linux_alsa_helloworld

simple audio playback example using ALSA
git clone https://0xdd.org/code/linux_alsa_helloworld.git
Log | Files | Refs | README | LICENSE

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++++
ALICENSE | 116+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
AMakefile | 23+++++++++++++++++++++++
AREADME | 7+++++++
Amain.c | 86+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Asample.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 + +The laws of most jurisdictions throughout the world automatically confer +exclusive Copyright and Related Rights (defined below) upon the creator and +subsequent owner(s) (each and all, an "owner") of an original work of +authorship and/or a database (each, a "Work"). + +Certain owners wish to permanently relinquish those rights to a Work for the +purpose of contributing to a commons of creative, cultural and scientific +works ("Commons") that the public can reliably and without fear of later +claims of infringement build upon, modify, incorporate in other works, reuse +and redistribute as freely as possible in any form whatsoever and for any +purposes, including without limitation commercial purposes. These owners may +contribute to the Commons to promote the ideal of a free culture and the +further production of creative, cultural and scientific works, or to gain +reputation or greater distribution for their Work in part through the use and +efforts of others. + +For these and/or other purposes and motivations, and without any expectation +of additional consideration or compensation, the person associating CC0 with a +Work (the "Affirmer"), to the extent that he or she is an owner of Copyright +and Related Rights in the Work, voluntarily elects to apply CC0 to the Work +and publicly distribute the Work under its terms, with knowledge of his or her +Copyright and Related Rights in the Work and the meaning and intended legal +effect of CC0 on those rights. + +1. Copyright and Related Rights. A Work made available under CC0 may be +protected by copyright and related or neighboring rights ("Copyright and +Related Rights"). Copyright and Related Rights include, but are not limited +to, the following: + + i. the right to reproduce, adapt, distribute, perform, display, communicate, + and translate a Work; + + ii. moral rights retained by the original author(s) and/or performer(s); + + iii. publicity and privacy rights pertaining to a person's image or likeness + depicted in a Work; + + iv. rights protecting against unfair competition in regards to a Work, + subject to the limitations in paragraph 4(a), below; + + v. rights protecting the extraction, dissemination, use and reuse of data in + a Work; + + vi. database rights (such as those arising under Directive 96/9/EC of the + European Parliament and of the Council of 11 March 1996 on the legal + protection of databases, and under any national implementation thereof, + including any amended or successor version of such directive); and + + vii. other similar, equivalent or corresponding rights throughout the world + based on applicable law or treaty, and any national implementations thereof. + +2. Waiver. To the greatest extent permitted by, but not in contravention of, +applicable law, Affirmer hereby overtly, fully, permanently, irrevocably and +unconditionally waives, abandons, and surrenders all of Affirmer's Copyright +and Related Rights and associated claims and causes of action, whether now +known or unknown (including existing as well as future claims and causes of +action), in the Work (i) in all territories worldwide, (ii) for the maximum +duration provided by applicable law or treaty (including future time +extensions), (iii) in any current or future medium and for any number of +copies, and (iv) for any purpose whatsoever, including without limitation +commercial, advertising or promotional purposes (the "Waiver"). 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In addition, to the extent the Waiver +is so judged Affirmer hereby grants to each affected person a royalty-free, +non transferable, non sublicensable, non exclusive, irrevocable and +unconditional license to exercise Affirmer's Copyright and Related Rights in +the Work (i) in all territories worldwide, (ii) for the maximum duration +provided by applicable law or treaty (including future time extensions), (iii) +in any current or future medium and for any number of copies, and (iv) for any +purpose whatsoever, including without limitation commercial, advertising or +promotional purposes (the "License"). The License shall be deemed effective as +of the date CC0 was applied by Affirmer to the Work. Should any part of the +License for any reason be judged legally invalid or ineffective under +applicable law, such partial invalidity or ineffectiveness shall not +invalidate the remainder of the License, and in such case Affirmer hereby +affirms that he or she will not (i) exercise any of his or her remaining +Copyright and Related Rights in the Work or (ii) assert any associated claims +and causes of action with respect to the Work, in either case contrary to +Affirmer's express Statement of Purpose. + +4. Limitations and Disclaimers. + + a. No trademark or patent rights held by Affirmer are waived, abandoned, + surrendered, licensed or otherwise affected by this document. + + b. Affirmer offers the Work as-is and makes no representations or warranties + of any kind concerning the Work, express, implied, statutory or otherwise, + including without limitation warranties of title, merchantability, fitness + for a particular purpose, non infringement, or the absence of latent or + other defects, accuracy, or the present or absence of errors, whether or not + discoverable, all to the greatest extent permissible under applicable law. + + c. Affirmer disclaims responsibility for clearing rights of other persons + that may apply to the Work or any use thereof, including without limitation + any person's Copyright and Related Rights in the Work. Further, Affirmer + disclaims responsibility for obtaining any necessary consents, permissions + or other rights required for any use of the Work. + + d. Affirmer understands and acknowledges that Creative Commons is not a + party to this document and has no duty or obligation with respect to this + CC0 or use of the Work. + +For more information, please see +<http://creativecommons.org/publicdomain/zero/1.0/> 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.