--- name: "glasscoder" section: "1" platform: "linux" package: "glasscoder" version: "2.0.1-2.1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/glasscoder" --- # glasscoder(1) Minimalist audio encoder for live streaming ## NAME glasscoder - Minimalist audio encoder for live streaming ## SYNOPSIS **glasscoder** \[*OPTIONS*\] ## DESCRIPTION [**glasscoder**(1)](/glasscoder/1.md) is an audio encoder that is capable of generating live streams using a variety of formats and sending them to an Icecast or Shoutcast audio streaming server or posting them as HTTP Live Streams \[HLS\]. It is also capable of acting as an Icecast-compatible server in its own right, serving streams directly to client players and thus eliminating the need for an intervening Icecast server instance. [**glasscoder**(1)](/glasscoder/1.md) has no GUI or configuration file components at all; its sole 'user interface' being its command-line invocation. As such, it is particularly well suited for being driven by an external process or controller such as [**glassgui**(1)](/glassgui/1.md) or [**glasscommander**(1)](/glasscommander/1.md). ## OPTIONS - **--audio-atomic-frames** Emit a stream consisting of self-contained frames --e.g. by disabling the MPEG-1 bit reservoir. Useful mostly for debugging. - **--audio-bitrate=***kbps* The constant stream data rate in kilobits per second. Default value is **128**. Use of this option is mutually exclusive with that of the **--audio-quality** option (see below). - **--audio-channels=***chans* The number of audio channels to use. Valid values are **1** or **2**. Default value is **2**. - **--audio-device=***type* The type of audio device to use. The default value is **JACK**. See the **DEVICE OPTIONS** section (below) for the options appropriate for each audio device type. Valid values are: **ALSA** The Advanced Linux Sound Architecture. **FILE** Stream directly from a file. **JACK** The Jack Audio Connection Kit. - **--audio-format=***fmt* The audio encoding format to use. The default value is **VORBIS**. Valid *fmt* values are: **MP2** MPEG-1/1.5 Layer 2 **MP3** MPEG-1/1.5 Layer 3 **OPUS** Ogg Opus (RFC-6716) **PCM16** PCM16 Uncompressed **VORBIS** Ogg Vorbis - **--audio-quality=***qual* Use variable bitrate streaming at the given audio quality. *qual* can be in the range **0.0** (lowest quality) to **1.0** (highest). Use of this option is mutually exclusive with that of the **--audio-bitrate** option (see above). - **--audio-samplerate=***rate* The audio sample rate to use for streaming. If the underlying audio layer is operating at a different sample rate, the input will be automatically resampled to this rate. Default value is **44100**. - **--credentials-file=***filename* Get the credentials for connecting to the server in the *filename* file. The contents of the file should be formatted as follows: ``` [Credentials] Username= Password= ``` When using the **--ssh-identity** option, the passphrase for the specified identity file should be used as the password value. - **--delete-credentials** Delete the file specified by **--credentials-file** after being read. - **--errors-string=***string* Prepend *string* to messages sent to the **syslog** service (see the **--errors-to** option, below). Useful for disambiguating messages from multiple [**glasscoder**(1)](/glasscoder/1.md) instances. - **--errors-to=***dest* Send error messages to *dest* (default standard error). Valid destinations are: **STDERR** Standard error. **SYSLOG** The system syslog service. **STDOUT** Standard output,in machine readable format (useful for communication with another 'controller' program). See also the **--meter-data** option below. - **--help** Print a short usage message and exit. - **--list-codecs** Print a list of available codecs and then exit. - **--list-devices** Print a list of available source devices and then exit. - **--metadata-port=***port* Accept metadata updates via HTTP at port *port*. Default value is **0**, which disables metadata updates. See the METADATA section (below) for information regarding the supported update formats. - **--meter-data** Output meter level updates on standard output. Useful for driving an external metering display. **--server-auth=**\[*username*\]\[**:***password*\] (DEPRECATED) The authentication parameters to use. This parameter has no default. NEVER USE THIS OPTION! It allows credentials to be seen by other users on the system. Use the **--credentials-file** option to specify server credentials