firened

UPDATE 2022.11.22: Find the updates about this Guide on GitHub: https://github.com/e...spberry-vigibot

## how to create timelapse videos with your robot
Vigibot has the possibility to take photos regularly. the following script will regularly create timelapse videos using the photos, the video can then be played directly from the Vigibot website.

Note: if your camera has a motorized IR cut filter, only do step 5 and check if it clicks every minute when it's dark. this would wear out the motorized IR cut filter rather quickly. an option is to unplug the motorized IR cut filter connector on the camera module. if you have other ideas, let me know.

1. login into your robot over ssh

2. add a tmpfs entry, run:
`sudo nano /etc/fstab`
add:
```
tmpfs /tmp tmpfs defaults,noatime, nosuid,size=20m 0 0
```

3. run `sudo reboot`

4. run `df` and make sure there's a `/tmp` entry.

5. In hardware config set `SNAPSHOTSINTERVAL` to `1` to take a photo every 1 minute.
Note: Snapshots are publicly accessible on https://vigibot.com/captures/

6. create folder
```
sudo mkdir /usr/local/timelapser/
```

7. install script
```
sudo wget -P /usr/local/timelapser/ https://raw.githubus...n/timelapser.sh
```

8. make script executable
```
sudo chmod +x /usr/local/timelapser/timelapser.sh
```

9. run the script manually and leave it running
```
sudo /usr/local/timelapser/timelapser.sh
```

10. open a second ssh connection to your robot

11. run
```
sudo ln -s /usr/bin/ffmpeg /usr/local/vigiclient/processdiffintro
```

12. run
```
sudo ln -s /tmp/timelapse_short.mp4 /usr/local/vigiclient/timelapse_short.mp4
```

13. run
```
sudo ln -s /tmp/timelapse_long.mp4 /usr/local/vigiclient/timelapse_long.mp4
```

14. copy the whole `CMDDIFFUSION` array from `/usr/local/vigiclient/sys.json` into your `/boot/robot.json` file. (if Vigibot pushes an update to `sys.json` you will have to manually update/re-copy the array.)

15. add the 2 following entries to the copied `CMDDIFFUSION` array.
```
] , [
"/usr/local/vigiclient/processdiffintro",
" -loglevel fatal",
" -stream_loop -1",
" -re",
" -i /usr/local/vigiclient/timelapse_short.mp4",
" -c:v h264_omx",
" -profile:v baseline",
" -b:v BITRATE",
" -flags:v +global_header",
" -bsf:v dump_extra",
" -f rawvideo",
" -vf 'scale=640x480:force_original_aspect_ratio=decrease,pad=ih*4/3:ih:(ow-iw)/2:(oh-ih)/2'",
" tcp://127.0.0.1:VIDEOLOCALPORT"
] , [
"/usr/local/vigiclient/processdiffintro",
" -loglevel fatal",
" -stream_loop -1",
" -re",
" -i /usr/local/vigiclient/timelapse_long.mp4",
" -c:v h264_omx",
" -profile:v baseline",
" -b:v BITRATE",
" -flags:v +global_header",
" -bsf:v dump_extra",
" -f rawvideo",
" -vf 'scale=640x480:force_original_aspect_ratio=decrease,pad=ih*4/3:ih:(ow-iw)/2:(oh-ih)/2'",
" tcp://127.0.0.1:VIDEOLOCALPORT"
]
```
`robot.json` should then look something like this:

16. restart the Vigibot client

17. add 2x `CAMERA` entries in hardware config and set `SOURCE` to the `CMDDIFFUSION` array index number of your entry. In the above screenshot that's array index number `8` and `9`.


18. add 2x `COMMAND` entries in remote control config and set `CAMERA` to the created camera number. for me it was `5` and `6`.

19. run `ls -l /tmp/`, check if `timelapse_short.mp4` and `timelapse_long.mp4` exist and check if it's working on vigibot.

