如何在 iOS 中添加带有 PCM 数据/缓冲区的可播放（如 wav、wmv）标头？
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【中文标题】如何在 iOS 中添加带有 PCM 数据/缓冲区的可播放（如 wav、wmv）标头？【英文标题】：How to add playable(such as wav,wmv) header with PCM data/buffer in iOS? 【发布时间】：2015-01-30 07:28:06 【问题描述】：我正在尝试在原始 PCM 数据之上添加一个 wav 标头，以使其可通过 AVAudioPlayer 播放。但我在 ios 上使用 Objective-C/Swift 找不到任何解决方案或源代码。虽然我找到了this，但它没有正确答案。
但我发现了一段代码here，它在 C 中，也包含一些问题。从该代码生成的 wav 文件无法正常播放。
我已经给出了我迄今为止编码的代码。
int NumChannels = AUDIO_CHANNELS_PER_FRAME;
short BitsPerSample = AUDIO_BITS_PER_CHANNEL;
int SamplingRate = AUDIO_SAMPLE_RATE;
int numOfSamples = [[NSData dataWithContentsOfFile:filePath] length];
int ByteRate = NumChannels*BitsPerSample*SamplingRate/8;
short BlockAlign = NumChannels*BitsPerSample/8;
int DataSize = NumChannels*numOfSamples*BitsPerSample/8;
int chunkSize = 16;
int totalSize = 36 + DataSize;
short audioFormat = 1;
if((fout = fopen([wavFilePath cStringUsingEncoding:1], "w")) == NULL)
printf("Error opening out file ");
fwrite("RIFF", sizeof(char), 4,fout);
fwrite(&totalSize, sizeof(int), 1, fout);
fwrite("WAVE", sizeof(char), 4, fout);
fwrite("fmt ", sizeof(char), 3, fout);
fwrite(&chunkSize, sizeof(int),1,fout);
fwrite(&audioFormat, sizeof(short), 1, fout);
fwrite(&NumChannels, sizeof(short),1,fout);
fwrite(&SamplingRate, sizeof(int), 1, fout);
fwrite(&ByteRate, sizeof(int), 1, fout);
fwrite(&BlockAlign, sizeof(short), 1, fout);
fwrite(&BitsPerSample, sizeof(short), 1, fout);
fwrite("data", sizeof(char), 3, fout);
fwrite(&DataSize, sizeof(int), 1, fout);
文件播放太快，声音失真，仅播放前 10 到 20（大约）秒。我认为，wav 标头没有正确生成（因为我能够使用 AudioUnit/AudioQueue 播放相同的 PCM 数据/缓冲区）。那么我的代码中缺少什么？任何帮助将不胜感激。
提前致谢。
【问题讨论】：
没人能回答我的问题？？？！！！我只是很惊讶...有人请回复.... iam 也面临同样的问题..您找到解决此问题的方法了吗？ 【参考方案1】：好的，如果它对其他人有帮助，我正在回答我自己的问题。经过几天的不懈努力，我终于让它工作了。下面是一个用 Objective-C 和 C 编写的完整函数。它将文件路径作为参数，其中包含直接从麦克风捕获的 RAW PCM 数据，并返回包含 PCM 数据和适当的 wav 头信息的文件路径。然后您可以使用 AVAudioPlayer 或 AVPlayer 播放该文件。这是代码...
- (NSURL *) getAndCreatePlayableFileFromPcmData:(NSString *)filePath
NSString *wavFileName = [[filePath lastPathComponent] stringByDeletingPathExtension];
NSString *wavFileFullName = [NSString stringWithFormat:@"%@.wav",wavFileName];
[self createFileWithName:wavFileFullName];
NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docsDir = [dirPaths objectAtIndex:0];
NSString *wavFilePath = [docsDir stringByAppendingPathComponent:wavFileFullName];
NSLog(@"PCM file path : %@",filePath);
FILE *fout;
short NumChannels = AUDIO_CHANNELS_PER_FRAME;
short BitsPerSample = AUDIO_BITS_PER_CHANNEL;
int SamplingRate = AUDIO_SAMPLE_RATE;
int numOfSamples = [[NSData dataWithContentsOfFile:filePath] length];
int ByteRate = NumChannels*BitsPerSample*SamplingRate/8;
short BlockAlign = NumChannels*BitsPerSample/8;
int DataSize = NumChannels*numOfSamples*BitsPerSample/8;
int chunkSize = 16;
int totalSize = 46 + DataSize;
short audioFormat = 1;
if((fout = fopen([wavFilePath cStringUsingEncoding:1], "w")) == NULL)
printf("Error opening out file ");
fwrite("RIFF", sizeof(char), 4,fout);
fwrite(&totalSize, sizeof(int), 1, fout);
fwrite("WAVE", sizeof(char), 4, fout);
fwrite("fmt ", sizeof(char), 4, fout);
fwrite(&chunkSize, sizeof(int),1,fout);
fwrite(&audioFormat, sizeof(short), 1, fout);
fwrite(&NumChannels, sizeof(short),1,fout);
fwrite(&SamplingRate, sizeof(int), 1, fout);
fwrite(&ByteRate, sizeof(int), 1, fout);
fwrite(&BlockAlign, sizeof(short), 1, fout);
fwrite(&BitsPerSample, sizeof(short), 1, fout);
fwrite("data", sizeof(char), 4, fout);
fwrite(&DataSize, sizeof(int), 1, fout);
fclose(fout);
NSMutableData *pamdata = [NSMutableData dataWithContentsOfFile:filePath];
NSFileHandle *handle;
handle = [NSFileHandle fileHandleForUpdatingAtPath:wavFilePath];
[handle seekToEndOfFile];
[handle writeData:pamdata];
[handle closeFile];
return [NSURL URLWithString:wavFilePath];
但该功能仅适用于以下音频设置。
// Audio settings.
