I'm writing code to create BWF files from scratch, and it would help me to have a couple of working files to use as reference. I have the WAV part down, been doing that for years. But adding the header is proving troublesome. I've read all the specs I can find, including EBU Tech 3285 and ancillary docs, but I must be missing a clue.

The content is unimportant, but the payload should be WAV and not MP3. All I really care about is the header, so the first 1K from any working files would do. I only need to be compliant with version 0 (1997) of the BWF spec.

Any help / links appreciated.

2 Answers 2


Don't think of it as the "header," since the bext chunk, like any other chunk, can be located at any point in the file. I've seen plenty of .wav files that have the bext chunk after the data chunk.

Getting to the bext chunk simply requires parsing the file chunk after chunk (like you're probably already doing for the fmt and data chunks) until you get to the bext id.

  • Fair enough. The way I'm building these, all other chunks precede the data chunk. This is the recommended practice, but as you say, is not required. But do you have access to any working BWF files you could share?
    – Jim Mack
    Jul 14, 2014 at 21:21

I'll answer this myself. The problem was a structure alignment issue that threw off the positions of some internal fields. Once that was resolved, the files work correctly.

I never needed metadata on WAV files before, but I can see how useful it'll be.

  • Since you were able to resolve the problem yourself, are you able to post a sample for others (like myself), that still need a working example to clear up their misunderstandings of the format?
    – UCS75
    Jul 16, 2016 at 0:13
  • What do you need an example of -- code that creates BEXT chunks, or working WAV files with a BEXT chunk, or...?
    – Jim Mack
    Jul 16, 2016 at 1:22
  • Since UCS75 can't comment, I've moved these comments to a chat thread that he can respond in. See here.
    – AJ Henderson
    Jul 17, 2016 at 0:25
  • @JimMack Since I have the same problem, I'm interested in code that create Wav file with Bext chunk
    – Grubshka
    Sep 26, 2022 at 5:45
  • @Grubshka - Ah, well it's been 6+ years, but I'll look to see if I have anything I can share.
    – Jim Mack
    Sep 26, 2022 at 17:33

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