Running Linux, 5th Edition - Matthias Kalle Dalheimer [176]
Network Multimedia Middleware (NMM)
NMM is a multimedia middleware package that allows the creation of distributed multimedia applications . A number of plug-ins supporting various media types, operations, and I/O devices are included. NMM has been used to implement a multimedia application that provides an extensible home entertainment system for DVD/CD playback and frame grabbing, TV with time-shifting, video recording, and playlist creation and playback for all supported media types.
More information can be found at http://www.networkmultimedia.org.
Media Applications Server (MAS)
The Media Application Server (MAS) is a time-aware arbiter of video and audio hardware, meant to scale the gamut of systems, from embedded to massively parallel, from handheld devices to supercomputers, from a microphone source to a speech recognition engine sink. MAS is a multimedia routing server. It moves multimedia data across the Internet virtually in real time, ensuring quality presentation of video, audio, and other time-sensitive information.
For more information on MAS, see http://www.mediaapplicationserver.net.
Multimedia distributions
There are some Linux distributions being developed that are optimized to be used as multimedia platforms. One such project is AGNULA, which stands for A GNU/Linux Audio distribution. With funding from the European Commission, it is developing two reference Linux distributions of free software: DeMuDi (Debian-based Multimedia Distribution) and ReHMuDi (Red Hat-based Multimedia Distribution). The project's home page is http://www.agnula.org.
Solutions to Common Problems
Listed here are answers to some commonly asked questions and solutions to common problems related to multimedia hardware and software:
Why doesn't my distribution include an MP3 encoder or DVD player?
Due to legal issues related to patents, many Linux distributions do not ship an MP3 encoder or DVD player application. You may be able to download these separately after determining for yourself that they can be used legally in your jurisdication.
Are there free alternatives to MP3 and DVD that are not encumbered by patents?
The Ogg project by the Xiph.org Foundation has developed several encoding formats and free implementations that are free of patent issues including Ogg Vorbis for audio and Ogg Theoris for video. See http://www.xiph.org for more information.
Kernel modules not loaded
This could be caused by incorrect module configuration files. It will also occur if the kernel module loader (kerneld or kmod) is not running. Make sure the module is available for loading in the appropriate directory (typically something like /lib/modules/2.4.17/kernel/drivers/sound).
Sound card not detected
You are probably using the wrong kernel driver or the wrong settings for I/O address, IRQ, or DMA channel.
IRQ/DMA timeout or device conflicts
You are using the wrong settings for I/O address, IRQ, and DMA, or you have a conflict with another card that is using the same settings.
No sound after rebooting
If sound was working and then stopped when the system was rebooted, you probably have a problem with the module configuration files. This can also occur if the system init scripts are not configured to initialize PnP cards or to load the modules. If the drivers are loaded, it could be that the mixer settings are set too low to hear any audio. Use a mixer program to adjust the sound levels while using a media player program to play a known good sound file.
If you are running KDE or GNOME, make sure that the appropriate sound server (aRts or esd) is running. On some systems, you may need to adjust the sound server settings using the control panel provided for this purpose. In the case of KDE you can also conveniently test the sound server from the control panel.
Sound works only for root
This probably indicates a permissions problem with the device files. Many systems allow only users who are members of the group "audio" to access the sound devices. Add the user(s) to this group or change the permissions