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feat: 将导入导出谱面的WAV<->MP3互转，改为基于FFMPEG的实现
详见#40中的讨论，NAudio对LAME MP3 Gapless并不支持，造成了严重的音频延迟行为不确定等问题。而经过测试FFMPEG对Gapless的支持是十分完善的，所以全部改用FFMPEG做音频编解码。
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3 files changed

Lines changed: 92 additions & 9 deletions

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‎MaiChartManager/Controllers/Music/MusicTransferController.cs‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -8,9 +8,7 @@
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using Microsoft.AspNetCore.Mvc;
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using Microsoft.VisualBasic.FileIO;
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using NAudio.Lame;
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using SimaiSharp;
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using Vanara.Windows.Forms;
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using Xabe.FFmpeg;
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using FolderBrowserDialog = System.Windows.Forms.FolderBrowserDialog;
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namespace MaiChartManager.Controllers.Music;
@@ -555,7 +553,7 @@ public async Task ExportAsMaidata(int id, string assetDir, bool ignoreVideo = fa
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simaiFile.AppendLine($"&title={music.Name}");
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simaiFile.AppendLine($"&artist={music.Artist}");
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simaiFile.AppendLine($"&wholebpm={music.Bpm}");
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simaiFile.AppendLine("&first=0.0333");
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simaiFile.AppendLine("&first=0");
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simaiFile.AppendLine($"&shortid={music.Id}");
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simaiFile.AppendLine($"&genreid={music.GenreId}");
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var genre = StaticSettings.GenreList.FirstOrDefault(it => it.Id == music.GenreId);

‎MaiChartManager/Utils/Audio.cs‎

Lines changed: 40 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,6 @@
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using NAudio.Lame;
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using NAudio.Wave;
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using Xabe.FFmpeg;
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using VGAudio;
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using VGAudio.Cli;
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using Xv2CoreLib.ACB;
@@ -59,7 +60,12 @@ public static byte[] LoadAndConvertFile(string path, FileType convertToType, boo
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public static Stream ConvertToWav(Stream src, bool isOgg, float padding = 0)
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{
62-
using WaveStream reader = isOgg ? new NAudio.Vorbis.VorbisWaveReader(src, true) : new StreamMediaFoundationReader(src);
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using WaveStream reader = isOgg
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? new NAudio.Vorbis.VorbisWaveReader(src, true)
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// 如果直接用StreamMediaFoundationReader的话，mp3转wav的过程会有问题，详见https://github.com/MuNET-OSS/MaiChartManager/issues/40#issuecomment-4029798667。
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// 因此，将使用ffmpeg完成从mp3到wav的转换；但由于需要进行padding，所以还是得再以sample的形式读出来然后重新保存。
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// PS：使用NAudio的WaveFileReader来直接处理wav文件是没有问题的，因为wav本身是一种基于sample的无损采样格式，没有encdelay之类的问题。只要确保不要使用NAudio进行MP3编解码即可。
68+
: new WaveFileReader(ConvertMp3ToWavViaFfmpeg(src));
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var sample = reader.ToSampleProvider();
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switch (padding)
@@ -82,6 +88,39 @@ public static Stream ConvertToWav(Stream src, bool isOgg, float padding = 0)
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return stream;
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}
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private static MemoryStream ConvertMp3ToWavViaFfmpeg(Stream src)
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{
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var tempFileGuid = Guid.NewGuid();
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var inputPath = Path.Combine(StaticSettings.tempPath, $"ConvertToWav_{tempFileGuid:N}.mp3");
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var outputPath = Path.Combine(StaticSettings.tempPath, $"ConvertToWav_{tempFileGuid:N}.wav");
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try
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{
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Directory.CreateDirectory(StaticSettings.tempPath);
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using (var inputFile = new FileStream(inputPath, FileMode.Create, FileAccess.Write))
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{
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src.CopyTo(inputFile);
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}
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var conversion = FFmpeg.Conversions.New()
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.AddParameter("-i " + inputPath.Escape())
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.AddParameter("-c:a pcm_s16le") // 转为16-bit little-endian PCM
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.SetOutput(outputPath)
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.SetOverwriteOutput(true);
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conversion.Start().GetAwaiter().GetResult();
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if (!File.Exists(outputPath) || new FileInfo(outputPath).Length == 0)
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throw new InvalidOperationException("ffmpeg produced empty wav file from mp3 input.");
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return new MemoryStream(File.ReadAllBytes(outputPath));
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}
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finally
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{
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File.Delete(inputPath);
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File.Delete(outputPath);
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}
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}
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public static byte[] ConvertFile(
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Stream s,
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FileType encodeType,