20. if it works, automatically start it on boot: run `sudo nano /etc/rc.local` and add the following above the line `exit 0`
```
/usr/local/timelapser/timelapser.sh > /dev/tty0 &
```



### additional information / explanations:
thanks to Pascal for some of the above instructions.

it seems `enfuse` hdr images cause ffmpeg to fail. do not set `EXPOSUREBRACKETING`

### for future reference: manual cli commands
- use most recent images for short clip. takes about 10 seconds to create.
```
#target length: 1h in 6s playback
#'-sseof 2': use only most recent 2 seconds of input
#ffmpeg may be assuming a different fps value in its -sseof calculation
#'-r 10': set conversion to 10 fps
#'-filter:v fps=fps=30': force 30 fps output so thr 30 fps vigibot captures work
```
```
sudo ffmpeg -sseof -2 -r 10 -pattern_type glob -i "/home/pi/timelapse/*.jpg" -s 640x480 -vcodec libx264 -filter:v fps=fps=30/tmp/timelapse_short.mp4 -y
```

- long clip. takes about 90 seconds to create.
```
#target length: 24h in 40s playback
#"-sseof 52": use only most recent 52 seconds of input
#ffmpeg may be assuming a different fps value in its -sseof calculation
#'-r 30': set conversion to 30 fps
#'-filter:v "setpts=0.5*PTS"': only pass 50% of the frames, drop the others. this halves timelapse_long playback duration. (e.g. '0.2' would only pass 20% of the frames).
```
```
sudo ffmpeg -sseof -52 -r 30 -pattern_type glob -i "/home/pi/timelapse/*.jpg" -filter:v "setpts=0.5*PTS" -s 640x480 -vcodec libx264 /tmp/timelapse_long.mp4 -y
```
 

UPDATE 2022.08.22: i didn't do a good job checking if the servos fit into the vigibot 3D files. unfortunately no metal gear 180° fit the vigibot 3D files. Doman DM-S0090MD 270° is the only metal gear servo that fits. Bokins plans on modifying the 3D files to make the DIYMore MG90S fit.

servo benchmark

goal: find robust servo models for a Minus-Type robot, in the hopes of extending time between servo failures and repairs. A per piece price of up to 20$ may be acceptable (N20 Pololu motors are also in that range). Minus-Type uses Micro Servos, also called 9g or sg90.

tested are the following servo models:

1) DIYMore SG90, plastic gear, 1$: recommended by Vigibot. are very quick which makes for a comically fast head nodding that people find hilarious. used on most of my robots (not WalterJakob's pan-tilt), personal failure rate is pretty high. EDIT: a resonating shaking may happen if the weight is too far from the axis line (used as pan servo on PepitoBots). i assume a drawback of the PID(?) regulator in use, which is probably also responsible for the desired comically fast nodding. same applies to DIYMore MG90S metal gear servo (used as pan servo on Briecam).

2) DIYMore MG90S, metal gear, 3$: had servos in the past that were DOA or didn't work on the lower battery voltage, unfortunately can't remember the exact reason. EDIT: read above servo #1 notes. EDIT: servo doesn't fit the current 3D printer files, requires adjustment.

3) TiankongRC TS90A, plastic gear, 270°, 3$

4) Doooman Hobby DM-S0090MD, metal gear, 270°, 6$

5) DFRobot DS-S006L, plastic gear, 9$: has a clutch to protect internal gears.

6) FiTec FS90MG, metal gear, 6$

7) Spektrum A330, plastic gear, 18$

8) Futaba S3114, plastic gear, 20$: "sub-micro" servo doesn't fit the current 3D printer files, requires adjustment.

9) HiTec HS-55+, plastic gear, 20$

10) HiTec HS-5055MG, metal gear, 30$

11) HiTec HS-65MG, metal gear, 30$

↓ See conclusions or table "benchmark table.xlsx" for servo failure times.

test tries to simulate real world usage, common scenarios:

• to work with Vbat voltage 3.3V - 4.2V

• usually low weight/momentum movements (camera is pretty lightweight)

• people may accidentally hit the robot

• robot may drive into walls or objects with a servo absorbing the hit

• servo may want to move into an object and be limited by it

stress test setup:

pre-test #0: power from 3.3V and check if servo is even functional (most servo specifications state a minimum operating voltage of 4V). stop movement with hand, to check if it stops immediately / gets stuck.

main test #1: power from 3.3V, move back and forth (90° - 0°) automatically (eg 1 cycle every 6s to keep temperature low), no weight attached. from time to time force into obstacle (180° position can't be reached) to simulate real world interaction. let run every night and check how many minutes they last before they stop working.

notes:

27.5.22: ran test #1 for 2400min (actual movement: 400min), 1 cycle (to 0° and back to 90°) every 6s, no failures.

