README for MPEG decoder for 68k/ColdFireRevision history:21-oct-1999: First release with ColdFire support, and under GPL. (Rob Scott)Backround:After searching the net for a MP3 decoder that wasn't too big, didn't requirea pentium, and that I could make sense of, I discovered that St閜hane TAVENARDhad written a 68K based decoder. I was able to convince him that releasingthe code under GPL would be a good thing, and started porting it to ColdFire.The port wasn't too difficult, mostly dealing with the executable sizelimitations of the binfmt loader, and elminating the use of floating pointfor table initialization.Thanks to St閜hane for making this possible!Building:The makefiles are currently set up to build with the uClinux ColdFire toolchain. Edit make.common to change the location of the toolchain. Go tompegdec_lib, perform a make, then go to mpegdec_demo and do another make.This will result in a coldfire executable. If you wish to build an x86version, comment out the ColdFire define the two directories' Makefiles,and do a "make clean && make" in both directories. Running:Currently, I copy the mpegdec_demo to the romfs/bin area, and do a make inthe uClinux directory, to have it included in the boot image. Then I useNFS to mount a directory that has the MP3 files.Performance:I haven't done accurate timing, but on a 54 MHz 5206e processor, it seemsthat decode is about .5 realtime. On a 90 MHz 5307 processor, it seemsclose to real time. I lack audio output hardware to actually hear the results.Caveats:Currently, the mpegdec_demo reads in a fixed amount of data and decodes it.It needs to be changed to continuously fill the mpeg data buffer, as thedecoder empties it.Todo list:Changing mpegdec_demo to continuously stream data.Translate the existing 68K assembly language routines to ColdFire, in thehope that decoding will get to real time on the 5206e.