@(#)RELNOTES 6.47 04/02/25 XMCD/CDA RELEASE NOTES ---------------------- General Notes ------------- Xmcd works best on an X display with a three-button mouse. Most features are operated with the left mouse button, and feature-specific help can be invoked with the right mouse button. In addition, xmcd supports copy-and-paste between its text fields as well as with other compliant X and Motif applications (such as xterm). The left button is used for highlighting and copying, and the middle button is used for pasting. This distribution comes with several 32x32 pixmap files suitable for use as an xmcd desktop icon. These are installed in XMCDLIB/pixmaps: xmcd.icon - for Novell/SCO UnixWare 2.x, 2 colors xmcd_a.px - for SCO Open Desktop (XPM2 format), 2 colors xmcd_b.px - for SCO Open Desktop (XPM2 C format), 2 colors xmcd.xpm - for other systems that use XPM format, 2 colors You can use the appropriate icon setup utilities under each of these environments to create an xmcd icon (with which you can use to launch xmcd). For SGI IRIX, the following files are used to implement a colorful SGI 4Dwm window manager icon for xmcd (these should be used only if xmcd is compiled with SGI desktop integration enabled): XMcd_sgi.icon xmcd.closed.fti xmcd.open.fti xmcd.ftr The XMcd_sgi.icon file should be renamed XMcd.icon and placed in the /usr/lib/images directory. Your xmcd/cda executable binary should only be run on the same OS platform group that it was compiled on. For example, UNIX SVR4.0 binaries must not be run on a UNIX SVR4.2 system. Likewise, a binary compiled on a SunOS 4.x platform cannot be used on a Sun Solaris 2.x and later system. The XMCDLIB/app-defaults/XMcd file contains several long lines broken into separate lines using the "\" continuation marker (in particular, the "XMcd*someWidgetName.fontList" lines). This has been known to cause error messages on some Motif implementations. If you encounter such a problem, the remedy is to remove the "\" continuation markers and join the multiple lines back into a single line. The default xmcd *.fontList resources in the XMCDLIB/app-defaults/XMcd file are appropriate for 75dpi fonts. If you are using 100dpi the *.fontList resource may need adjustments. Use the xlsfonts(1) command to see the list of available fonts for your display. Do not use xmcd/cda if the CD drive contains a mounted filesystem data disc (ISO-9660, High Sierra or other formats). Always use the "df" or "mount" command to check if such a filesystem is mounted before invoking the application. Certain OS platforms will print console error messages or record error messages in a log file if the CD device is accessed without a CD loaded in the drive. If you encounter this situation, the workaround is to load a CD in the drive before starting xmcd or cda, and refrain from leaving xmcd in the "no disc" state for an extended period of time. Unless otherwise instructed by your OS or system hardware vendor, it is generally a bad idea to turn off the power of the CD drive while the operating system is running. Cycling the power may glitch the data bus, which is not always gracefully handled by the I/O adapter or your system's device driver (i.e., possible system hang or crash). Thus, it is best to turn on the CD drive before booting the OS, and do not turn it off until after OS shutdown. Security Notes -------------- Xmcd and cda must be installed as a suid-root program on many platforms. This is because these utilities use the SCSI pass-through mechanism to control the CD drive, which requires root privilege on many systems. Security issues have been addressed, however, since they will refuse to send any more command to a device if the initial inquiry shows that the device is not a CD-ROM or WORM device. Also, xmcd changes the uid and gid to that of the real user before reading/writing any files, accessing CDDB services or executing external programs. On systems that do not require super-user privilege for SCSI pass-through, it is actually more secure to turn off the user and group permissions of the SCSI device nodes, and make xmcd and cda suid-root. This prevents malicious users from writing other programs that send arbitrary commands to the devices. Xmcd and cda have also been developed, debugged, scrutinized and rigorously tested with security as a very high priority. If, despite this, you feel uncomfortable about the suid aspect of xmcd/cda then please do not use these applications. Exceptions to the suid-root requirement: If you configure xmcd and cda to operate the drive via the "SunOS/Solaris/Linux ioctl method" the "FreeBSD/NetBSD/OpenBSD ioctl method" or the "AIX IDE ioctl method" (see the NON-SCSI DRIVES section in the DRIVES file), suid-root privilege is not required. Likewise, suid-root permissions is not required on Solaris systems. Also, the suid requirement