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Subject: Re[2]: Video Converter Windows GUI
From: Uwe Freese (mail_at_uwe-freese.de)
Date: 2004-02-20


Hello John,

John Wunder wrote on Friday, February 20, 2004, 2:12:00 AM:

JW> On Thu, 19 Feb 2004 15:29:49 +0100, Uwe Freese <mail_at_uwe-freese.de> wrote:
>> Read the first Bytes. If the file starts with "RIFF", it's w WAV. You
>> can use StripHdr.exe (command line prog) from WinDac to strip off the
>> wav header, or do it yourself in with your GUI program (WAV header is
>> 48(?) bytes).

JW> Yeah, I'm replying to the same thing twice. Sue me. Anyway, both start
JW> with RIFF. Apparently avi2wav thinks it's extracting a wav so puts the
JW> wav header on it. So I tested it. Made 2 short clips of AVI, one with
JW> PCM audio and one with MP3 audio. Extracted both with avi2wav. Both had
JW> similar headers:
JW> WAV: RIFF~²' WAVEfmt   D¬ ±   dataX²'
JW> MP3: RIFF‚Ÿ WAVEfmt  U  "V X  ¶ qdataPŸ
JW> (In hex of course...this is just what I got in notepad cause I don't have
JW> a hex editor).

Ah, ok, MP3 with WAV header then.

The WAV header is 58 bytes long. Look at byte 59+60. If it starts with
11 "1" bits, it's the sync word of an mp3. Then you strip off the
first 58 bytes and feed this mp3 file into lame.

Bye, Uwe.

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