-> replaced with 10A 3.3V power supply. increased speed from 1 cycle every 6s to 1 cycle every 2s. now movement from 3 servos overlap. can still be doubled. temperature IR meter: room = 27°C, servo avg = 35°C, servo max = 37°C.

28.5.22: ran test #1 for 480min (actual movement: 240min), 1 cycle every 2s no failures.

-> increased speed to 1 cycle every 1s. movement from 6 servos overlap, maximum possible. temperature IR meter: servo avg = 42°C, servo max = 46°C

29.5.22: ran test #1 for 800min (actual movement: 800min), 1 cycle every 1s,

-> divided runtime value by intensity to "actual movement" value.
 VID_20220606_211516.mp4   13,93 Mo   95 téléchargement(s)
Conclusion for Botkins / Minus-Type Robot:

6 servos had good behavior and more than acceptable runtime until failure.

Metal Gears:

• DIYMore MG90S: Okay. EDIT: .stl doesn't fit! 

• FiTec FS90MG: Okay. EDIT: .stl doesn't fit! 

• Doooman Hobby DM-S0090MD: Okay (Pan 270°: cable fatigue!)

Plastic Gears:

• DIYMore SG90: Okay

• TiankongRC TS90A: Okay (Pan 270°: cable fatigue!)

not recommend servos:

• DFRobot DS-S006L: Okay EDIT: auto-revert is annoying, drops objects in gripper by itself!

• Spektrum A330: No (failed early)

• Futaba S3114: No (.stl doesn't fit)

• HiTec HS-55+: No (Slow)

• HiTec HS-5055MG: No (3.3V unsupported)

• HiTec HS-65MG: No (Slow)

See table "benchmark table.xlsx" for servo failure times.

 benchmark table (1).xlsx   7,24 Ko   74 téléchargement(s)

    },
,
    {
      "NAME": "Right wheel rear",

      "GAINS8": [
        1,
        1
      ],

"CMDTTS": "cat /tmp/tts.txt | /usr/games/cowsay | /usr/games/lolcat -F 0.3 > /dev/tty0"

"CMDTTS": "cat /tmp/tts.txt | /usr/bin/figlet -f small | /usr/games/lolcat > /dev/tty0"

sudo apt install socat ncat

sudo nano /usr/local/ncat_esp.sh

#!/bin/bash

sudo socat pty,link=/dev/ttyVigi0,rawer,shut-none pty,link=/dev/ttySrv,rawer,shut-none &

while true
do
  sleep 1
  sudo ncat -l -k -4 --idle-timeout 15 7070 </dev/ttySrv >/dev/ttySrv
  date
  echo "restarting ncat"
done

sudo chmod +x /usr/local/ncat_esp.sh

sudo /usr/local/ncat_esp.sh

/*
  Author:   firened
  File:     vigibot_ESP32_slave_client.ino
  Version:
  V1.0      10.2020
  V1.2      12.2020

  Description:
  Vigibot Pi to ESP32 over WLAN, based on the Arduino Uart example by Mike118.
  check the robot-maker post for up to date setup instructions.

  pinout GPIO:


*/

#include <WiFi.h>
#include <ESPmDNS.h>

const char* ssid = "your_ssid";
const char* pass = "your_pass";

const char * host = "192.168.1.63"; // ip or dns
const uint16_t port = 7070;

// Use WiFiClient class to create TCP connections
WiFiClient client;

// Meta Type :

typedef struct {
  union {
    struct {
      int16_t x;
      int16_t y;
    };
    int16_t coordonnees[2];
    uint8_t bytes[4];
  };
} Point;

typedef struct {
  union {
    struct {
      int8_t x;
      int8_t y;
      int8_t z;
    };
    uint8_t bytes[3];
  };
} Vitesses;


// CONFIG

#define NBPOSITIONS 2
#define FAILSAFE 250 // ms


// TTS

#define TTSBUFFERSIZE 255
uint8_t ttsBuffer[TTSBUFFERSIZE];
uint8_t ttsCurseur = 0;


