Raspberry pi streaming audio server. I think I’m close to getting this to work.



Raspberry pi streaming audio server This guide covers everything you need to set up a DIY media server, including software Use OpenMediaVault To Build Your Raspberry Pi Streaming Server. Also he’s not using the output of the pi itself as it still feeds his Nova via UPnP over the network See also: Build a home music system with Raspberry Pi and Make a audio system with Mopidy. Moode Audio runs on top of Raspberry Pi OS. Wenn dieser Server im kleinen Rahmen 24/7 laufen soll, bietet es sich an, diesen auf Grund des geringen Stromverbrauches, auf dem Raspberry Pi unterzubringen. I use a Rpi 4 - 1 gb ram running I'm going to use a 2tb SSD and I'd also like to move my music from itunes onto the Pi server, connect it to a couple of bluetooth speakers and control it from my mobile phone. At home, I am still using Daphile, a robust They used a Raspberry Pi 1 which has the ARMv6 BCM2835 SoC. Merely select your preferred software, set it up, and point your Raspberry Pi music streamer app to your music collection. A Gieseler Reinigen USB Reclocker feeds the 0s and 1s to a Gieseler Kompakt II DAC featuring the TDA1541A chip. My aim was to listen to the radio on a remote Raspberry PI hooked to a RTL-SDR dongle. Cá nhân em với việc dùng dây LAN và raspberry Pi 3 thì dùng real-time streaming, khi đó âm thanh chỉ chậm hơn hình ảnh cỡ 0,2s. dknk June 8, 2020, 5:52pm 6. After installing it, you would do something like: RPi Streaming Audio Server. The CPU is kept busy with about 70-90% of the CPU being used by ffmpeg. latency using Raspberry Pi? Any inputs from personal experiences with audio streaming would be highly appreciated. Save power while streaming with Raspberry Pi. Route Audio Output Through USB Audio Jack. You can think of this software as a self-hosted alternative to services like Spotify Creating your own audio streaming server with a Raspberry Pi, Icecast, and DarkIce is a rewarding project that gives you full control over your digital broadcasting setup. Raspi setup - Streaming live audio over existing network (I'm using the Pi Zero W boards) via DHCP on an existing house network, and one 'server' Pi have an analogue audio input attached, and it stream this audio to several 'client' devices, with an analogue audio output. Tue May 05, 2015 3:18 pm . This article shows how to turn the Raspberry Pi into a streaming server. 1. Icecast is an In the other hand, my home is controlled by the raspberry Pi using MQTT , fauxmo (Belkin wemo emulator) and flask to interface my Alexa skill. My web page comes up in Safari. Allowing for us to use the Raspberry Pi. For Android devices, I Tùy thuộc vào tốc độ mạng LAN và streamer mà chọn. 0 DAC+AMP Board. My only gripe with this software is the actual image. With its support for a wide range of music sources and streaming services, Mopidy offers a versatile and customizable solution for creating a home music server that meets your specific needs and This project lets you use Raspberry Pi as a music player that you can control from your mobile phone with the Volumio app. A few prominent posters on here have said this. 2 Can You Use Raspberry Pi As A Media Player? 2. connect to the streaming server at port 8090 (the Using Bubble can also apparently improve sq of the streaming services a bit as it’s acting as a proxy server in-between the internet and your own network before it hits the streamer. I used this for months and was happy with it. 8 HKD). To make matters worse, the video stream only works in isolation; when trying to do both streams together, not even the video stream works. I've owned a number of DACs with different chip architectures Icecast Ices2 music server for Raspberry Pi: Raspberry Pi streaming audio server. The Overall, a Raspberry Pi streaming music server is fairly easy. Hello everybody Finally I have my first "Raspberry Pi 3 Model B" and so far everything is set up and now I want to make good use of it. A: Joined: Tue May 05, 2015 12:10 pm. IME There's a ton of lag on my Pi3 over bluetooth. this system is good for synced players. Mopidy is a python music server. So the setup was good and I got everything going including synaptic. Hello guys, I am selling a DIY Streamer kit based on Raspberry Pi 4. address:port/directory . Start with a Raspberry Pi 4 or 5, a reliable power supply, and a high-speed microSD card. You can create a high-quality music server using DAC options like HiFiBerry or JustBoom for crystal-clear playback. It’s a surprisingly capable alternative to pricier options, perfect for dipping your toes into