[alsa-devel] [RFC][PATCH 01/23] aplay: add an abstraction of container to parse/build audio-specific data format
Takashi Sakamoto
o-takashi at sakamocchi.jp
Thu Aug 17 13:59:42 CEST 2017
Current implementation of aplay supports three types of data format for
file; Microsoft/IBM RIFF/Wave (.wav), Sparc AU (.au) and Creative Tech.
voice (.voc). These formats were designed to handle audio-related data
with interleaved frame alignment.
This commit adds an abstraction of the file format, named as 'container'
module. This abstraction includes several functions to build/parse
the format data from any file descriptors. Furthermore, this includes
several helper functions for implementations for each builders/parsers.
---
aplay/Makefile.am | 14 ++-
aplay/container.c | 340 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
aplay/container.h | 114 ++++++++++++++++++
3 files changed, 463 insertions(+), 5 deletions(-)
create mode 100644 aplay/container.c
create mode 100644 aplay/container.h
diff --git a/aplay/Makefile.am b/aplay/Makefile.am
index c3256e9..44143e0 100644
--- a/aplay/Makefile.am
+++ b/aplay/Makefile.am
@@ -3,13 +3,17 @@ LIBRT = @LIBRT@
AM_CPPFLAGS = -I$(top_srcdir)/include
LDADD = $(LIBINTL) $(LIBRT)
-# debug flags
-#LDFLAGS = -static
-#LDADD += -ldl
-
bin_PROGRAMS = aplay
man_MANS = aplay.1 arecord.1
-noinst_HEADERS = formats.h
+noinst_HEADERS = \
+ formats.h \
+ container.h
+
+aplay_SOURCES = \
+ formats.h \
+ aplay.c \
+ container.h \
+ container.c
EXTRA_DIST = aplay.1 arecord.1
EXTRA_CLEAN = arecord
diff --git a/aplay/container.c b/aplay/container.c
new file mode 100644
index 0000000..7f8e31b
--- /dev/null
+++ b/aplay/container.c
@@ -0,0 +1,340 @@
+/*
+ * container.c - utilities for I/O to file.
+ *
+ * Copyright (c) 2017 Takashi Sakamoto <o-takashi at sakamocchi.jp>
+ *
+ * Licensed under the terms of the GNU General Public License, version 2.
+ */
+
+#include "container.h"
+
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <fcntl.h>
+#include <gettext.h>
+
+static const char *const cntr_type_labels[] = {
+ [CONTAINER_TYPE_PARSER] = "parser",
+ [CONTAINER_TYPE_BUILDER] = "builder",
+};
+
+static const char *const cntr_format_labels[] = {
+ [CONTAINER_FORMAT_COUNT] = "",
+};
+
+static const char *const suffixes[] = {
+ [CONTAINER_FORMAT_COUNT] = "",
+};
+
+const char *const container_suffix_from_format(enum container_format format)
+{
+ return suffixes[format];
+}
+
+int container_recursive_read(struct container_context *cntr, void *buf,
+ unsigned int size)
+{
+ char *dst = buf;
+ ssize_t result;
+ size_t consumed = 0;
+
+ while (consumed < size && !cntr->interrupted) {
+ result = read(cntr->fd, dst + consumed, size - consumed);
+ if (result < 0) {
+ /*
+ * This descriptor was configured with non-blocking
+ * mode. EINTR is not cought when get any interrupts.
+ */
+ if (cntr->interrupted)
+ return -EINTR;
+ if (errno == EAGAIN)
+ continue;
+ return -errno;
+ }
+ /* Reach EOF. */
+ if (result == 0) {
+ cntr->eof = true;
+ return 0;
+ }
+
+ consumed += result;
+ }
+
+ return 0;
+}
+
+int container_recursive_write(struct container_context *cntr, void *buf,
+ unsigned int size)
+{
+ char *src = buf;
+ ssize_t result;
+ size_t consumed = 0;
+
+ while (consumed < size && !cntr->interrupted) {
+ result = write(cntr->fd, src + consumed, size - consumed);
+ if (result < 0) {
+ /*
+ * This descriptor was configured with non-blocking
+ * mode. EINTR is not cought when get any interrupts.
