btstack/example/a2dp_mitm_demo.c

/*
 * Copyright (C) 2016 BlueKitchen GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 * 4. Any redistribution, use, or modification is done solely for
 *    personal benefit and not for any commercial purpose or for
 *    monetary gain.
 *
 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
 * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * Please inquire about commercial licensing options at 
 * contact@bluekitchen-gmbh.com
 *
 */

#define BTSTACK_FILE__ "a2dp_mitm_demo.c"

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "btstack_config.h"
#include "btstack_debug.h"
#include "btstack_event.h"
#include "btstack_memory.h"
#include "btstack_run_loop.h"
#include "gap.h"
#include "hci.h"
#include "hci_cmd.h"
#include "hci_dump.h"
#include "l2cap.h"
#include "classic/a2dp_sink.h"
#include "classic/a2dp_source.h"
#include "classic/avdtp_sink.h"
#include "classic/avdtp_source.h"
#include "classic/avdtp_util.h"
#include "classic/btstack_sbc.h"


#ifdef HAVE_BTSTACK_STDIN
#include "btstack_stdin.h"
#endif

#define MAX_SBC_FRAME_SIZE 120
#define MAX_NUM_SBC_FRAMES 100
#define PREBUFFER_BYTES 10000
#define FILL_AUDIO_BUFFER_TIMEOUT_MS 5 
#define A2DP_SAMPLE_RATE         44100

#define SBC_STORAGE_SIZE 1030

typedef struct {
    // bitmaps
    uint8_t sampling_frequency_bitmap;
    uint8_t channel_mode_bitmap;
    uint8_t block_length_bitmap;
    uint8_t subbands_bitmap;
    uint8_t allocation_method_bitmap;
    uint8_t min_bitpool_value;
    uint8_t max_bitpool_value;
} adtvp_media_codec_information_sbc_t;

typedef struct {
    int reconfigure;
    int num_channels;
    int sampling_frequency;
    int channel_mode;
    int block_length;
    int subbands;
    int allocation_method;
    int min_bitpool_value;
    int max_bitpool_value;
    int frames_per_buffer;
} avdtp_media_codec_configuration_sbc_t;

typedef struct {
    uint16_t source_cid;
    uint8_t  source_local_seid;
    
    // uint16_t sink_cid;
    // uint8_t  sink_local_seid;
    
    uint32_t time_audio_data_sent; // ms
    uint32_t acc_num_missed_samples;
    uint32_t samples_ready;
    btstack_timer_source_t fill_audio_buffer_timer;
    uint8_t  streaming;
                            
    int      max_media_payload_size;
    
    uint8_t  sbc_storage[1030];
    uint8_t  sbc_ready_to_send;
} a2dp_media_sending_context_t;

typedef enum {
    AVDTP_SINK_APPLICATION_IDLE,
    AVDTP_SINK_APPLICATION_CONNECTED,
    AVDTP_SINK_APPLICATION_STREAMING
} avdtp_sink_application_state_t;

static const char * smartphone_addr_string = "BC:EC:5D:E6:15:03";
static const char * headset_addr_string    = "00:21:3C:AC:F7:38";

#ifdef HAVE_BTSTACK_STDIN
static bd_addr_t smartphone_addr;
static bd_addr_t headset_addr;
#endif

// audio through
static btstack_ring_buffer_t ring_buffer;
static uint8_t ring_buffer_storage[MAX_NUM_SBC_FRAMES * MAX_SBC_FRAME_SIZE];
static int forward_active;

// generic
static btstack_packet_callback_registration_t hci_event_callback_registration;

// sdp
static uint8_t sdp_avdtp_sink_service_buffer[150];
static uint8_t sdp_avdtp_source_service_buffer[150];

static uint8_t sbc_frame_size;
static avdtp_sep_t sep;
static avdtp_media_codec_configuration_sbc_t sbc_configuration;
static int media_initialized = 0;

static uint16_t a2dp_sink_cid   = 0;
static uint16_t a2dp_source_cid = 0;

static avdtp_sink_application_state_t app_sink_state = AVDTP_SINK_APPLICATION_IDLE;

static void handle_l2cap_media_data_packet(uint8_t seid, uint8_t *packet, uint16_t size);

static uint8_t media_sbc_codec_capabilities[] = {
    (AVDTP_SBC_44100 << 4) | AVDTP_SBC_STEREO,
    0xFF,//(AVDTP_SBC_BLOCK_LENGTH_16 << 4) | (AVDTP_SBC_SUBBANDS_8 << 2) | AVDTP_SBC_ALLOCATION_METHOD_LOUDNESS,
    2, 53
}; 

