我在IEEE浮点数16000Hz,32位,1通道格式的字节数组(来自数据库)中有WAV数据。我希望将其转换为mp3,并通过WCF服务的响应对象将其流出。
使用NAudio包,到目前为止我所使用的是使用MediaFoundationEncoder.EncodetoMp3()写入文件。但是,一旦该文件被写入响应,它就没用了。我想跳过文件写入步骤并输出到流或字节数组并将其写入响应对象。
有没有办法让MediaFoundationEncoder在某种内存对象(没有文件)中输出mp3?
或者,尝试使用LameMP3FileWriter,它写入流, 我可以直接将IEEE float wav输入发送到LameMP3FileWriter,但是无论我使用的输出格式如何(44100,16,1),(22050,16,1),(11025,16, 1),...
当我尝试将IEEE浮点源转换为PCM或使用WaveFormatConversion对其进行上采样时,它会出错
AcmNotPossible调用acmStreamOpen
如果我在IEEE浮动源上使用Wave32to16Stream,它不会出错但没有音频。这条链对我不起作用:
byte[] bytes = (Byte[])dt.Rows[0]["AudioContent"];//this is the dataTable from the database query containing the WAV audio
var ms = new MemoryStream(bytes);
var OLDfmt = WaveFormat.CreateIeeeFloatWaveFormat(16000,1);
var NEWfmt = new WaveFormat(16000, 16, 1);//tried many
var readr = new RawSourceWaveStream(ms,OLDfmt);
//the following line errors on 'AcmNotPossible calling acmStreamOpen'
//var wav16 = new WaveFormatConversionStream(NEWfmt, readr);
//the following does not error but no mp3 streams out at the end
var wav16 = new Wave32To16Stream(readr);
var outptMP3 = new MemoryStream();
var writr = new LameMP3FileWriter(outptMP3, NEWfmt, LAMEPreset.STANDARD);
wav16.CopyTo(writr);
HttpContext.Current.Response.BufferOutput = true;
HttpContext.Current.Response.AddHeader("Content-Type", "audio/mpeg");
HttpContext.Current.Response.BinaryWrite(outptMP3.ToArray());
如果我只使用ms MemoryStream的BinaryWrite,原始音频在Chrome中可以正常播放(作为WAV流),所以我认为IEEE浮动源数据是有效的。
如果错误,请纠正我,但该错误(AcmNotPossible)似乎意味着我的机器上没有用于IEEE浮动格式的ACM编解码器?我查询我的机器,似乎没有32位ACM编解码器,这就是我尝试Wave32To16Stream转换的原因。
Lame MP3管道的临时步骤是从IEEE float 32位转到mp3吗?
答案 0 :(得分:1)
抱歉,关于将IEEE浮点32位波转码为mp3流的主要问题有很多子问题,但我至少可以告诉你如何使用ACM编解码器(我认为)我简单的WCF服务:
否则上面的链实际上对我有效。为了完整起见,我将提供完整的代码以及所有无关的SQL内容,因为我在一个不相关的SO问题中找到了答案:
public Stream playWAVEFileFromDB() {
//if using the file output method, I change the return type to string and return text instead of streams
try
{
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["myconnectionstring"].ConnectionString);
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = "SELECT theWAVEColumn FROM myTable WHERE allThoseAudiosAreStored";
SqlDataAdapter sda = new SqlDataAdapter();
DataTable dt = new DataTable();
conn.Open();
sda.SelectCommand = cmd;
sda.Fill(dt);
//read the raw audio from database into a byte array
byte[] bytes = (Byte[])dt.Rows[0]["colName"];
var ms = new MemoryStream(bytes);
var NEWfmt = new WaveFormat(16000, 16, 1);
var OLDfmt = WaveFormat.CreateIeeeFloatWaveFormat(16000,1);//how its stored
var readr = new RawSourceWaveStream(ms,OLDfmt);
var wav16 = new Wave32To16Stream(readr);
var outptMP3 = new MemoryStream();
var writr = new LameMP3FileWriter(outptMP3, NEWfmt, LAMEPreset.STANDARD);
wav16.CopyTo(writr);
outptMP3.Position = 0;
HttpContext.Current.Response.BufferOutput = true;
HttpContext.Current.Response.AddHeader("Content-Type", "audio/mpeg");
conn.Close();
conn.Dispose();
sda.Dispose();
return outptMP3;
}
catch (Exception e)
{
//do the error logging stuff
return Stream.Null;
}
}