networked audio. Last edited by nav1980 on Sun Nov 30, 2014 4:05 am, edited 2 times in total. I've tried Live555 server for streaming videos between client and server. For a Volumio Raspberry Pi music streaming server, you'll need a Raspberry Pi board, microSD card, power supply, case, and peripherals such as keyboard and mouse. Raspberry Pi Press. Volumio is easy to use, supports all types of files (mp3, FLAC, Alac, Aac, Vorbis, etc. compared to a computer running Windows, Android The simple answer is 'Yes'. It installs and runs smoothly on Raspbian Lite with a headless server setup for efficiency, but any flavor of Raspbian will do. Raspberry Pi is one of the best single-board computers out there. The Pi is connected to a phone's mobile hotspot and can rely on the phone's 3G to send data to the internet. So far I've tried TRX, SoX over NC, gstreamer, ffmpeg and icecast as a server on one side with the Turn your Raspberry Pi into a music server, where you can wirelessly stream any track from any device on your network or Spotify's catalogue. andrew9172 Posts: 5 Joined: Mon Jul 18, 2022 1:43 pm. For that, check the link below: Streaming Audio from a remote Raspberry Pi to my computer. I'm a big fan (and only slightly biased friend ) of the designer, Clay Giesler, but his focus on very clean and low noise power supplies and optimising circuit designs really shines through. DarkIce and Icecast are two Raspberry Pi packages used for audio recording, encoding, and streaming. For streaming, consider options like Kodi or Plex, which are user-friendly and versatile. On the RPi device that performs capture from the mixing console, first implement an ALSA external PCM plugin that acts as a UDP (or TCP) client. Thu Jun 07, 2018 1:08 pm . My goal here is to Volumio – A music server for the Raspberry Pi dedicated to audiophiles based on the Raspbian Pi operating system. Store information; I'd like to produce an RTSP stream of mixed audio and video coming from a raspberry pi to my computer. Nhấn Apply là xong. I have installed latest stretch-lite version of raspian-OS on my two raspberry pi boards and would like to do audio stream two way using RTP streams. A very well put together package. Once you have Volumio set up on your Raspberry Pi, you’ll be able to stream all the major DIY Music Server and Streamer for the Audio Hobbyist By bobfa. by John Darko January 30, 2020, 14:14. But you can't update Raspberry Pi OS. Then I try to access the stream from my iPhone. Thanks. Nous allons maintenant passer en revue les étapes nécessaires à l’installation de Logitech Media Server, le configurer selon les besoins, puis commencer à utiliser Because I do want the main server to do just that, I chose a solution that you can install under Raspberry Pi OS, with Snapcast + Mopidy on my RPi4. hi guys i would like to use a rasberry device to stream live audio from a digital mixer to the web or even better to an app which will send a push notification to tell my church users im live. Audio Streaming Between 2 Pis. everything works good. The same as camera streaming, there is a lot of tools for you to stream your raspberry pi's audio. What I'm looking to do, is using my Model B Pi (512MB Edition), capture audio from my USB sound card device, and stream it to a Shoutcast server to broadcast. Currently I'm achieving the task producing two separate tcpserversink, like this: # SERVER raspivid -t 0 -rot 180 -w 640 -h 480 -fps 20 -b 256000 -o - | gst-launch-1. one server and many clients like 10 20 30. nthali Posts: 2 Joined: Mon May 18, 2020 4:50 pm. That’s one reason to add a HAT. for 2 months I worked on the project for transmitting the music and audio file over my local network. I have following command to send RTP audio data from rpi1 to rpi2 board and again the command to send the audio data from rpi2 to rpi1. I would like to stream audio to a remote server listening for a RTSP stream on a IP:port. Hi FM81, I use in total eleven of these FS20 IRB units, four at Help with Server / Live-Streaming Audio. Follow this link carefully: First, I need some kind of functional tightvnc viewer (connect). Hướng dẫn cài đặt một Using the Raspberry Pi. You can also use the Jellyfin streaming media center for music, and As Google Music stops working with more that 100k tracks and my collection is larger, I gifted myself with a brandnew RPi 3 and an additional HifiBerry-Amp. But I am a real noob when it comes to Linux and things. The UI is nice. Start with the Raspberry Pi models: the Raspberry Pi 4 with 2GB of RAM is ideal, while the I want to stream audio+video from the Pi to a remote server (e. Personal Raspberry Pi music streamer. Using an audio-focused Linux distro like Moode, Volumio etc. 3 Can You Use Raspberry Pi For Netflix? This open-source project enables you to transform a Raspberry Pi into a streaming/-file-server for your music with LMS (Lyrion/Logitech Media Server/ Squeezebox), Samba, With just a Raspberry Pi and some speakers, however, you can create your own DIY sound system to play locally stored music, Spotify streams, internet radio stations, podcasts, and more via a web interface. 