从 AVAsset 中查找通道数

Posted 2023-03-11

【中文标题】从 AVAsset 中查找通道数

【英文标题】：Finding the number of Channels from an AVAsset

【发布时间】：2011-08-03 17:49:52

【问题描述】：

我正在通过 AVAssets 加载音频资产。我想弄清楚资产中有多少通道（基本上是单声道或立体声）。最好的方法是什么？

【参考方案1】：

这似乎是我要找的。​​p>

AVAssetTrack* songTrack = [mAssetToLoad.tracks objectAtIndex:0];
NSArray* formatDesc = songTrack.formatDescriptions;
for(unsigned int i = 0; i < [formatDesc count]; ++i) 
    CMAudioFormatDescriptionRef item = (CMAudioFormatDescriptionRef)[formatDesc objectAtIndex:i];
    const AudiostreamBasicDescription* bobTheDesc = CMAudioFormatDescriptionGetStreamBasicDescription (item);
    if(bobTheDesc && bobTheDesc->mChannelsPerFrame == 1) 
        mIsMono = true;
    

【参考方案2】：

TurqMage 答案的 Swift 5 实现

//
//  AVAssetTrack+IsStereo.swift
//

import AVFoundation

extension AVAssetTrack 
    
    var isStereo: Bool 
        
        for item in (formatDescriptions as? [CMAudioFormatDescription]) ?? [] 
            
            let basic = CMAudioFormatDescriptionGetStreamBasicDescription(item)
            let numberOfChannels = basic?.pointee.mChannelsPerFrame ?? 0
            
            if numberOfChannels == 2 
                return true
            
        
        return false