[Gnash-commit] [bug #45887] `gnash --audio-dump` produces corrupted WAV file

[Nutchanon Wetchasit]

Follow-up Comment #2, bug #45887 (project gnash):

Looking at the `chime_gnash0.8.11dev-dc51f53.wav` under hex editor reveals
following RIFF structure:
(@nnn means offset from file's beginning, numbers are in decimal unless
prefixed with `0x`)

RIFF "WAVE"    (address@hidden, payload address@hidden, payload size 40)
 
  +- fmt       (address@hidden, address@hidden, payload size 16)
  |
  +- data      (address@hidden, address@hidden, payload size 0)
  |
  +-      *(address@hidden, address@hidden, payload size 0xFFFFFFFF)
      .
     (Audio data goes here...)


* Last chunk is invalid (invalid name, and chunk size exceeded main RIFF
chunk).

This shows two problems:

1. Gnash pre-filled `data` chunk size as `0` and filled
`RIFF` chunk's size accordingly, before writing out the audio data.
But when it is about to terminate, it didn't come back to update
the corresponding size fields of `data` and `RIFF` chunk.

2. Gnash put an invalid chunk in the output file. (Not sure if this is
a placeholder for audio data or something)

So when other programs tried to read the dump file, it either interpret
that this is an empty WAV file (0 byte in `data` chunk), or this is a
corrupted WAVE file (due to an invalid chunk of mystery, or garbage that
followed the RIFF chunk).

Side note: following is minimal RIFF structure of a _valid_ empty WAVE file

RIFF "WAVE"    (address@hidden, payload address@hidden, payload size 32)
 
  +- fmt       (address@hidden, address@hidden, payload size 16)
  |
  +- data      (address@hidden, address@hidden, payload size 0)


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