instead. - **--server-exit-on-last** Exit the program upon closure of the last player connection. This setting is used only by the IceStreamer server. - **--server-max-connections=***conns* Allow a maximum of *conns* simultaneous player connections. Players beyond this maximum attempting to connect will receive an immediate TCP disconnect before the HTTP handshake. This setting is used only by the IceStreamer server. - **--server-no-deletes** Do not clean up or delete content previously posted to the publishing point. This setting is used only by the HLS server type. - **--server-pipe=***pathname* Location to create a UNIX socket for piping connection socket descriptors. Useful for implementing proxy connectors for the IceStreamer server. For further details about this feature, see the Proxy Connections section of the [**glasscoder-ipc**(7)](/glasscoder-ipc/7.md) man page. The default is to create no UNIX socket. This setting is used only by the IceStreamer server. - **--server-script-down=***cmd* Run the command *cmd* when the connection enters the disconnected state. - **--server-script-up=***cmd* Run the command *cmd* when the connection enters the connected state. - **--server-start-connections=***conns* Do not start the audio transport until at least *conns* connections have been established. Used only by the IceStreamer server in conjunction with the **FILE** audio device. Default value is **0** --i.e. start the transport immediately. - **--server-type=***type* The type of streaming server to use (default is **Icecast2**). Valid values for *type* are: **FILE** Local file **FILEARCHIVE** Local file archive. Stream to a set of files on the local system, starting a new file at the beginning of each hour. **HLS** HLS/HTTP Live Streaming **IceCast2** IceCast v2 **IceOut** Output an Icecast-compatible stream on standard output. **IceStreamer** Stream directly to players using the internal Icecast-compatible server. **Shout1** Shoutcast v1 **Shout2** Shoutcast v2 - **--server-url=***url* The URL describing the server resource to stream to. See the SUPPORTED URL SCHEMES section (below) for a list of what URL schemes are appropriate for which server types. When used with a **--server-type** of **IceStreamer**, the host part of the URL is used to specify the address of the network interface to use for streaming (use **0.0.0.0** to indicate ALL interfaces). This parameter has no default. - **--server-user-agent=***agent-string* The User-Agent header value to use when connecting to external servers. Default value is **GlassCoder/2.0.1**. This setting is used only by **IceCast2** and **HLS** servers. - **--ssh-identity=***filename* The path to the file containing an [ssh(1)](/ssh/1.md) identity to use when connecting via SFTP. When using this option, the passphrase for the identity file should be provided as the server password. See the **--credentials-file** option for details. - **--stream-aim=***aim* The AOL Instant Messenger ID to associate with the stream. There is no default value. This setting is used only by Shoutcast servers. - **--stream-description=***string* The string to show as the stream description. There is no default value. This setting is used only by Icecast servers. - **--stream-genre=***string* The string to show as the stream genre. There is no default value. This setting is used only by Icecast and Shoutcast servers. - **--stream-icq=***icq* The ICQ ID to associate with the stream. There is no default value. This setting is used only by Shoutcast servers. - **--stream-irc=***irc* The Internet Relay Chat ID to associate with the stream. There is no default value. This setting is used only by Shoutcast servers. - **--stream-name=***string* The string to show as the stream name. There is no default value. This setting is used only by Icecast and Shoutcast servers. - **--stream-timestamp-offset=***offset* The offset to add to the value of stream timestamps, in seconds. Default value is **0**. This setting is used only for HLS streams. - **--stream-url=***url* The URL to show for a page giving more information about the stream. There is no default value. This setting is used only by Icecast and Shoutcast servers, but is ignored by Shoutcast v2 servers. - **--verbose** Increase verbosity level of information printed to standard error. WARNING: this may cause cleartext passwords to printed! - **--version** Output version information and exit. ## DEVICE OPTIONS **Advanced Linux Sound