[alsa-devel] [PATCH 03/35] axfer: add a common interface to handle a file with audio-specific data format
Takashi Sakamoto
o-takashi at sakamocchi.jp
Tue Nov 13 07:41:15 CET 2018
Current aplay supports several 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 a common interface to handle the file format, named as
'container' module. This includes several functions to build/parse
the format data from any file descriptors. Furthermore, this includes
several helper functions for implementations of each builder/parser.
Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>
---
axfer/Makefile.am | 7 +-
axfer/container.c | 423 ++++++++++++++++++++++++++++++++++++++++++++++
axfer/container.h | 110 ++++++++++++
3 files changed, 538 insertions(+), 2 deletions(-)
create mode 100644 axfer/container.c
create mode 100644 axfer/container.h
diff --git a/axfer/Makefile.am b/axfer/Makefile.am
index 4e37b92..3913d0c 100644
--- a/axfer/Makefile.am
+++ b/axfer/Makefile.am
@@ -15,10 +15,13 @@ LDADD = \
noinst_HEADERS = \
misc.h \
- subcmd.h
+ subcmd.h \
+ container.h
axfer_SOURCES = \
misc.h \
subcmd.h \
main.c \
- subcmd-list.c
+ subcmd-list.c \
+ container.h \
+ container.c
diff --git a/axfer/container.c b/axfer/container.c
new file mode 100644
index 00000000..77bbd6c
--- /dev/null
+++ b/axfer/container.c
@@ -0,0 +1,423 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// container.c - an interface of parser/builder for formatted files.
+//
+// Copyright (c) 2018 Takashi Sakamoto <o-takashi at sakamocchi.jp>
+//
+// Licensed under the terms of the GNU General Public License, version 2.
+
+#include "container.h"
+#include "misc.h"
+
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <fcntl.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 byte_count)
+{
+ char *dst = buf;
+ ssize_t result;
+ size_t consumed = 0;
+
+ while (consumed < byte_count && !cntr->interrupted) {
+ result = read(cntr->fd, dst + consumed, byte_count - 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 byte_count)
+{
+ char *src = buf;
+ ssize_t result;
+ size_t consumed = 0;
+
+ while (consumed < byte_count && !cntr->interrupted) {
+ result = write(cntr->fd, src + consumed, byte_count - 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;
+
+ assert(cntr);
+ assert(path);
+ assert(path[0] != '\0');
+
+ // Detect forgotten to destruct.
+ assert(cntr->fd == 0);
+ assert(cntr->private_data == NULL);
+
+ memset(cntr, 0, sizeof(*cntr));
+
+ // Open a target descriptor.
+ if (!strcmp(path, "-")) {
+ cntr->fd = fileno(stdin);
+ err = set_nonblock_flag(cntr->fd);
+ if (err < 0)
+ return err;
+ cntr->stdio = true;
+ } 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;
+
+ assert(cntr);
+ assert(path);
+ assert(path[0] != '\0');
+
+ // Detect forgotten to destruct.
+ assert(cntr->fd == 0);
+ assert(cntr->private_data == NULL);
+
+ memset(cntr, 0, sizeof(*cntr));
+
+ // 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;
+ cntr->stdio = true;
+ } else {
+ cntr->fd = open(path, O_RDWR | O_NONBLOCK | O_CREAT | O_TRUNC,
+ 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)
+{
+ uint64_t byte_count;
+ unsigned int bytes_per_frame;
+ int err;
+
+ assert(cntr);
+ assert(format);
+ assert(samples_per_frame);
+ assert(frames_per_second);
+ assert(frame_count);
+
+ if (cntr->type == CONTAINER_TYPE_BUILDER)
+ byte_count = cntr->max_size;
+
+ if (cntr->ops->pre_process) {
+ err = cntr->ops->pre_process(cntr, format, samples_per_frame,
+ frames_per_second, &byte_count);
+ if (err < 0)
+ return err;
+ if (cntr->eof)
+ return 0;
+ }
+
+ assert(*format >= SND_PCM_FORMAT_S8);
+ assert(*format <= SND_PCM_FORMAT_LAST);
+ assert(*samples_per_frame > 0);
+ assert(*frames_per_second > 0);
+ assert(byte_count > 0);
+
+ 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;
+
+ bytes_per_frame = cntr->bytes_per_sample * *samples_per_frame;
+ *frame_count = byte_count / bytes_per_frame;
+ cntr->max_size -= cntr->max_size / bytes_per_frame;
+
+ if (cntr->verbose > 0) {
+ fprintf(stderr, "Container: %s\n",