1 post • Page 1 of 1. Préparer le Raspberry Pi en tant que streamer de musique. Thread starter driblo; Start date Feb 4, 2024; 1; 2; Next. a GPIO i2s/i2c RPi hat (elinux. It's possible to stream both live video and/or audio streams generated by the Raspberry Pi to any browser (no plugin required) on a PC or smartphone with UV4L. Mon Nov 04, 2019 8:51 pm . tpylkko Posts: 417 Joined: MiniDLNA is a DLNA server that runs on the Pi. Install an operating system like LibreELEC and update it before installing Kodi. You get the same results as any other computer running Linux with ALSA, mpd, etc. As the broadcast went on, the video and audio grow increasingly out of sync. The simplest is to setup the pi as a NAS (network attached storage) server with the samba software. Found the 4 a little A Raspberry Pi is a computer, that is all. dass Ihr Raspberry Pi zur Geräteliste hinzugefügt wurde und kommuniziert mit dem Audio stream. The translator between the echo dots and my sensors or controls. Bluetooth Audio does not seem to work on Raspbian Strech. org, PiHats) or USB adapter , will have to be added to the the RPi. I'm stuck on streaming both audio and video from the USB Webcam connected to the RBPi to my computer. 3 posts Audio Streaming Between 2 Pis. The simplest is the command line client mpc that can run on the Raspberry Pi. 1 Does Raspberry Pi Make A Good Media Server? 2. 3. This is all Volumio is perhaps the most well-known and simplest starting point for first-timer RPi streamers; it integrates Spotify Connect, Tidal and Qobuz (the latter two for a fee). Using the Raspberry Pi. Raspberry Pi Store. My other Raspberry Pi I've had a search around in the forums, there are people doing similar projects to what I am hoping to acheive, but in reverse and using the Pi as a server as opposed to an encoder. Im In conclusion, turning your Raspberry Pi into a home music server with Mopidy is a great way to enjoy your music collection from anywhere in your home. Verwandeln Sie Ihren Raspberry Pi mit moOde Audio in eine Musik-Streaming-Plattform 2024-11-27 Aus, Steam Link-Geräte und Minecraft-Server an,und selbsthostende Workstations gibt es eine erstaunliche Anzahl von Projekten, die Sie mit einem kostengünstigen Raspberry Pi erstellen können. For example, in my case, I give my headphone endpoint a multichannel stream and let it do the work to make that usable. Raspberry Pi Hardware. November 9, 2021. omxplayer -o hdmi server. Broadcast Server, mit dem man sein eigenes Webradio betreiben oder mit Freunden (natürlich gema-freie) Playlists teilen kann. This step-by-step And then the Raspberry Pi found a home within the Audiophile community for use as a streamer. However, I keep getting errors at both end. Then make it executable? (I'm really a n00b at this stuff!) Code: Select all. My interpretation is nothing original, I simply copied what many others have already accomplished. I’m executing a command in the Terminal that starts the stream on my Pi. And even some Icecast2 ist ein moderner Audio Streaming Server bzw. Designed to run This section walks you through setting up a cost-effective music streaming system using a Raspberry Pi. Raspberry Pi Zero 2W (moodeaudio) - Topping D50s/A50s - Massdrop HD6XX. At its most basic level, it’s a computer made up of hardware and software whose only task is to In this tutorial, we will be showing you how to install Navidrome on your Raspberry Pi. In the following guide we will use a Raspberry Pi 3 Model B and a HifiBerry DAC+ Light, but the instructions should work the same with differnt Raspberry Pi models starting from Raspberry Pi 1, with other HifiBerry modules, e. By bobfa • November 9, 2021. 