366 lines
12 KiB
C
366 lines
12 KiB
C
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/* lowpass.c - WinMain() and dialog procedures for LOWPASS, along with
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* initialization and support code.
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*
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* LOWPASS is a sample application illustrating how to use the multimedia
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* file I/O services to read and write RIFF files.
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*
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* LOWPASS runs a simple low-pass filter over an 8-bit-per-sample
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* mono WAVE file. Note that this program does not copy unknown chunks
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* to the output file.
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*
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*
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* (C) Copyright Microsoft Corp. 1991. All rights reserved.
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*
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* You have a royalty-free right to use, modify, reproduce and
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* distribute the Sample Files (and/or any modified version) in
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* any way you find useful, provided that you agree that
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* Microsoft has no warranty obligations or liability for any
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* Sample Application Files which are modified.
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*/
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#include <windows.h>
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#include <mmsystem.h>
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#include "lowpass.h"
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/* Globals
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*/
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char gszAppName[] = "LowPass"; // for title bar, etc.
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HANDLE ghInst; // app's instance handle
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/* DoLowPass - Gets the name of the input and output WAVE files from
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* the dialog box; reads waveform data from the input file, performs
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* a simple low-pass filter by averaging adjacent samples, and writes
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* the filtered waveform data to the output WAVE file.
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*
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* Params: hWnd - Window handle for our dialog box.
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*
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* Returns:
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*/
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void DoLowPass(HWND hWnd)
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{
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char achInFile[200]; // name of input file
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char achOutFile[200]; // name of output file
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HMMIO hmmioIn = NULL; // handle to open input WAVE file
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HMMIO hmmioOut = NULL; // handle to open output WAVE file
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MMCKINFO ckInRIFF; // chunk info. for input RIFF chunk
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MMCKINFO ckOutRIFF; // chunk info. for output RIFF chunk
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MMCKINFO ckIn; // info. for a chunk in input file
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MMCKINFO ckOut; // info. for a chunk in output file
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PCMWAVEFORMAT pcmWaveFormat; // contents of 'fmt' chunks
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MMIOINFO mmioinfoIn; // current status of <hmmioIn>
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MMIOINFO mmioinfoOut; // current status of <hmmioOut>
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long lSamples; // number of samples to filter
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BYTE abSamples[3]; // this, last, and before-last sample
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/* Read filenames from dialog box fields.
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*/
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achInFile[0] == 0;
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GetDlgItemText(hWnd, ID_INPUTFILEEDIT, achInFile, sizeof(achInFile));
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achOutFile[0] == 0;
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GetDlgItemText(hWnd, ID_OUTPUTFILEEDIT, achOutFile, sizeof(achOutFile));
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/* Open the input file for reading using buffered I/O.
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*/
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hmmioIn = mmioOpen(achInFile, NULL, MMIO_ALLOCBUF | MMIO_READ);
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if (hmmioIn == NULL)
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goto ERROR_CANNOT_READ; // cannot open WAVE file
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/* Open the output file for writing using buffered I/O. Note that
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* if the file exists, the MMIO_CREATE flag causes it to be truncated
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* to zero length.
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*/
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hmmioOut = mmioOpen(achOutFile, NULL,
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MMIO_ALLOCBUF | MMIO_WRITE | MMIO_CREATE);
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if (hmmioOut == NULL)
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goto ERROR_CANNOT_WRITE; // cannot open WAVE file
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/* Descend the input file into the 'RIFF' chunk.
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*/
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if (mmioDescend(hmmioIn, &ckInRIFF, NULL, 0) != 0)
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goto ERROR_CANNOT_READ; // end-of-file, probably
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/* Make sure the input file is a WAVE file.
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*/
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if ((ckInRIFF.ckid != FOURCC_RIFF) ||
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(ckInRIFF.fccType != mmioFOURCC('W', 'A', 'V', 'E')))
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goto ERROR_FORMAT_BAD;
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/* Search the input file for for the 'fmt ' chunk.
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*/
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ckIn.ckid = mmioFOURCC('f', 'm', 't', ' ');
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if (mmioDescend(hmmioIn, &ckIn, &ckInRIFF, MMIO_FINDCHUNK) != 0)
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goto ERROR_FORMAT_BAD; // no 'fmt ' chunk
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/* Expect the 'fmt' chunk to be at least as large as <pcmWaveFormat>;
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* if there are extra parameters at the end, we'll ignore them
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*/
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if (ckIn.cksize < (long) sizeof(pcmWaveFormat))
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goto ERROR_FORMAT_BAD; // 'fmt ' chunk too small
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/* Read the 'fmt ' chunk into <pcmWaveFormat>.
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*/
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if (mmioRead(hmmioIn, (HPSTR) &pcmWaveFormat,
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(long) sizeof(pcmWaveFormat)) != (long) sizeof(pcmWaveFormat))
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goto ERROR_CANNOT_READ; // truncated file, probably
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/* Ascend the input file out of the 'fmt ' chunk.
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*/
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if (mmioAscend(hmmioIn, &ckIn, 0) != 0)
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goto ERROR_CANNOT_READ; // truncated file, probably
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/* Make sure the input file is an 8-bit mono PCM WAVE file.
