Avplayer playing a video file from document directory - volume issue - ios

Question

I'm playing a video file from the documents directory, but I can't change the volume.
Actually I can play a file from the music video library and change the volume, but not for the precharged ( from iTunes with File Sharing ) videos!
What can I do?
That's the slider that is used like a crossfader between the videos for manage the volume:
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

I found the solution.
When I load the track in the avplayeritem, that is divided in an "array" of audio, video, timecode ( if present ).
In case of video loaded from iTunes, the file had video, sound, timecode and I must load the sound part in the audiomix.
Before I discover that I load the avplayeritem[0] but it's wrong because in the file loaded from document library the sound part is in another position.
That's the solution:
//load the sound part in an array
audioTrackssx = [videoSinistra tracksWithMediaType:AVMediaTypeAudio];
//the sound part must be only one
[audioInputParams setTrackID:[audioTrackssx[0] trackID]];