******************** * FalcAMP v1.08 * ******************** > Plugin: Icecast and Shoutcast < Version: 1.08c Released: 24/06/2001 Audio MPEG Layer 3 player for Atari Falcon 030 computers By Denis "STGhost" HUGUET and David "Splash" CARRERE ----------- ˝Sector One 1998-2001 Sector One is proud to present this new plugin for our MP3 player for Atari Falcon 030 computers. Table Of Contents: I / What are Shoutcast and Icecast ? II / System requirements III/ The player IV / Features V / Known bugs and limits of this version VI / What's new in this version ? VII/ Contact authors I/ What are Shoutcast and Icecast ? ----------------------------------- These are 2 methods of broadcasting audio data in MP3 format. These 2 kinds of servers provides a kind of internet radio service ;) MP3 has become one of the most used audio format in the world. As it has been developped especially to obtain a rather good quality at low bitrates, it perfectly fits this radio broadcasting system. You can find more infos on http://www.shoutcast.com and http://www.icecast.org (you'll also find URLs of stations on these sites). II/ System requirements ----------------------- This plugins needs: - a Falcon 030 - 2.4 megabytes of free ram - a STIK compatible internet stack - an internet connection Optionnal but recommended: - accelerated Falcon (CT1, CT2, Nemesis an Afterburner are known to work) - external audio clock (CD, DAT or dual) - using plip or ethernet instead of a serial-port modem III/ The player -------------- Well, we spent again alot of time on this main plugin. This plugin will allow you to play broadcasted MP3 datas: -only layer 3 is supported -MPEG 1, MPEG 2 and MPEG 2.5 streams are supported -Mono, Stereo and Dual-channel files are accepted, not Joint-Stereo. (Joint-Stereo files will be played as mono automatically) -your connection is fast enough for the incoming flow of the server. -sent datas are not severly damaged (simple error-recovery built-in) If the file is recognized, the player will prepare the replay according to the commands from the interface. The decoder is partly interrupt based, so it should run rather well under any environment. But, remember that it will use a lot of available CPU time on high quality streams. Because of the internet structure, the plugins has to buffer incoming datas to cope with delayed stream packets. This will cause long init and stop delays when using this plugin. It will take more memory. We had to use a non-interrupted 030 decoder that prepares a queue of half-decoded blocks for the DSP. This will cause a delay in the volume change control linked to that queue (blocks with new volume won't reach DSP immediately). We'll try to modify this behaviour by moving the volume control on DSP side for next release. Please keep in mind that any GEM action will prevent the plugin kernel to be called, what will quickly dry up the queue ! Please keep in mind that both processors, even though they're working in parallel, need to synchronize so if you have not a correct replay (noises into the sound most of the time, and slowed tempo) it means that one of the processor is too slow...either you're doing too much things in parallel on the 030 side or the dsp is simply too slow (should only happen if you don't use an audio clock on a standard Falcon for playing an MPEG 1 stream at 44Khz or 48kHz). However, if you want to high quality MP3 streams on a standard Falcon, you should avoid big screen resolution because this may cause some slowdown of the replay. This should be very important if you have a VGA screen on your Falcon. You can either keep a large screen by shrinking the number of colours or use a small screen with a lot of colours... IV/ Features ------------- Basically, the DSP decoder is identical to the MP3 plugin. Only the interrupt system has been organized differently... Here's a summary of the features supported: -External audio clocks automatically detected and used (dual clocks and FDI recognized too) (contact us if some clock isn't well recognized) -Linear sample interpolation to convert MPEG replay frequency to Falcon audio frequency. Useful only if you have not an external clock. -Fake ID3 tag v1.0 generated on the fly according to server's informations -Displays details about the stream format in the file info window (along with the fake ID3 tag). These infos are based on the first received frame, but it supports format-changes on the fly (except for frequency) -Variable bitrate supported (but I've not seen a station that uses it yet) -CPU speed boards accepted and recommended (especially if you don't have any external audio clock and you want to play 44.1kHz or 48kHz stereo files). -Severe error recovery: to cope with possible sync errors with the stream, a very severe sync system has been used to avoid detection of a wrong stream format. It should handle small structural errors by resynchronizing quickly (just like the MP3 plugin) with a glitch limitation system. - DSP timeout has been lowered so that a DSP crash can be detected faster. The delay should be 4 seconds before a timeout warning to the gem interface - Preliminary joint-stereo computations added on 030 side, it will reduce the load of the DSP part for this kind of file. But no JS replay yet ! - The player computes the minimum number of IMDCT required to replay the file with the best accuracy. This allows the DSP decoder to work faster with Stereo files (up to 7% faster). This is helpful for a 32Mhz DSP and hardly slows down the 030 side. - Completely new requantizing method used giving a better accuracy !!! - Half interrupted decoders, be aware of not