我正在使用 Alvas Audio 库将文件从 Mp3 转换为 Wave 格式，以便我可以编辑它们，然后将它们转换回 Mp3。转换为 Wave 工作正常，但是当我尝试转换回 Mp3 时遇到了麻烦。出于某种原因，此失败与我使用后台工作程序执行初始转换的事实有关。
我知道如果没有库的源代码，很难尝试弄清楚发生了什么，但我希望有人可能对可能出现的问题提出建议。
当我在没有后台工作人员的情况下同步调用相同的代码时，它可以完美运行。有任何想法吗？
这是我从后台工作人员调用以执行转换的代码：
public Tuple<float, float> convertMp3ToWav(Track track) //with Detection, duration check, and TODO: silence removal
{
try
{
string baseFile = Path.GetFileName(track.location);
////////////////////////////
//string baseFile = track.location.Remove(track.location.Length - 4);
string outputFile = directory + "Temp\\" + baseFile.Remove(baseFile.Length - 4) + ".wav";
cleanupFiles.Add(outputFile);
if (!File.Exists(outputFile))
{
int soundStart = -1;
int soundEnd = 0;
Mp3Reader mr = new Mp3Reader(File.OpenRead(track.location));
IntPtr mp3Format = mr.ReadFormat();
IntPtr pcmFormat = AudioCompressionManager.GetCompatibleFormat(mp3Format, AudioCompressionManager.PcmFormatTag);
AcmConverter acm = new AcmConverter(mp3Format, pcmFormat, false);
int sec = 1024;
int i = 0;
bool soundFound = false;
while (true)
{
byte[] mp3Data = mr.ReadDataInBytes(i, sec);
if (mp3Data.Length == 0)
{
break;
}
byte[] pcmData = acm.Convert(mp3Data);
foreach (byte d in pcmData) //THIS SECTION CHECKS IF THE Section in question has silence
{
if (d != 0)
{
soundFound = true;
}
}
if ((soundStart == -1) && (soundFound == true)) //if no beginning sound has been found yet, but has now been found
{
soundStart = i; //This will be precise to whatever value of sec has been chosen
}
else if ((soundStart != -1) && (soundFound == true)) //this is a possible end value
{
soundEnd = i; //this value will be rewritten each time there is sound found after soundstart is set.
//so this value will remain the same if no further sound is found in the track, and will represent the
//end of sound in the track
}
soundFound = false;
i += sec;
}
int finalDuration = soundEnd - soundStart;
mr.Close();
Mp3Reader reader = new Mp3Reader(File.OpenRead(track.location));
IntPtr thisFormat = reader.ReadFormat();
byte[] completeTrack = reader.ReadDataInBytes(soundStart, finalDuration);
byte[] convertedTrack = AudioCompressionManager.Convert(thisFormat, pcmFormat, completeTrack, false);
WaveWriter ww = new WaveWriter(File.OpenWrite(outputFile), AudioCompressionManager.FormatBytes(pcmFormat));
ww.WriteData(convertedTrack);
ww.Close();
reader.Close();
float bpm = performBeatDetection(track);
float duration = getTrackDuration(track);
return new Tuple<float, float>(bpm, duration);
}
else
{
//File already exists, just remove silence, get bpm and duration
//string silenceRemoved = removeSilenceFromTrack(outputFile);
float bpm = performBeatDetection(track);
float duration = getTrackDuration(track);
return new Tuple<float, float>(bpm, duration);
}
}
catch (Alvas.Audio.AudioException e)
{
MessageBox.Show("ERROR: " + e.ToString());
return new Tuple<float, float>(0f, 0f);
}
}
编辑：
特定的失败是库中的异常。当您想使用 Alvas 将文件从一种音频格式转换为另一种时，您首先读取文件当前格式的格式，就像您看到的那样
IntPtr mp3Format = mr.ReadFormat();
然后转换，你调用静态方法
AudioCompressionManager.GetCompatibleFormat(oldFormat, newFormatTag);
当我在使用后台工作程序后调用最后一个方法时，它会以糟糕的英语抛出异常“格式转换不成功”。在库中使用稍微不同的方法：
AudioCompressionManager.GetCompatibleFormatList(oldFormat);
揭示当我不使用后台工作者，而我使用后一种方法（GetCompatibleFormatList）时，它会返回 51 个结果，其中一个是转换为我想要的 mp3 格式。
如果我在使用后台工作程序执行初始转换后执行相同的方法，它只返回 20 个结果，其中没有一个是兼容的 mp3 格式。