[osflash] flv file format question

[Jeff Ramin]

I want to read an FLV file for the purpose of transcoding the audio, and I'm using classes from the red5 project to iterate through the tags in the file. The section of the http://osflash.org/flv page on audio states: FLV Tag 0x08: AUDIO The first byte of an audio packet contains bitflags that describe the codec used, with the following layout: Name _expression_ Description soundType (byte & 0×01) » 0 0: mono, 1: stereo soundSize (byte & 0×02) » 1 0: 8-bit, 1: 16-bit soundRate (byte & 0x0C) » 2 0: 5.5 kHz, 1: 11 kHz, 2: 22 kHz, 3: 44 kHz soundFormat (byte & 0xf0) » 4 0: Uncompressed, 1: ADPCM, 2: MP3, 5: Nellymoser 8kHz mono, 6: Nellymoser, 11: Speex The rest of the audio packet is simply the relevant data for that format, as per a SWF SoundStreamBlock. However, when I dump the first few bytes of audio data from consecutive tags, I see this pattern: tag 1: b2 2a d7 5b tag 2: b2 2a d7 5a tag 3: b2 2a d7 5a tag 4: b2 2a d7 5a It seems there is more header data than a single byte. Is anybody familiar with FLV file formats and audio data (speex encoded, in this instance) that could clear this up for me? Thanks. -- Jeff Ramin Software Engineer Singlewire Software PO Box 46218 Madison, WI 53744-6218 Phone Direct - 608.298.1024 www.singlewire.com

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