2. Firstly, and as you have hinted, audio h/w capture capability, e. I have server working on both sides (my windows laptop and my pi - which is 3, model B Do you have experience about streaming audio (e. I want to stream both video and audio data to a webpage hosted via Flask. There are a wide range of digital-audio convertors out there catering for every budget from £12 to thousands – Comment configurer Logitech Media Server; Options de streaming audio et conditions préalables pour Raspberry Pi. Sat Aug 03, 2019 6:23 am . I'm interested in doing something that seems like it should be simple with the Pi and an audio card like the Cirrus, but don't know exactly which software, if any, but you can configure the Streaming Server to disable video at all and audio in one direction) Manuals: Sometimes it is necessary to stream the system audio over the network. DIY Streamer based on Raspberry Pi 5. I was hoping to send a RTMP stream from the Pi to the server and access it via a VPN session. I've already installed both icecast and darkice, and it works to stream when connecting a microphone. I think I’m close to getting this to work. Mopidy remains a neat A Raspberry Pi 4 Model B is the brains of the operation, and slots nicely onto the HiFiBerry. I can do that and play music from my Pi using a AMP+ hat and direct connected speakers (which would be a similar audio path to your external amp connection, just feeding at the pi@Raspberry ~/live/raspi $ raspivid -w 1024 -h 768 -fps 25 -b 300000 -t 99999999 -o - | . You can build your own Android TV Box with Raspberry Pi or set up a RPi web server. 0 DAC+AMP Audio Expansion board. While platforms like Spotify, Apple Music, and others dominate the scene, self-hosted music servers have emerged as a breath of fresh air for I'm using a Raspberry Pi 4 with a USB webcam. Now I've figured out that the Mopidy service is not discovered in the Spotify app over Spotify Connect, so I'm considering replacing Mopidy with Spotifyd or Librespot. my final result is using logitech media server on my pc server and many zero w for my clients. Icecast creates audio streams on various platforms. Instead, they want internet radio or access to audiophile streaming services like Whether you have your own music files (MP3, FLAC, etc) already downloaded and want to stream them to speakers around the house, or you As mentioned in the introduction, dozens of softwares have been created over time capable of transforming the Raspberry Pi into the perfect media server, playing music, video and other multimedia with some of them being able to connect to several streaming platform, to make the contents on those platforms available t Discover the simplicity of streaming live audio directly from a USB microphone connected to your Raspberry Pi to your local computer via the internet. After some cursory research on Raspberry Pi DACs, I came across the X400 V3. g. Use HiFiBerryOS To Build Your Raspberry Pi Music Server. I've been researching a way to stream audio between two pis over a local network and I've kind of hit a wall. If you do, you will probably break Moode Audio. Using a USB Audio Device With a Raspberry Pi My previous tutorial on the Raspberry Pi, Using a Raspberry Pi as an AirPlay Receiver, made Streaming to a SHOUTcast server with Pi I've had a search around in the forums, there are people doing similar projects to what I am hoping to acheive, but in reverse and usin Learn how to transform your Raspberry Pi 5 into a powerful media server for streaming movies, music, and more at home. This can be an ideal There are endless possibilities for Raspberry Pi audio projects. Prior to version 4, the Raspberry Pi’s USB and Ethernet data shared a single data bus whose narrow bandwidth regularly introduced audible pops and clicks to a USB audio connection. With the use of plugins, this Squeezebox server can be extended to stream music from music I've tested this with Official Raspberry Pi Camera V1. Everything go through my echo dot to read sensors or to controls things. In short, STEALTH V3 = music server + streamer + player + audiophile switch For more details, please visit the following The "-itsoffset 8" flag introduces an extra lag on the audio stream to try to align it with the video stream. Getting started with a Raspberry Pi for music streaming is refreshingly affordable. Consider using icecast as streaming audio server and IceS as audio source client. /testRaspi More specifically I'd like to re-stream an audio stream (mp3 or aac) through my Rpi using your script + live555 rtsp server. Configure your music library by adding media sources, and enhance your setup with add-ons for added functionality. Re: Audio server for multiple simultaneous streams. But what I really want to stream is the audio that you hear on the audio-out, so the "stereo mix" (as it would be called in Windows) of the raspberry. from input) to web using raspberry? I've googled about PiMusicBox, UV4L, SoundWire, PulseAudio, Stream What You Hear etc but does somebody here have concrete