Avplayer播放文档目录中的视频文件-卷问题

Question

我正在播放documents目录中的视频文件，但无法更改音量。事实上，我可以从音乐视频库中播放文件并更改音量，但不适用于预充电（从带有文件共享的iTunes）视频！我能做什么？

这是一个滑块，它像视频之间的交叉阅读器一样用于管理音量：

AVMutableAudioMixInputParameters* audioInputParams2 = [AVMutableAudioMixInputParameters audioMixInputParameters];
CMTime currentTime = [videoItemDestra currentTime];
//se il video non c'è setta il tempo a zero, almeno non crasha
if(CMTIME_IS_INVALID(currentTime)){
    currentTime = kCMTimeZero;
}

//se il pulsante muto è attivo non cambiare volume
if( mutedx ==1){
    [audioInputParams2 setVolume:0 atTime:currentTime];
}else{
    [audioInputParams2 setVolume:(_volumeSliderAvplayer2.value/100) atTime:currentTime];
}
[audioInputParams2 setTrackID:[videoDestra.tracks[0] trackID]];
NSMutableArray * allAudioParams2= [[NSMutableArray alloc]initWithObjects:audioInputParams2, nil];
AVMutableAudioMix * audioMix2 = [AVMutableAudioMix audioMix];
[audioMix2 setInputParameters:allAudioParams2];

AVMutableAudioMixInputParameters* audioInputParams = [AVMutableAudioMixInputParameters audioMixInputParameters];
CMTime currentTime2 = [videoItemSinistra currentTime];
//se il video non c'è setta il tempo a zero, almeno non crasha
if(CMTIME_IS_INVALID(currentTime2)){
    currentTime2 = kCMTimeZero;
}
//se il pulsante muto è attivo non cambiare volume
if( mutesx ==1){
    [audioInputParams setVolume:0 atTime:currentTime2];
}else{
    [audioInputParams setVolume:(1-(_volumeSliderAvplayer2.value/100)) atTime:currentTime2];
}
[audioInputParams setTrackID:[videoSinistra.tracks[0] trackID]];
NSMutableArray *allAudioParams= [[NSMutableArray alloc]initWithObjects:audioInputParams, nil];
AVMutableAudioMix* audioMix = [AVMutableAudioMix audioMix];
[audioMix setInputParameters:allAudioParams];
[videoItemSinistra setAudioMix:audioMix];
[videoItemDestra setAudioMix:audioMix2];

Answer 1

我找到了解决方案。

当我在avplayeritem中加载曲目时，它被划分为音频、视频、时间码（如果存在）的"数组"。在从iTunes加载视频的情况下，该文件有视频、声音、时间代码，我必须在混音中加载声音部分。在我发现我加载了avplayeritem[0]之前，它是错误的，因为在从文档库加载的文件中，声音部分位于另一个位置。这就是解决方案：

//load the sound part in an array
audioTrackssx = [videoSinistra tracksWithMediaType:AVMediaTypeAudio];

//the sound part must be only one
[audioInputParams setTrackID:[audioTrackssx[0] trackID]];