#ifdef HAVE_BTSTACK_STDIN
static uint8_t media_sbc_codec_configuration[] = {
    (AVDTP_SBC_44100 << 4) | AVDTP_SBC_STEREO,
    (AVDTP_SBC_BLOCK_LENGTH_16 << 4) | (AVDTP_SBC_SUBBANDS_8 << 2) | AVDTP_SBC_ALLOCATION_METHOD_LOUDNESS,
    2, 53
}; 

// avdtp source
static uint8_t a2dp_source_local_seid = 0;
static uint8_t a2dp_sink_local_seid = 0;
static a2dp_media_sending_context_t media_tracker;
static int headset_stream_ready;


static void dump_sbc_configuration(avdtp_media_codec_configuration_sbc_t configuration){
    printf("Received media codec configuration:\n");
    printf("    - num_channels: %d\n", configuration.num_channels);
    printf("    - sampling_frequency: %d\n", configuration.sampling_frequency);
    printf("    - channel_mode: %d\n", configuration.channel_mode);
    printf("    - block_length: %d\n", configuration.block_length);
    printf("    - subbands: %d\n", configuration.subbands);
    printf("    - allocation_method: %d\n", configuration.allocation_method);
    printf("    - bitpool_value [%d, %d] \n", configuration.min_bitpool_value, configuration.max_bitpool_value);
}


// avdtp sink
static int media_processing_init(avdtp_media_codec_configuration_sbc_t configuration){
    UNUSED(configuration);

    memset(ring_buffer_storage, 0, sizeof(ring_buffer_storage));
    btstack_ring_buffer_init(&ring_buffer, ring_buffer_storage, sizeof(ring_buffer_storage));
    media_initialized = 1;
    return 0;
}

static void media_processing_close(void){
    if (!media_initialized) return;
    media_initialized = 0;
}

static void a2dp_fill_audio_buffer_timeout_handler(btstack_timer_source_t * timer){
    a2dp_media_sending_context_t * context = (a2dp_media_sending_context_t *) btstack_run_loop_get_timer_context(timer);
    btstack_run_loop_set_timer(&context->fill_audio_buffer_timer, FILL_AUDIO_BUFFER_TIMEOUT_MS); 
    btstack_run_loop_add_timer(&context->fill_audio_buffer_timer);
    uint32_t now = btstack_run_loop_get_time_ms();

    uint32_t update_period_ms = FILL_AUDIO_BUFFER_TIMEOUT_MS;
    if (context->time_audio_data_sent > 0){
        update_period_ms = now - context->time_audio_data_sent;
    } 

    uint32_t num_samples = (update_period_ms * A2DP_SAMPLE_RATE) / 1000;
    context->acc_num_missed_samples += (update_period_ms * A2DP_SAMPLE_RATE) % 1000;
    
    while (context->acc_num_missed_samples >= 1000){
        num_samples++;
        context->acc_num_missed_samples -= 1000;
    }
    context->time_audio_data_sent = now;
    context->samples_ready += num_samples;

    if (context->sbc_ready_to_send) return;

    // do we have enough samples to send?

    // calculate num sbc frames per outgoing packet
    uint16_t payload_max_size = a2dp_max_media_payload_size(context->source_cid, context->source_local_seid);
    // a2dp_max_media_payload_size(media_tracker.source_local_seid);
    

    int sbc_frames_per_packet = payload_max_size / sbc_frame_size;

    // calculate num frames "ready" - using hard-coded
    int num_samples_per_frame = 128;
    int sbc_frames_ready = context->samples_ready / num_samples_per_frame;