Architecture** (**--audio-device=ALSA**) - **--alsa-device=***dev* The name of the ALSA device to use. If no **--audio-device** option is given, then the **hw:0** device will be used. **Direct File Streaming** (**--audio-device=FILE**) - **--file-name=***name* The name of the file to stream. If no **--file-name** option is given, then the name of the file will be read from standard input. **The Jack Audio Connection Kit** (**--audio-device=JACK**) - **--jack-client-name=***name* The name of the JACK client to use. Default is **glasscoder**. - **--jack-gain=***gain* Apply a fixed gain of *gain* dB before encoding. Default is **0** dB. - **--jack-server-name=***name* The name of the JACK server instance to use. ## SUPPORTED URL SCHEMES Not all URL schemes are supported by all server types. The following chart breaks down the options. **Table 1. Supported URL Schemes by Server Type** | | | | | | --- | --- | --- | --- | | **Server Type** | **FILE://** | **HTTP://** | **SFTP://** | | FILE | Yes | No | No | | FILEARCHIVE | Yes | No | No | | HLS | Yes | Yes \[1\] | Yes | | IceCast2 | No | Yes \[2\] | No | | IceOut | No | Yes | No | | IceStreamer | No | Yes | No | | Shout1 | No | Yes \[2\] | No | | Shout2 | No | Yes \[2\] | No | | \[1\] Utilizes the HTTP *PUT* and *DELETE* methods | | \[2\] Utilizes the HTTP *GET* method | ## METADATA GlassCoder supports the notion of two types of metadata: "channel-based" metadata, which applies to the stream as a whole and does not change for the duration of an encoding session; and "timed" metadata, which can be changed in synchronization with the content of the audio stream. Channel-based metadata can be specified by means of options given to [**glasscoder**(1)](/glasscoder/1.md) and will be covered in detail in the sections devoted to specific server types (below). The primary mechanism for supplying timed metadata in GlassCoder is by means of a JSON document containing the desired metadata, sent to the target [**glasscoder**(1)](/glasscoder/1.md) instance at the port specified by the **--metadata-port** option by means of an HTTP *POST* operation. The basic format of the JSON document is as follows: ``` { "Metadata": { "Field1": "Some value", "Field2": "Some other value" } } ``` Not all server types support metadata, and those that do utilize wildly different schemas. Following is a breakdown of the available metadata options by server type: ### IceCast2 **Channel Metadata** IceCast2 supports the following channel metadata fields: Name Specified by the **--stream-name** option. Description Specified by the **--stream-description** option. URL Should be a link to content related to the stream. Specified by the **--stream-url** option. Genre Should be a single word describing the nature of the stream content. Specified by the **--stream-genre** option. **Timed Metadata** IceCast2 provides one field of text, called StreamTitle, which can be dynamically updated to reflect the content currently playing on the stream. By convention, this is usually formatted as '**Artist** - **Title**' on streams containing musical content. For example, to set the StreamTitle field to **The Beatles - Hey Jude**, the following JSON could be used: ``` { "Metadata": { "StreamTitle": "The Beatles - Hey Jude" } } ``` **Legacy Interface** In addition to the primary JSON interface, the StreamTitle can be set by sending an HTTP *GET* request to a running [**glasscoder**(1)](/glasscoder/1.md) instance, using the TCP port specified in the **--metadata-port=***port* option. The request must be in the following format: ``` http://hostname:tcp-port/admin/metadata?mount=mount-point&mode=updinfo&song=string ``` Where: *hostname* - The hostname or IP address of the system running [**glasscoder**(1)](/glasscoder/1.md) *tcp-port* - The TCP port number specified in the **--metadata-port** option to [**glasscoder**(1)](/glasscoder/1.md) *mount-point* - The mountpoint of the stream *string* - The string to set, encoded as specified in Section 2 of RFC3986 For example, to set a string of "The Beatles - Hey Jude" via a [**glasscoder**(1)](/glasscoder/1.md) instance running at **encoder.example.com** with a **--metadata-port** value of **1234** for a mountpoint of **MyStream**, the URL would be: **http://encoder.example.com:1234/admin/metadata?mount=MyStream&mode=updinfo&song=The%20Beatles%20-%20Hey%20Jude** ### ShoutCast **Channel Metadata** ShoutCast supports the following channel metadata fields: Name Specified by the **--stream-name** option. URL Should be a