users] 回复： tempo effect leaves unexpected near-zero amplitude dataat end of segment

[纯. <634...@qq...>]

Hi, anyone know this error in IOS? 
play FAIL libsox: Sorry, there is no default audio device configured


I use the sox library in IOS, and I play a wav file, it can not work.




------------------ 原始邮件 ------------------
发件人: "forget color"<for...@gm...>; 
发送时间: 2015年7月31日(星期五) 晚上11:47
收件人: "sox-users"<sox...@li...>; 
主题: [SoX-users] tempo effect leaves unexpected near-zero amplitude dataat end of segment



Hi,

I've been working with the tempo effect and have found something unexpected. When I use tempo on a segment of a file, such as:


> sox in.wav out.wav trim 0 1 tempo -m 1.1


I get a file with the appropriate adjustment (faster, same pitch), but the end of the file (the last .006 seconds in this case) is silence (or near it---I haven't spit out the sample values to see if they're truly 0 or not).


This behavior appears to hold true regardless of the direction of tempo change, so:


> sox in.wav out.wav trim 0 1 tempo -m 0.9



Also leaves silence at the end of the file (in this case, about .025 worth).


This behavior isn't a problem for single segments, but I'm trying to make sequential adjustments to a file, such as:


> sox in.wav out.wav trim 0 1 tempo -m 0.9 : trim 0 1 tempo -m 1.1 : ...


And so the silence at the end of every segment is causing issues.


Is there a way around this, and/or is this intended/expected behavior? If I could predict how much silence it will append/insert, I could trim it off with silence, but I don't see how to predict it.


Thanks,
fg