    // log_info("Samples ready %u - Frames ready %u / frames per packet %u\n", context->samples_ready, sbc_frames_ready, sbc_frames_per_packet);

    if (sbc_frames_ready >= sbc_frames_per_packet){
        // schedule sending
        context->sbc_ready_to_send = 1;
        a2dp_source_stream_endpoint_request_can_send_now(context->source_cid, context->source_local_seid);
    }
}

static void a2dp_fill_audio_buffer_timer_start(a2dp_media_sending_context_t * context){
    // context->max_media_payload_size = a2dp_max_media_payload_size(context->source_local_seid);
    context->max_media_payload_size = btstack_min(a2dp_max_media_payload_size(context->source_cid, context->source_local_seid), SBC_STORAGE_SIZE);

    context->sbc_ready_to_send = 0;
    context->streaming = 1;
    btstack_run_loop_remove_timer(&context->fill_audio_buffer_timer);
    btstack_run_loop_set_timer_handler(&context->fill_audio_buffer_timer, a2dp_fill_audio_buffer_timeout_handler);
    btstack_run_loop_set_timer_context(&context->fill_audio_buffer_timer, context);
    btstack_run_loop_set_timer(&context->fill_audio_buffer_timer, FILL_AUDIO_BUFFER_TIMEOUT_MS); 
    btstack_run_loop_add_timer(&context->fill_audio_buffer_timer);
}

static void a2dp_fill_audio_buffer_timer_stop(a2dp_media_sending_context_t * context){
    context->time_audio_data_sent = 0;
    context->acc_num_missed_samples = 0;
    context->samples_ready = 0;
    context->streaming = 1;
    context->sbc_ready_to_send = 0;
    btstack_run_loop_remove_timer(&context->fill_audio_buffer_timer);
} 

#if 0
static void a2dp_fill_audio_buffer_timer_pause(a2dp_media_sending_context_t * context){
    // context->time_audio_data_sent = 0;
    btstack_run_loop_remove_timer(&context->fill_audio_buffer_timer);
} 
#endif

static void handle_l2cap_media_data_packet(uint8_t seid, uint8_t *packet, uint16_t size){
    UNUSED(seid);
    // if no sink, drop data
    if (!headset_stream_ready) {
        printf("DEMO: Audio from smartphone, but headset not ready -> dropping\n");
        return;
    }

    UNUSED(size);

    int pos = 0;
    
    avdtp_media_packet_header_t media_header;
    media_header.version = packet[pos] & 0x03;
    media_header.padding = get_bit16(packet[pos],2);
    media_header.extension = get_bit16(packet[pos],3);
    media_header.csrc_count = (packet[pos] >> 4) & 0x0F;

    pos++;

    media_header.marker = get_bit16(packet[pos],0);
    media_header.payload_type  = (packet[pos] >> 1) & 0x7F;
    pos++;

    media_header.sequence_number = big_endian_read_16(packet, pos);
    pos+=2;

    media_header.timestamp = big_endian_read_32(packet, pos);
    pos+=4;

    media_header.synchronization_source = big_endian_read_32(packet, pos);
    pos+=4;

    UNUSED(media_header);

    // TODO: read csrc list
    
    // printf_hexdump( packet, pos );
    // printf("MEDIA HEADER: %u timestamp, version %u, padding %u, extension %u, csrc_count %u\n", 
    //     media_header.timestamp, media_header.version, media_header.padding, media_header.extension, media_header.csrc_count);
    // printf("MEDIA HEADER: marker %02x, payload_type %02x, sequence_number %u, synchronization_source %u\n", 
    //     media_header.marker, media_header.payload_type, media_header.sequence_number, media_header.synchronization_source);
    
    avdtp_sbc_codec_header_t sbc_header;
    sbc_header.fragmentation = get_bit16(packet[pos], 7);
    sbc_header.starting_packet = get_bit16(packet[pos], 6);
    sbc_header.last_packet = get_bit16(packet[pos], 5);
    sbc_header.num_frames = packet[pos] & 0x0f;
    pos++;

    UNUSED(sbc_header);
    // printf("SBC HEADER: num_frames %u, fragmented %u, start %u, stop %u\n", sbc_header.num_frames, sbc_header.fragmentation, sbc_header.starting_packet, sbc_header.last_packet);
    // printf_hexdump( packet+pos, size-pos );

    // num frames
    uint16_t num_frames = sbc_header.num_frames;

    // sbc frame size
    sbc_frame_size = (size-pos)/ sbc_header.num_frames;
    
    // log_info("IN: Ringbuffer: %u bytes free", btstack_ring_buffer_bytes_free(&ring_buffer));

