samplerate converter, id3 tags

.gitignore

@@ -1,3 +1,5 @@
 *.so
 playmp3
 *.mp3
+install
+playmp3.tgz

playmp3.c

@@ -19,13 +19,35 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
+#include <wchar.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <errno.h>
 
 #include <sys/ioctl.h>
 
 #include "minimp3.h"
 
+static void print_id3_string(size_t len, uint8_t type, uint8_t * data) {
+	if (type == 0) {
+		printf("%.*s\n", len, data);
+	} else if (type == 1) {
+		char * out = malloc(len * 3);
+		char * t = out;
+		for (size_t i = 0; i < len / 2; ++i) {
+			wchar_t c[] = {((uint16_t*)data)[i], 0};
+			if (c[0] == 0xFEFF) continue;
+			if (c[0] == 0x0000) break;
+			t += wcstombs(t, c, 7);
+		}
+		printf("%s\n", out);
+		free(out);
+	} else {
+		printf("(unsupported ID3 tag encoding: %d)\n", type);
+	}
+
+}
+
 int main(int argc, char * argv[]) {
 	/* minimp3 stuff */
 	mp3_decoder_t mp3;
@@ -41,7 +63,10 @@ int main(int argc, char * argv[]) {
 	int spkr = open("/dev/dsp", O_WRONLY);
 	int song;
 
-	if (argc < 2) return 1;
+	if (argc < 2) {
+		fprintf(stderr, "usage: %s song.mp3\n", argv[0]);
+		return 1;
+	}
 
 	song = open(argv[1], O_RDONLY);
 
@@ -51,7 +76,7 @@ int main(int argc, char * argv[]) {
 	}
 
 	if (song == -1) {
-		fprintf(stderr, "audio file not found\n");
+		fprintf(stderr, "%s: %s: %s\n", argv[0], argv[1], strerror(errno));
 		return 2;
 	}
 
@@ -62,15 +87,50 @@ int main(int argc, char * argv[]) {
 	file_data = malloc(bytes_left);
 	read(song, file_data, bytes_left);
 	stream_pos = (unsigned char *) file_data;
-	fprintf(stderr, "%2x %2x %2x %2x %2x %2x %2x %2x\n",
-			stream_pos[0],
-			stream_pos[1],
-			stream_pos[2],
-			stream_pos[3],
-			stream_pos[4],
-			stream_pos[5],
-			stream_pos[6],
-			stream_pos[7]);
+
+	/* See if it has IDv3v2.3 tags */
+	if (!memcmp(stream_pos, "ID3", 3)) {
+		printf("ID3v2.%d.%d:\n", stream_pos[3], stream_pos[4]);
+		int unsynchronization = (stream_pos[5] & (1 << 7));
+	//	int experimental      = (stream_pos[5] & (1 << 5));
+		int extendedheader    = (stream_pos[5] & (1 << 6));
+
+		if (unsynchronization) {
+			printf("This file uses unsynchronization, so this probably won't work.\n");
+		}
+
+		uint32_t size =
+			((stream_pos[6] & 0x7F) << 21) |
+			((stream_pos[7] & 0x7F) << 14) |
+			((stream_pos[8] & 0x7F) << 7) |
+			((stream_pos[9] & 0x7F) << 0);
+
+		uint8_t * tag = &stream_pos[10];
+		if (extendedheader) {
+			uint32_t esize =
+				((stream_pos[10] & 0x7F) << 21) |
+				((stream_pos[11] & 0x7F) << 14) |
+				((stream_pos[12] & 0x7F) << 7) |
+				((stream_pos[13] & 0x7F) << 0);
+			tag = stream_pos + 10 + esize;
+		}
+
+		while (tag) {
+			uint32_t size = (tag[4] << 24) | (tag[5] << 16) | (tag[6] << 8) | (tag[7]);
+			if (size == 0) break;
+			//printf("Tag '%c%c%c%c', %u bytes\n", tag[0], tag[1], tag[2], tag[3], size);
+			if (!memcmp(tag, "TPE1", 4) || !memcmp(tag, "TIT2", 4)) {
+				print_id3_string(size-1, tag[10], &tag[11]);
+			}
+			tag = tag + 10 + size;
+		}
+	} else if (!memcmp(&stream_pos[bytes_left - 128], "TAG", 3)) {
+		printf("ID3v1:\n%30s\n%30s\n%30s\n",
+			&stream_pos[bytes_left - 128 + 3],
+			&stream_pos[bytes_left - 128 + 33],
+			&stream_pos[bytes_left - 128 + 63]);
+	}
+
 	bytes_left -= 100;
 
 	mp3 = mp3_create();
@@ -80,17 +140,48 @@ int main(int argc, char * argv[]) {
 		return 1;
 	}
 
-	fprintf(stderr, "Playing, sample rate is %d, bytes left is %d\n", info.sample_rate, bytes_left);
-	fprintf(stderr, "Frame size is %d, file data is at 0x%x\n", frame_size, file_data);
+	if (info.audio_bytes == -1) {
+		fprintf(stderr, "This MP3 has frames I can't understand. Try re-encoding it.\n");
+		return 1;
+	}
+
+	fprintf(stderr, "%d.%d kHz, %d bytes per frame\n",
+		info.sample_rate / 1000, (info.sample_rate / 100) % 10,
+		info.audio_bytes);
+
+	uint64_t sample_count = sample_count = info.audio_bytes / 4;
+
+	uint64_t expanded_length;
+	int expand_ratio;
+	int16_t * snd;
+
+	if (info.sample_rate != 48000) {
+		expanded_length = (sample_count * 48000) / info.sample_rate;
+		expand_ratio = (sample_count << 8) / expanded_length;
+		snd = malloc(expanded_length * sizeof(int16_t) * 2);
+	}
 
 	while ((bytes_left >= 0) && (frame_size > 0)) {
-		size_t w = 0;
-		while (w < info.audio_bytes) {
-			w += write(spkr, (const void *)( (char *)sample_buf + w), info.audio_bytes - w);
+		if (info.sample_rate != 48000) {
+			for (int CH = 0; CH < 2; ++CH) {
+				for (int i = 0; i < expanded_length; ++i) {
+					int src = (i * expand_ratio) >> 8;
+					snd[i * 2 + CH] = sample_buf[src * 2 + CH];
+				}
+			}
+			size_t w = 0;
+			while (w < info.audio_bytes) {
+				w += write(spkr, (const void *)( (char *)snd + w), expanded_length * sizeof(int16_t) * 2 - w);
+			}
+		} else {
+			size_t w = 0;
+			while (w < info.audio_bytes) {
+				w += write(spkr, (const void *)( (char *)sample_buf + w), info.audio_bytes - w);
+			}
 		}
 		stream_pos += frame_size;
 		bytes_left -= frame_size;
-		frame_size = mp3_decode(mp3, stream_pos, bytes_left, sample_buf, NULL);
+		frame_size = mp3_decode(mp3, stream_pos, bytes_left, sample_buf, &info);
 	}
 
 	return 0;