doing too many blocking GEM actions... else the stream will have to be resynchronized - Displays the filling of the half-decoded block queue in the position slider - Delayed volume control (CPU side) - You can make FalcAMP directly called by CAB for shoutcast & icecast stations. Just go to 'External Programs' in CAB and associates *.M3U,PLS to FalcAMP and check the VA_START box. Don't forget to select the path to FalcAMP and to save your settings. This is only useful in multitasking environment of course. - No serial trouble as with MP3 plugin (hopefully :) V/ Known bugs and limits of this version ----------------------------------------- - There may still be some DSP timeouts or unexpected troubles... - If you're getting alot of datas from serial port, this may cause some slowdowns in the decoder... That was the only way of avoiding the corruption of all incoming datas that occured in previous version. - 1-level http redirection supported (a '302 Moved Temporarily' reply) - If you try to listen a stream with a too high bitrate, you may get transfer trouble. Here's a simple rule to be sure your connection is fast enough: connection_speed * 8 /10 = maximum_possible_bitrate for a 33600 bauds modem, you have a maximum mp3 bitrate of 26880 bps (which rounds up to 24 kbps as closest value). As mp3 is an already compressed format, modem compression doesn't help much ! - Joint-stereo encoding scheme is not yet available but should come soon. Everything in the code is ready for it but because of some other bugs, we had no time to finish that. These files will be played in mono for now... - We did our best to make this player works with 16Mhz 030/32Mhz DSP. Most of the time, the file will be replayed correctly, even if it could use most of the available time of your Falcon. But problems are possible sometimes with 44kHz and 48Khz stereo MP3 files, resulting in a kind of echo effect or adding noisy clicks. If you have a 50Mhz 030/50Mhz DSP, you should never have this kind of problem ! Anyway, to let standard Falcons users listen to all MP3, we added a special "Standard Falcon" mode, which will output Joint stereo and Stereo files as if they were mono. A 32Mhz DSP has then enough time to process the file at correct rate. This special mode is activated using the "Force Mono output" setup of the GEM interface. The DSP decoder has become very fast and should be able to handle most stations. No test has been done with high bitrate stations ! -=> Bug reports <=- We tried to make this software system friendly, and to prevent any unexpected freezing of your computer. But, please, keep in mind that we cannot guarantee a complete reliability. You have been warned ! For bug reports, please send an email to STGHOST or SPLASH, using more or less the following model. See Contact section for our email addresses. Try to fill it with maximum accuracy. FAMP's standard bug report: ~~~~~~~~~~~~~~~~~~~~~~~~~~~ a- Executable files and configuration My FalcAMP GEM version is the: _____, CAST.PLG version is: _____ and plugin filesize is ______ bytes. (check plugin infos in GEM interface to get plugin version) Hardware configuration of your Falcon: model, memory, and additional hardware (clocks, faster CPU/FPU/DSP, enhanced sound system, ...). Software configuration of your Falcon (when you found FAMP's bug, else the most frequently used): TOS version, additonal OS, inet stack, connection speed... b- station A bug occured with this URL : ... Stream's bitrate is: ___ kbps Displayed infos are: ... Kind of error: -> FalcAMP give me the following error message: -> FalcAMP is blocked/crashed -> The sound is not correct. -> ... Here is a short description of what occured. VI/ What's new in this version ? -------------------------------- Here are the changes made since 1st release of this FalcAMP CAST plugin: - Added a faster protocol initiator - Now supports more stations (esp. live365 ones) - Can handle stations that don't provide bitrate - Updated dsp engine to same version as mp3 plugin - Fixed the station change freeze-bug - some instability possibly added in case of stream loss :/ VII/ Contact authors -------------------- Who did what in this plugin: STGHOST (030 part) deunstg@free.fr Inet code, tag update, stream bufferings, scalefactor decoding, fast Huffman decoding, clock detection, IMDCT estimation, joint-stereo precomputing, error recovery and many weeks of debugging... SPLASH (DSP part) dcarrere@worldnet.fr Sound system init, MFI system, DMA-DSP transfer, new requantisation, antialiasing butterflies, IMDCT, polyphase filerbank, linear interpolation, and many more weeks of debugging... This is a 100% assembler product, based on AMP 0.71, AMP 0.76, MPEGA and ISO MPEG sourcecodes, that we completely changed, improved, and optimized for the Falcon 030. We'd like to thank: -Tomislav Uzelac for spreading his sources of AMP -Stephane Tavenard for giving us his sources of MPEGA -Dan Ackerman for his help on inet coding and for stik2 ! -All people who supported and helped us to remove bugs -All people who believed in us... We decided to spread this software as a freeware. We did it for the fun, and also because we were dying to listen MP3 radios on our Falcon ! Also, maybe we did it because people used to say that it would be probably impossible to do, and we were convinced that it was possible. Anyway, because of the huge work we put into this player, we're expecting -at least- some support and aknowledgements, and -at most- some money if you think it's worth the price. If you use FalcAMP often, please, do not forget us... It may speed-up the release of next version ! :-) Have fun !