All,
Please find attached a conceptual new API between the audio service and
whatever audio framework we have (ALSA, GStreamer, PulseAudio, or
whatever). :-)
This new API would be defined under LGPL, so that guys like me can use
it for some in house closed source projects( Luiz, and Johan,
i hope that's OK with you :-) ).
The principles of the API are the following:
- define a set of messages (that would be the functions in
traditionnal C programming)
- define a set of structs, *one per message* (that would be the
list of arguments in traditionnal C programming).
- define a reduced set of a few helper functions to bootstrap the
message exchange process, as well as to retrieve the data fd through
ancilliary data.
The usage of the API should be relatively straightforward : you would
use bz_audio_service_open() to retrieve the file descriptor, and then
integrated it in your main loop or whatever.
Then you would read fixed size data chunks that you would cast to
t_bz_audio_msg_header to retrieve the message type. Once you have the
message type, you would cast again the result to a structure that
matches the message name, and obtain the list of parameters that are
relevant for this message.
I didn't want to bring more features in the API as otherwise we would
start to implement toolkit-dependant behaviours (such as need a
mainloop, or a need for GLIB, or ...)
I think this API is a lot easier to maintain in the long term that what
we have today, where structure are shared between messages, and some
messages have more that one data structure. :-)
If we can reach an agreement quite rapidly (that would mean today :-)),
then i could start implementing it right away and hopefully have a
mostly working implementation on sunday night.
As always, comments are welcomed !
Cheers,
Fabien
All,
Updated file, contains messages for stream suspend/resume.
Fabien
> All,
>
> Please find attached a conceptual new API between the audio service and
> whatever audio framework we have (ALSA, GStreamer, PulseAudio, or
> whatever). :-)
>
> This new API would be defined under LGPL, so that guys like me can use
> it for some in house closed source projects( Luiz, and Johan,
> i hope that's OK with you :-) ).
>
> The principles of the API are the following:
> - define a set of messages (that would be the functions in traditionnal
> C programming)
> - define a set of structs, *one per message* (that would be the
> list of arguments in traditionnal C programming).
> - define a reduced set of a few helper functions to bootstrap the
> message exchange process, as well as to retrieve the data fd through
> ancilliary data.
>
> The usage of the API should be relatively straightforward : you would
> use bz_audio_service_open() to retrieve the file descriptor, and then
> integrated it in your main loop or whatever.
>
> Then you would read fixed size data chunks that you would cast to
> t_bz_audio_msg_header to retrieve the message type. Once you have the
> message type, you would cast again the result to a structure that
> matches the message name, and obtain the list of parameters that are
> relevant for this message.
>
> I didn't want to bring more features in the API as otherwise we would
> start to implement toolkit-dependant behaviours (such as need a
> mainloop, or a need for GLIB, or ...)
>
> I think this API is a lot easier to maintain in the long term that what
> we have today, where structure are shared between messages, and some
> messages have more that one data structure. :-)
>
> If we can reach an agreement quite rapidly (that would mean today :-)),
> then i could start implementing it right away and hopefully have a
> mostly working implementation on sunday night.
>
> As always, comments are welcomed !
>
> Cheers,
>
> Fabien
>
>
> ------------------------------------------------------------------------
>
> /*
> *
> * BlueZ - Bluetooth protocol stack for Linux
> *
> * Copyright (C) 2004-2007 Marcel Holtmann <[email protected]>
> *
> * This library is free software; you can redistribute it and/or
> * modify it under the terms of the GNU Lesser General Public
> * License as published by the Free Software Foundation; either
> * version 2.1 of the License, or (at your option) any later version.
> *
> * This library is distributed in the hope that it will be useful,
> * but WITHOUT ANY WARRANTY; without even the implied warranty of
> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> * Lesser General Public License for more details.
> *
> * You should have received a copy of the GNU Lesser General Public
> * License along with this library; if not, write to the Free Software
> * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
> *
> */
>
> /*
> Message sequence chart of streaming sequence for A2DP transport
>
> Audio daemon User
> on snd_pcm_open
> <--BZ_GETCAPABILITIES_REQ
>
> BZ_GETCAPABILITIES_RSP-->
>
> on snd_pcm_hw_params
> <--BZ_SETCONFIGURATION_REQ
>
> BZ_SETCONFIGURATION_RSP-->
>
> on snd_pcm_prepare
> <--BZ_STREAMSTART_REQ
>
> <Moves to streaming state>
> BZ_STREAMSTART_RSP-->
>
> BZ_DATAFD_IND -->
>
> < streams data >
> ..........