+ */
+ if (cntr->interrupted)
+ return -EINTR;
+ if (errno == EAGAIN)
+ continue;
+ return -errno;
+ }
+
+ consumed += result;
+ }
+
+ return 0;
+}
+
+enum container_format container_format_from_path(const char *path)
+{
+ const char *suffix;
+ const char *pos;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(suffixes); ++i) {
+ suffix = suffixes[i];
+
+ /* Check last part of the string. */
+ pos = path + strlen(path) - strlen(suffix);
+ if (!strcmp(pos, suffix))
+ return i;
+ }
+
+ /* Unsupported. */
+ return CONTAINER_FORMAT_COUNT;
+}
+
+int container_seek_offset(struct container_context *cntr, off64_t offset)
+{
+ off64_t pos;
+
+ pos = lseek64(cntr->fd, offset, SEEK_SET);
+ if (pos < 0)
+ return -errno;
+ if (pos != offset)
+ return -EIO;
+
+ return 0;
+}
+
+/*
+ * To avoid blocking execution at system call iteration after receiving UNIX
+ * signals.
+ */
+static int set_nonblock_flag(int fd)
+{
+ int flags;
+
+ flags = fcntl(fd, F_GETFL);
+ if (flags < 0)
+ return -errno;
+
+ flags |= O_NONBLOCK;
+ if (fcntl(fd, F_SETFL, flags) < 0)
+ return -errno;
+
+ return 0;
+}
+
+int container_parser_init(struct container_context *cntr,
+ const char *const path, unsigned int verbose)
+{
+ const struct container_parser *parsers[] = {
+ NULL,
+ };
+ const struct container_parser *parser;
+ unsigned int size;
+ int i;
+ int err;
+
+ /* Open a target descriptor. */
+ if (path == NULL || path == '\0')
+ return -EINVAL;
+ if (!strcmp(path, "-")) {
+ cntr->fd = fileno(stdin);
+ err = set_nonblock_flag(cntr->fd);
+ if (err < 0)
+ return err;
+ } else {
+ cntr->fd = open(path, O_RDONLY | O_NONBLOCK);
+ if (cntr->fd < 0)
+ return -errno;
+ }
+
+ /* 4 bytes are enough to detect supported containers. */
+ err = container_recursive_read(cntr, cntr->magic, sizeof(cntr->magic));
+ if (err < 0)
+ return err;
+ for (i = 0; i < ARRAY_SIZE(parsers); ++i) {
+ parser = parsers[i];
+ size = strlen(parser->magic);
+ if (size > 4)
+ size = 4;
+ if (!strncmp(cntr->magic, parser->magic, size))
+ break;
+ }
+ /*
+ * Don't forget that the first 4 bytes were already read for magic
+ * bytes.
+ */
+ cntr->magic_handled = false;
+
+ /*
+ * Unless detected, use raw container.
