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Acmstreamopen return value problem

2022-06-25 04:10:00 【Small waves-】

explain :

It was more than ten years ago that I first encountered this function , Recently, I turned to the back , It feels very interesting , Why didn't you use it very much , It seems that not many people use it now , I called , I don't know whether the calling environment has changed after many years or what , How to return 512. So I began to search for the answer .

Understand this function , Still want to know windows In the library msacm, This thing comes from Windows Multimedia, Already more than 20 Years of old technology . Usually called ACM（Audio Compression Manager, Audio Compression Manager ）, They are responsible for managing all audio codecs in the system . As long as the number decoder is registered in the system, it can be used acm decode , Applications can be ACM or VCM The provided programming interface calls the off the shelf codec in these systems to realize the compression and decompression of audio or video data .

Use acm Can be played and registered in the system , Convert any format of sound file driven , For example, my machine has mp3 Format driver and have conversion driver , I can play it . From the official website ,acm There are enough correlation functions , The function is also powerful enough , Why not ？

Problems encountered :

acmStreamOpen return 512

Take out the old routine and run , Enumerating devices is no problem , Also found GSM And so on , And then I recorded a PCM（8000,1,8） The audio of , I want to change to GSM, Go to the acmStreamOpen It's stuck , I can't go on , return 512.

What the hell is it ？ If you look at the process carefully, you can't see the problem , The return value is not explained . Search online , That's all. N The old problem years ago , And most of them have no follow-up .

No documents , There are no examples , Use fewer people , It seems that it can only be stuck , It doesn't mean anything to me , Just give up . Can it be said that after 20 It can still be preserved for many years windows There is a problem with the technology in the library , No .

But it doesn't seem to be without a clue , Before the program or run , So the function call order is adjusted , Find out acmStreamOpen Back to 8, There are some invisible pits . Return value 8 There are still explanations MMSYSERR_NOTSUPPORTED function isn't supported. Someone has met this thing , It is said that the format is wrong , After adjustment, you can pass .

Write the encoded audio into wav file , Play it , I found that the first few seconds were silent , It seems that transcoding is not so normal , Let's talk about it when we have time .

summary ：

MSACM This thing is very unfriendly to people who come into contact for the first time ,MSDN There are only function descriptions on the but not how to use them , And the return value of the encapsulated codec function is not clear , It makes people crazy , A large number of codec libraries on the Internet are more direct ?

This thing looks powerful , It may not be good to use .