>
> on snd_pcm_drop/snd_pcm_drain
>
> <--BZ_STREAMSTOP_REQ
>
> <Moves to open state>
> BZ_STREAMSTOP_RSP-->
>
> on IPC close or appl crash
> <Moves to idle>
>
> */
>
> #ifndef NEWIPC_H
>
> #include <stdint.h>
> #include <stdio.h>
> #include <unistd.h>
> #include <sys/socket.h>
> #include <sys/un.h>
> #include <errno.h>
>
> #define BZ_AUDIO_IPC_MTU 128
> #define BZ_IPC_SOCKET_NAME "\0/org/bluez/audio"
>
> #ifndef UNIX_PATH_MAX
> #define UNIX_PATH_MAX 108
> #endif
>
> /* Generic message header definition */
> typedef struct {
> uint8_t msg_type;
> } __attribute__ ((packed)) t_bz_audio_msg_header;
>
> /* Messages list */
> #define BZ_GETCAPABILITIES_REQ 0
> #define BZ_GETCAPABILITIES_RSP 1
>
> #define BZ_SETCONFIGURATION_REQ 2
> #define BZ_SETCONFIGURATION_RSP 3
>
> #define BZ_STREAMSTART_REQ 4
> #define BZ_STREAMSTART_RSP 5
>
> #define BZ_STREAMSTOP_REQ 6
> #define BZ_STREAMSTOP_RSP 7
>
> #define BZ_CONTROL_REQ 8
> #define BZ_CONTROL_RSP 9
> #define BZ_CONTROL_IND 10
>
> #define BZ_DATAFD_IND 11
>
> /* BZ_CAPABILITIES_REQ */
>
> #define BZ_CAPABILITIES_REQ_TRANSPORT_A2DP 0
> #define BZ_CAPABILITIES_REQ_TRANSPORT_SCO 1
> #define BZ_CAPABILITIES_REQ_TRANSPORT_ANY 2
>
> struct bz_capabilites_req {
> t_bz_audio_msg_header h;
> uint8_t transport;
> } __attribute__ ((packed));
>
> /* BZ_CAPABILITIES_RSP */
>
> /**
> * SBC Codec parameters as per A2DP profile 1.0 ? 4.3
> */
>
> #define BZ_A2DP_SAMPLING_FREQ_16000 (1 << 3)
> #define BZ_A2DP_SAMPLING_FREQ_32000 (1 << 2)
> #define BZ_A2DP_SAMPLING_FREQ_44100 (1 << 1)
> #define BZ_A2DP_SAMPLING_FREQ_48000 1
>
> #define BZ_A2DP_CHANNEL_MODE_MONO (1 << 3)
> #define BZ_A2DP_CHANNEL_MODE_DUAL_CHANNEL (1 << 2)
> #define BZ_A2DP_CHANNEL_MODE_STEREO (1 << 1)
> #define BZ_A2DP_CHANNEL_MODE_JOINT_STEREO 1
>
> #define BZ_A2DP_BLOCK_LENGTH_4 (1 << 3)
> #define BZ_A2DP_BLOCK_LENGTH_8 (1 << 2)
> #define BZ_A2DP_BLOCK_LENGTH_12 (1 << 1)
> #define BZ_A2DP_BLOCK_LENGTH_16 1
>
> #define BZ_A2DP_SUBBANDS_4 (1 << 1)
> #define BZ_A2DP_SUBBANDS_8 1
>
> #define BZ_A2DP_ALLOCATION_SNR (1 << 1)
> #define BZ_A2DP_ALLOCATION_LOUDNESS 1
>
> typedef struct {
> uint8_t channel_mode:4;
> uint8_t frequency:4;
> uint8_t allocation_method:2;
> uint8_t subbands:2;
> uint8_t block_length:4;
> uint8_t min_bitpool;
> uint8_t max_bitpool;
> } __attribute__ ((packed)) t_SBC_capabilities ;
>
> /* To be defined */
> typedef struct {
> } __attribute__ ((packed)) t_MPEG_capabilities;
>
> struct bz_capabilites_rsp {
> t_bz_audio_msg_header h;
> uint8_t posix_errno;
> uint8_t transport; /* Selected transport */
> uint8_t pkt_len; /* Max length that transport supports */
> t_SBC_capabilities sbc_capabilities; /* A2DP only */
> t_MPEG_capabilities mpeg_capabilities; /* A2DP only */
> uint16_t sampling_rate; /* SCO only */
> } __attribute__ ((packed));
>
> /* BZ_CONFIGURATION_REQ */
> struct bz_configuration_req {
> t_bz_audio_msg_header h;
> t_SBC_capabilities sbc_capabilities; /* A2DP only - only one of this field
> and next one must be filled */
> t_MPEG_capabilities mpeg_capabilities; /* A2DP only */
> } __attribute__ ((packed));
>
> /* BZ_CONFIGURATION_RSP */
> struct bz_configuration_rsp {
> t_bz_audio_msg_header h;
> uint8_t posix_errno;
