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authorwiz <wiz@pkgsrc.org>1999-12-25 22:34:00 +0000
committerwiz <wiz@pkgsrc.org>1999-12-25 22:34:00 +0000
commitfeac0bcd3bcf74682fcbeacf8f4168fb3a20804f (patch)
treeeaf96fec270badf45e11710b84321ec3d9b737f5 /audio/maplay
parent455a75b809fef238340ae8241b1c32a1eceef443 (diff)
downloadpkgsrc-feac0bcd3bcf74682fcbeacf8f4168fb3a20804f.tar.gz
shortened description to the relevant part
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diff --git a/audio/maplay/pkg/DESCR b/audio/maplay/pkg/DESCR
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-/*
- * @(#) MPEG Audio Player maplay 1.2, last edit of this file: 6/23/94 13:02:49
- * @(#) Copyright (C) 1993, 1994 Tobias Bading (bading@cs.tu-berlin.de)
- * @(#) Berlin University of Technology
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- */
-
-
-This is the README file of the MPEG Audio Player maplay, Version 1.2.
-Besides this file, you should now own a copy of the following files:
-
- ANNOUNCEMENT the announcement for this release
- INSTALL infos about compiling and installing the program
- COPYING the GNU General Public License
- Makefile a makefile
- configuration.sh a shell script used by the makefile
-
-and the source files
-
- all.h maplay.cc subband_layer_1.h
- crc.cc obuffer.cc subband_layer_2.cc
- crc.h obuffer.h subband_layer_2.h
- header.cc scalefactors.cc synthesis_filter.cc
- header.h scalefactors.h synthesis_filter.h
- ibitstream.cc subband.h ulaw.cc
- ibitstream.h subband_layer_1.cc ulaw.h
-
--------------------------------------------------------------------------------
-
-0) Introduction
-
-MPEG is a standard created by the ISO (International Organization for
-Standardization) and the IEC (International Electrotechnical Commission).
-The full name of this standard is "ISO/IEC DIS 11172: Information
-Technology - Coding of moving pictures and associated audio for digital
-storage media ut to about 1.5 Mbit/s". As the name already states,
-it deals with digital video and audio. The video part of this standard has
-inspired many people to write decoders and a few encoders for it.
-Best known should be the Berkeley player. Players for the audio part on
-the other hand are very rare. The ones I know are the XING player for Windoze
-and a sample implementation of the ISO, which also includes an encoder.
-
-The audio part of the MPEG standard specifies three layers, whereat each
-layer specifies its own file format. All three layers are using similar
-audio coding techniques, but they vary in efficiency and complexity.
-Layer I needs the fewest calculation time for en-/decoding a stream, layer III
-the most. But a layer I MPEG audio stream is bigger than a layer III stream
-at the same quality. This program is able to decode and play only layer I
-and II streams, layer III is not supported (yet?!?).
-
-Like the MPEG video standard, the audio part also uses a lossy compression
-algorithm, which means that you can't get back 100% the original from a
-MPEG audio stream. Layer II MPEG audio streams are compressed by ratios
-from 1:3 up to 1:24 compared to raw PCM data, like on an audio CD.
-But the quality is still very (very) near to the original at ratios between
-1:5 and 1:12. You'll love it... :-)
-
--------------------------------------------------------------------------------
-
-1) What does maplay?
-
-maplay version 1.2 is the second release of my MPEG audio player/decoder.
-It decodes layer I and layer II MPEG audio streams and plays them
-using a CD-quality audio device. Currently supported devices are the
-dbri device of SPARC 10 computers and the audio ports of Silicon
-Graphics Indigo machines. Thanks to Louis P. Kruger (lpkruger@phoenix.
-Princeton.EDU), maplay 1.2 can also use the /dev/dsp device under Linux.
-Louis has tested it with the Pro Audio Spectrum 16 soundcard. Sound Blaster 16
-and Gravis Ultrasound cards should also work, but a bug in the dsp driver
-prevents stereo playback on Gravis Ultrasound cards. An amd device of a
-SPARC 2/IPX/... machine can be used, too, but this device is only capable of
-producing audio output at 8 kHz in u-law format, which sounds like transmitted
-through a telephone. Other audio device are not supported directly, but can be
-used with the "decode to stdout" option and an audio format converter.
-Besides it shouldn't be a problem to adapt the program to other audio devices.
-
-The player supports all modes, which are single channel, stereo,
-joint stereo and dual channel, and all bitrates except free mode.
-The missing free mode support should not be a problem for now,
-because I haven't seen such a stream yet.
-
-maplay needs approximately 46% CPU time on SPARC 10/40 machines and 50%
-on Indigos for realtime stereo playback of a 44.1 kHz 128 kbit/s stream.