does not apply on the OpenVMS platform. Lastly, suid-root privilege is required on QNX. If your platform does not require suid-root priviledge and you are installing xmcd and cda as a non-root user, then you must have read and write permissions to the specified BINDIR, XMCDLIB and MANDIR directories. If you run xmcd/cda without suid-root privilege, then you must make sure that the CD drive device node has the appropriate permissions for "other" users. On most platforms it is sufficient to have read-only permission, others may also require write permission. CDDA (CD digital audio) Notes ----------------------------- Please refer to the xmcd and cda man pages for a general description of the "standard" and "CDDA" playback modes. The default xmcd start-up mode can be altered via the playMode parameter in the device-specific configuration files. Platform support for the CDDA modes for this release of xmcd/cda is as follows: AIX 4.x and later (*) BSD/OS 3.x and later (*) Digital UNIX 4.x, Tru64 UNIX 5.x (OSF1) FreeBSD 3.x and later HP-UX 9.x and later IRIX 5.x and later Linux 2.x and later OpenVMS 7.1 and later SCO UNIX 3.2v4.x, Open Desktop 2.x, Open Desktop 3.x, Open Server 5.x Solaris 2.x and later SunOS 4.1.x UnixWare 2.1.x, 7.x, Caldera Open UNIX 8 CDDA support for platforms denoted with (*) is implemented, but not well tested. The OSS (Open Sound System http://www.opensound.com) CDDA write method is supported on the above listed platforms, if OSS is available for it. The native AIX, HP-UX, IRIX, Linux, Solaris and Tru64 UNIX (OSF1) MMS audio drivers are also supported on each of these respective platforms. Linux systems running the ALSA sound driver (ALSA 0.9.x and later http://www.alsa-project.org) are supported either with the native ALSA write method or the OSS write method. When the OSS write method is used with the ALSA sound driver, the OSS compatibility kernel module must be loaded. ALSA versions 0.5.x and earlier are not supported. Support for the native SunOS 4.1.x audio driver is not implemented at this time. Thus, CDDA real-time playback is disabled on this platform; only CDDA save-to-file and pipe-to-program modes are enabled. The MP4 file format will work only if the faac(3) encoder software installed on your system was compiled with MP4 output capability (i.e., supports the "-w" command line option). For OpenVMS, the only currently supported compressed file format is MP3, because LAME is the only encoder that has been ported to this platform. Moreover, on OpenVMS, the "CDDA pipe-to-program" mode does not support any compressed data formats. Not all CD drives nor all hardware configurations support real-time CDDA playback. On some of these systems only the CDDA "save-to-file" and "pipe-to-program" modes can be used with xmcd and cda. The CDDA modes impose a heavier system CPU load than the standard mode, and requires a high performance computer system not laden with other CPU-intensive tasks in order to play smoothly without audible glitches and drop-outs. This is particularly true if jitter correction is enabled (which is needed with many CD drives). CDDA performance is heavily dependent on the speed of the CD drive, the read chunk size, and the system's overall performance. Note that many drives transfer CDDA much more slowly than CD-ROM data (e.g., Some drives advertised as "15x" can only transfer CDDA at 1x, and are not well suited for real-time CDDA playback). In general, a minimum configuration for CDDA playback is as follows: 250MHz CPU or better CD drive capable of sustained 4x CDDA transfer or better CD drive connected via a bus-mastering controller Systems with a non bus-mastering controller for the CD drive may not perform well for real-time CDDA playback, because too many CPU cycles are consumed to simultaneously service the CD drive as well as the sound card DSP. This could occur even on systems with a very fast CPU. The result is garbled/distorted audio quality or dropouts. Linux systems with a recent ATAPI/IDE CD drive may gain improvements by tuning some parameters using the hdparm(8) command (DMA mode may not be enabled to the CD drive by default). If this doesn't resolve the problem, the ultimate answer may be to go with a high-performance bus-mastering SCSI host adapter and CD drive (or alternatively, a USB or IEEE1394/Firewire setup if your platform supports it). The performance of the CPU and I/O subsystem becomes even more critical if you wish to simultaneously do CDDA playback and save-to-file or pipe-to-program operations, especially if the file format you choose requires on-the-fly encoding (compression). The "CDDA Performance Monitor" feature in xmcd can be used to determine the CDDA performance of your setup and the impact of various user-settable parameters. To enable the Performance Monitor, click the "tools" symbol button on