如何解决如何提高 mp3 解码质量 (Media Foundation)?
我有文件 .wav
,我需要在 .mp3
中进行转换,我正在使用 MediaFoundation
。这是我使用的方法:
#include "TV_AudioEncoderMF.h"
#include <windows.h>
#include <windowsx.h>
#include <atlstr.h>
#include <comdef.h>
#include <exception>
#include <mfapi.h>
#include <mfplay.h>
#include <mfreadwrite.h>
#include <mmdeviceapi.h>
#include <Audioclient.h>
#include <mferror.h>
#include <Wmcodecdsp.h>
#pragma comment(lib,"mf.lib")
#pragma comment(lib,"mfplat.lib")
#pragma comment(lib,"mfplay.lib")
#pragma comment(lib,"mfreadwrite.lib")
#pragma comment(lib,"mfuuid.lib")
#pragma comment(lib,"wmcodecdspuuid")
TV_AudioEncoderMF::TV_AudioEncoderMF()
{
}
TV_AudioEncoderMF::~TV_AudioEncoderMF()
{
}
template <class T> void SafeRelease(T **ppT)
{
if (*ppT)
{
(*ppT)->Release();
*ppT = nullptr;
}
}
HRESULT TV_AudioEncoderMF::GetoutputMediaTypes(
GUID cAudioFormat,UINT32 cSampleRate,UINT32 cBitPerSample,UINT32 cChannels,IMFMediaType **ppType
)
{
// Enumerate all codecs except for codecs with field-of-use restrictions.
// Sort the results.
DWORD dwFlags =
(MFT_ENUM_FLAG_ALL & (~MFT_ENUM_FLAG_FIELDOFUSE)) |
MFT_ENUM_FLAG_SORTANDFILTER;
IMFCollection *pAvailableTypes = NULL; // List of audio media types.
IMFMediaType *pAudioType = NULL; // Corresponding codec.
HRESULT hr = MFTranscodeGetAudioOutputAvailableTypes(
cAudioFormat,dwFlags,NULL,&pAvailableTypes
);
// Get the element count.
DWORD dwMTCount;
hr = pAvailableTypes->GetElementCount(&dwMTCount);
// Iterate through the results and check for the corresponding codec.
for (DWORD i = 0; i < dwMTCount; i++)
{
hr = pAvailableTypes->GetElement(i,(IUnkNown**)&pAudioType);
GUID majorType;
hr = pAudioType->GetMajorType(&majorType);
GUID subType;
hr = pAudioType->GetGUID(MF_MT_SUBTYPE,&subType);
if (majorType != MFMediaType_Audio || subType != MFAudioFormat_FLAC)
{
continue;
}
UINT32 sampleRate = NULL;
hr = pAudioType->GetUINT32(
MF_MT_AUdio_SAMPLES_PER_SECOND,&sampleRate
);
UINT32 bitRate = NULL;
hr = pAudioType->GetUINT32(
MF_MT_AUdio_BITS_PER_SAMPLE,&bitRate
);
UINT32 channels = NULL;
hr = pAudioType->GetUINT32(
MF_MT_AUdio_NUM_CHANNELS,&channels
);
if (sampleRate == cSampleRate
&& bitRate == cBitPerSample
&& channels == cChannels)
{
// Found the codec.
// Jump out!
break;
}
}
// Add the media type to the caller
*ppType = pAudioType;
(*ppType)->AddRef();
SafeRelease(&pAudioType);
return hr;
}
void TV_AudioEncoderMF::decode()
{
HRESULT hr = S_OK;
// Initialize com interface
CoInitializeEx(0,COINIT_MULTITHREADED);
// Start media foundation
MFStartup(MF_VERSION);
IMFMediaType *pInputType = NULL;
IMFSourceReader *pSourceReader = NULL;
IMFMediaType *pOuputMediaType = NULL;
IMFSinkWriter *pSinkWriter = NULL;
// Create source reader
hr = MFCreateSourceReaderFromURL(
L"D:\\buffer\\del\\out\\test.wav",&pSourceReader
);
// Create sink writer
hr = MFCreateSinkWriterFromURL(
L"D:\\buffer\\del\\out\\test_out.mp3",&pSinkWriter
);
// Get media type from source reader
hr = pSourceReader->GetCurrentMediaType(
MF_SOURCE_READER_FirsT_AUdio_STREAM,&pInputType
);
// Get sample rate,bit rate and channels
UINT32 sampleRate = NULL;
hr = pInputType->GetUINT32(
MF_MT_AUdio_SAMPLES_PER_SECOND,&sampleRate
);
UINT32 bitRate = NULL;
hr = pInputType->GetUINT32(
MF_MT_AUdio_BITS_PER_SAMPLE,&bitRate
);
UINT32 channels = NULL;
hr = pInputType->GetUINT32(
MF_MT_AUdio_NUM_CHANNELS,&channels
);
// Try to find a media type that is fitting.