// TX

#define TXFRAMESIZE (NBPOSITIONS * 4 + 17)

typedef struct {
  union {
    struct {
      uint8_t sync[4];               // 4
      Point positions[NBPOSITIONS];  // NBPOSITIONS * 4
      uint16_t val16[2];             // 2 * 2
      uint8_t choixCameras;          // 1
      Vitesses vitesses;             // 3
      uint8_t interrupteurs;         // 1
      uint8_t val8[4];               // 4
    };

    uint8_t bytes[TXFRAMESIZE];
  };
} TrameTx;


// RX

#define RXFRAMESIZE (NBPOSITIONS * 4 + 9)

typedef struct {
  union {
    struct {                       // Sizes
      uint8_t sync[4];              // 4
      Point positions[NBPOSITIONS]; // NBPOSITIONS * 4
      uint8_t choixCameras;         // 1
      Vitesses vitesses;            // 3
      uint8_t interrupteurs;        // 1
    };

    uint8_t bytes[RXFRAMESIZE];
  };
} TrameRx;


TrameTx trameTx;
TrameRx trameRx;

uint32_t lastTrameTimestamp = millis();
uint32_t lastSleepBeacon;
uint32_t lastConnectAttempt;

void setup()
{
  Serial.begin(115200);

  // We start by connecting to a WiFi network

  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.setSleep(false);
  WiFi.config(INADDR_NONE, INADDR_NONE, INADDR_NONE); //required for hostname to take effect on ESP32 (workaround)
  WiFi.setHostname("Vigibot_ESP_0");
  WiFi.begin(ssid, pass);
  while (WiFi.waitForConnectResult() != WL_CONNECTED) {
    Serial.println("Connection Failed! Rebooting...");
    delay(5000);
    ESP.restart();
  }

  Serial.println("WiFi connected.");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());

  // add all your init here

}

void loop() {
  while (WiFi.waitForConnectResult() != WL_CONNECTED) {
    Serial.println("WLAN Connection Failed! reconnecting...");
    WiFi.mode(WIFI_STA);
    WiFi.begin(ssid, pass);
    delay(10000);
  }
  checkClient();

  if (readPiSerial()) {
    // each time we receive a full trame run repeatedly:
    // use values inside trameRx to tell your robot how to move ...
    // trameRx.vitesses.x , trameRx.vitesses.y, trameRx.vitesses.z
    // trameRx.positions[i].x trameRx.positions[i].y  etc....

    /*if (trameTx.interrupteurs & 0b00100000) { //testing purposes
      trameRx.vitesses.y = 10;
    }*/

    //writePiSerial(); //make sure only one esp sends replies
    lastTrameTimestamp = millis();
  }
  if ( millis() - lastTrameTimestamp > FAILSAFE ) {
    if ((millis() - lastSleepBeacon > 10000) ) { // every 10 seconds
      //writePiSerial();                        // Beacon to say that the robot is alive
      lastSleepBeacon = millis();
    }
    // Stop the robot in case the robot lost connection with the Pi

  } else {
    // put your main code here, to run repeatedly:
    // avoid abstacle, run speed ...

  }
  //check for millis() overflow
  if (millis() < lastSleepBeacon) {
    lastSleepBeacon = millis();
  }
  if (millis() < lastConnectAttempt) {
    lastConnectAttempt = millis();
  }
}

void checkClient(){
  static byte lastClientState = 2;
  if (client.connected()) {
    if (lastClientState != 0) {
      lastClientState = 0;
      Serial.println("Client connected.");
    }
  } else {
    if (lastClientState == 0) { //if client is not actively connected anymore, stop and reconnect
      lastClientState = 1;
      // close the connection:
      client.stop();
      Serial.println("Client Disconnected.");
    }
    if ((millis() - lastConnectAttempt) > 5000) {
      lastConnectAttempt = millis();
      Serial.print("Connecting to ");
      Serial.println(host);
      if (!client.connect(host, port)) {
        Serial.println("Connection failed. Waiting 5 seconds before retrying...");
      }
    }
  }
}

bool readPiSerial() {
  uint8_t current;
  static uint8_t lastType = 0;
  static uint8_t n = 0;
  static uint8_t frame[RXFRAMESIZE];
  while (client.available()) {
    current = client.read();
    //Serial.write(current); //debug

    switch (n) {

      case 0:
        if (current == '$')
          n = 1;
        break;

      case 1:
        if (current != 'T' && lastType == 'T')
          writeTtsBuffer('\n');

        if (current == 'S' || current == 'T') {
          lastType = current;
          n = 2;
        } else
          n = 0;
        break;

      default:
        frame[n++] = current;

        if (n == RXFRAMESIZE) {

          if (lastType == 'T') {

            for (uint8_t i = 4; i < RXFRAMESIZE; i++) // Do not send the 4 sync data in tts
              writeTtsBuffer(frame[i]);