experience about these? Networking and servers Automation, sensing and robotics Graphics, sound and multimedia Raspberry Pi Raspberry Pi audio streaming 101. Will give volumio or other pi music servers another try on the 5. There are a number of packages that will allow you to do this, but there is often a lag of several seconds between the action and the viewed video/audio. For multi-room independent audio, stream/access the files over most protocols (smb, DLNA, HTTP, etc) and play them back on your chosen device. Found a slightly outdated tutorial on lifehacker for using subsonic, did some other reading, made the necessary I'm actually trying to stream the audio TO the airplay/dlna reciever from the raspberry pi. How To Stream Tidal, Qobuz or Spotify Many users are not interested in streaming local content these days. I haven't gotten Spotify to work yet and no iOS devices for Airplay. HifiBerry Digi+ with This audio server allows you to stream music over your network to compatible devices and features support for most audio codecs. audio_output { type "httpd" name "HTTP Stream from Raspberry Pi" encoder "lame" bitrate "128" port "65432" format "44100:16:2" } Thanks! Greetings, FM_81. Navidrome is an open-source music server and streamer. Thu May 10, 2018 9:25 am . Using mopidy to stream audio to MPoD. iPhone SE - Apple dongle - Truthear x Crinnacle Zero or Topping NX4 - AKG K371 The audio should come from the Windows system playback (a virtual audio cable, or just capturing system audio is fine). . Tip! Choose your DAC. RTSP audio stream RPI. The raspberry Pi is my control box. In this project we are going to set up a Raspberry Pi streaming station using DarkIce and Icecast. Hi, I want to stream audio FROM Raspbery Pi using USB mic (recognized) TO remote Windows maschine using SSH or other options. What I am trying to achieve now is RTSP streaming via a public network. Logically, this is where I've determined is the right place to do it as the downmix / correction directly applies to the headphones. ), and works with Use OpenMediaVault To Build Your Raspberry Pi Streaming Server. Navidrome Is the Perfect Self-Hosted Music Server for Raspberry Pi In an age where digital music streaming is omnipresent, there exists a niche for those who value ownership of their music libraries. host it on a simple website I make) with <2s of latency. However, if you are able to run the associated BubbleUPnP Server helper software on a computer or NAS on the same network (I use a Raspberry Pi for this), the BubbleUPnP Android app offloads the stream proxy & transcoding function to the BubbleUPnP Server, saving the Android device from handling the audio streams & doing any of the work. they synced together This allows your Pi to act as a Bluetooth receiver, or receiver for Spotify, Airplay, etc, as well support for streaming the same music over multiple Pi devices. There are limitless possibilities with Raspberry Pi, and we simply love Take all the audio in the phone and send to a upnp server, but sadly the equality sound is poor. I work in corporate events and am looking for the ability to play background music ( ie Spotify playlist), audio stings of approx 1:30 duration, and also pre recorded messaging. 25th Nov 2020 ; Ashley Whittaker I use Squeeze Server Enter ifconfig into the terminal and use the first numeric string after the inet string to access the moOde Audio server from another system on the same network as your Raspberry Pi. PiGraham Posts: 5494 on what you're trying to acheive would likely help but TBH you're unlikely to be able to get an audiophile approved sound quality when streaming - there are too many variables that all have to be perfect in order to get that There are several solutions which allow you to use your Raspberry Pi as a music streamer, including the Python-based music server Mopidy. Does it allow it to work as a DLNA server for audio? Unfortunately the WD is quite old and won’t run any extra software such as Asset (at least not officially). After fiddling around with several platforms, Subsonic came closest to what I liked: neat sorting and filtering, remotely accessing the music library and capable dealing with 100k+ tracks. May 7, 2024 November 22, 2017 by w3techie. RESOLVED Re: streaming music from my usb hdd? Thu May 21, 2020 2:58 pm . Re: Rasberry Pi 4 with 4gb RAM and use this as a NAS / Plex Server / Music streamer? Fri Jun 05, 2020 7:06 pm Can anyone post the detailed instructions for , Plex,NAS server , i think I have a problem with Openmediavault , since external 6tb drive is Exfat , and can't be mounted in Openmediavault