the xmcd main window to open the Options window, select the "Playback mode" category, and then click the "Perf monitor" button). It is advisable to run ATAPI/IDE drives under SCSI emulation (on Linux using the ide-scsi driver, or FreeBSD with ATAPI-CAM) and configure xmcd to run the drive as a generic SCSI drive. This often yields better results. See the appropriate documentation about configuring the kernel. The xmcd/cda drive configuration table has been expanded to add support for CDDA capabilities. The author does not have samples of all the drives to personally test the settings, therefore it is likely that the xmcd configuration process may yield incorrect results for some drives. If you have a CDDA-capable drive running on one of the above supported platforms, and the CDDA feature does not work, try following the procedures outlined in the "Xmcd Configuration Guide" at http://www.amb.org/xmcd/ (Click on "Configuration Guide"). Kindly send any updated configuration information to xmcd@amb.org so that the configuration table may be corrected for future releases. Some CD drives lose their positional accuracy when performing CDDA transfers, often in conjunction with a high jitter error rate. When this occurs, the track and time indicator, as well as the CDDA save-to-file mode track file breaks can become shifted (e.g., part of the next track is contained at the end of the current track file). Ripping the tracks in random order (with shuffle mode enabled), or defining a play program sequence of all tracks 1,2,3,...,n should alleviate this problem in most cases. When running in a CDDA mode, xmcd and cda runs in three separate threads. The first thread is the "control", which in xmcd is the main graphical user interface, and in cda is the "cda daemon". The second thread is the "reader", which is responsible for reading the CDDA data from the drive and filling a memory buffer. The third thread is the "writer", which drains the audio data from the memory buffer and sends it to the system's sound DSP device, an output file, and/or to a pipe connected to an external program. This design allows concurrent execution for maximum performance and smoothest audio playback, while keeping the user interface responsive. This multi-threading design is implemented in xmcd and cda using two distinct methods: 1. System V IPC method Each thread is a separate OS process, and the memory buffer between the reader and writer processes uses the System V shared memory mechanism. The synchronization between the reader and writer processes are done via the System V semaphores. This method works well and supports the widest selection of platforms. 2. POSIX threads method This method uses the multi-threading facilities specified by the POSIX 1003.1c standard ("pthreads"). On some systems the threads are separately scheduled execution units within a single OS process, but on Linux each thread is a separate process. All threads can access the same data space within the program, so the audio memory buffer is simply a dynamically-allocated chunk of heap memory. Synchronization between the reader and writer threads are done using pthreads mutex locking facilities. This method is slightly more efficient than the System V IPC method, but is not universally available on all platforms. On some OS platforms, only the System V IPC method is available. Whereas on others, both are available. On OpenVMS, only the POSIX threads method is possible because the OS does not supply the System V IPC services. Old platforms that supports neither facilities cannot be used for CDDA operations with xmcd and cda. The following is a table of CDDA method platform support and the minimum OS version required (valid when the xmcd/cda executable is compiled and run on the same OS version): Platform System V IPC POSIX threads ------------------------ -------------- -------------- AIX all 4.1 BSD/OS all 4.1 Digital UNIX, Tru64 UNIX all 4.0 FreeBSD all 4.0 HP-UX all 11.0 IRIX all 6.3 Linux all glibc 2.1 OpenVMS - 7.1 SCO UNIX, Open Server all - Solaris all 2.5 SunOS 4 all - UnixWare all 7.0.1 Currently, the default configuration for CDDA operation on all platforms except OpenVMS is the System V IPC method. With xmcd and cda executables compiled and run on an OS platform that supports pthreads, you may change the setting of the cddaMethod parameter in the xmcd device-specific configuration file to use the POSIX threads method if you wish. If your xmcd/cda executable is compiled and run on a Linux system with glibc 2.0.x, the pthreads support code is included. However, only the SysV IPC method is recommended. This restriction does not apply to Linux with glibc 2.1 or later. In this release, the xmcd "Options"->"Encoding parameters" Encode option menu selections has changed from previous releases. Rather than explicitly marked with