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*/
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if ((pcmWaveFormat.wf.wFormatTag != WAVE_FORMAT_PCM) ||
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(pcmWaveFormat.wf.nChannels != 1) ||
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(pcmWaveFormat.wBitsPerSample != 8))
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goto ERROR_FORMAT_BAD; // bad input file format
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/* Search the input file for for the 'data' chunk.
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*/
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ckIn.ckid = mmioFOURCC('d', 'a', 't', 'a');
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if (mmioDescend(hmmioIn, &ckIn, &ckInRIFF, MMIO_FINDCHUNK) != 0)
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goto ERROR_FORMAT_BAD; // no 'data' chunk
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/* Create the output file RIFF chunk of form type 'WAVE'.
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*/
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ckOutRIFF.fccType = mmioFOURCC('W', 'A', 'V', 'E');
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if (mmioCreateChunk(hmmioOut, &ckOutRIFF, MMIO_CREATERIFF) != 0)
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goto ERROR_CANNOT_WRITE; // cannot write file, probably
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/* We are now descended into the 'RIFF' chunk we just created.
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* Now create the 'fmt ' chunk. Since we know the size of this chunk,
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* specify it in the MMCKINFO structure so MMIO doesn't have to seek
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* back and set the chunk size after ascending from the chunk.
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*/
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ckOut.ckid = mmioFOURCC('f', 'm', 't', ' ');
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ckOut.cksize = sizeof(pcmWaveFormat); // we know the size of this ck.
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if (mmioCreateChunk(hmmioOut, &ckOut, 0) != 0)
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goto ERROR_CANNOT_WRITE; // cannot write file, probably
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/* Write the PCMWAVEFORMAT structure to the 'fmt ' chunk.
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*/
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if (mmioWrite(hmmioOut, (HPSTR) &pcmWaveFormat, sizeof(pcmWaveFormat))
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!= sizeof(pcmWaveFormat))
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goto ERROR_CANNOT_WRITE; // cannot write file, probably
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/* Ascend out of the 'fmt ' chunk, back into the 'RIFF' chunk.
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*/
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if (mmioAscend(hmmioOut, &ckOut, 0) != 0)
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goto ERROR_CANNOT_WRITE; // cannot write file, probably
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/* Create the 'data' chunk that holds the waveform samples.
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*/
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ckOut.ckid = mmioFOURCC('d', 'a', 't', 'a');
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if (mmioCreateChunk(hmmioOut, &ckOut, 0) != 0)
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goto ERROR_CANNOT_WRITE; // cannot write file, probably
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/* Read samples from the 'data' chunk of the input file, and write
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* samples to the 'data' chunk of the output file. Each sample in
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* the output file equals the average of the corresponding sample
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* in the input file and the previous two samples from the input file.
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* Access the I/O buffers of <hmmioIn> and <hmmioOut> directly,
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* since this is faster than calling mmioRead() and mmioWrite()
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* for each sample.
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*/
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abSamples[0] = abSamples[1] = abSamples[2] = 128;
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/* Begin direct access of the I/O buffers.
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*/
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if (mmioGetInfo(hmmioIn, &mmioinfoIn, 0) != 0)
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goto ERROR_UNKNOWN;
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if (mmioGetInfo(hmmioOut, &mmioinfoOut, 0) != 0)
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goto ERROR_UNKNOWN;
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/* For each input sample, compute and write the output sample.
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*/
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for (lSamples = ckIn.cksize; lSamples > 0; lSamples--)
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{
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/* If we are at the end of the input file I/O buffer, fill it.
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* Test to see that we don't hit end of file while (lSamples > 0).
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*/
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if (mmioinfoIn.pchNext == mmioinfoIn.pchEndRead)
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{
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if (mmioAdvance(hmmioIn, &mmioinfoIn, MMIO_READ) != 0)
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goto ERROR_CANNOT_READ;
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if (mmioinfoIn.pchNext == mmioinfoIn.pchEndRead)
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goto ERROR_CANNOT_READ;
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}
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/* If we are the end of the output file I/O buffer, flush it.
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*/
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if (mmioinfoOut.pchNext == mmioinfoOut.pchEndWrite)
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{
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mmioinfoOut.dwFlags |= MMIO_DIRTY;
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if (mmioAdvance(hmmioOut, &mmioinfoOut, MMIO_WRITE) != 0)
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goto ERROR_CANNOT_WRITE;
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}
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/* Keep track of the last 3 samples so we can average.
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*/
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abSamples[2] = abSamples[1]; // next-to-last sample
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abSamples[1] = abSamples[0]; // last sample
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abSamples[0] = *(mmioinfoIn.pchNext)++; // current sample
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/* The output file sample is the average of the last
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* 3 input file samples.
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*/
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*(mmioinfoOut.pchNext)++ = (BYTE) (((int) abSamples[0]
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+ (int) abSamples[1] + (int) abSamples[2]) / 3);
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}
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/* We are through processing samples, end direct access of
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* the I/O buffers. Set the MMIO_DIRTY flag for the output buffer
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* to flush it.