    // store individual framees: { len_16, frame }
    int i;
    for (i=0;i<num_frames;i++){
        uint16_t frame_size = sbc_frame_size;
        if (btstack_ring_buffer_bytes_free(&ring_buffer) < (2 + frame_size)){
            log_info("RING: cannot store frame of size %u, only %u free", frame_size,
                     btstack_ring_buffer_bytes_free(&ring_buffer));
            break;
        }
        // log_info("RING: store frame of size %u", frame_size);
        btstack_ring_buffer_write(&ring_buffer, (uint8_t*) &frame_size, 2);
        btstack_ring_buffer_write(&ring_buffer, packet+pos, sbc_frame_size);
        pos += sbc_frame_size;
    }

    // printf("DEMO: Audio from smartphone, ringbuffer avail %u\n", btstack_ring_buffer_bytes_available(&ring_buffer));


    if (!forward_active && btstack_ring_buffer_bytes_available(&ring_buffer) > PREBUFFER_BYTES){
        forward_active = 1;
        a2dp_fill_audio_buffer_timer_start(&media_tracker);
    }
}

static void packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
    UNUSED(channel);
    UNUSED(size);
    bd_addr_t event_addr;

    if (packet_type != HCI_EVENT_PACKET) return;
 
    switch (hci_event_packet_get_type(packet)) {
        case HCI_EVENT_PIN_CODE_REQUEST:
            // inform about pin code request
            printf("Pin code request - using '0000'\n");
            hci_event_pin_code_request_get_bd_addr(packet, event_addr);
            hci_send_cmd(&hci_pin_code_request_reply, &event_addr, 4, "0000");
            break;
        default:
            break;
    }
}

static void a2dp_sink_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
    UNUSED(channel);
    UNUSED(size);
    bd_addr_t event_addr;
    uint8_t status;

    if (packet_type != HCI_EVENT_PACKET) return;
    if (hci_event_packet_get_type(packet) != HCI_EVENT_A2DP_META) return;

    switch (packet[2]){
         case A2DP_SUBEVENT_SIGNALING_CONNECTION_ESTABLISHED:
             printf("A2DP Sink: A2DP_SUBEVENT_SIGNALING_CONNECTION_ESTABLISHED, cid 0x%02x seid %d\n", a2dp_sink_cid, a2dp_sink_local_seid);
            
             a2dp_subevent_signaling_connection_established_get_bd_addr(packet, event_addr);
             status = a2dp_subevent_signaling_connection_established_get_status(packet);
             if (status != ERROR_CODE_SUCCESS){
                 printf("A2DP Sink: Connection failed with status 0x%02x\n", status);
                 break;
             }
             a2dp_sink_cid = a2dp_subevent_signaling_connection_established_get_a2dp_cid(packet);
             printf("A2DP Sink: Connected to device with addr %s, a2dp cid 0x%02x.\n", bd_addr_to_str(event_addr), a2dp_sink_cid);
             break;

        case A2DP_SUBEVENT_SIGNALING_MEDIA_CODEC_SBC_CONFIGURATION:{
            printf("A2DP Sink: received SBC codec configuration.\n");
            sbc_configuration.reconfigure = a2dp_subevent_signaling_media_codec_sbc_configuration_get_reconfigure(packet);
            sbc_configuration.num_channels = a2dp_subevent_signaling_media_codec_sbc_configuration_get_num_channels(packet);
            sbc_configuration.sampling_frequency = a2dp_subevent_signaling_media_codec_sbc_configuration_get_sampling_frequency(packet);
            sbc_configuration.channel_mode = a2dp_subevent_signaling_media_codec_sbc_configuration_get_channel_mode(packet);
            sbc_configuration.block_length = a2dp_subevent_signaling_media_codec_sbc_configuration_get_block_length(packet);
            sbc_configuration.subbands = a2dp_subevent_signaling_media_codec_sbc_configuration_get_subbands(packet);
            sbc_configuration.allocation_method = a2dp_subevent_signaling_media_codec_sbc_configuration_get_allocation_method(packet);
            sbc_configuration.min_bitpool_value = a2dp_subevent_signaling_media_codec_sbc_configuration_get_min_bitpool_value(packet);
            sbc_configuration.max_bitpool_value = a2dp_subevent_signaling_media_codec_sbc_configuration_get_max_bitpool_value(packet);
            sbc_configuration.frames_per_buffer = sbc_configuration.subbands * sbc_configuration.block_length;
            dump_sbc_configuration(sbc_configuration);