          } else if (lastType == 'S') {

            for (uint8_t p = 0; p < RXFRAMESIZE; p++)
              trameRx.bytes[p] = frame[p];

          }
          n = 0;
          return true;
        }
        //break;
    }
  }
  return false;
}

void writePiSerial() {
  // Header, do not modify
  trameTx.sync[0] = '$';
  trameTx.sync[1] = 'R';
  trameTx.sync[2] = ' ';
  trameTx.sync[3] = ' ';

  // modify the feedback according your need. By default we copy the trameRx content ...
  for (uint8_t i = 0; i < NBPOSITIONS; i++) {
    trameTx.positions[i].x = trameRx.positions[i].x;
    trameTx.positions[i].y = trameRx.positions[i].y;
  }
  trameTx.val16[0] = 0;   // Voltage (will be updated by Raspberry pi)
  trameTx.val16[1] = 0;   // Percent (will be updated by Raspberry pi)
  trameTx.choixCameras = trameRx.choixCameras;
  trameTx.vitesses.x = trameRx.vitesses.x;
  trameTx.vitesses.y = trameRx.vitesses.y;
  trameTx.vitesses.z = trameRx.vitesses.z;
  trameTx.interrupteurs = trameRx.interrupteurs;
  trameTx.val8[0] = 0;   // CPU load (will be updated by Raspberry pi)
  trameTx.val8[1] = 0;   // Soc temp (will be updated by Raspberry pi)
  trameTx.val8[2] = 0;   // link (will be updated by Raspberry pi)
  trameTx.val8[3] = 0;   // RSSI (will be updated by Raspberry pi)

  for ( uint8_t i = 0; i < TXFRAMESIZE; i++)
    client.write(trameTx.bytes[i]);
}

void displayTtsBuffer (uint8_t * ttsBuffer, uint8_t bufferSize) {
  // you can modify this function to display text on a screen depending on your hardware...
  for ( uint8_t i = 0; i < bufferSize; i++) {
    Serial.write(ttsBuffer[i]);
  }
  Serial.println("");
}

void writeTtsBuffer( uint8_t ttsChar) {
  static uint8_t ttsCurseur = 0;
  if ( ttsCurseur < TTSBUFFERSIZE && ttsChar != '\n') {
    ttsBuffer[ttsCurseur] = ttsChar;
    ttsCurseur ++;
  }
  if ( ttsCurseur == TTSBUFFERSIZE || ttsChar == '\n') {
    displayTtsBuffer (ttsBuffer, ttsCurseur);
    ttsCurseur = 0;
  }
}

su -

echo '$T  hello from cli       $n' > /dev/ttyVigi0

sudo nano /etc/rc.local

/usr/local/socat-esp.sh &

sudo socat tcp:localhost:7070 -

sudo cat /dev/ttySrv

it's possible to add a custom intro / instructions video to your robot.
be aware that this is to add an intro video to your existing robot with a real camera already in place, and not to add a «video only bot», check the #rules-documentation channel on discord for the official rules.
you can use the intro so people see your robot from a different perspective (like a mirror would), or for special instructions that may not be apparent.
also make sure that the intro video is not the default view of your robot (explained in step 5).
 
Standard setup, without video sound:

1) login via ssh and create a symlink to ffmpeg:

sudo ln -s /usr/bin/ffmpeg /usr/local/vigiclient/processdiffintro

2) create a second symlink to your video (change the Rick _Astley path) :

sudo ln -s /home/pi/Rick_Astley_Never_Gonna_Give_You_Up.mp4 /usr/local/vigiclient/intro

3) dublicate HARDWARE CONFIGURATION -> CAMERAS -> 0 , and set CAMERAS -> 1 -> SOURCE : 7
(use "TREE" or "TEXT" layout, SOURCE number is currently 7, but may change)


4) dublicate REMOTE CONFIGURATION -> COMMANDES -> 0 , and set your created camera number in COMMANDES -> 0 -> CAMERA : 1
(use "TREE" or "TEXT" layout)

5) set REMOTE CONFIGURATION -> DEFAUTCOMMANDE : 1 , so that it doesn't always start playing when clicking the stop button. (instead requires pressing the prev/left button)
 
restart robot client, now your robot will play the video.
 