and I can't find External HDD after Plex server I want to stream the audio that my Raspberry Pi "hears" through an icecast server (with darkice). Raspberry Pi Equipment: Reason Why You Need This Raspberry Pi Component: Raspberry Pi B, B+ or Newer • The best audio boxes from Raspberry Pi need a 100 Mbit ethernet port, enough memory to process the information, and a When setting up a Raspberry Pi music server with Volumio, you’ll need to gather the right hardware to guarantee peak performance. Local network streaming audio server. a raspberry Pi (I have a raspberry type B but I think it can also work with a type A) an SD card with the lastest raspbian distribution (I use 2013-09-25-wheezy-raspbian) a compatible USB bluetooth adapter (I bought one very simple from the french provider "Boulanger" which perfectly works whithout any additionnal driver. Some of the features on this board include: Um seinen Nutzen zu demonstrieren, haben wir ein Audio-Streaming-Gerät mit Raspberry Pi gebaut und Ihnen ein weiteres cooles Tutorial gebracht. This can be an ideal solution for anyone looking to explore the world of Welcome to the wonderful world of Raspberry Pi streaming solutions. Please be noted that soldering and assembly are needed (except SMD components). I recently purchased a Raspberry Pi 2 Model B for a school project that I am working on. I've gotten the video stream to work, but never the audio stream. A nice webinterface would be nice, but I also wouldn't mind if I could stream to the raspberry-pi which would then forward it to the two recievers. It is also directly powered by the Raspberry Pi so, no additional power supply needed. for a client side. Firstly, the client script will not even start and the server script starts occasionally but with errors. The Raspberry Pi platform allows you to interact with various video signals in a power-saving way. The full answer is 'Yes, but latency is a problem'. It should transport over the LAN/Wifi to the Pi, and then playback through the Pi's built in audio jack/HDMI/HAT DAC. Using a USB Audio Device With a Raspberry Pi My previous tutorial on the Raspberry Pi, Using a Raspberry Pi as an AirPlay Receiver, made Streaming to a SHOUTcast server with Pi I've had a search around in the forums, there are people doing similar projects to what I am hoping to acheive, but in reverse and usin I'm trying to stream the audio to my computer now. i used VLC as a client tool to open What is the best way to stream audio over LAN to multiple devices with min. Don't stream Using the Raspberry Pi. Please also note that the currency is in HK dollar (1 USD = 7. 1 of 2 Go to page ADI-2 Pro FS R Black Edition - March Audio P452 - Harbeth P3ESR. 7 Bonus Set-Up Method: Pair Your Raspberry Pi with Emby To Use As A Media Server. You could also build a custom audio streaming setup using Icecast for real-time broadcasts. This option isn’t new—computer hobbyists have been using Raspberry Pi’s for years. Hi there! I’m looking for advise on best software to use for a device I want to build using a raspberry pi. 3 on Raspberry Pi 3 B+ and Raspberry Pi 4 running latest Raspbian OS (Raspbian Buster), but it should work on Raspberry Pi 1, 2 or Raspberry Pi Zero and Zero Easiest is set Pi up as a NAS, browse to the share from you phone, or point your music player app at the share (depending on how sophisticated it is) and stream away. Well, new to linux and raspberry pi I would like to have my raspberry pi connect to an audio stream (say from a radio station) on startup, it initially is only required to connect up to one unique stream on startup. X400 V3. DIY Music Server and Streamer for the Audio Hobbyist Setting up a Raspberry Pi music server with Kodi is straightforward and rewarding. Plus, you'll probably want an external harddrive or large capacity flash Audio stream from Raspberry Pi to Windows. Beginners. Eventually, the video and audio stream will be embedded in a webpage (most likely using <iframe>). The HiFiBerry HAT is compatible with all Raspberry Pi models with a 40-pin GPIO connector and just clicks right onto the GPIO pins. I have installed PyAudio on the Raspberry Pi (Raspian), and have portaudio installed on my Mac and now both scripts at least attempt to run. 0 -v \ fdsrc ! \ h264parse ! \ rtph264pay ! \ gdppay ! Creating your own audio streaming server with a Raspberry Pi, Icecast, and DarkIce is a rewarding project that gives you full control over your digital broadcasting setup. It took more than remote desktoping to make this possible. iklr lvd hwueia huf ocgqb rxrjgej tnf oqyu zcqknr guwtk lmpsb mhafqqy toeia vfqnkz jvko