hr = GetoutputMediaTypes(
MFAudioFormat_MP3,sampleRate,bitRate,channels,&pOuputMediaType);
DWORD dwWriterStreamIndex = -1;
// Add the stream
hr = pSinkWriter->AddStream(
pOuputMediaType,&dwWriterStreamIndex
);
// Set input media type
hr = pSinkWriter->SetInputMediaType(
dwWriterStreamIndex,pInputType,NULL
);
// Tell the sink writer to accept data
hr = pSinkWriter->BeginWriting();
// Forever alone loop
while (true)
{
DWORD nStreamIndex,nStreamFlags;
LONGLONG nTime;
IMFSample *pSample;
// Read through the samples until...
hr = pSourceReader->ReadSample(
MF_SOURCE_READER_FirsT_AUdio_STREAM,&nStreamIndex,&nStreamFlags,&nTime,&pSample);
if (pSample)
{
hr = pSinkWriter->WriteSample(
dwWriterStreamIndex,pSample
);
}
// ... we are at the end of the stream...
if (nStreamFlags & MF_SOURCE_READERF_ENDOFSTREAM)
{
// ... and jump out.
break;
}
}
// Call finalize to finish writing.
hr = pSinkWriter->Finalize();
// Done :D
}
问题是 - 音频质量有很大差异,当我播放(通过 win 标准播放器).wav
文件时听起来不错,但是当我播放压缩为 .mp3
文件时听起来像人用录音机录制了他的声音,质量很差。
这里可能有什么问题?我没有看到任何可能的方式来设置质量,例如 setoutQualityInPersent(100)
编辑
void co_AudioEncoderMF::decode()
{
HRESULT hr = S_OK;
// Initialize com interface
CoInitializeEx(0,&pOuputMediaType);
bitRate = bitRate + 2; <------- This line
pOuputMediaType->SetUINT32(MF_MT_AUdio_BITS_PER_SAMPLE,bitRate); <------- This line
DWORD dwWriterStreamIndex = -1;
// Add the stream
hr = pSinkWriter->AddStream(
pOuputMediaType,pSample
);
}
// ... we are at the end of the stream...
if (nStreamFlags & MF_SOURCE_READERF_ENDOFSTREAM)
{
// ... and jump out.
break;
}
}
// Call finalize to finish writing.
hr = pSinkWriter->Finalize();
// Done :D
}
EDIT2
有 2 个文件 - https://drive.google.com/drive/folders/1yzB2u0TvMSnwsTpYnDDPFBDkTB75ZFwM?usp=sharing
结果和来源
解决方法
这部分坏了:
// Try to find a media type that is fitting.
hr = GetOutputMediaTypes(
MFAudioFormat_MP3,sampleRate,bitRate,channels,&pOuputMediaType);
bitRate = bitRate + 2; <------- This line
pOuputMediaType->SetUINT32(MF_MT_AUDIO_BITS_PER_SAMPLE,bitRate); <------- This line
为了让您重回正轨,请将上面的片段替换为:
MFCreateMediaType(&pOuputMediaType);
pOuputMediaType->SetGUID(MF_MT_MAJOR_TYPE,MFMediaType_Audio);
pOuputMediaType->SetGUID(MF_MT_SUBTYPE,MFAudioFormat_MP3);
pOuputMediaType->SetUINT32(MF_MT_AUDIO_AVG_BYTES_PER_SECOND,128000 / 8);
pOuputMediaType->SetUINT32(MF_MT_AUDIO_NUM_CHANNELS,channels);
pOuputMediaType->SetUINT32(MF_MT_AUDIO_SAMPLES_PER_SECOND,sampleRate);
然后你就会开始获得合适的 MP3。
请注意,以上属性直接取自文档:MP3 Audio Encoder。在您的应用程序中,您需要确保目标值保持有效并与记录的选项匹配。例如,您可能需要重新采样音频。
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