commit 7f19bbcf1f1b75fbf11a213c2ae12630ee5a2acb
Author: David DiPaola <DavidDiPaola@users.noreply.github.com>
Date: Fri, 1 Feb 2019 14:27:17 -0500
initial commit
Diffstat:
| A | .gitignore | | | 4 | ++++ |
| A | LICENSE | | | 116 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
| A | Makefile | | | 23 | +++++++++++++++++++++++ |
| A | README | | | 7 | +++++++ |
| A | main.c | | | 86 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
| A | sample.ogg | | | 0 | |
6 files changed, 236 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1,4 @@
+*.raw
+
+audio_helloworld
+
diff --git a/LICENSE b/LICENSE
@@ -0,0 +1,116 @@
+CC0 1.0 Universal
+
+Statement of Purpose
+
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+affirms that he or she will not (i) exercise any of his or her remaining
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+4. Limitations and Disclaimers.
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+ a. No trademark or patent rights held by Affirmer are waived, abandoned,
+ surrendered, licensed or otherwise affected by this document.
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diff --git a/Makefile b/Makefile
@@ -0,0 +1,23 @@
+# 2018 David DiPaola
+# licensed under CC0 (public domain, see https://creativecommons.org/publicdomain/zero/1.0/)
+
+BIN = audio_helloworld
+
+_CFLAGS = -Wall -Wextra \
+ $(CFLAGS)
+_LIBS = \
+ -lasound
+
+.PHONY: all
+all: $(BIN)
+
+.PHONY: clean
+clean:
+ rm -rf $(BIN) sample.raw
+
+sample.raw: sample.ogg
+ ffmpeg -v 0 -i $< -f s16le -acodec pcm_s16le -ac 1 -ar 44100 $@
+
+$(BIN): main.c sample.raw
+ $(CC) $(_CFLAGS) $< $(_LIBS) -o $@
+
diff --git a/README b/README
@@ -0,0 +1,7 @@
+# linux_alsa_helloworld
+simple audio playback example using ALSA
+
+## dependencies
+ - ALSA development library
+ - ffmpeg (to convert the .ogg file to raw audio)
+
diff --git a/main.c b/main.c
@@ -0,0 +1,86 @@
+/*
+2018 David DiPaola
+licensed under CC0 (public domain, see https://creativecommons.org/publicdomain/zero/1.0/)
+*/
+
+#include <stdio.h>
+
+#include <alsa/asoundlib.h>
+
+int
+main() {
+ int exitcode = 0;
+ int status;
+
+ printf("getting default sound playback stream..." "\n");
+ snd_pcm_t * pcm = NULL;
+ status = snd_pcm_open(&pcm, "default", SND_PCM_STREAM_PLAYBACK, 0);
+ if (status < 0) {
+ printf("ERROR: %s" "\n", snd_strerror(status));
+ exitcode = 1;
+ goto cleanup;
+ }
+
+ printf("setting parameters..." "\n");
+ const unsigned int channels = 1;
+ const unsigned int rate = 44100;
+ const int resample = 1;
+ const unsigned int latency_us = 100;
+ status = snd_pcm_set_params(pcm, SND_PCM_FORMAT_S16_LE, SND_PCM_ACCESS_RW_INTERLEAVED, channels, rate, resample, latency_us);
+ if (status < 0) {
+ printf("ERROR: %s" "\n", snd_strerror(status));
+ exitcode = 1;
+ goto cleanup;
+ }
+
+ printf("getting number of frames in stream..." "\n");
+ snd_pcm_sframes_t snd_frames = snd_pcm_avail(pcm);
+ if (snd_frames < 0) {
+ printf("ERROR: %s" "\n", snd_strerror(status));
+ exitcode = 1;
+ goto cleanup;
+ }
+ printf("\t" "number of frames: %li" "\n", snd_frames);
+
+ printf("reading frames from file..." "\n");
+ FILE * file = fopen("sample.raw", "r+");
+ if (!file) {
+ fprintf(stderr, "ERROR: fopen()");
+ exitcode = 1;
+ goto cleanup;
+ }
+ fseek(file, 0, SEEK_END);
+ long file_size = ftell(file);
+ fseek(file, 0, SEEK_SET);
+ short * buffer = malloc(file_size);
+ size_t buffer_length = file_size / sizeof(*buffer);
+ fread(buffer, file_size, 1, file);
+ fclose(file);
+ file = NULL;
+
+ printf("writing %zi frames to stream..." "\n", buffer_length);
+ size_t i = 0;
+ while (i < buffer_length) {
+ snd_pcm_sframes_t written = snd_pcm_writei(pcm, &(buffer[i]), (buffer_length - i));
+ if (written < 0) {
+ while (snd_pcm_recover(pcm, written, 0) != 0) {
+ fprintf(stderr, "\t" "INFO: recovery failed" "\n");
+ }
+ continue;
+ }
+
+ i += written;
+ }
+
+ cleanup:
+ printf("closing sound playback stream..." "\n");
+ status = snd_pcm_close(pcm);
+ if (status < 0) {
+ printf("ERROR: %s" "\n", snd_strerror(status));
+ return 1;
+ }
+ pcm = NULL;
+
+ return exitcode;
+}
+
diff --git a/sample.ogg b/sample.ogg
Binary files differ.
