i7remux -- video converter for COWON iAUDIO 7 (and other products)

***WARNING***
USE THIS SOFTWARE COMPLETELY AT YOUR OWN RISK. ALTHOUGH I MADE EVERY EFFORT
TO MAKE THIS SOFTWARE USEFUL, IT POTENTIALLY CAUSES SERIOUS DAMAGE TO YOUR
MP3 PLAYERS. THIS SOFTWARE IS PROVIDED AS IS WITHOUT ANY WARRANTIES.

1. What is i7remux?

I7remux is a video converter for COWON iAUDIO 7. While it was developed for
iAUDIO 7, it may be used for other COWON's products with video playback such
as iAUDIO U3. In fact, i7remux is greatly inspired by MaxSt's work, U3Video,
which is a similar tool for iAUDIO U3.

Note that i7remux is NOT a real video converter. Rather, i7remux is a tool to
tweak AVI files which other prevailing video converters made, and playback
them on iAUDIO 7. The current goal is to fix some subtle problems in the AVI
files created by FFmpeg and MEncoder for iAUDIO 7.


2. What are "problems" in AVI files?

Basically, iAUDIO 7 playbacks very usual AVI files (Xvid video and MP3 audio).
Although there are some restrictions on fps or bitrates, it is an easy task to
convert other video formats into such an AVI format using video converters
you can find on the Internet. However, video files they produce are usually
NOT playable on iAUDIO 7 or other COWON's products. In other words, there are
some more "restrictions" in AVI files their products can correctly playback.
I7remux tries fix or relieve such restrictions.


3. Why not jetAudio?

JetAudio is a relatively large and comprehensive audio utility provided by
COWON and has ability to produce iAUDIO 7 compatible video files. It nicely
works, however, there are some unfavorable shortcomings; (1) JetAudio has
fewer adjustable parameters in its video conversion. (2) JetAudio puts small
"COWON" logo in the beginning of its video output. (3) JetAudio creates
video files which make unpleasant random noise on playback. (4) JetAudio ex-
clusively runs in Windows. All of them are never preferable "features" to me.


4. System Requirements

I7remux is a tool for Unix-like environment. And, today's average UNIX systems
mush have sufficient tools to compile i7remux. I guess many of you want to use
it on your Windows, but unfortunately I do not have enough resources to prepare
Windows version. If you port this to Windows or even other operation systems,
please contact me. I will merge your efforts into my source code.


5. Install

I7remux is a usual free software. I hope everything works fine.

  $ ./configure
  $ make
  $ su
  # make install


6. Usage

First of all, you have to prepare a sophisticated video converter and make
AVI files which roughly satisfies iAUDIO 7. Even though, as I mentioned above,
I wrote i7remux using FFmpeg and MEncoder, i7remux should be able to treat
with any output of other converters. If you have tried, send me the results.
Your tries will uncover many hidden bugs in i7remux :-)

6.1 Step 1: Create initial AVI files

In the user's manual, you can find that iAUDIO 7 requires AVI video files to
be encoded in the following setting.

  Video: Xvid 1-pass, 256-384kbps, 160x128, 15 fps
  Audio: MP3 128kbps CBR

The sample configuration below will satisfy the requirements and I am actually
using them with those options.

  FFmpeg:
  $ ffmpeg -i <input> -f avi -g 1 -b 256k -r 12 -s 160x128 -vtag XVID \
    -vcodec libxvid -ab 128k -ar 44100 -ac 2 -acodec libmp3lame <output>

  MEncoder:
  $ mencoder -ofps 12 -vf scale=160:128 -ovc xvid -xvidencopts \
    bitrate=384:max_bframes=0:max_key_interval=1 \
    -oac mp3lame -lameopts cbr:preset=128 -of avi -o <output> <input>

6.2 Step 2: Remux AVI for iAUDIO 7

Once you have gotten an AVI file using video converters such as FFmpeg and
MEncoder, i7remux dose the final work for you. Note that input files to
i7remux were originally output files from the above video converters.

  $ i7remux <input> <output>

There are some options available. You can list them as usual. The -x option
may be relevant to the noise problem I mentioned above. JetAudio splits
a frame of MP3 stream at arbitrary position to store them in AVI chunks.
I suspect that such discontinuous frames increase the processor load of iAUDIO
and make random noise while decoding MP3 stream. In default, i7remux saves
boundary of MP3 frames. But, the -x option simulates jetAudio if you like.

  $ i7remux -h
  usage: i7remux [-dhvxyV] [[-i] <input avi>] [[-o] <output avi>]
    -d   dry run (read input, but do not actually write output)
    -v   verbose (useful with -d to parse and verify input)
    -x   ignore MP3 frame boundary (simulate jetAudio; NOT recommended)
    -y   overwrite output
    -h   print this message
    -V   print version


7. Copyright

This software is provided under so-called "as is" condition. You can do
anything you like with this software as long as you follow GNU Public License
version 2. I avoided the newer version of GPL intentionally, but you are
allowed to apply version 3 (or any later version) to your products derived
from this software. See the COPYING file included in the source package.


8. Link

U3 Video Converter (simple, drag-and-drop)
http://www.iaudiophile.net/forums/showthread.php?t=12808

FFmpeg
http://ffmpeg.mplayerhq.hu/

MPlayer and MEncoder
http://www.mplayerhq.hu/design7/news.html