Simple experiment with parsing wav-files

analyzewav.c

#include <stdio.h>
#include <stdlib.h>

#define FormatID 'fmt '   /* chunkID for Format Chunk. NOTE: There is a space at the end of this ID. */

struct GlobalFormat {
  unsigned int id;
  unsigned int size;
  unsigned int type;
};

struct FormatChunk {
  short          wFormatTag;
  unsigned short wChannels;
  unsigned long  dwSamplesPerSec;
  unsigned long  dwAvgBytesPerSec;
  unsigned short wBlockAlign;
  unsigned short wBitsPerSample;

/* Note: there may be additional fields here, depending upon wFormatTag. */

};

int main(int argc, char** argv)
{
	if (argc != 2) {
		printf("specify file.\n");
		return 0;
	}

	FILE* fh = fopen(argv[1], "r");

	struct GlobalFormat format;

	fread(&format, sizeof(struct GlobalFormat), 1, fh);

	char id[5];
	memcpy(&id, &format.id, 4);
	id[4] = 0;

	int size = format.size;

	char type[5];
	memcpy(&type, &format.type, 4);
	type[4] = 0;

	printf("chunkid: %s\n", id);
	printf("size: %d\n", format.size);
	printf("type: %s\n", type);

	printf("\n");

	while (!feof(fh)) {

		char chunkid[5];
		fread(chunkid, sizeof(char), 4, fh);
		chunkid[4] = 0;

		int i_chunkid = *((int*)chunkid);

		printf("chunkid: %s\n", chunkid);
		printf("hex: %x\n", i_chunkid);

		int chunksize;
		fread(&chunksize, sizeof(int), 1, fh);
		printf("chunksize: %d\n", chunksize);

		long pos;
		int done = 0;
		double avg = 0;
		unsigned short a;
		long c;
		struct FormatChunk* fmt = (struct FormatChunk*)malloc(sizeof(struct FormatChunk));
		switch (i_chunkid) {
			case 0x20746d66: // fmt
				fread(fmt, sizeof(struct FormatChunk), 1, fh);
				printf("formatTag: %d\n", fmt->wFormatTag);
				printf("channels: %d\n", fmt->wChannels);
				printf("samplesPerSec: %d\n", fmt->dwSamplesPerSec);
				printf("dwAvgBytesPerSec: %d\n", fmt->dwAvgBytesPerSec);
				printf("wBlockAlign: %d\n", fmt->wBlockAlign);
				printf("wBitsPerSample: %d\n", fmt->wBitsPerSample);
				break;

			case 0x61746164: // data
				for (c = 0; c < chunksize; c+=2) {
					fread(&a, sizeof(unsigned short), 1, fh);
					printf("%d\n", a);
					avg += a;
				}
				avg /= c;
				printf("average amplitude: %d\n", avg);
				break;

			default:
				pos = ftell(fh);

				if (pos + chunksize >= size) {
					done = 1;
				}

				if (fseek(fh, chunksize, SEEK_CUR) == -1) {
					done = 1;
				}
		}

		if (done == 1) {
			break;
		}

		printf("\n");
	}

	fclose(fh);

	return 0;
}