+ */
+ if (i == ARRAY_SIZE(parsers))
+ return -EINVAL;
+
+ /* Allocate private data for the parser. */
+ if (parser->private_size > 0) {
+ cntr->private_data = malloc(parser->private_size);
+ if (cntr->private_data == NULL)
+ return -ENOMEM;
+ memset(cntr->private_data, 0, parser->private_size);
+ }
+
+ cntr->type = CONTAINER_TYPE_PARSER;
+ cntr->process_bytes = container_recursive_read;
+ cntr->format = parser->format;
+ cntr->ops = &parser->ops;
+ cntr->max_size = parser->max_size;
+ cntr->verbose = verbose;
+
+ return 0;
+}
+
+int container_builder_init(struct container_context *cntr,
+ const char *const path, enum container_format format,
+ unsigned int verbose)
+{
+ const struct container_builder *builders[] = {
+ NULL,
+ };
+ const struct container_builder *builder;
+ int err;
+
+ /* Open a target descriptor. */
+ if (path == NULL || path == '\0')
+ return -EINVAL;
+ if (!strcmp(path, "-")) {
+ cntr->fd = fileno(stdout);
+ err = set_nonblock_flag(cntr->fd);
+ if (err < 0)
+ return err;
+ } else {
+ cntr->fd = open(path, O_RDWR | O_NONBLOCK | O_CREAT, 0644);
+ if (cntr->fd < 0)
+ return -errno;
+ }
+
+ builder = builders[format];
+
+ /* Allocate private data for the builder. */
+ if (builder->private_size > 0) {
+ cntr->private_data = malloc(builder->private_size);
+ if (cntr->private_data == NULL)
+ return -ENOMEM;
+ memset(cntr->private_data, 0, builder->private_size);
+ }
+
+ cntr->type = CONTAINER_TYPE_BUILDER;
+ cntr->process_bytes = container_recursive_write;
+ cntr->format = builder->format;
+ cntr->ops = &builder->ops;
+ cntr->max_size = builder->max_size;
+ cntr->verbose = verbose;
+
+ return 0;
+}
+
+int container_context_pre_process(struct container_context *cntr,
+ snd_pcm_format_t *format,
+ unsigned int *samples_per_frame,
+ unsigned int *frames_per_second,
+ uint64_t *frame_count)
+{
+ int err;
+
+ if (cntr->ops->pre_process) {
+ err = cntr->ops->pre_process(cntr, format, samples_per_frame,
+ frames_per_second, frame_count);
+ if (err < 0) {
+ printf("%s(): %s\n", __func__, snd_strerror(err));
+ return err;
+ }
+ }
+
+ cntr->bytes_per_sample = snd_pcm_format_physical_width(*format) / 8;
+ cntr->samples_per_frame = *samples_per_frame;
+ cntr->frames_per_second = *frames_per_second;
+
+ if (cntr->verbose > 0) {
+ printf(_("Container: %s\n"), cntr_type_labels[cntr->type]);
+ printf(_(" format: %s\n"), cntr_format_labels[cntr->format]);
+ printf(_(" sample format: %s\n"), snd_pcm_format_name(*format));
+ printf(_(" bytes/sample: %u\n"), cntr->bytes_per_sample);
+ printf(_(" samples/frame: %u\n"), cntr->samples_per_frame);
+ printf(_(" frames/second: %u\n"), cntr->frames_per_second);
+ printf(_(" frames: %lu\n"), *frame_count);
+ printf("\n");
+ }
+
+ return 0;
+}
+
+int container_context_process_frames(struct container_context *cntr,
+ void *frame_buffer,
+ unsigned int *frame_count)
+{
+ char *buf = frame_buffer;
+ unsigned int size = cntr->bytes_per_sample * cntr->samples_per_frame *
+ *frame_count;
+ int err;
+
+ /* All of supported containers include interleaved PCM frames. */
+ err = cntr->process_bytes(cntr, buf, size);
+ if (err < 0) {
+ *frame_count = 0;
+ return err;
+ }
+
+ /* NOTE: For simplicity, drop the last chunk. */
+ if (cntr->eof) {
+ *frame_count = 0;
+ return 0;
+ }
+
+ cntr->handled_byte_count += size;
+
+ return 0;
+}
+
+int container_context_post_process(struct container_context *cntr,
+ uint64_t actual_frame_count)
+{
+ /* We cannot seek when using standard input/output. */
+ if (cntr->fd == fileno(stdin) || cntr->fd == fileno(stdout))
+ return 0;
+ if (cntr->verbose && cntr->handled_byte_count > 0) {
+ printf("%s:\n", __func__);
+ printf(" Handled bytes: %lu\n", cntr->handled_byte_count);
+ }
+
+ if (!cntr->ops || !cntr->ops->post_process)
+ return 0;
+
+ return cntr->ops->post_process(cntr, actual_frame_count);
+}
+
+void container_context_destroy(struct container_context *cntr)
+{
+ close(cntr->fd);
+ if (cntr->private_data)
+ free(cntr->private_data);
+}
diff --git a/aplay/container.h b/aplay/container.h
new file mode 100644
index 0000000..df1a90c
--- /dev/null
+++ b/aplay/container.h
@@ -0,0 +1,114 @@
+/*
+ * container.h - a header file for parser/builder of any containers.