            if (sbc_configuration.reconfigure){
                media_processing_close();
            }
            // prepare media processing
            media_processing_init(sbc_configuration);
            break;
        }  
        case A2DP_SUBEVENT_SIGNALING_MEDIA_CODEC_OTHER_CONFIGURATION:
            printf("A2DP Sink: received non SBC codec. It will be ignored.\n");
            break;
       
        case A2DP_SUBEVENT_STREAM_ESTABLISHED:
            app_sink_state = AVDTP_SINK_APPLICATION_STREAMING;
            a2dp_sink_local_seid = a2dp_subevent_stream_established_get_local_seid(packet);
            a2dp_sink_cid = a2dp_subevent_stream_established_get_a2dp_cid(packet);
            printf("A2DP Sink: stream established a2dp_cid 0x%02x, local seid %d, remote seid %d\n",
                a2dp_sink_cid, a2dp_sink_local_seid, a2dp_subevent_stream_established_get_remote_seid(packet));
            break;

        case A2DP_SUBEVENT_STREAM_RELEASED:
            printf("A2DP Sink: stream released\n");
            media_processing_close();
            break;

        case A2DP_SUBEVENT_SIGNALING_CONNECTION_RELEASED:
            a2dp_sink_cid = 0;
            printf("A2DP Sink: signaling connection released\n");
            break;
        default:
            // printf("A2DP Sink: event %d not parsed\n", packet[2]);
            break; 
    }
}

static void a2dp_source_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
    UNUSED(channel);
    UNUSED(size);
    bd_addr_t event_addr;
    uint8_t status;

    if (packet_type != HCI_EVENT_PACKET) return;
    if (hci_event_packet_get_type(packet) != HCI_EVENT_A2DP_META) return;

    switch (packet[2]){
        case A2DP_SUBEVENT_SIGNALING_CONNECTION_ESTABLISHED:
            a2dp_subevent_signaling_connection_established_get_bd_addr(packet, event_addr);
            status = a2dp_subevent_signaling_connection_established_get_status(packet);
            if (status != ERROR_CODE_SUCCESS){
                printf("A2DP Sink: Connection failed with status 0x%02x\n", status);
                break;
            }
            a2dp_source_cid = a2dp_subevent_signaling_connection_established_get_a2dp_cid(packet);
            printf("A2DP Source: Connected to device with addr %s, a2dp cid 0x%02x.\n", bd_addr_to_str(event_addr), a2dp_source_cid);
            break;

         case A2DP_SUBEVENT_SIGNALING_MEDIA_CODEC_SBC_CONFIGURATION:{
            printf("A2DP Source: Received SBC codec configuration.\n");
            sbc_configuration.reconfigure = a2dp_subevent_signaling_media_codec_sbc_configuration_get_reconfigure(packet);
            sbc_configuration.num_channels = a2dp_subevent_signaling_media_codec_sbc_configuration_get_num_channels(packet);
            sbc_configuration.sampling_frequency = a2dp_subevent_signaling_media_codec_sbc_configuration_get_sampling_frequency(packet);
            sbc_configuration.channel_mode = a2dp_subevent_signaling_media_codec_sbc_configuration_get_channel_mode(packet);
            sbc_configuration.block_length = a2dp_subevent_signaling_media_codec_sbc_configuration_get_block_length(packet);
            sbc_configuration.subbands = a2dp_subevent_signaling_media_codec_sbc_configuration_get_subbands(packet);
            sbc_configuration.allocation_method = a2dp_subevent_signaling_media_codec_sbc_configuration_get_allocation_method(packet);
            sbc_configuration.min_bitpool_value = a2dp_subevent_signaling_media_codec_sbc_configuration_get_min_bitpool_value(packet);
            sbc_configuration.max_bitpool_value = a2dp_subevent_signaling_media_codec_sbc_configuration_get_max_bitpool_value(packet);
            sbc_configuration.frames_per_buffer = sbc_configuration.subbands * sbc_configuration.block_length;
            break;
        }  

        case A2DP_SUBEVENT_STREAM_ESTABLISHED:
            media_tracker.source_local_seid = a2dp_subevent_stream_established_get_local_seid(packet);
            media_tracker.source_cid = a2dp_subevent_stream_established_get_a2dp_cid(packet);
            
            printf("A2DP Source: stream established a2dp_cid 0x%02x, local seid %d, remote seid %d\n", 
                media_tracker.source_cid, media_tracker.source_local_seid, a2dp_subevent_stream_established_get_remote_seid(packet));