#define AUDIO_SAMPLE_RATE 8000
#define AUDIO_FRAMES_PER_PACKET 1
#define AUDIO_CHANNELS_PER_FRAME 1
#define AUDIO_BITS_PER_CHANNEL 16
#define AUDIO_BYTES_PER_PACKET 2
#define AUDIO_BYTES_PER_FRAME 2
【讨论】：
什么是 [self createFileWithName:wavFileFullName];? 非常有帮助。谢谢！ 首先非常感谢您发布伟大的代码，这对我很有帮助，您能告诉我如何从波形文件中获取 PCM 数据吗？ iam 也面临同样的问题。您找到解决方案了吗？ 谢谢！非常方便，正是我需要的。【参考方案2】：非常有帮助的问题和答案，非常感谢。
这个快速版本是为有需要的人准备的：
static func createWAV(from pcmFilePath: String, to wavFilePath: String) -> Bool
// Make sure that the path does not contain non-ascii characters
guard let fout = fopen(wavFilePath.cString(using: .ascii), "w") else return false
guard let pcmData = try? Data(contentsOf: URL(fileURLWithPath: pcmFilePath)) else return false
var numChannels: CShort = 1
let numChannelsInt: CInt = 1
var bitsPerSample: CShort = 16
let bitsPerSampleInt: CInt = 16
var samplingRate: CInt = 16000
let numOfSamples = CInt(pcmData.count)
var byteRate = numChannelsInt * bitsPerSampleInt * samplingRate / 8
var blockAlign = numChannelsInt * bitsPerSampleInt / 8
var dataSize = numChannelsInt * numOfSamples * bitsPerSampleInt / 8
var chunkSize: CInt = 16
var totalSize = 46 + dataSize
var audioFormat: CShort = 1
fwrite("RIFF".cString(using: .ascii), MemoryLayout<CChar>.size, 4, fout)
fwrite(&totalSize, MemoryLayout<CInt>.size, 1, fout)
fwrite("WAVE".cString(using: .ascii), MemoryLayout<CChar>.size, 4, fout);
fwrite("fmt ".cString(using: .ascii), MemoryLayout<CChar>.size, 4, fout);
fwrite(&chunkSize, MemoryLayout<CInt>.size,1,fout);
fwrite(&audioFormat, MemoryLayout<CShort>.size, 1, fout);
fwrite(&numChannels, MemoryLayout<CShort>.size,1,fout);
fwrite(&samplingRate, MemoryLayout<CInt>.size, 1, fout);
fwrite(&byteRate, MemoryLayout<CInt>.size, 1, fout);
fwrite(&blockAlign, MemoryLayout<CShort>.size, 1, fout);
fwrite(&bitsPerSample, MemoryLayout<CShort>.size, 1, fout);
fwrite("data".cString(using: .ascii), MemoryLayout<CChar>.size, 4, fout);
fwrite(&dataSize, MemoryLayout<CInt>.size, 1, fout);
fclose(fout);
guard let handle = FileHandle(forUpdatingAtPath: wavFilePath) else return false
handle.seekToEndOfFile()
handle.write(pcmData)
handle.closeFile()
return true
【讨论】：
【参考方案3】：根据 quiz 对 swift 5 的回答修改
func extractSubchunks(data:Data) -> RiffFile?
var data = data
var chunks = [SubChunk]()
let position = data.subdata(in: 8..<12)
let filelengthBytes = data.subdata(in: 4..<8).map UInt32($0)
let filelength: UInt32 = filelengthBytes[0] << 24 + filelengthBytes[1] << 16 + filelengthBytes[2] << 8 + filelengthBytes[3]
let wave = String(bytes: position, encoding: .utf8) ?? "NoName"
guard wave == "WAVE" else
print("File is \(wave) not WAVE")
return nil
data.removeSubrange(0..<12)
print("Found chunks")
while data.count != 0
let position = data.subdata(in: 0..<4)
let lengthBytes = data.subdata(in: 4..<8).map UInt32($0)
let length: UInt32 = lengthBytes[0] << 24 + lengthBytes[1] << 16 + lengthBytes[2] << 8 + lengthBytes[3]
guard let current = String(bytes: position, encoding: .utf8) else
return nil
data.removeSubrange(0..<8)
let chunkData = data.subdata(in: 0..<Int(length))
data.removeSubrange(0..<Int(length))
let subchunk = SubChunk(name: current, size: Int(length), data: chunkData)
chunks.append(subchunk)
print(subchunk.debugDescription)
let riff = RiffFile(size: Int(filelength), subChunks: chunks)
return riff
【讨论】：
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