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*/
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if (mmioSetInfo(hmmioIn, &mmioinfoIn, 0) != 0)
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goto ERROR_UNKNOWN;
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mmioinfoOut.dwFlags |= MMIO_DIRTY;
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if (mmioSetInfo(hmmioOut, &mmioinfoOut, 0) != 0)
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goto ERROR_CANNOT_WRITE; // cannot flush, probably
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/* Ascend the output file out of the 'data' chunk -- this will cause
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* the chunk size of the 'data' chunk to be written.
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*/
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if (mmioAscend(hmmioOut, &ckOut, 0) != 0)
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goto ERROR_CANNOT_WRITE; // cannot write file, probably
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/* Ascend the output file out of the 'RIFF' chunk -- this will cause
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* the chunk size of the 'RIFF' chunk to be written.
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*/
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if (mmioAscend(hmmioOut, &ckOutRIFF, 0) != 0)
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goto ERROR_CANNOT_WRITE; // cannot write file, probably
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/* We are done -- files are closed below.
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*/
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goto EXIT_FUNCTION;
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ERROR_FORMAT_BAD:
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MessageBox(NULL, "Input file must be an 8-bit mono PCM WAVE file",
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gszAppName, MB_ICONEXCLAMATION | MB_OK);
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goto EXIT_FUNCTION;
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ERROR_CANNOT_READ:
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MessageBox(NULL, "Cannot read input WAVE file",
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gszAppName, MB_ICONEXCLAMATION | MB_OK);
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goto EXIT_FUNCTION;
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ERROR_CANNOT_WRITE:
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MessageBox(NULL, "Cannot write output WAVE file",
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gszAppName, MB_ICONEXCLAMATION | MB_OK);
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goto EXIT_FUNCTION;
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ERROR_UNKNOWN:
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MessageBox(NULL, "Unknown error",
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gszAppName, MB_ICONEXCLAMATION | MB_OK);
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goto EXIT_FUNCTION;
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EXIT_FUNCTION:
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/* Close the files (unless they weren't opened successfully).
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*/
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if (hmmioIn != NULL)
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mmioClose(hmmioIn, 0);
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if (hmmioOut != NULL)
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mmioClose(hmmioOut, 0);
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}
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/* WinMain - Entry point for LowPass.
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*/
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int PASCAL WinMain(HINSTANCE hInst, HINSTANCE hPrev, LPSTR lpszCmdLine, int iCmdShow)
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{
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FARPROC fpfn;
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/* Save instance handle for dialog boxes.
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*/
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ghInst = hInst;
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/* Display our dialog box.
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*/
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fpfn = MakeProcInstance((FARPROC) LowPassDlgProc, ghInst);
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DialogBox(ghInst, "LOWPASSBOX", NULL, (DLGPROC)fpfn);
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FreeProcInstance(fpfn);
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return TRUE;
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}
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/* AboutDlgProc - Dialog procedure function for ABOUTBOX dialog box.
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*/
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BOOL FAR PASCAL
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AboutDlgProc(HWND hWnd, UINT wMsg, WPARAM wParam, LPARAM lParam)
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{
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switch (wMsg)
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{
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case WM_INITDIALOG:
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return TRUE;
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case WM_COMMAND:
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if (LOWORD(wParam) == IDOK)
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EndDialog(hWnd, TRUE);
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break;
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}
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return FALSE;
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}
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/* LowPassDlgProc - Dialog procedure function for LOWPASSBOX dialog box.
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*/
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BOOL FAR PASCAL
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LowPassDlgProc(HWND hWnd, UINT wMsg, WPARAM wParam, LPARAM lParam)
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{
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FARPROC fpfn;
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HMENU hmenuSystem; // system menu
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HCURSOR ghcurSave; // previous cursor
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switch (wMsg)
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{
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case WM_INITDIALOG:
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/* Append "About" menu item to system menu.
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*/
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hmenuSystem = GetSystemMenu(hWnd, FALSE);
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AppendMenu(hmenuSystem, MF_SEPARATOR, 0, NULL);
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AppendMenu(hmenuSystem, MF_STRING, IDM_ABOUT,
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"&About LowPass...");
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return TRUE;
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case WM_SYSCOMMAND:
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switch (wParam)
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{
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case IDM_ABOUT:
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/* Display "About" dialog box.
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*/
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fpfn = MakeProcInstance((FARPROC) AboutDlgProc, ghInst);
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DialogBox(ghInst, "ABOUTBOX", hWnd, (DLGPROC)fpfn);
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FreeProcInstance(fpfn);
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break;
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}
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break;
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case WM_COMMAND:
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switch (LOWORD(wParam))
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{
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case IDOK: // "Begin"
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/* Set "busy" cursor, filter input file, restore cursor.
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*/
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ghcurSave = SetCursor(LoadCursor(NULL, IDC_WAIT));
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DoLowPass(hWnd);
|
||
|
|
SetCursor(ghcurSave);
|
||
|
|
break;
|
||
|
|
|
||
|
|
case IDCANCEL: // "Done"
|
||
|
|
EndDialog(hWnd, TRUE);
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
return FALSE;
|
||
|
|
}
|