C#+VideoLan.LibVLC示例音频流并将其保存到磁盘

Question

我使用VideoLan.VLC每30秒获得20秒的音频流。我有一个循环，类似

private LibVLC libvlc = new LibVLC();
private MediaPlayer mediaPlayer = null;
private Media Media = null;
private string AudioSampleFileName { get {
return "audio_" + DateTime.Now.ToString("yyyyMMdd_HHmmss")+
".ts";             
} }
public void Start(){
mediaPlayer = new MediaPlayer(libvlc);

while(...){
Get_20_seconds_audio_sample();
Wait_30_Seconds();            
}
}

public void Get_sample(Uri playPathUri, string FileName)
{

var currentDirectory = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);
var destination = Path.Combine(currentDirectory, FileName);

var mediaOptions = new string[]
{
":sout=#file{dst=" + destination + ",channels=1,samplerate=16000}",
":sout-keep"
};

if (Media == null)
{
Media = new Media(libvlc, playPathUri, mediaOptions);
mediaPlayer.Media = Media;
}
else {
Media.AddOption(":sout=#file{dst=" + destination + ",channels=1,samplerate=16000}");
}            
mediaPlayer.Play();            
}

public void Get_20_seconds_audio_sample(){

Get_sample(RadioURI,AudioSampleFileName);
Wait_20_seconds();
Stop();
}

public void Stop()
{
mediaPlayer.Stop();            
}

问题是，广播节目通常从一个持续约25秒的广告开始。每一个样品都是商业广告。似乎Stop((关闭了流，直到再次调用Play((并重新启动流。我很想暂停音频，但是。。。停下来玩没有多大意义。

我可以接受只在第一个样本中获得广告，但我想要常规的广播音频。有没有办法不每次都关闭流？我没有绑定到VideoLan dll，所以如果你有更好的方法，我可以从头开始。

Answer 1

使用音频回调并自己保存音频流。全样本：

class Program
{
// This sample shows you how you can use SetAudioFormatCallback and SetAudioCallbacks. It does two things:
// 1) Play the sound from the specified video using NAudio
// 2) Extract the sound into a file using NAudio
static void Main(string[] args)
{
Core.Initialize();
using var libVLC = new LibVLC(enableDebugLogs: true);
using var media = new Media(libVLC,
new Uri("http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ElephantsDream.mp4"),
":no-video");
using var mediaPlayer = new MediaPlayer(media);
using var outputDevice = new WaveOutEvent();
var waveFormat = new WaveFormat(8000, 16, 1);
var writer = new WaveFileWriter("sound.wav", waveFormat);
var waveProvider = new BufferedWaveProvider(waveFormat);
outputDevice.Init(waveProvider);
mediaPlayer.SetAudioFormatCallback(AudioSetup, AudioCleanup);
mediaPlayer.SetAudioCallbacks(PlayAudio, PauseAudio, ResumeAudio, FlushAudio, DrainAudio);
mediaPlayer.Play();
mediaPlayer.Time = 20_000; // Seek the video 20 seconds
outputDevice.Play();
Console.WriteLine("Press 'q' to quit. Press any other key to pause/play.");
while (true)
{
if (Console.ReadKey().KeyChar == 'q')
break;
if (mediaPlayer.IsPlaying)
mediaPlayer.Pause();
else
mediaPlayer.Play();
}
void PlayAudio(IntPtr data, IntPtr samples, uint count, long pts)
{
int bytes = (int)count * 2; // (16 bit, 1 channel)
var buffer = new byte[bytes];
Marshal.Copy(samples, buffer, 0, bytes);
waveProvider.AddSamples(buffer, 0, bytes);
writer.Write(buffer, 0, bytes);
}
int AudioSetup(ref IntPtr opaque, ref IntPtr format, ref uint rate, ref uint channels)
{
channels = (uint)waveFormat.Channels;
rate = (uint)waveFormat.SampleRate;
return 0;
}
void DrainAudio(IntPtr data)
{
writer.Flush();
}
void FlushAudio(IntPtr data, long pts)
{
writer.Flush();
waveProvider.ClearBuffer();
}
void ResumeAudio(IntPtr data, long pts)
{
outputDevice.Play();
}
void PauseAudio(IntPtr data, long pts)
{
outputDevice.Pause();
}
void AudioCleanup(IntPtr opaque) { }
}
}