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Subject: Re: Noticable Pop Between Tracks (Sansa)

Re: Noticable Pop Between Tracks (Sansa)

From: R.L. Horn <lists_at_eastcheap.org>
Date: Tue, 17 Feb 2009 01:40:13 -0600 (CST)

Michael Sevakis <jethead71_at_sbcglobal.net> wrote:

> I do recall a bug when I first started using rockbox that seems to gone
> now where I would get a small glitch between contiguous tracks. It was
> Frank Zappa (who tends to do alot of gapless tracks), not classical but
> still quite audible.

Ah, the golden age of epic albums.

> I have sinewave test tracks that stitch together seamlessly but it's been
> awhile.

Once I had some free time, I was able to do some real testing (hopefully,
this will be specific enough to keep even Paul happy).

First, I did a from-scratch (i.e. rm -rf .rockbox) install of r20029 from
build.rockbox.org on one of my C240s.

I generated a ten-second 440Hz tone, cut it in half, and added wav
headers:

   sox -n -c2 -r44100 -2 -s test.raw synth 10 sine 440 vol -6dB
   dd if=test.raw of=test1.raw bs=882000 count=1
   dd if=test.raw of=test2.raw bs=882000 skip=1
   sox -c2 -r44100 -2 -s test1.raw test1.wav
   sox -c2 -r44100 -2 -s test2.raw test2.wav

The PCM files were then encoded using:

   bladeenc -256 -nogap test[12].wav
   lame --nogap test[12].wav
   oggenc test[12].wav
   flac test[12].wav

Once I'd verified that the mp3 streams were truly gapless (I just catted
them together and had a listen), I copied everything to the player and
played them with the following results:

   wav, flac: Seamless, as expected.
   vorbis: Ditto.

   mp3 (both lame and bladeenc): Not so good. An obvious hiccough between
   tracks.

Results on an E260 with my handrolled r19889 were similar.
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Received on 2009-02-17


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