            printf("A2DP Source: start stream to headset\n");
    
            a2dp_source_start_stream(media_tracker.source_cid, media_tracker.source_local_seid);
            break;
        
        case A2DP_SUBEVENT_STREAM_STARTED:
            headset_stream_ready = 1;
            printf("A2DP Source: headset stream ready\n");
            break;       

        case A2DP_SUBEVENT_STREAMING_CAN_SEND_MEDIA_PACKET_NOW: {

            uint16_t num_frames;
            uint16_t len = 0;
            uint32_t bytes_read = 0;
            int pos = 0;

            // calculate max num sbc frames for outgoing earlier
            uint16_t payload_max_size = a2dp_max_media_payload_size(media_tracker.source_cid, media_tracker.source_local_seid);
            int max_sbc_frames = payload_max_size / sbc_frame_size;

            for (num_frames = 0 ; num_frames < max_sbc_frames && btstack_ring_buffer_bytes_available(&ring_buffer); num_frames++){
                btstack_ring_buffer_read(&ring_buffer, (uint8_t*) &len, 2, &bytes_read);
                // log_info("RING: read frame of size %u", len);
                btstack_ring_buffer_read(&ring_buffer, &media_tracker.sbc_storage[pos], len, &bytes_read);
                pos += len;
            }

            a2dp_source_stream_send_media_payload(media_tracker.source_cid, media_tracker.source_local_seid, media_tracker.sbc_storage, pos, num_frames, 0);
            
            media_tracker.sbc_ready_to_send = 0;

            int num_samples_per_frame = 128;
            int samples_consumed = num_frames * num_samples_per_frame;
            media_tracker.samples_ready -= samples_consumed; 


            // printf("DEMO: audio packet sent, ring buffer %u\n", btstack_ring_buffer_bytes_available(&ring_buffer));
            log_info("OUT: Ringbuffer: %u bytes available", btstack_ring_buffer_bytes_available(&ring_buffer));
            if (btstack_ring_buffer_bytes_available(&ring_buffer) == 0){
                log_info("Stream dried out. stop");
                printf("Stream dried out. restart\n");
                forward_active = 0;
                a2dp_fill_audio_buffer_timer_stop(&media_tracker);
                break;
            }
            break;

        }
        case A2DP_SUBEVENT_STREAM_SUSPENDED:
            printf(" A2DP_SUBEVENT_STREAM_SUSPENDED, local seid %d\n", media_tracker.source_local_seid);
            // a2dp_fill_audio_buffer_timer_pause(&media_tracker);
            // TODO: ??
            break;

        case A2DP_SUBEVENT_STREAM_RELEASED:
            printf("A2DP Source: stream released\n");
            media_processing_close();
            break;

        case A2DP_SUBEVENT_SIGNALING_CONNECTION_RELEASED:
            a2dp_source_cid = 0;
            printf("A2DP Source: signaling connection released\n");
            break;

        default:
            // printf("A2DP Source: event %d not parsed\n", packet[2]);
            break; 
    }
       
}

#ifdef HAVE_BTSTACK_STDIN
static void show_usage(void){
    bd_addr_t      iut_address;
    gap_local_bd_addr(iut_address);

    printf("\n");
    printf("--- Bluetooth A2DP MITM Console on %s ---\n", bd_addr_to_str(iut_address));

    printf("p      - create connection to smartphone %s\n", bd_addr_to_str(smartphone_addr));
    printf("h      - create connection to headset    %s\n", bd_addr_to_str(headset_addr));
    printf("d      - disconnect all\n");
    printf("c      - delete all link keys\n");
    printf("\nTo setup MITM, please connect to Headphone using 'h',\n");
    printf("then connect from smartphone/laptop to BTstack.\n");
    printf("Ctrl-c - exit\n");
    printf("---\n");
}
#endif