> } __attribute__ ((packed));
>
> /* BZ_STREAMSTART_REQ */
> #define BZ_STREAM_ACCESS_READ 0
> #define BZ_STREAM_ACCESS_WRITE 1
> #define BZ_STREAM_ACCESS_READWRITE 2
> struct bz_streamstart_req {
> t_bz_audio_msg_header h;
> uint8_t stream_access;
> } __attribute__ ((packed));
>
> /* BZ_STREAMSTART_RSP */
> struct bz_streamstart_rsp {
> t_bz_audio_msg_header h;
> uint8_t posix_errno;
> } __attribute__ ((packed));
>
> /* BZ_DATAFD_IND */
> /* This message is followed by one byte of data containing the stream data fd
> as ancilliary data */
> struct bz_datafd_ind {
> t_bz_audio_msg_header h;
> } __attribute__ ((packed));
>
>
> /* BZ_CONTROL_REQ */
>
> #define BZ_CONTROL_KEY_POWER 0x40
> #define BZ_CONTROL_KEY_VOL_UP 0x41
> #define BZ_CONTROL_KEY_VOL_DOWN 0x42
> #define BZ_CONTROL_KEY_MUTE 0x43
> #define BZ_CONTROL_KEY_PLAY 0x44
> #define BZ_CONTROL_KEY_STOP 0x45
> #define BZ_CONTROL_KEY_PAUSE 0x46
> #define BZ_CONTROL_KEY_RECORD 0x47
> #define BZ_CONTROL_KEY_REWIND 0x48
> #define BZ_CONTROL_KEY_FAST_FORWARD 0x49
> #define BZ_CONTROL_KEY_EJECT 0x4A
> #define BZ_CONTROL_KEY_FORWARD 0x4B
> #define BZ_CONTROL_KEY_BACKWARD 0x4C
>
> struct bz_control_req {
> t_bz_audio_msg_header h;
> uint8_t mode; /* Control Mode */
> uint8_t key; /* Control Key */
> } __attribute__ ((packed));
>
> /* BZ_CONTROL_RSP */
> struct bz_volume_rsp {
> t_bz_audio_msg_header h;
> uint8_t posix_errno;
> uint8_t mode; /* Control Mode */
> uint8_t key; /* Control Key */
> } __attribute__ ((packed));
>
> /* BZ_CONTROL_IND */
> struct bz_volume_ind {
> t_bz_audio_msg_header h;
> uint8_t mode; /* Control Mode */
> uint8_t key; /* Control Key */
> } __attribute__ ((packed));
>
> /* Function definitions */
>
> static inline int bz_audio_service_open()
> {
> int sk;
> int err;
> struct sockaddr_un addr = {
> AF_UNIX, "\0/org/bluez/audio"
> };
>
> sk = socket(PF_LOCAL, SOCK_STREAM, 0);
> if (sk < 0) {
> err = errno;
> fprintf(stderr, "%s: Cannot open socket: %s (%d)\n", __FUNCTION__, strerror(err), err);
> errno = err;
> return -1;
> }
>
> if (connect(sk, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
> err = errno;
> fprintf(stderr, "%s: Connection fail: %s (%d)\n", __FUNCTION__, strerror(err), err);
> close(sk);
> errno = err;
> return -1;
> }
> }
>
> static inline int bz_audio_service_close(int sk)
> {
> return close(sk);
> }
>
> static inline int bz_audio_service_get_data_fd(int sk)
> {
> char cmsg_b[CMSG_SPACE(sizeof(int))], m;
> int err, ret;
> struct iovec iov = { &m, sizeof(m) };
> struct msghdr msgh;
> struct cmsghdr *cmsg;
>
> memset(&msgh, 0, sizeof(msgh));
> msgh.msg_iov = &iov;
> msgh.msg_iovlen = 1;
> msgh.msg_control = &cmsg_b;
> msgh.msg_controllen = CMSG_LEN(sizeof(int));
>
> ret = recvmsg(sk, &msgh, 0);
> if (ret < 0) {
> err = errno;
> fprintf(stderr, "%s: Unable to receive fd: %s (%d)\n", __FUNCTION__, strerror(err), err);
> errno = err;
> return -1;
> }
>
> /* Receive auxiliary data in msgh */
> for (cmsg = CMSG_FIRSTHDR(&msgh); cmsg != NULL;
> cmsg = CMSG_NXTHDR(&msgh, cmsg)) {
> if (cmsg->cmsg_level == SOL_SOCKET
> && cmsg->cmsg_type == SCM_RIGHTS) {
> return (*(int *) CMSG_DATA(cmsg));
> }
> }
>
> errno = EINVAL;
> return -1;
> }
>
> #endif /* NEWIPC_H */