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Subject: Re: Video plugin and tools problems/limitations
From: Jens Arnold (arnold-j_at_t-online.de)
Date: 2004-02-17


Hello [IDC]Dragon

On 17.02.2004, you wrote:

> BTW, what's the battery life with video, since you seem to do
> long runs? I haven't tried, and for 8MB it's much longer.

I didn't do a full battery run-down with video only but I expect
around 4 to 5 hours (estimated from the battery level after
watching ~2.5 h continuously). I use Recorder V1 20 GB with
stock 1500 mAh cells.

I could conduct a test here, but I'd like to have 2 things for
it:

- Question: Is it possible to set the "repeat" flag in the RVFh
  for long videos that do not fit into the buffer completely and
  the plugin repeats the whole video over and over? (I would do
  this with a hex editor then.)

- Perhaps on the 2 MB recorder it is better to not spin down the
  disk between reads. Could you prepare a modified plugin to
  test this?

>> Problems with the tools and the video conversion path:

>> - "AVItoYUV" does not read AVIs >= 2 GB (about 1:06h at ...

> This tool is from Microsoft. I don't have the sourcecode for
> it.

Ok. I supposed this.

>> - "Halftone" does not read YUVs >= 2 GB (about 2:12h at ...

> I think this can be changed to 4 GB, have to look into it.

It should be possible to read even >4 GB on windows if you use
NTFS. Don't know about linux here.

>> - "RVF_MUX" has problems multiplexing the video with audio
>> that uses MPEG2 or MPEG2.5 sample rates ...

> MPEG2 should work. I have not implemented the 2.5 audio
> formats, but this can be easily changed.

MPEG2 definitely doesn't work most of the time. I did the
following thorough tests:

I have prepared the same sound file (1 minute) with different
sample rates (48000-44100-32000-24000-22050-16000-12000-11025
-8000) with Audacity. All files are 16 bit stereo. The files
were compressed with LAME 3.95.1 on windows. VBR files done
with "--preset medium", CBR with "--preset cbr <bitrate>". I
couldn't test 8000 Hz because LAME has a bug.

Here are the results:

Freq | MP3 mode | results
--------------------------------------
24000 | VBR | 318x ASE, FG, LB
24000 | CBR 96k | works!
22050 | VBR | 155x ASE, F0, hangs
22050 | CBR 96k | 158x ASE, FG, AL
16000 | VBR | 221x ASE, FG, AL
16000 | CBR 64k | works!
12000 | VBR | 1x ASE, FG, VU
12000 | CBR 48k | 4x ASE, FG, VU
11025 | VBR | F0, hangs
11025 | CBR 48k | 3x ASE, F0, hangs

(ASE = "Audi sync error in file..."
 FG = result file was generated
 F0 = result file has zero bytes
hangs = you have to press ctrl-c

 LB = loops back on playback
 AL = audio runs significantly longer than video
 VU = lots of video underruns and stuttering audio)

I could send you my test files (10 MP3's and one RVF) by mail,
but these are 8.77 MB in total.

>> Problems with the video.rock:

>> The plugin resets ALL audio settings EXCEPT volume to their
>> defaults (on the chip, but not in the firmware!) (that ...

> Strange, I only set the volume, because it can be muted when
> the plugin starts. The others I don't touch. ...

But it definitely does reset these. I tested this with really
strange setting, e. g. set balance all to the left - as soon as
you start playing a video, it's back to the center and stays
there after it, but when you enter sound settings, it still shows
"all left"! Perhaps this related to another glitch in the
plugin - there are two rather loud "pops" at the start of any
video with audio. Do you somehow reset the MAS?

> I try. I'm (slowly) working on a one-click tool to convert AVI
> and MPEG. This will be Windows-only, since it uses the
> DirectShow infrastructure. halftone and rvf_mux are portable.

Don't know if a one-click tool makes much sense since there are
many special things in the conversion process which require
manual correction (e. g. I do rigorous clipping of widescreen
films because the display is so small, encode audio with
different settings with lame etc). Most appreciated would be a
tool (could be a portable command line tool too) that

- does all steps of AVItoYUV, Halftone and Rvf_mux at once, i. e.
  takes a properly scaled AVI (112x64 RGB24, perhaps also
  YUV/YV2) and an MP2/MP3 and spits out the already multiplexed
  RVF.

- can read AVI >2 GB and even >4 GB on NTFS

This way you don't even need to create the intermediate AVI
physically - have a look at "AVIsynth" (http://www.avisynth.org).
This is also open source!

Regards, Jens

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