The structure of the AUDIO_PP.IFO integrates information on video linking, although not for all DVD specifications (consistently found with spec 0x0012). Further, this file may be useful in identifying "gapless" tracks, as will be made clearer in Some notes on Hybrids. The main change in this new version is the use of chapters instead of tracks as basic count units.
The structure of the AUDIO_PP.IFO is as follows:
AUDIO_PP.IFO Version 2.1 Table [Dec 2007, F. Nicol from original work by D. Chapman]
| Offset | Size (bytes) | Description | Values |
|---|---|---|---|
| 0 | 12 | Identifier string | "DVDAUDIOSAPP" |
| 12 | 2 | Total number of chapters on the disk | max 99 |
| 14 | 2 | DVD Specifications Version | 0x0012 [0x0200, 0x0000] |
| The following record appears once for each chapter, sorted by Group and then chapter number: | |||
| +0 | 2 | Padding | (0) |
| +2 | 1 | Group Number | 1...9 |
| +3 | 1 | Chapter Number within Group | 1...99 |
| +4 | 4 | Start Presentation Timestamp (PTS) for chapter. | This is the PTS in the AOB file. Video linking titles tested with 0x0249, irrespective of audio characteristics of video titles linked to. First title in video titlesets were used for tests. |
| +8 | 4 | Length of chapter | in PTS ticks. Video linking titles have a null PTS length. |
| +12 | 4 | Padding | (0) |
| +16 | 4 | Audio format (samplerate and depth) plus other currently unidentified information | First byte: 0xC8 : start of group Linking groups considered as groups 0x48 : chapter that does not start a group Single title groups are coded with 0xC8 Second byte: 0F : 16 bits 1F : 20 bits 2F : 24 bits Third byte: 8F : 44kHz 0F : 48kHz 1F : 96kHz 2F : 192kHz Fourth byte: 00 : 1 channel 01 : 2 channels Video linking groups: last three bytes are null, hence the coding is either C8 00 00 00 or 48 00 00 00 For each chapter |
| +20 | 20 | Padding | (0) |
| +40 | 4 | Absolute sector pointer to first sector of AOB for this chapter | |
| +44 | 4 | Absolute sector pointer to first sector of AOB for this chapter | |
| +48 | 4 | Absolute sector pointer to last sector of AOB for this chapter | |
According to the Sonic DVD White Paper (PDF file) and other sources, a DVD-Audio disk can contain two "content managers". The first is for simple audio-only DVD players (such as portables or in-car units) and according to that white paper, this can store details on up to 314 chapters. This is known as the Simple Audio Manager (SAMG) and contains enough information by itself for full playback of the audio content within the DVD.
The AUDIO_PP.IFO appears to always be exactly 128 kilobytes in size, and contains 8 identical copies of a 16K block of data. This 16K block of data contains a 16 byte header plus one 52 byte record for each chapter on the DVD. This allows a maximum of 314 records in the 16K block - the same number as mentioned in the above white paper - which implies that the AUDIO_PP.IFO file should be referred to as the Simple Audio Manager (SAMG).
Next: AUDIO_TS.IFO