(old)Puppy Linux Discussion Forum

technosaurus wrote:If you have a link to a mp3 that won't play, post it ... I'm really sick of /usr/share/audio/ivy.mp3 anyhow. I'm still planning to add id3 tag support (you can try using the id tag stripper from a few posts back ... which is where I will ultimately get the code from)

... you may be right about the sound; while reviewing the code I noticed some things that were "iffy"

the original author of minimp3 on this thread also wrote a mp2 player ... parts of which were released to the public domain... I'm not sure about layer 1 though... not sure if I have ever seen it.

Audio file with ID3 version 2.3.0, contains: MPEG ADTS, layer III, v1, 128 kbps, 44.1 kHz, JntStereo

Ibidem wrote:Having downloaded those recordings a while ago, I tried it out.
Results:
-Same errors when played without modification
-id3 and id3tool don't recognize the id3 tags, but id3v2 can remove them.
-mp3dec_opt plays the result nicely, at ~25% CPU on my 1.6GHz Atom N270.
-mp3dec plays the result, but runs ~66% CPU.
I'll try out the id3 tag stripper referred to.

UPDATE:
Yup, the id3 tag stripper works (meaning it removes enough); <unistd.h> should be added, though.
It does point out an issue with the PDMP3 code:
the API and code almost seem like they were designed to prevent use with pipes.
- rather than passing a file handle / descriptor, you copy a name to the global

Code: Select all

char filename[256]

(256 is the max length for a file name...without a path!).
- it apparently checks if it has hit the end of the file, via ftell(), rather than whether reading has failed; if ftell() fails, it is treated as an EOF.
- the overuse of globals results in the relevant code being rather well hidden.

technosaurus wrote: I am working on those ... as to resource usage, I added lookup tables for the IMDCT cos function which can be enabled with the CFLAG -DIMDCT_NTABLES ... that reduces CPU usage to ~15% after initialization.
Also need to set up a separate initialization function.

Edit:
I have updated https://github.com/technosaurus/PDMP3 with my current code and added a todo list in the readme.md ... For further issues, please add an issue via github.

Ibidem wrote:Thanks for the IDMCT bit!
You have a new pull request on github.

Each sample counts as 0.01 seconds.
  %   cumulative   self              self     total           
 time   seconds   seconds    calls  us/call  us/call  name    
 56.82      0.25     0.25                             L3_Subband_Synthesis
 27.27      0.37     0.12                             L3_Reorder
  6.82      0.40     0.03   437169     0.07     0.07  __do_global_dtors_aux
  4.55      0.42     0.02   181361     0.11     0.11  Read_Header
  2.27      0.43     0.01    78785     0.13     0.13  Get_Bytes
  2.27      0.44     0.01                             Get_Side_Bits
  0.00      0.44     0.00   167430     0.00     0.00  Get_Main_Pos
  0.00      0.44     0.00     9734     0.00     0.00  frame_dummy
  0.00      0.44     0.00     2629     0.00     0.00  Requantize_Pow_43
  0.00      0.44     0.00     1859     0.00     2.29  Read_Audio_L3

technosaurus wrote:I reworked Krister Lagerstrom's public domain code a bit... my modifications are also public domain... work is still in progress adding the optimizations in as compile time options, but the big ones are there, (however if you want to add more optimizations, see https://github.com/technosaurus/PDMP3)

You can use this in any project, commercial or otherwise without attribution (I'm still working on making this part easy though - patches welcome)