link to content related to the stream. Specified by the **--stream-url** option. Genre Should be a single word describing the nature of the stream content. Specified by the **--stream-genre** option. ICQ ID Should be User Identification Number for an ICQ user associated with the stream content. Specified by the **--stream-icq** option. AOL Instant Messenger ID Should be an ID for an AOL Instant Messenger user associated with the stream content. Specified by the **--stream-aim** option. IRC ID Should be an ID for an Internet Relay Chat channel associated with the stream content. Specified by the **--stream-irc** option. **Timed Metadata** ShoutCast provides two fields of text which can be dynamically updated to reflect the content currently playing on the stream, called StreamTitle and StreamUrl. By convention, the StreamTitle is usually formatted as '**Artist** - **Title**' on streams containing musical content, while StreamUrl is used to provide a URL whence stream specific content --e.g. album cover art -- can be retrieved. For example, to set the StreamTitle field to **The Beatles - Hey Jude** and the StreamUrl field to **http://images.example.com/1234.png**, the following JSON could be used: ``` { "Metadata": { "StreamTitle": "The Beatles - Hey Jude", "StreamUrl": "http://images.example.com/1234.png" } } ``` **Note**\ The use of either of these fields is optional in any given metadata update. If only one field is given, the other will remain unchanged. **Legacy Interface** In addition to the primary JSON interface, the StreamTitle and StreamUrl fields can be set by sending an HTTP *GET* request to a running [**glasscoder**(1)](/glasscoder/1.md) instance, using the TCP port specified in the **--metadata-port=***port* option. The request must be in the following format: ``` http://hostname:tcp-port/admin.cgi?pass=password&mode=updinfo&song=stream-title&url=stream-url ``` Where: *hostname* - The hostname or IP address of the system running [**glasscoder**(1)](/glasscoder/1.md) *tcp-port* - The TCP port number specified in the **--metadata-port** option to [**glasscoder**(1)](/glasscoder/1.md) *password* - The ShoutCast password, encoded as specified in Section 2 of RFC3986 *stream-title* - The string to set for StreamTitle, encoded as specified in Section 2 of RFC3986 *stream-url* - The string to set for StreamUrl, encoded as specified in Section 2 of RFC3986 For example, to set a StreamTitle of "The Beatles - Hey Jude" and a StreamUrl of "http://image.example.com/1234.png" with a password of "MyPassword" via a [**glasscoder**(1)](/glasscoder/1.md) instance running at **encoder.example.com** with a **--metadata-port** value of **1234**, the URL would be: **http://encoder.example.com:1234/admin.cgi?pass=MyPassword&mode=updinfo&song=The%20Beatles%20-%20Hey%20Jude&url=http://image.example.com/1234.png** ### HTTP Live Streams (HLS) **Timed Metadata** HLS supports timed metadata in the form of embedded ID3v2.4 tags. Available fields thus include the entire set of text tags defined in the ID3v2.4 frame specification (available at http://id3.org/id3v2.4.0-frames). For example, a typical metadata update could use the following JSON: ``` { "Metadata": { "TIT2": "Hey Jude", "TPE1": "The Beatles", "TALB": "The White Album", "TRSO": "WXYZ Radio" } } ``` A user defined text information frame (**TXXX**) can be sent by using the following special notation for the field identifier: TXXX*desc* Where: *desc* - The TXXX Description string (see Section 4.2.6 of the ID3v2.4 Frame Specification) For example: ``` { "Metadata": { "TIT2": "Hey Jude", "TPE1": "The Beatles", "TALB": "The White Album", "TRSO": "WXYZ Radio", "TXXXxyz": "TXXX frame with a description string of \"xyz\"" } } ``` ## NOTES The Debian version of GlassCoder does not support the MPEG-4 HE-AAC+ encoding, as it is non-free. The AudioScience HPI source device is excluded for the same reason. ## BUGS Never use the **--server-auth** option; it allows credentials to be seen by other users on the system. Use the **--credentials-file** option to specify server credentials instead. Ogg metadata support is still missing. ## AUTHOR Fred Gleason \ ## SEE ALSO [**glasscoder-ipc**(7)](/glasscoder-ipc/7.md), [**glasscommander**(1)](/glasscommander/1.md), [**glassgui**(1)](/glassgui/1.md), [**jackd**(1)](/jackd/1.md) RFC3986 - Uniform Resource Identifier (URI): Generic Syntax ID3v2.4 Native Frame Specification (http://id3.org/id3v2.4.0-frames) ## AUTHOR **Fred Gleason** \ Application Author