static void stdin_process(char cmd){
    uint8_t status = ERROR_CODE_SUCCESS;
    sep.seid = 1;
    switch (cmd){
        case 'p':
            status = a2dp_sink_establish_stream(smartphone_addr, a2dp_sink_local_seid, &a2dp_sink_cid);
            printf("Creating A2DP Connection to remote audio source (smartphone) %s, a2dp sink cid 0x%02x\n", bd_addr_to_str(smartphone_addr), a2dp_sink_cid);
            break;
        case 'h':
            status = a2dp_source_establish_stream(headset_addr, a2dp_source_local_seid, &a2dp_source_cid);
            printf("Creating A2DP Connection to remote audio sink (headset) %s, a2dp source cid 0x%02x\n", bd_addr_to_str(headset_addr), a2dp_source_cid);
            break;
        case 'd':
            printf("Disconnect all\n");
            a2dp_sink_disconnect(a2dp_sink_cid);
            a2dp_source_disconnect(a2dp_source_cid);
            break;
        case 'c':
            printf("Deleting all link keys\n");
            gap_delete_all_link_keys();
            break;
        default:
            show_usage();
            break;

    }

    if (status != ERROR_CODE_SUCCESS){
        printf("A2DP: Could not perform command \'%c\', status 0x%2x\n", cmd, status);
    }
}
#endif


int btstack_main(int argc, const char * argv[]);
int btstack_main(int argc, const char * argv[]){

    UNUSED(argc);
    (void)argv;

    /* Register for HCI events */
    hci_event_callback_registration.callback = &packet_handler;
    hci_add_event_handler(&hci_event_callback_registration);

    l2cap_init();
    sdp_init();


    // Initialize A2DP Sink.
    a2dp_sink_init();
    // Register A2DP Sink for HCI events.
    a2dp_sink_register_packet_handler(&a2dp_sink_packet_handler);
    // Register A2DP Sink for receiving media data.
    a2dp_sink_register_media_handler(&handle_l2cap_media_data_packet);

    // Create a stream endpoint to which the streaming channel will be opened.
    avdtp_stream_endpoint_t * local_sink_stream_endpoint = a2dp_sink_create_stream_endpoint(AVDTP_AUDIO, AVDTP_CODEC_SBC, media_sbc_codec_capabilities, sizeof(media_sbc_codec_capabilities),
                                                                                       media_sbc_codec_configuration, sizeof(media_sbc_codec_configuration));
    if (!local_sink_stream_endpoint){
        printf("A2DP Sink: not enough memory to create local stream endpoint\n");
        return 1;
    }
    a2dp_sink_local_seid = avdtp_local_seid(local_sink_stream_endpoint);

    memset(sdp_avdtp_sink_service_buffer, 0, sizeof(sdp_avdtp_sink_service_buffer));
    a2dp_sink_create_sdp_record(sdp_avdtp_sink_service_buffer, 0x10001, 1, NULL, NULL);
    sdp_register_service(sdp_avdtp_sink_service_buffer);


    // Initialize  A2DP Source.
    a2dp_source_init();
    // Register A2DP Source for HCI events.
    a2dp_source_register_packet_handler(&a2dp_source_packet_handler);
    // Create stream endpoint.

    avdtp_stream_endpoint_t * local_source_stream_endpoint = a2dp_source_create_stream_endpoint(AVDTP_AUDIO, AVDTP_CODEC_SBC, media_sbc_codec_capabilities, sizeof(media_sbc_codec_capabilities), media_sbc_codec_configuration, sizeof(media_sbc_codec_configuration));
    if (!local_source_stream_endpoint){
        printf("A2DP Source: not enough memory to create local stream endpoint\n");
        return 1;
    }
    a2dp_source_local_seid = avdtp_local_seid(local_source_stream_endpoint);
    printf("A2DP Source: created stream endpoint with seid %d\n", a2dp_source_local_seid);
    
    memset(sdp_avdtp_source_service_buffer, 0, sizeof(sdp_avdtp_source_service_buffer));
    a2dp_source_create_sdp_record(sdp_avdtp_source_service_buffer, 0x10002, 1, NULL, NULL);
    sdp_register_service(sdp_avdtp_source_service_buffer);


    // GAP
    gap_set_local_name("A2DP MITM Demo 00:00:00:00:00:00");
    gap_discoverable_control(1);
    gap_set_class_of_device(0x200408);

    // parse human readable Bluetooth address
    sscanf_bd_addr(smartphone_addr_string, smartphone_addr);
    sscanf_bd_addr(headset_addr_string, headset_addr);

    // turn on!
    hci_power_control(HCI_POWER_ON);

#ifdef HAVE_BTSTACK_STDIN
    btstack_stdin_setup(stdin_process);
#endif

    return 0;
}