-Single channel playback needs about the half CPU time. On a SPARCstation IPX,
-maplay needs about 43% CPU time for realtime mono playback. Stereo playback
-is not possible via an amd device.
-
-Besides realtime playing of audio streams, maplay can decode streams to
-stdout for further conversions. The output consists of 16 bit signed PCM
-values. For stereo streams, the values are interleaved, which means that
-a value for the left channel is followed by a value for the right channel
-and so on. If maplay has been compiled for u-law output, the output consists
-of 8 bit u-law samples at a rate of 8 kHz, no matter what frequency the stream
-uses.
-
--------------------------------------------------------------------------------
-
-2) How to create a maplay binary?
-
-Please read the install file for this topic.
-
--------------------------------------------------------------------------------
-
-3) How to start the program?
-
-For a quick mono test enter "./maplay -v -l filename", where filename is the
-name of an audio stream, like "things.mp2". This stream has been posted along
-with the sources and is the beginning of Roxette's song "Things Will Never Be
-The Same". It is coded in joint stereo mode with 128 kbit/s, which is a
-compression ratio of 1:11. If the output is ok, you can test stereo playback
-by leaving out the -l option. If the stereo output stutters, the problem is
-not enough free CPU time in most cases. Stereo output is not possible when
-using an amd u-law device. If maplay shows error messages like
-"ioctl AUDIO_GETDEV on /dev/audio: ..."
-and maplay was compiled for u-law output, please try out the -amd option.
-This option forces maplay to treat /dev/audio as an amd device and may be
-required on SPARC clones.
-
-To convert a MPEG audio stream into other audio formats, you can use
-"maplay -v -s filename | your_converter". Unfortunately, I can't be of much
-help for you to find such a converter. The only good converter I know is the
-"soundfiler" on Indigos. But if you would have an Indigo, you wouldn't need a
-converter...
-
--------------------------------------------------------------------------------
-
-4) Command line options
-
-maplay [-v] [-s] [-l] [-r] [-us] [-uh] [-ul] [-amd] [-c] [-f ushort] filename
-
-with these options:
- filename filename of a MPEG audio stream or - for stdin
- -h short help
- -v verbose mode
- You will get information about the stream, like mode, bitrate,
- copyright etc., if you use this option.
- -s stdout mode
- This option tells the program to decode the stream to stdout.
- The created output contains 16 bit signed PCM samples. If the
- binary has been compiled for 8 kHz u-law format usage, the
- output consists of 8 bit u-law samples at a 8 kHz rate. If the
- stream is in stereo mode, the samples of both channels are
- interleaved, the sample for the left channel first.
- -l maplay decodes (and plays) the left channel of stereo streams
- only. This option halves the required CPU time.
- -r Same as above, but decodes the right channel only
- -us, -uh These options are available on SPARCstations only.
- They specify where the audio signal should be send to:
- "-us" means speaker and "-uh" headphone jack.
- -ul This option is available on machines with the dbri device
- and sends the audio output to the line out jack.
- -amd This option forces maplay to treat /dev/audio as an amd
- device. Use it if your SPARC clone has an amd device, but
- maplay doesn't recognize it. You may also use this option on a
- machine with a dbri device, because the dbri device can also
- produce u-law output. But I suggest to recompile the program
- without the ULAW define in this case to get the CD-quality
- output.
- -c This option instructs the program to report filter range
- violations to stderr. Sometimes PCM values calculated by
- the synthesis filter exceede the 16 bit boundary and must
- be mapped to these boundaries. If you can hear this, you
- may use the next option.
- -f ushort maplay uses this scalefactor instead of the default value 32768
- for the synthesis filter. You can reduce or eliminate range
- violations with this option, but lower scalefactor values
- reduce the signal-to-noise ratio, too. I can't remember when
- I used this option the last time myself.
-
-
-Ok, that's all for now and this release,
-I hope you like it,
- Tobias Bading (bading@cs.tu-berlin.de)
+maplay version 1.2 is the second release of my MPEG audio
+player/decoder. It decodes layer I and layer II MPEG audio streams
+and plays them using a CD-quality audio device.
+
+The player supports all modes, which are single channel, stereo, joint
+stereo and dual channel, and all bitrates except free mode. The
+missing free mode support should not be a problem for now, because I
+haven't seen such a stream yet.
+
+Besides realtime playing of audio streams, maplay can decode streams
+to stdout for further conversions. The output consists of 16 bit
+signed PCM values. For stereo streams, the values are interleaved,
+which means that a value for the left channel is followed by a value
+for the right channel and so on. If maplay has been compiled for u-law
+output, the output consists of 8 bit u-law samples at a rate of 8 kHz,
+no matter what frequency the stream uses.