8088 Corruption TMV

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Overview

For a description of the basic method, see 8088 Corruption DAT.

TMV File Format

TMV files have the following header:

'TMAV'     - 4 bytes, header signature
samplerate - 2 bytes, word value, playback sample rate
chunksize  - 2 bytes, word value, audio chunk size per frame
compmethod - 1 byte, specifies the compression method (currently only 0)
charcols   - 1 byte, number of text chars across (currently always 40)
charrows   - 1 byte, number of text chars down (currently always 25)
features   - bitfield, reserved for special handling:

The features bitfield was never used in practice, so its settings are undocumented.

To get the playback rate of the file, divide the samplerate by the audio chunk size. For example, a samplerate of 22050 divided by an audio chunksize of 735 gives 22050/735=30, so the playback framerate of the file is 30.

The remainder of the data after the header is made up of frames consisting of video+audio data, repeating until the end of the file is reached. Each frame consists of the video data and then immediately afterward is the audio data. The video data is of size (charcols*charrows*2) and the audio data is of size chunksize.

While charcols and charrows can be any non-zero value, all TMV files as of 20140724 have targeted CGA's 40x25 text mode.

Video Format

For details on the video format, consult 8088 Corruption DAT

Audio Format

The audio format used in 8088 Corruption is simply unsigned, 8-bit PCM played at the rate specified in the header.

Data Resources