+ cntr_type_labels[cntr->type]);
+ fprintf(stderr, " format: %s\n",
+ cntr_format_labels[cntr->format]);
+ fprintf(stderr, " sample format: %s\n",
+ snd_pcm_format_name(*format));
+ fprintf(stderr, " bytes/sample: %u\n",
+ cntr->bytes_per_sample);
+ fprintf(stderr, " samples/frame: %u\n",
+ cntr->samples_per_frame);
+ fprintf(stderr, " frames/second: %u\n",
+ cntr->frames_per_second);
+ if (cntr->type == CONTAINER_TYPE_PARSER) {
+ fprintf(stderr, " frames: %lu\n",
+ *frame_count);
+ } else {
+ fprintf(stderr, " max frames: %lu\n",
+ *frame_count);
+ }
+ }
+
+ return 0;
+}
+
+int container_context_process_frames(struct container_context *cntr,
+ void *frame_buffer,
+ unsigned int *frame_count)
+{
+ char *buf = frame_buffer;
+ unsigned int bytes_per_frame;
+ unsigned int byte_count;
+ int err;
+
+ assert(cntr);
+ assert(!cntr->eof);
+ assert(frame_buffer);
+ assert(frame_count);
+
+ bytes_per_frame = cntr->bytes_per_sample * cntr->samples_per_frame;
+ byte_count = *frame_count * bytes_per_frame;
+
+ // Each container has limitation for its volume for sample data.
+ if (cntr->handled_byte_count > cntr->max_size - byte_count)
+ byte_count = cntr->max_size - cntr->handled_byte_count;
+
+ // All of supported containers include interleaved PCM frames.
+ // TODO: process frames for truncate case.
+ err = cntr->process_bytes(cntr, buf, byte_count);
+ if (err < 0) {
+ *frame_count = 0;
+ return err;
+ }
+
+ cntr->handled_byte_count += byte_count;
+ if (cntr->handled_byte_count == cntr->max_size)
+ cntr->eof = true;
+
+ *frame_count = byte_count / bytes_per_frame;
+
+ return 0;
+}
+
+int container_context_post_process(struct container_context *cntr,
+ uint64_t *frame_count)
+{
+ int err = 0;
+
+ assert(cntr);
+ assert(frame_count);
+
+ if (cntr->verbose && cntr->handled_byte_count > 0) {
+ fprintf(stderr, " Handled bytes: %lu\n",
+ cntr->handled_byte_count);
+ }
+
+ // NOTE* we cannot seek when using standard input/output.
+ if (!cntr->stdio && cntr->ops && cntr->ops->post_process) {
+ // Usually, need to write out processed bytes in container
+ // header even it this program is interrupted.
+ cntr->interrupted = false;
+
+ err = cntr->ops->post_process(cntr, cntr->handled_byte_count);
+ }
+
+ // Ensure to perform write-back from disk cache.
+ if (cntr->type == CONTAINER_TYPE_BUILDER)
+ fsync(cntr->fd);
+
+ if (err < 0)
+ return err;
+
+ if (cntr->bytes_per_sample == 0 || cntr->samples_per_frame == 0) {
+ *frame_count = 0;
+ } else {
+ *frame_count = cntr->handled_byte_count /
+ cntr->bytes_per_sample /
+ cntr->samples_per_frame;
+ }
+
+ return 0;
+}
+
+void container_context_destroy(struct container_context *cntr)
+{
+ assert(cntr);
+
+ close(cntr->fd);
+ if (cntr->private_data)
+ free(cntr->private_data);
+
+ cntr->fd = 0;
+ cntr->private_data = NULL;
+}
diff --git a/axfer/container.h b/axfer/container.h
new file mode 100644
index 00000000..4a94d7f
--- /dev/null
+++ b/axfer/container.h
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// container.h - an interface of parser/builder for formatted files.
+//
+// Copyright (c) 2018 Takashi Sakamoto <o-takashi at sakamocchi.jp>
+//
+// Licensed under the terms of the GNU General Public License, version 2.
+
+#ifndef __ALSA_UTILS_AXFER_CONTAINER__H_
+#define __ALSA_UTILS_AXFER_CONTAINER__H_
+
+#define _LARGEFILE64_SOURCE
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include <alsa/asoundlib.h>
+
+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;
+ bool stdio;
+
+ 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 *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 *byte_count);
+ int (*post_process)(struct container_context *cntr,
+ uint64_t handled_byte_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 byte_count);
+int container_recursive_write(struct container_context *cntr, void *buf,
+ unsigned int byte_count);
+int container_seek_offset(struct container_context *cntr, off64_t offset);
+
+#endif
--
2.19.1
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