mmr_input_attach()

Synopsis:

#include <mm/renderer.h>

int mmr_input_attach( mmr_context_t *ctxt, 
                      const char *url, 
                      const char *type )

Arguments:

ctxt

A context handle.

url

The URL of the new input.

type

The input type. You must place quotes around the text naming the input type, which can be one of the following:

track: One track played in isolation from the rest of the media
playlist: A track sequence, with ordering information and track metadata contained in a playlist file
autolist: A single track formatted as a playlist; you can play the track continuously using the repeat parameter

Library:

mmrndclient

Description:

Attach an input track or playlist. If the context already has an input, the function detaches it first.

The input type affects how mm-renderer responds to certain playback requests. For example, when seeking to track positions using mmr_seek(), you must specify the desired position differently for each of the supported input types. Also, mmr_list_change() and mmr_track_parameters() apply to "playlist" only.

Which input types are supported depends on the configuration of mm-renderer; however, the playback behavior for a given input type does not depend on the configuration.

Valid input URLs for the "track" and "autolist" input types are:

An http: or https: URL containing the full path of an HTTP-accessible file or an HTTP stream. When the URL refers to a file, the http: prefix is optional.

HTTP Live Streaming (HLS) is supported just as any HTTP stream, with the following caveats:
- For HLS realtime broadcast, the seek operation is disabled. Therefore, if your application issues a seek command it will fail.
- Pause (play speed of 0) is supported but the playback may jump forward when resumed because the current stream may have become unavailable.
- For HLS Video on Demand, the seek operation places the play position at the start of the video chunk that is closest to the requested time. The pause operation works as expected.
The mm-renderer service supports HLS version 3, with media segments encoded as follows:
- Transport stream MPEG2-TS with H.264 Video, with either MP3 or AAC Audio (when the appropriate codecs are available on the platform)
- Video only and audio only when embedded in the MPEG2-TS stream
Note: For secure video and audio playback of HTTP streams, mm-renderer allows you to set cookies, SSL, and authentication properties by defining context parameters, input parameters, or track parameters.
An rtsp: URL naming an RTSP source, which will deliver video streamed over RTP. The source is indicated by either a host name or an IP address, followed by the path. To authenticate with the RTSP server, you can provide a username and password, separated by a colon and followed by the AT sign, in front of the source:
```
rtsp://username:password@10.222.97.225/axis-media/media.amp
```
An rtp: URL specifying a port on which to listen for a unicast RTP stream. The port number is prefixed with the AT sign and a colon, as in this example:
```
rtp://@:49152
```
This will listen for an RTP stream on port 49152. This URL type is useful if you want to configure a camera to stream to a QNX Neutrino host.
A full pathname starting with a "/" character, with or without a file: prefix. The pathname may refer to an audio or a video file.
A file2b: URL containing the full pathname of a dynamically growing file (i.e., a progressive download). Not all formats are supported. If parsing the file requires knowing its size or reading more data than currently in the file, the input attachment operation may fail. If it succeeds, any attempt to play from beyond the end of file will cause the playback to underrun. Your application must pay attention to the buffering status and appropriately present the state to the user, depending on whether the download is happening at the same time.
An snd: URL targeting an audio capture device (microphone) whose device file is located in /dev/snd. The URL can specify device configuration options in a comma-separated list, as follows:
```
snd:/dev/snd/pcmPreferredc?frate=44100&nchan=2
```
Supported options include:
- frate — the sampling rate, in Hertz
- frag_ms — the fragment size, in milliseconds
- nchan — the number of channels (1 for mono, 2 for stereo)
- depth — the number of bits per sample (e.g., 16)
- bsize — the preferred read size, in bytes
Currently, this URL format works only with the "file" output type. The resulting behavior is identical to that for the audio: URL format except that the Audio Manager is bypassed, which means you can't provide hints such as audio type to control audio routing. The advantage of the snd: prefix is that you can use it on systems that don't have Audio Manager.
An audio: URL naming an audio capture device (microphone) whose name is defined by the AUDIO_DEVICE_NAMES set of string constants, which is listed in the Audio Manager Library reference. The URL can specify any of the options supported for snd: URLs, for example:
```
audio:voice?nchan=1&frate=44100&depth=16
```
Currently, this URL format works only with the "file" output type. Client applications should use audio:default to specify automated routing for the audio stream unless there's a good reason to use one particular device. When a non-default device is named, the audio stream routing depends solely on that device. In this case, the removal of the device could result in no audio being outputted or an error returned to the client.
Note: Not all audio devices may work with the current application. It's the client's responsibility to determine if a particular device is supported before trying to use it. See the mmr_output_attach() example for a demo of how to check if an audio device is supported before configuring the audio routing.

Valid input URLs for the "playlist" input type are:

A full pathname of an M3U playlist file, with or without a file: or http: prefix
An SQL URL in the form sql:database?query=query, where database is the full path to the database file, and query contains an SQL query that results in a single column containing URLs in a form acceptable for the "track" input type. Note that any special characters in the query must be URL-encoded (e.g., spaces encoded as %20).

Returns:

Zero on success, -1 on failure (use mmr_error_info()).

Classification:

QNX Neutrino

Safety:
Interrupt handler	No
Signal handler	No
Thread	Yes

Example:

See the mmr_output_attach() example for a demo of how to select one audio device to use.