‎MaiChartManager/Utils/AudioConvert.cs‎

Lines changed: 51 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,6 @@
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using NAudio.Lame;
2-
using NAudio.Wave;
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using NAudio.Wave.SampleProviders;
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using Standart.Hash.xxHash;
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using Xabe.FFmpeg;
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65
namespace MaiChartManager.Utils;
76

@@ -76,8 +75,55 @@ public static async Task<string> GetCachedWavPath(string acbPath, string awbPath
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public static void ConvertWavPathToMp3Stream(string wavPath, Stream mp3Stream, ID3TagData? tagData = null)
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{
79-
using var reader = new WaveFileReader(wavPath);
80-
using var writer = new LameMP3FileWriter(mp3Stream, reader.WaveFormat, 256, tagData);
81-
reader.CopyTo(writer);
78+
var outputPath = Path.Combine(StaticSettings.tempPath, $"ConvertToMp3_{Guid.NewGuid():N}.mp3");
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string? albumArtPath = null;
80+
try
81+
{
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Directory.CreateDirectory(StaticSettings.tempPath);
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84+
var conversion = FFmpeg.Conversions.New()
85+
.AddParameter($"-i " + wavPath.Escape());
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87+
if (tagData != null)
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{
89+
if (tagData.AlbumArt != null && tagData.AlbumArt.Length > 0)
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{
91+
// 把专辑封面写到临时文件，然后让ffmpeg把它嵌入mp3
92+
albumArtPath = Path.Combine(StaticSettings.tempPath, $"ConvertToMp3_{Guid.NewGuid():N}.png");
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File.WriteAllBytes(albumArtPath, tagData.AlbumArt);
94+
conversion.AddParameter($"-i {albumArtPath.Escape()}");
95+
} // 顺序不能换！这个必须在第一个，因为-i必须在任何其他参数之前。
96+
if (!string.IsNullOrEmpty(tagData.Title)) conversion.AddParameter($"-metadata title=" + tagData.Title.Escape());
97+
if (!string.IsNullOrEmpty(tagData.Artist)) conversion.AddParameter($"-metadata artist=" + tagData.Artist.Escape());
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if (!string.IsNullOrEmpty(tagData.Album)) conversion.AddParameter($"-metadata album=" + tagData.Album.Escape());
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if (!string.IsNullOrEmpty(tagData.Year)) conversion.AddParameter($"-metadata date=" + tagData.Year.Escape());
100+
if (!string.IsNullOrEmpty(tagData.Comment)) conversion.AddParameter($"-metadata comment=" + tagData.Comment.Escape());
101+
if (!string.IsNullOrEmpty(tagData.Genre)) conversion.AddParameter($"-metadata genre=" + tagData.Genre.Escape());
102+
if (!string.IsNullOrEmpty(tagData.Track)) conversion.AddParameter($"-metadata track=" + tagData.Track.Escape());
103+
}
104+
105+
conversion.AddParameter("-c:a libmp3lame -b:a 256k"); // 把wav编码为256kbps的LAME mp3
106+
107+
if (albumArtPath != null)
108+
{ // 如果有专辑封面，还需要加一堆参数以写入专辑封面
109+
conversion.AddParameter("-map 0:a -map 1:v -c:v copy -disposition:v attached_pic");
110+
}
111+
112+
conversion.SetOutput(outputPath).SetOverwriteOutput(true);
113+
conversion.Start().GetAwaiter().GetResult();
114+
115+
if (!File.Exists(outputPath) || new FileInfo(outputPath).Length == 0)
116+
{
117+
throw new InvalidOperationException("ffmpeg produced empty mp3 file from wav input.");
118+
}
119+
120+
using var outputFile = new FileStream(outputPath, FileMode.Open, FileAccess.Read);
121+
outputFile.CopyTo(mp3Stream);
122+
}
123+
finally
124+
{
125+
File.Delete(outputPath);
126+
if (albumArtPath != null) File.Delete(albumArtPath);
127+
}
82128
}
83129
}

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