CBR, VBR and ABR selections, the menu selections now indicate Mode 1 through Mode 4. These modes are file format specific. Please invoke the xmcd help window on this menu for details (click the right mouse button while the cursor is over the Encode menu button). Similarly, the command line sub-arguments for the xmcd and cda "compress" command have changed as well. Please refer to the xmcd(1) and cda(1) man page for details. Known Issues ------------ 1. During xmcd's beta test phase a crash in the Ogg Vorbis library was discovered on some versions of the following OS platforms: HP-UX (bug #216) SCO UNIX, Open Desktop, Open Server (patched) SunOS 4.1.x (bug #220) Sun Solaris (patched) The symptom is a message from xmcd that says "CDDA writer thread failure!". A core dump may also be found in the current directory. The cause for these crashes vary between the listed platforms. These problems, as of this writing, has occurred with libvorbis version 1.0 and 1.0.1. The bug IDs shown are as entered on the Bugzilla system for the Ogg Vorbis project (http://bugs.xiph.org). Fixed versions of the Ogg Vorbis libraries are available for the platforms marked "patched". You may download them from the xmcd web site (http://www.amb.org/xmcd). This is only needed if you are compiling xmcd from source code. The official pre-compiled binaries for these platforms already contain the fix. Current versions of the Ogg Vorbis code (directly from their web site) may or may not contain fixes for these problems. If you experience a crash while saving or piping CDDA in the Ogg Vorbis format, you are encouraged to debug the problem and/or report it to the Ogg Vorbis developers via their Bugzilla system. 2. Due to a bug in some versions of Motif 2.1.x, some of xmcd's "Options" window toggle buttons may refuse to be selected after you click on the "Reset" button. This occurs only with those toggle button groups that have "radio" behavior (i.e., only one of the group can be selected at a time). These toggle buttons have either a diamond shape or a round shape. The workaround is to click on the currently selected button first, and then click on the button you desire. This problem does not occur when xmcd is linked with Motif 1.2.x or earlier, or with Lesstif. 3. Various versions of Lesstif may exhibit appearance anomalies in xmcd, such as missing bottom borders in checkbox frames, incorrect font sizes and line spacings, etc. This is evident in Lesstif version 0.93.36 and possibly other versions. If you encounter these problems try a more recent version of Lesstif. 4. With cda only, if the CDDA save-to-file mode is enabled, and the output file path template contains tokens that require CDDB data, and if the CDDB lookup for the loaded CD produces multiple matches, the first match will be automatically used to expand the path names. This is because the output path names are expanded by the cda daemon, which cannot invoke a dialog with the user to let the user choose an alternate selection. The xmcd program does not exhibit this behavior because there is no daemon, and there is always an active graphical user interface. Problem Reporting ----------------- Although xmcd and cda should run reliably on the supported platforms and CD hardware as noted, if you encounter a problem, please send a report to "xmcd@amb.org" with detailed descriptions of the configuration and problem symptoms. It would also be helpful to reproduce the problem while running either application with the -debug option (see the xmcd(1) and cda(1) man pages for the appropriate debug levels to use), and capture the diagnostic output. Send the output to the author for examination. Please also include detailed information about your software and hardware configuration. Better yet, send bug fixes! Porting Xmcd ------------ The modular design of xmcd and cda is such that support for other UNIX environments and CD drives can be readily added. See the PORTING file for details if you are interested in contributing to the development effort. Before you start a porting effort or add significant code, contact the author to ensure that this effort isn't being duplicated by others. Uninstalling Xmcd ----------------- If you wish to remove the installed xmcd and cda executables and support files from your system, this is how to do it: 1. Log in as root 2. cd BINDIR rm xmcd cda .xmcd_start 3. rm -r XMCDLIB BINDIR is the executable directory that you specified when installing xmcd. XMCDLIB is the top level directory of the xmcd library directory hierarchy. In addition, each xmcd user will have a $HOME/.xmcdcfg directory that may be removed. You may also remove the CDDB library symbolic link, if it exists. These are usually named libcddb.so.1 and libcddb.so, installed in the /usr/lib or /usr/local/lib directory on your system (on HP-UX, the file is libcddb.sl).