+ *
+ * Copyright (c) 2017 Takashi Sakamoto <o-takashi at sakamocchi.jp>
+ *
+ * Licensed under the terms of the GNU General Public License, version 2.
+ */
+
+#ifndef __ALSA_UTILS_APLAY_CONTAINER__H_
+#define __ALSA_UTILS_APLAY_CONTAINER__H_
+
+#define _LARGEFILE64_SOURCE
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/* Not portable to all of UNIX platforms. */
+#include <endian.h>
+
+#include <alsa/asoundlib.h>
+
+#define ARRAY_SIZE(array) (sizeof(array)/sizeof(array[0]))
+
+enum container_type {
+ CONTAINER_TYPE_PARSER = 0,
+ CONTAINER_TYPE_BUILDER,
+ CONTAINER_TYPE_COUNT,
+};
+
+enum container_format {
+ CONTAINER_FORMAT_COUNT,
+};
+
+struct container_ops;
+
+struct container_context {
+ enum container_type type;
+ int fd;
+ int (*process_bytes)(struct container_context *cntr,
+ void *buffer, unsigned int byte_count);
+ bool magic_handled;
+ bool eof;
+ bool interrupted;
+
+ enum container_format format;
+ uint64_t max_size;
+ char magic[4];
+ const struct container_ops *ops;
+ void *private_data;
+
+ /* Available after pre-process. */
+ unsigned int bytes_per_sample;
+ unsigned int samples_per_frame;
+ unsigned int frames_per_second;
+
+ unsigned int verbose;
+ uint64_t handled_byte_count;
+};
+
+const char *const container_suffix_from_format(enum container_format format);
+enum container_format container_format_from_path(const char *path);
+int container_parser_init(struct container_context *cntr,
+ const char *const path, unsigned int verbose);
+int container_builder_init(struct container_context *cntr,
+ const char *const path, enum container_format format,
+ unsigned int verbose);
+void container_context_destroy(struct container_context *cntr);
+int container_context_pre_process(struct container_context *cntr,
+ snd_pcm_format_t *format,
+ unsigned int *samples_per_frame,
+ unsigned int *frames_per_second,
+ uint64_t *frame_count);
+int container_context_process_frames(struct container_context *cntr,
+ void *frame_buffer,
+ unsigned int *frame_count);
+int container_context_post_process(struct container_context *cntr,
+ uint64_t actual_frame_count);
+
+/* For internal use in 'container' module. */
+
+struct container_ops {
+ int (*pre_process)(struct container_context *cntr,
+ snd_pcm_format_t *format,
+ unsigned int *samples_per_frame,
+ unsigned int *frames_per_second,
+ uint64_t *frame_count);
+ int (*post_process)(struct container_context *cntr,
+ uint64_t actual_frame_count);
+};
+struct container_parser {
+ enum container_format format;
+ const char const *magic;
+ uint64_t max_size;
+ struct container_ops ops;
+ unsigned int private_size;
+};
+
+struct container_builder {
+ enum container_format format;
+ const char const *suffix;
+ uint64_t max_size;
+ struct container_ops ops;
+ unsigned int private_size;
+};
+
+int container_recursive_read(struct container_context *cntr, void *buf,
+ unsigned int size);
+int container_recursive_write(struct container_context *cntr, void *buf,
+ unsigned int size);
+int container_seek_offset(struct container_context *cntr, off64_t offset);
+
+#endif
--
2.11.0
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