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Michael Giacomelli 6ffbee954b wmapro: fix the level and accuracy of 16 bit streams 
A WMA Professional stream of 16 bits per sample played about 48 dB
too quiet and with a noise floor near -70 dBFS.

ffmpeg scales the transform's output by the stream's sample size.
That was dropped when the decoder was converted to fixed point
(d884af2b99, 16284ae8ae), and the output is passed to the DSP as if
every stream had 24 bits. A stream of fewer bits has a lower
quantization step to match, so it came out low by the difference,
and it used the bottom of the integer quantization table, where the
factors have only a few significant bits.

Decode a 16 or 20 bit stream at the level of a 24 bit stream: use
that stream's quantization step, and scale each band's factor by
the ratio that is left. 24 bit streams are not affected.

Checked with perfsim (Sansa e200v1 build) against ffmpeg's decode
of a 16 bit, 192 kbps stereo file, the only such file to hand:

            level      SNR vs ffmpeg   noise
  before    -48 dB     37 dB           -70 dBFS
  after     correct    85 dB           -117 dBFS

A 24 bit file's output is byte-identical before and after. The
20 bit case follows the same rule but is untested.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-05 20:13:48 -04:00
android chore: Get rid of *all* vestigal CVS '$Id:$' tags 2026-06-01 16:01:18 -04:00
apps test_codec: keep the log if the plugin is left early 2026-10-05 11:20:17 -04:00
backdrops ap80max: New hosted port 2026-08-13 17:55:06 -07:00
bootloader Support ROCKBOX_DIR in HibyOS hosted bootloader 2026-10-05 19:42:58 -04:00
docs docs: Fix case of "iPod" in area name and history 2026-10-01 17:32:24 -04:00
firmware YP-CP3: make the WM8750 the I2S master 2026-10-05 22:35:12 +02:00
fonts chore: Get rid of *all* vestigal CVS '$Id:$' tags 2026-06-01 16:01:18 -04:00
icons chore: Get rid of *all* vestigal CVS '$Id:$' tags 2026-06-01 16:01:18 -04:00
lib wmapro: fix the level and accuracy of 16 bit streams 2026-10-05 20:13:48 -04:00
manual manual: Fix case of "iPod" 2026-09-30 07:58:19 -04:00
packaging 3ds: Port refactor. 2026-09-01 08:39:07 -04:00
tools makezip: Don't install classic_statusbar.rsbs on targets without remotes 2026-10-05 14:10:57 -04:00
uisimulator YP-CP3: simulator 2026-10-02 16:42:34 +02:00
utils Fix case of "iPod" in docs and CLI tools help 2026-10-01 17:32:24 -04:00
wps cabbiev2: Don't generate certain entries for monochrome devices 2026-10-05 14:11:34 -04:00
.gitattributes Add a gitattributes file for the migration. 2011-12-01 14:14:59 +00:00
.gitignore misc: Update gitignore to cover a bunch of utils/* binaries 2026-06-17 13:56:29 -04:00
.gitreview misc: Add a .gitreview file for better gerrit integration 2021-06-24 07:22:19 -04:00

docs/README 

               __________               __   ___.
     Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
     Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
     Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
     Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
                       \/            \/     \/    \/            \/

Build Your Own Rockbox

1. Clone 'rockbox' from git (or extract a downloaded archive).

   $ git clone git://git.rockbox.org/rockbox

     or

   $ tar xJf rockbox.tar.xz

2. Create a build directory, preferably in the same directory as the firmware/
   and apps/ directories. This is where all generated files will be written.

   $ cd rockbox
   $ mkdir build
   $ cd build

3. Make sure you have mips/m68k/arm-elf-gcc and siblings in the PATH. Make sure
   that you have 'perl' in your PATH too. Your gcc cross compiler needs to be
   a particular version depending on what player you are compiling for. These
   can be generated using the rockboxdev.sh script in the /tools/ folder of the
   source.

   $ which arm-elf-eabi-gcc
   $ which perl

4. In your build directory, run the 'tools/configure' script and enter what
   target you want to build for and if you want a debug version or not (and a
   few more questions). It'll prompt you. The debug version is for making a
   gdb version out of it. It is only useful if you run gdb towards your target
   Archos.

   $ ../tools/configure

5. *ploink*. Now you have got a Makefile generated for you.

6. Run 'make' and soon the necessary pieces from the firmware and the apps
   directories have been compiled, linked and scrambled for you.

   $ make
   $ make zip

7. unzip the rockbox.zip on your music player, reboot it and
   *smile*.

If you want to build for more than one target, just create several build
directories and create a setup for each target:

   $ mkdir build-fuzeplus
   $ cd build-fuzeplus
   $ ../tools/configure

   $ mkdir build-xduoox3
   $ cd build-xduoox3
   $ ../tools/configure

Questions anyone? Ask on the mailing list or on IRC. We'll be happy to help you!