OPTIONAL: Play video sound on the robots speaker:
 
6) copy the whole "CMDDIFFUSION" array from /usr/local/vigiclient/sys.json into your /boot/robot.json file. (if Vigibot pushes an update to sys.json you will have to manually update/re-copy the array.)
 
7) in your robot.json, replace the ".../processdiffintro" array entry, with the following ffmpeg command. On the last line " plughw:1" enter your PLAYBACKDEVICE number, you can figure that out with the command `alsamixer` -> F6.

] , [
   "/usr/local/vigiclient/processdiffintro",
   " -loglevel fatal",
   " -stream_loop -1",
   " -re",
   " -i /usr/local/vigiclient/intro",
   " -c:v h264_omx",
   " -profile:v baseline",
   " -b:v BITRATE",
   " -flags:v +global_header",
   " -bsf:v dump_extra",
   " -f rawvideo",
   " -vf 'scale=640x480:force_original_aspect_ratio=decrease,pad=ih*4/3:ih:(ow-iw)/2:(oh-ih)/2'",
   " tcp://127.0.0.1:VIDEOLOCALPORT",
   " -f alsa",
   " -filter:a volume=0.25",
   " plughw:1"
  ]

robot.json should then look something like this:

 
OPTIONAL 2: Route video sound directly into the Vigibot audio channel (without playing on the speaker):
Todo: ask Pierre

Thanks mike118 for the official vigibot logo animation that we can use in our custom intro video.
it's here as direct download:
https://www.robot-ma...igibotintro.mov
and here on youtube:

post your results here of all the speakers you've tested for a raspberry pi. 

simply post a photo or/and link, and say how good or bad the audio quality is. 

i find it difficult to find a small, easy to install speaker for my robots that has good audio quality so people understand the Text-To-Speech. but this thread is not limited to robots' TTS, and may be helpful for other applications too! 

so far i see these different methods of using a speaker on raspberry pi: 

• 3.5mm speaker without amp (psa: usually too quiet) 
• 3.5mm speaker with amp, maybe battery too 
• a product with amplifier & speaker together 
• separate amplifier & separate speaker 
• bluetooth speaker, maybe with battery

sudo chmod +x /usr/local/aws-polly-signed-signal

sudo apt install mpg123

sudo nano /boot/robot.json

,
"CMDTTS":"pkill -x -o -SIGUSR1 -f '/usr/local/aws-polly-signed-signal -a plughw:PLAYBACKDEVICE -v Mathieu' || /usr/local/aws-polly-signed-signal -a plughw:PLAYBACKDEVICE -v Mathieu &"

,
"CMDTTS": "/usr/bin/espeak -v en -m -f /tmp/tts.txt --stdout | /usr/bin/aplay -D plughw:PLAYBACKDEVICE"

<prosody pitch="0" rate="0"> lol

wget http://ftp.us.debian.org/debian/pool/non-free/s/svox/libttspico0_1.0+git20130326-9_armhf.deb 
wget http://ftp.us.debian.org/debian/pool/non-free/s/svox/libttspico-utils_1.0+git20130326-9_armhf.deb 
sudo apt-get install -f ./libttspico0_1.0+git20130326-9_armhf.deb ./libttspico-utils_1.0+git20130326-9_armhf.deb  

,
"CMDTTS": "cat /tmp/tts.txt | pico2wave -l fr-FR -w /tmp/tts.wav && /usr/bin/aplay -D plughw:PLAYBACKDEVICE /tmp/tts.wav" 

sudo apt install sox 

,
"CMDTTS": "cat /tmp/tts.txt | pico2wave -l fr-FR -w /tmp/tts.wav && /usr/bin/sox /tmp/tts.wav /tmp/sox.wav treble +15 && /usr/bin/aplay -D plughw:PLAYBACKDEVICE /tmp/sox.wav"